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Review on Template Removal Techniques for Synthesis of Mesoporous Silica MaterialsClick to copy article linkArticle link copied!
- Hosein Ghaedi
- Ming Zhao*Ming Zhao*Email: [email protected]. Tel/Fax: +861062784701.School of Environment, Tsinghua University, Beijing 100084, ChinaResearch Institute for Environmental Innovation (Suzhou), Tsinghua, Suzhou 215263, ChinaMore by Ming Zhao
Energy & Fuels
Cite this: Energy Fuels 2022, 36, 5, 2424–2446
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Abstract
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The key step in the preparation of mesoporous silica materials is the removal of organic templates occluded inside the pores including nonionic, cationic, anionic surfactants and even ionic liquid (IL). The most common method to remove templates is conventional calcination under air at 550 °C. Although templates can be completely removed from the pores, calcination suffers many serious drawbacks including significant framework shrinkage, the collapse of the ordered structure, reduction of silanol concentrations on the pore wall (which are of high importance for postmodification), generation of large amounts of CO2 and organic amine compounds, the presence of carbon deposits or coke as a contaminant, elimination of organic functionalities (such as organoalkoxysilanes with amino groups), and the inability to recover or reuse expensive organic templates. That is why many attempts have been reported in the literature to develop novel methods for removing organic templates that are favorable from both economic and environmental standpoints for potentially large-scale applications. The current study reviews the recent development methods for template removal from various types of mesoporous silica materials. We have divided the template removal approaches into two categories: physical method and chemical method. The effects of those methods are discussed in detail on the textural and structural properties of mesoporous silica materials along with the template removal mechanism and their pores and coins.
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Copyright © 2022 The Authors. Published by American Chemical Society
1. Introduction
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Mesoporous silica materials, for instance, the SBA (Santa Barbara Amorphous) series, MCM (Mobil Composition of Matter) series, and KIT (Korean Advanced Institute of Science and Technology) series have gained extensive attention over the last decades due to their highly tunable textural and chemical characteristics and are therefore used in different fields: biomedical and pharmaceutical applications, (1−3) adsorption of pollutants from wastewater, (4,5) catalysis, (6−9) aromatization, (10) biogas purification and upgrading, (11) sensing, (12) desulfurization, (13−20) for CO2 capture, (21−27) Li-ion battery application, (28) upgrading microalgal biocrude, (29) hydrodenitrogenation, (30) and hydrogen production. (31,32)Figure 1(a) displays the number of publications for mesoporous silica materials, and Figure 1(b) shows their applications in different research areas from 2000 to 2021 (Web of Science). Poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) (P123 copolymer), poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (pluronic F-127) as nonionic surfactants, cetyltrimethylammonium bromide (CTABr), and cetyltriethylammonium bromide (CTEABr) as cationic surfactants, and anionic surfactants such as sodium dodecyl benzenesulfonate (SDBS) and sodium dodecyl sulfate (SDS) as well as ionic liquid (IL) are the common organic templates used for the synthesis of mesoporous silica materials. The elimination of these templates from the pores is a crucial step in the synthesis of mesoporous silica materials. Thermal calcination is a common method for template removal in the laboratory due to high efficiency, easy operation, and required simple equipment. The significant reduction of silanol concentrations happens during calcination (which renders the sample unsuitable for postmodification), and accordingly, the structural shrinkage is invariably detected following template removal. Also, the recovery or reuse of expensive templates is not possible due to burning out of the template which results in CO2 and hazardous gas emissions that are both economically and environmentally unfavorable. Furthermore, calcination burns off not only the template but also the functional groups when the mesoporous silica materials are modified via a co-condensation method with functional groups. Therefore, alternate detemplating procedures to calcination are needed, and more recent attention has focused on new technologies and methods offering superior template removal performance. To the best of our knowledge, this is the first study to review the latest developed methods for template removal including chemical methods such as solvent extraction, chemical oxidation, and ionic liquid (IL) treatment and physical methods such as calcination, supercritical CO2 (SC–CO2), microwave-assisted treatment, ultrasonic-assisted treatment, ozone treatment, and plasma technology. This review paves the way for researchers to get more information about these developed methods by weighing their benefits and drawbacks before developing and designing new template removal methods. Therefore, in this current study, the methods for the elimination of templates from mesoporous silica materials will be comprehensively reviewed, and finally a new, green, and efficient method will be proposed for template removal.
Figure 1
Figure 1. (a) Number of publications for mesoporous silica materials from 2000 to 2021. (b) Applications of mesoporous silica materials in different research fields published on the Web of Science with the keyword of “mesoporous silica material” (accessed December 25, 2021).
2. Template Removal Approaches
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Several template removal methods have been reported in the literature. We have categorized these methods into physical and chemical methods. The physical methods are calcination, supercritical fluid, ozone treatment, microwave-assisted treatment, ultrasonic-assisted treatment, and plasma technology. The chemical methods are solvent extraction, chemical oxidation, and ionic liquid (IL) treatment.
2.1. Physical Methods
2.1.1. Calcination
Calcination in air is a common method and is widely used for template removal from pores. (33) Basso et al. (34) investigated the influence of calcination conditions (temperature and time) on the carbon content, silanol groups, and physical properties of SBA-15 and KIT-6. As shown in Figure 2, at 300 °C, the remaining carbon contents were 0.32% and 19% for SBA-15 and 0.42% and 0.30% for KIT-6 after 300 and 600 min, respectively. By increasing temperature to 400 and 500 °C, less of a difference in the amount of carbon was observed for both SBA-15 and KIT-6. Also, it can be seen that increasing the calcination time to 10 h at higher temperatures did not have a substantial effect on the removal of organic material. However, increasing the calcination period from 300 to 600 min resulted in a significant change in the carbon percent of SBA-15 at 300 °C, while residual carbon remained almost the same by increasing the calcination time from 300 to 600 min at a temperature more than 300 °C. Table 1 presents the physical properties of SBA-15 at various temperatures and times.
Figure 2
Figure 2. Residual carbon content for calcined SBA-15 and KIT-6 at various temperatures and times. Reproduced from ref (34). [Basso, A. M.; Nicola, B. P.; Bernardo-Gusmão, K.; Pergher, S. B. C. Tunable Effect of calcination of the silanol groups of KIT-6 and SBA-15 Mesoporous Materials. Applied Sciences2020, 10 (3), 970]. Copyright 2020, MDPI.
Table 1. Physical Properties of SBA-15 and KIT-6 in Ref (34)
| SBET (m2 g–1) | Pore diameter (nm) | VT (cm3 g–1) | Wall thickness (nm) | ||||||
|---|---|---|---|---|---|---|---|---|---|
| Temperature (°C) | Time (min) | SBA-15 | KIT-6 | SBA-15 | KIT-6 | SBA-15 | KIT-6 | SBA-15 | KIT-6 |
| 300 | 300 | 572 | 695 | 7.5 | 7.2 | 0.79 | 0.82 | 4.5 | 15.8 |
| 300 | 600 | 632 | 826 | 7.5 | 6.1 | 0.86 | 0.98 | 4.4 | 17.9 |
| 400 | 300 | 641 | 905 | 7.8 | 7.5 | 0.84 | 1.07 | 4.7 | 16.0 |
| 400 | 600 | 1197 | 852 | 7.5 | 7.9 | 1.52 | 1.03 | 5.0 | 15.9 |
| 500 | 300 | 1099 | 1174 | 9.0 | 7.3 | 1.69 | 1.44 | 3.3 | 16.7 |
| 500 | 600 | 770 | 874 | 7.8 | 7.4 | 0.98 | 1.20 | 4.2 | 15.6 |
SBA-15 had the highest specific surface area (SBET) at 400 °C calcination for 10 h. The SBET decreased as the calcination temperature increased to 500 °C, even increasing calcination time at this temperature decreased slightly the SBET of SBA-15 due to the dehydroxylation of the material. The pore diameter and total pore volume (VT) followed the same trend, reaching their maximum values of 0.9 nm and 1.69 cm3 g–1, respectively, after 3000 min 500 °C. The highest wall thickness of 5.0 nm was at 400 °C for 600 min. Regarding KIT-6, the highest SBET was obtained at 500 °C for 5 h, further increasing calcination time decreased its SBET, as presented in Table 1. KIT-6 had the highest VT and wall thickness at 500 °C for 5 h, while it has the highest pore diameter at the lower temperature of 400 °C for 10 h.
Moreover, by increasing the temperature, the conversion of geminal silanols has happened to siloxane. It was found that more silanol groups are preserved at 300 °C for 300 min rather than calcination at 400 °C. Nevertheless, calcination at 300 °C resulted in a small pore volume. It was suggested that calcination at a higher temperature, for example, 600 for 300 min, is unnecessary, time consuming, and a waste of silanol groups. Although the template is completely removed through calcination, there are some concerns with using this conventional method. The expensive organic template cannot be recovered after calcination. A high temperature and a long time are required to eliminate the template. During calcination, terrible smells, toxic and noxious gases, are produced leading to environmental pollution. Preserving large numbers of surface silanol groups is essential to functionalize the mesoporous siliceous materials for the desired application. During the calcination, the number of surface silanol groups reduces because of the dehydroxylation at higher temperatures for a prolonged time, and a significant structural shrinkage is observed resulting in the destruction of microporosity. (35,36) Moreover, calcination is not recommended if the material is functionalized with a less stable organic part because it might be eliminated together with the template.
Calcination was assisted by catalytic template treatment. Catalytic template removal is a fascinating technique in which metal acts as a catalyst for the oxidative elimination of the surfactant molecules during the calcination process. The calcination temperature in this process is less than the usual calcination temperature. The metals are injected in one step, as shown in Figure 3, or separately through impregnation. This technique has the benefit of lowering the calcination temperature substantially. This method was employed by Krawiec et al. (37) to prepare Pt/MC-41 and Pt/SBA-15. The calcination temperature and time were 450 °C and 5 h. They reported that Pt incorporation into SBA-15 pores was less successful in comparison to MCM-41 due to the long time required for the synthesis of SBA-15 (28 h). Indeed, during the long time synthesis, the diffusion of the metal precursor happened from the toluene to the mixture of ethanol–water resulting from TEOS hydrolysis. The surface area of sample 1 wt % Pt/SBA-15 was 825 m2 g–1, while that of of free metal SBA-15 was 786 m2 g–1. Other metals such as Pd and V2O5 have been used in this method.
Figure 3
Figure 3. In situ preparation of Pt/mesoporous composite materials using catalytic template removal method. Reproduced from ref (37). [Krawiec, P.; Kockrick, E.; Simon, P.; Auffermann, G.; Kaskel, S. Platinum-Catalyzed Template Removal for the in Situ Synthesis of MCM-41 Supported Catalysts. Chem. Mater.2006, 18 (11), 2663–2669].Copyright 2006, American Chemical Society.
The remaining trace of carbon after calcination is another disadvantage which is required further treatment, for example, in an oxygen (O2) or hydrogen (H2) stream to remove carbon on the silica surface. (38,39) Goworek et al. (40) have made efforts to remove surfactants from MCM-41 using H2 flow treatment at the temperature range from 110 to 250 °C for 15 h. The elemental analysis showed that the amounts of hydrocarbon species and nitrogen compounds are significantly reduced by increasing temperature to 250 °C as presented in Table 2. According to data in Table 2, calcined MCM-41 in O2 and MCM-41 treated in H2 flow at 250 °C exhibited almost the same SBET and VT values. The pore size distribution curves of calcined and H2-treated samples were quite narrow centered at 2.4 nm indicating high template removal efficiency of H2 flow treatment. The 29Si MAS NMR confirmed the high surface silanols content of MCM-41 treated in H2 flow at 250 °C. The gas chromatography–mass spectrometry (GC-MS) analysis showed that the retention times of aliphatic hydrocarbons for both calcined and H2 flow-treated MCM-41 are not identical due to differences in the surface properties of these materials. The collected products after H2 flow treatment were condensed and analyzed by GC-MS. The peaks observed in GC-MS were assigned to hexadecane and hexadecane-N,N-dimethylamine indicating that the structures of surfactant molecules were damaged during the H2 flow treatment only within the headgroup, and finally, the degradation products were evaporated. It was stated that the Hoffman degradation resulted in partial removal of amine groups and production of unsaturated product at a temperature below 250 °C. It might be possible to remove the remaining amount of amine compound in the MCM-41 skeleton through the burnoff process at high temperatures under oxidizing conditions. Although this method template can be removed at low temperatures, the deposition of carbon is more compared to calcination. Also, the removal time is long. The template cannot be recovered and reused, and a complex device is required.
Table 2. Elemental Analysis and Textural Properties of Calcined MCM-41 and H2-Treated MCM-41 in Ref (40)
| Template removal method and condition | C (%) | H (%) | N (%) | SBET (m2 g–1) | VT (cm3 g–1) |
|---|---|---|---|---|---|
| H2 flow treatment at 110 for 15 h | 28.44 | 5.72 | 1.74 | 143 | 0.22 |
| H2 flow treatment at 150 for 15 h | 22.25 | 4.55 | 1.49 | 282 | 0.29 |
| H2 flow treatment at 200 for 15 h | 6.52 | 1.69 | 0.32 | 1006 | 0.95 |
| H2 flow treatment at 250 for 15 h | 3.89 | 1.25 | 0.12 | 1169 | 1.10 |
| Calcination in O2 at 550 for 8 h | 2.78 | 1.20 | 0.11 | 1126 | 1.07 |
2.1.2. Supercritical CO2 (SC–CO2) Extraction
Supercritical CO2 (SC–CO2) extraction is used not only for the synthesis of adsorbent but also for template removal. The main advantage of this method is the adjustable physical and chemical properties including density, viscosity, diffusivity, and mass transfer by changing the operating pressure and temperature. For example, supercritical fluid (SCF) possesses high diffusivity and negligible surface tension, and penetration of solvent into cavities of mesoporous materials is rapid due to the gas-like viscosity of SFC. Since CO2 as a special chemical with a low critical temperature of 304.21 K and modest critical pressure of 7.38 MPa is cost effective, available, low toxic, and nonflammable, (41,42) SC–CO2 has attracted more attention of material scientists. SC–CO2 in the presence or absence of cosolvents has been employed for template removal from mesoporous materials, (35,36,43−47) as shown in Figure 4. van Grieken et al. (45) extracted the nonionic surfactant from SBA-15 using SC–CO2 in the presence and absence of ethanol as a cosolvent at various pressures and temperatures ranging from 60 to 110 °C for 24 h. The results disclosed that optimum removal efficiency of 79% is obtained upon using SC–CO2 at 90 °C and 140 atm, while the efficiency is decreased to 76% by increasing temperature to 110 °C at 210 atm due to the lower density of the supercritical fluid. A higher extraction efficiency can be achieved using SC–CO2 in comparison to the ethanol extraction method with a removal efficiency of 74%. The removal of the P123 copolymer from SBA-15 was enhanced by the addition of ethanol as a cosolvent so that removal efficiency increased to 81% at 90 °C and 130 atm. The silanol group concentration on the surface of SBA-15 was evaluated using 29Si nuclear magnetic resonance (NMR) by obtaining a Q3/Q4 ratio. This ratio for calcined SBA-15 was 0.14, much lower than that of SBA-15 treated by SC–CO2 in the absence and presence of ethanol having the values of 0.48 and 0.42, respectively. This result confirms that SC–CO2 preserves more silanol groups on the surface of SBA-15 compared to calcination. Finding optimum experimental conditions is important which was not considered in the experimental conditions reported by van Grieken et al. (45) It seems that temperature, pressure, extraction time, and type of cosolvent (if used) and flow rates of liquid CO2 and cosolvent (if used) are the main factors affecting the template removal efficiency, as reported in the literature. (35,43,46,47) When SC–CO2 was employed without adding cosolvents, the cationic surfactant was not removed from MCM-41, (44) while van Grieken et al. (45) observed that SC–CO2 alone was successful in removing the P123 copolymer from SBA-15 with a high removal efficiency, despite the extended reaction time (24 h).
Figure 4
Figure 4. Schematic of SC–CO2 extraction technique.
The extracted organic template can be recovered and reused at the end of the process. It should be mentioned again that adding cosolvent can increase the template removal efficiency compared to SC–CO2 alone because adding cosolvents can improve the solvating strength of SC–CO2. The supercritical conditions can facilitate the transfer and desorption of templates through the inner and outer diffusion in the mesopores of materials due to SC–CO2’s low viscosity and high diffusivity properties. Huang and co-workers (35,36) used methanol-modified SC–CO2 to extract cationic surfactant templates such as CTABr from MCM-41, MCM-48, and SBA-3 and cetyltriethylammonium bromide (CTEABr) from SBA-1. Their results showed the highest template removal efficiency of 95% for as-synthesized SBA-3 followed by as-synthesized MCM-48, SBA-1, and MCM-41 with efficiencies of 93%, 88%, and 78%, respectively. However, the destruction of the mesoporous framework of as-synthesized MCM-48 happened after template removal. They employed a curing treatment under vacuum for 14 h to improve the mesoporous structural stability of materials. Although cured as-synthesized materials had better ordered mesoporous structures and were stable after template removal, the template removal efficiency was reduced. Overall, it is not easy to carry out SC–CO2 because of equipment limitations and difficulty in achieving the appropriate temperature, pressure, and CO2 flow speed. (48)
2.1.3. Microwave-Assisted Treatment
Figure 5(a) illustrates a schematic of microwave-assisted treatment. Tian et al. (49) used microwave digestion to remove the template from SBA-15 and MCM-41. The sample was mixed with nitric acid (HNO3) and hydrogen peroxide (H2O2) and placed in a reactor. These chemicals are utilized in the chemical oxidation process for template removal, which is discussed later. The oxidation of the template by HNO3 and H2O2 is facilitated by the instantaneous high temperature (∼200 °C) and pressure (∼1.3 MPa) created by microwave radiation. The template in SBA-15 was completely removed within 2–3 min and confirmed by Fourier transform infrared spectroscopy (FT-IR) results. Also, the relative intensity of Si–OH bending bands at around 960 cm–1 was higher for SBA-15 treated by this method than calcined SBA-15. It suggests that microwave digestion-assisted treatment can preserve more silanol groups on the pore wall surface in comparison to calcination. Lai et al. (50) used microwave-assisted treatment to eliminate the template from the pores of as-synthesized SBA-15. The sample was mixed with 20 mL of ethanol/hexane (V/V, 1/1) as extract solvents and put on a watch glass, then heated for 2 min by microwave irradiation. The process for template removal was repeated three times. The obtained results were the same as those reported by Tian et al. (49) suggesting the effectiveness of this method in template removal. Chen et al. (48) used a combination of H2O2 treatment and a microwave to eliminate the template from SBA-15 and MCM-41. The process was catalyzed by Fe (NO3)3·9H2O or Cr (NO3)3·9H2O based on the Fenton reaction. Their results showed that the d-spacing values and the unit cell parameters (a0) of SBA-15 and MCM-41 treated by this method were the same as the as-synthesized samples, while larger than those of the calcined SBA-15 and MCM-41 demonstrating that the shrinkage of the textural framework was significantly reduced using this method compared to calcination. As Fe (NO3)3·9H2O was used as a Fenton reagent, SBA-15 has better pore properties. However, MCM-41 exhibited better textural parameters as Cr (NO3)3·9H2O was used as Fenton reagent. Figure 5(b) shows the proposed mechanism for template removal. There was a stronger interaction between Fe(III) and anionic silicate species (I–) due to higher coordination ability Fe(III) compared to Cr(III); therefore, removal of the cationic surfactant (S+) from the MCM-41 system was not efficient. Moreover, trimethylamine species were produced by the decomposition of cationic surfactant CTABr (S+I–) resulting in the activity loss of Fe(III) and Cr(III). That is why the cationic template was removed from MCM-41 in the presence of the Cr–H2O2 reagent. The H+ groups were significant in the removal of nonionic surfactant (S0) from SBA-15 in, as well as inhabiting, the interaction between Fe(III) and cationic silicate species (I+); As a result, employing Fe–H2O2 reagents, nonionic surfactant (S0) was efficiently removed from SBA-15.
Figure 5
Figure 5. (a) Schematic of microwave-assisted treatment. (b) Possible mechanism for template removal from MCM-41 and SBA-15 using H2O2 treatment assisted by microwave. Reproduced from ref (48). [Chen, L.; Jiang, S.; Wang, R.; Zhang, Z.; Qiu, S. A novel, efficient and facile method for the template removal from mesoporous materials. Chemical Research in Chinese Universities2014, 30 (6), 894–899]. Copyright 2014, Springer.
Although the microwave-assisted treatment has some advantages such as efficient and quick elimination of the organic template, less shrinkage of the framework, and less energy consumption, it suffers several drawbacks including difficulty in controlling the conditions of the microwave-assisted treatment in the case of some mesoporous materials, emission of CO2 and toxic gases at the end of process due to the decomposition of surfactant, using solvents for assisting the process, and inability to recover or reuse the surfactant. (51,52)
2.1.4. Ultrasonic-Assisted Treatment
The ultrasonic technique is the well-defined process based on sonochemistry principles in which molecules undergo a chemical reaction owing to the application of powerful ultrasound irradiation (20 kHz–10 MHz). (53,54) Essentially, there is no chemical reaction during the direct interaction of ultrasonic radiation with the molecules; however, when ultrasonic radiation interacts with liquid, an alternating pattern of pressures is developed. Indeed, the acoustic cavitation (process of bubble formation, growth, and collapse under altering pressure) happens due to the interaction of ultrasonic radiation with the liquids and release of the accumulated ultrasonic energy in the bubbles producing energy with a very high local temperature of 5000 K and pressure of 1000 bar in few microseconds, (55−59) as shown in Figure 6(a).
Figure 6
Figure 6. (a) Generation of acoustic bubbles by ultrasonic irradiation. (b) Schematic of ultrasonic-assisted treatment.
Figure 6(b) depicts a schematic of ultrasonic-assisted treatment. This method has been utilized for template elimination from the pores of mesoporous materials. The ultrasonic treatment was used for detemplating MCM-41 by Jabariyan and Zanjanchi (60,61) for the first time and later by Pirez et al. (62) for template removal from SBA-15 and propylsulfonic acid (PrSO3H)-functionalized SBA-15.
Jabariyan and Zanjanchi (60) have optimized the template removal conditions assisted by ethanol such as sonication time and temperature. The results disclosed that the SBET and VT values increased as the sonication time and temperature increased within the studied ranges. Longer sonication time resulted in a slight reduction of SBET thanks to the slight destruction to the mesoporous structure of MCM-41. At the temperature of 60 °C and sonication time of 30 min, MCM-41 exhibited a higher SBET of 1325 m2 g–1 and VT of 0.471 cm3 g–1 than calcined MCM-41 possessing the SBET and VT of 1276 m2 g–1 and 0.454 cm3 g–1, respectively. This confirms the efficiency of this method for the template removal from as-synthesized MCM-41.
Ultrasonication was shown to be an effective technique for removing P123 from PrSO3H-SBA-15 by Pirez et al. (62) However, in the case of virgin SBA-15, there was a great difference between the P123 percentage removed by ultrasonic irradiation and reflux extraction. As shown in Table 3, ultrasonication was ineffective in removing the template from the synthesized SBA-15 in methanol, while template removal of 90% was obtained reflux extraction. This may indicate that thermal activation is required to overcome hydrogen bonding interactions between the P123 template and isolated silanol groups, or ultrasonic irradiation could be conducted at moderate temperature for example 60 °C. As reported by Jabariyan and Zanjanchi, (60) the rate of template extraction from MCM-41 is relatively fast under ultrasonic irradiation in ethanol at a temperature of 60 °C rather than 25 °C providing a higher SBET and VT.
| Template removal method | Solvent | Time (h or min) | Solvent:Sample (cm3 g–1) | Template removed (%) |
|---|---|---|---|---|
| SBA-15 | ||||
| Calcination | – | – | – | 98 |
| Toluene | 24 h | 500 | 35 | |
| Reflux | Tetrahydrofuran (THF) | 24 h | 500 | 80 |
| Reflux | Acetone | 24 h | 500 | 76 |
| Reflux | Ethanol | 24 h | 500 | 76 |
| Reflux | Methanol | 24 h | 500 | 80 |
| Reflux | Methanol | 24 h | 1000 | 90 |
| Ultrasonication | Methanol | 5 min | 500 | 39 |
| Ultrasonication | Methanol | 30 min | 500 | 45 |
| Ultrasonication | Methanol | 1 h | 500 | 43 |
| PrSO3-SBA-15 | ||||
| Reflux | Toluene | 24 h | 500 | 62 |
| Reflux | THF | 24 h | 500 | 69 |
| Reflux | Acetone | 24 h | 500 | 78 |
| Reflux | Ethanol | 24 h | 500 | 72 |
| Reflux | Methanol | 24 h | 500 | 74 |
| Reflux | Methanol | 24 h | 1000 | 89 |
| Ultrasonication | Methanol | 5 min | 500 | 89 |
| Ultrasonication | Methanol | 5 min | 100 | 90 |
| Ultrasonication | Methanol | 1 h | 500 | 90 |
a
Reflux method and ultrasonic extraction were conducted at 60 °C and room temperature, respectively.
On the other hand, the template was efficiently removed from PrSO3H-SBA-15 under ultrasonic irradiation in comparison to the solvent extraction method (as will be discussed later). As shown in Table 3, template extraction using methanol was more efficient than other studied solvents. After the second reflux with methanol, about 89% template was removed, as confirmed from Thermogravimetric analysis (TGA) between 150 and 350 °C. Using reflux for extraction of template required a long time about 24 h consuming 3600 W. Therefore, methanol was used for ultrasonic irradiation. The obtained result is interesting so that the template was efficiently removed from the pores within 5 min at room temperature using ultrasonic irradiation consuming about 3 W. Their results disclosed that ultrasonic irradiation leads to a less lattice shrinkage of PrSO3H-SBA-15 which possessed a higher a0 of 11.2 nm and the pore wall thickness of 5.1 nm in comparison to that of PrSO3H-SBA-15 treated by solvent extraction having a0 of 11 nm and the pore wall thickness of 4.9 nm. All of these findings suggest that ultrasonic-assisted treatment is an efficient method and comparable with SC–CO2 and microwave methods.
One of the notable advantages of ultrasonic-assisted treatment is that the recovery of the template is possible at the end of the template removal process. Jabariyan and Zanjanchi (60) studied the structure of the template removed from MCM-41 after sonication. Figure 7(a) displays the FT-IR spectrum of the CTABr–ethanol mixture for the sake of comparison. Figure 7(b) and (c) depicts FT-IR spectra of effluents obtained after 15 min sonication at 40 °C and 60 min sonication at 60 °C, respectively. As seen in Figure 7(a)–(c), the spectra of all samples were similar, indicating that the structure of CTABr was preserved after sonication in ethanol. In another study, (61) these authors investigated the concentration of CTABr after ultrasonic irradiation using a double-beam UV spectrophotometer. As shown in Figure 7(d), the concentration of CTABr was increased by increasing the sonication time; however, further increasing sonication time resulted in a decrease of CTABr concentration indicating that degradation of CTABr happened at longer sonication times. During ultrasonic irradiation, the surfactant molecules migrate apart from each other, causing micelle disruption in the alcohol solution. This matter was already well established in the field of drug delivery. (63−65) It was stated that ultrasonic vibrations cannot damage the hydrophobic tail of the organic template flocked in the micelle core. By acceleration of micelle disruption, they converted to monomers. The hydroxyl radicals (HO•) attack these monomers through the hydrophilic head of micelles in bulk solution; consequently, their nature is changed as a monomer in the CTABr structure. Therefore, provided that only micelle disruption happens during the ultrasonic irradiation, the structure of the surfactant removed by ultrasonic treatment is unaffected in alcohol and may be utilized for further synthesis.
Figure 7
Figure 7. FT-IR spectra of (a) fresh CTABr-ethanol solution, (b) effluents after 15 min sonication at 40 °C, and (c) effluents after 60 min sonication at 40 °C. Panels (a) and (b) were reproduced from ref (60). [Jabariyan, S.; Zanjanchi, M. A. A simple and fast sonication procedure to remove surfactant templates from mesoporous MCM-41. Ultrason. Sonochem.2012, 19 (5), 1087–1093]. Copyright 2012 Elsevier. (d) UV–vis spectra for the methanol–effluent solutions after sonication at 40 °C and different times. Reproduced from ref (61). [Zanjanchi, M. A.; Jabariyan, S. Application of ultrasound and methanol for rapid removal of surfactant from MCM-41. J. Serb. Chem. Soc.2014, 79 (1), 25–38]. Copyright 2014, Serbian Chemical Society.
2.1.5. Ozone Treatment
Low-pressure mercury lamps are applied in ozone generation. These lamps will emit ultraviolet (UV) light with two peaks in the UV light band, one at 254 nm with the energy of 472 kJ/mol and another at 185 nm with the energy of 647 kJ mol–1. Since these energy values are higher than bonding energies in organic compounds such as C–H (413 kJ mol–1), C–C (348 kJ/mol), and C–O (352 kJ mol–1); UV lights are capable of removing the template at room temperature by breaking these bonds in the organic template. (66,67) The UV lamp is protected by a quartz tube, and both together are placed at the central axis of a reactor chamber. By passing air or O2 through the chamber, it is subjected to photolysis of the O2 molecule resulting in the formation of ozone.
Keene et al. (68) used this method for the first time to remove surfactant from MCM-41. In their study, ozone was generated from a simple UV lamp from atmospheric O2 at room temperature (although the temperature within the pores of MCM-41was higher). The FT-IR and TGA results indicated that the template was efficiently removed from MCM-41. However, the reaction time was longer by about 24 h, and CO2 is generated at the end of the process. Later, since the amount of generated ozone cannot be adjusted, and the reaction was long because of the low concentration of ozone (less than 1% by weight), instead of using a UV lamp, they employed an ozone generator. (69) To reduce the reaction time, ozone was generated via an electric discharge method. Their results showed that most of the CTABr surfactants were removed after 14 h from MCM-41 with a high SBET of 1019 m2 g–1 and pore diameter of 2.7 nm as well as a 5.52% carbon percentage. The structure of MCM-41 collapsed when the ozonation period was increased up to 26 h. Also, it was reported that template removal efficiency is lowered if the ozonation time is less than 14 h. (52,69)
Joshi et al. (70) used ozone treatment for P123 removal from as-synthesized SBA-15 at 80 °C for 120 min. Figure 8(a) shows the ozone reaction setup. It was stated that the carbon backbone of the P123 copolymer is highly oxygenated; thus, it reacts easily with ozone, causing the polymeric chains to become oligomers and further oxidation of the polymeric chains to occur through alcoholic and carbonyl groups. The results revealed that SBA-15 treated by ozone has a surface area of 711 m2 g–1 which was comparable with that of calcined SBA-15 (749 m2 g–1). Also, Barett–Joyner–Halenda (BJH) pore size and VT values for SBA-15 treated by ozone were higher than calcined SBA-15. The remained carbon values for both SBA-15 treated by ozone and calcination were 3% and 0.5%, respectively. As shown in the IR spectroscopy spectra, the intensity of C–H vibration bonds decreased significantly after ozone treatment indicating the elimination of the P123 copolymer from SBA-15 (Figure 8(b)). Moreover, the transmission electron microscopy (TEM) image shows that SBA-15 treated by ozone is a highly ordered structure (Figure 8(c)). The template removal efficiency of ozone treatment through the TGA analysis was not investigated by Joshi et al. (70) in order to compare with calcination or other methods discussed here.
Figure 8
Figure 8. (a) Schematic of ozone treatment set up, (b) normalized ATR spectra of samples, and (c) TEM image of SBA-15 treated by H2O2. Reproduced from ref (70). [Joshi, H.; Jalalpoor, D.; Ochoa-Hernández, C.; Schmidt, W.; Schüth, F. Ozone Treatment: A Versatile Tool for the Postsynthesis Modification of Porous Silica-Based Materials. Chem. Mater.2018, 30 (24), 8905–8914]. Copyright 2018, American Chemical Society.
The OH• radicals can be generated by UV light in conjunction with H2O2 to get rid of organic contaminants in wastewater. (71,72) In this process, organic pollutants are oxidized to CO2 and water by OH• radicals produced by the interaction between ultraviolet light and H2O2. Later, Xiao et al. (73) used the UV/H2O2 process to eliminate the P123 copolymer from as-synthesized SBA-15 by dispersion in an aqueous solution of H2O2 and adjusting pH values with hydrochloric acid (HCl). Then, the mixture was irradiated using a medium-pressure Hg light for 3 to 4 h while stirring. The pH of the aqueous solution of H2O2 had a great influence on the physicochemical properties of the sample. The rate of formation of OH• radicals and their reactions with organic molecules are affected by pH. TGA results showed that the template can be more completely removed at lower pH than higher pH. Moreover, the sample treated at higher pH had a lower SBET and smaller VT than the sample treated under acidic conditions. The main disadvantages of this method can be that the organic templates cannot be recovered, and toxic gases are produced leading to pollution of the environment. (35)
2.1.6. Plasma Technology
Nonthermal plasma (NTP) or cold plasma is an efficient method to eliminate organic molecules through a highly oxidizing environment at ambient temperature. The glow discharge (GD) and dielectric barrier discharge (DBD, or silent discharge) are two examples of NTP which have been used to degrade templates from zeolite and mesoporous silica materials. (74−80)
For the production and treatment of catalysts, GD is employed as NTP with a high electron temperature (104–105 K) and a low gas temperature (as low as room temperature) because it is energy efficien and works at very mild conditions, and its operational time is shortened. (81−84) A schematic of GD plasma is depicted in Figure 9(a). It comprises two electrodes in a chamber that is filled with O2 as the plasma-forming gas after evacuation to below 1 Torr. The temperature of GD plasma could be lower than 50 °C. To prevent the entering of fine particles into the vacuum pump, a few drops of water are added to the SBA-15 before starting the template removal. Figure 9(b) shows the moving striations observed in the positive column when the as-synthesized SBA-15 is loaded. Then, in this positive column, the template is decomposed due to a strong interaction between the fluxes of plasma-active species (e.g., O2+, O, electron) and the SBA-15 surface. The color of the glow is determined by the type of gas in the tube. A blue-violet color is observed in the glow discharge plasma shown in Figure 9(b) because the chamber was fed with O2 as the plasma-forming gas. It should be noted that some gases are produced during template removal which could influence the GD performance; therefore, the amount of O2-forming GD gas should be sufficient for maintaining the stable discharge plasmas. The elemental analysis result shows that the carbon contents of the SBA-15 template were removed by GD plasma (SBA-15-GD) over 120 min and calcination (SBA-15-C) at 550 °C for 5 h under the heating rate of 1.75 °C min–1 were 1.28% and 0.3%. These results indicate that the template removal efficiency of GD plasma is much higher than that of methanol extraction, as discussed before. Figure 9(c) illustrates the N2 adsorption–desorption isotherms of samples. From the obtained results, SBA-15-GD possessed a higher SBET of 1025 m2 g–1 than SBA-15-C with the SBET of 827 m2 g–1. Moreover, the higher unit-cell size and the pore wall thickness of SBA-15-GD indicate that the shrinkage by GD is less than that by calcination because of applying low temperature for the elimination of the template. Also, it was found that more silanol densities are preserved on the surfaces by employing GD plasma rather than conventional calcination which is beneficial for postsynthesizing of silica support. Overall, it can be concluded that although about 94.8% of the template was removed by using GD plasma, the exposure time still is long at about 120 min.
Figure 9
Figure 9. (a) Schematic of GD plasma, (b) loaded sample on a quartz boat placed in the positive column of O2-forming GD, and (c) N2 isotherms and BJH pore size distributions (inset) of SBA-15-C and SBA-15-GD. Reproduced from ref (78). [Yuan, M.-H.; Wang, L.; Yang, R. T. Glow Discharge Plasma-Assisted Template Removal of SBA-15 at Ambient Temperature for High Surface Area, High Silanol Density, and Enhanced CO2 Adsorption Capacity. Langmuir2014, 30 (27), 8124–8130]. Copyright 2014, American Chemical Society.
DBD is generally considered a low-temperature plasma oxidation technology due to its operation under ambient conditions (at room temperature and atmosphere). DBD has been extensively utilized in many applications such as catalyst preparation and modification, (85−87) surface modification of nanofibers, (88) pollutant control (wastewater purification and engine exhaust control), (89−93) ozone generation, (94,95) hydrogen production from the reforming of biogas, (96) oxygen reduction reaction of electrocatalysts, (97) removal of volatile organic compounds (VOCs), (98,99) and remediation of pyrene and ciprofloxacin contaminated soil. (100−102) Recently, DBD was employed to eliminate the template from mesoporous materials, (75−77) particularly SBA-15. (74,80) The DBD plasma technology can be categorized into single dielectric-barrier discharge (SDBD) and double dielectric-barrier discharge (DDBD).
SDBD plasma is a promising technique that has exhibited a better performance to remove the template accompanied by less structure shrinkage and increased silanol density. A schematic of SDBD is shown in Figure 10(a) which has been employed for the template removal from SBA-15, (80) MCM-41, (76) and Zeolite Socony Mobil-5 (ZSM-5). (77) Wang et al. (80) used the SDBD reactor to eliminate the P123 copolymer from SBA-15. The FT-IR spectra of as-synthesis SBA-15, SBA-15-C, and SBA-15-DBD are illustrated in Figure 10(b). Normally, the aliphatic stretching and bending vibrations are observed at wavenumbers between 2950 and 2840 cm–1 and 1500–1350 cm–1, respectively. (103) As can be seen in Figure 10(b), these peaks appeared in the spectrum of as-synthesized SBA-15 signifying the presence of P123 copolymer. However, it was completely removed after SDBD treatment and calcination. Another interesting feature of Figure 10(b) is that there was a dramatic decrease in the intensity of the Si–OH bending band after calcination thanks to the dehydroxylation at higher temperatures for a prolonged time. The intensity of the Si–OH bending band of SBA-15-DBD is almost the same as the as-synthesized SBA-15, indicating that the DBD treatment can preserve more silanol groups on the pore wall as already proved from template removal of SBA-15 via GD plasma. The remaining silanol groups were further confirmed by 29Si solid sate NMR spectra. Figure 10(c) shows the N2 sorption–desorption isotherms of SBA-15-C and SBA-15-DBD together with their physicochemical properties. The wall thicknesses of both samples are the same, while SBA-15-DBD possessed higher SBET, VT, and larger pore size values because of the less lattice shrinkage in comparison to SBA-15-C treated at high temperature.
Figure 10
Figure 10. (a) Schematic of the SDBD apparatus. Reproduced from ref (85). [Guo, Q.; With, P.; Liu, Y.; Gläser, R.; Liu, C.-j. Carbon template removal by dielectric-barrier discharge plasma for the preparation of zirconia. Catal. Today2013, 211, 156–161]. Copyright 2013, Elsevier. (b) FT-IR spectra of samples and (c) N2 sorption–desorption isotherms of the sample treated by calcination and NTP along with their physicochemical properties. Panels (b) and (c) were reproduced from ref (80). [Wang, L.; Yao, J.; Wang, Z.; Jiao, H.; Qi, J.; Yong, X.; Liu, D. Fast and low-temperature elimination of organic templates from SBA-15 using dielectric barrier discharge plasma. Plasma Science and Technology2018, 20 (10), 101001]. Copyright 2018, IOPscience.
Aumond et al. (74) used a quartz reactor for template removal of SBA-15. A mixture of 80/20 helium/O2 was used as the feed gas. It has been well established that helium is a better energy carrier, and using this gas can considerably reduce plasma treatment time. The results showed that the pronounced lattice shrinkage by NTP is less because of the development of ultramicroporosity and larger hexagonal structured mesoporosity in comparison with the calcination method. Since NTP using a quartz reactor is working at room temperature, more silanol densities were preserved on the surfaces. Another advantage of using this method is that a less exposure time of about 15 min is needed for the template removal. The authors did not explain further the reaction mechanism of the template degradation using NTP. The interaction between the SBA-15 powder surface and active species such as positive ion O2+ and negative ions O– and O2– as well as O3 resulted in the decomposition of the template. Indeed, the composition of the exhaust gases (mainly CO and CO2 associated with H2O) indicated direct oxidation of the template molecules.
Alternatively, plasma in an aqueous solution, also known as solution plasma, is a high potential plasma that was used to remove templates. Pootawang et al. (104,105) used the solution plasma process to eliminate the P123 template from mesoporous silica materials, as depicted in Figure 11(A). Various active species, such as high active radicals (e.g., H•, O•, OH•, HO2•), high energy electrons, and UV radiation can be physically created during discharge in an aqueous solution. The effects of discharge solution pH and discharge time were investigated on the template removal. There is no substantial variation in the intensity of the first peak in the small-angle X-ray diffraction (SAXRD) patterns shown in Figure 11(B), but the strength of the second peak was clearly identified in the different amounts.
Figure 11
Figure 11. Plasma solution process. (A) Scheme image of the solution plasma experimental setup. (B) SAXRD patterns of mesoporous silica discharged in different pHs at fixed 15 min of discharge time: (a) as-synthesized silica, (b) pH 3, (c) pH 7, and (d) pH 11. (C) SAXRD patterns of mesoporous silica discharged at different discharge times in pH 3: (a) as-synthesized silica, (b) 1 min, (c) 5 min, and (d) 15 min. TEM images of mesoporous silica discharged in different pH values at fixed 15 min of discharge time: (D) pH 3, (E) pH 7, and (F) pH 11. Reproduced from ref (104). [Pootawang, P.; Saito, N.; Takai, O. Solution plasma for template removal in mesoporous silica: pH and discharge time varying characteristics. Thin Solid Films2011, 519 (20), 7030–7035]. Copyright 2015, Elsevier.
The intensity of the second peak was lower at a pH of 7, while the sample exhibited a high intensity of the second peak when the pH of the discharge solution was adjusted to 7 or 11. This result indicates a high capability of the template removal process in acid and base solutions rather than neutral pH. Figure 11(C) shows the effect of discharge time on structural properties. As seen in Figure 11(C), the second peak intensity was much higher at the discharge time of 15 min. This result demonstrated that the rate of organic decomposition increased as discharge duration increased and was influenced by the number of active species, which had a strong tendency to create more as the system’s temperature and energy increased. The parallel channels with a uniaxial cylindrical mesopore arrangement are visible in the TEM images presented in Figure 11(D)–(F). The structural morphology of the mesopore structure was unaffected by changes in pH and discharge time.
Despite its advantages, for instance, simple experimental setup, stable and reproducible plasma conditions, and operating at atmospheric pressure and relatively low temperature, (78,85,99) SDBD plasma still has some significant limitations, including the need for a greater electrical voltage to create a strong electric field and the deposition of solid byproducts on the reactor’s inner surface and electrodes, which affect its performance. DDBD plasma technology is a modified version of SDBD plasma that has a better discharge efficiency and longer electrode lifespan. (49) DDBD plasma has been mostly utilized to remove air pollutants, particularly VOCs. (98,99) So far, there is no report on using DDBD plasma for template removal; therefore, DDBD plasma can be utilized for the template elimination from mesoporous siliceous materials. Furthermore, the plasma solution technique has some drawbacks, including the need for a high voltage to generate a continuous plasma discharge and low energy efficiency.
The oxidation mechanism of template elimination for the production of molecular sieves such as MCM-41 and ZSM-5 using DBD plasma was studied by Liu et al. (75) As illustrated in Figure 12(a), the infrared image showed that the template was removed at the highest temperature of 125 °C for 75 min. As can be seen in Figure 12(c), the color of MCM-41 was changed during template removal by increasing time. The fresh white sample became yellow after 15 min, showing that the template and plasma species were reacting. By increasing the time to 60 min, the sample became brown. The sample becomes white again after around 75 min. This marks the end of the template removal process. The mechanism study of template removal under DBD plasma is difficult due to complex reactions between active species and template molecules. The electrons play a vital role in the dissociation of template molecules. The energetic electron bombardment can decompose template molecules producing H2 and methane gases during the process. CO2 is also formed through oxidation with active oxygen species (O and O3). During the template elimination from MCM-41, mass spectra of gases revealed the presence of N2O gas as one of the products. As shown in Figure 12(b), FT-IR results of MCM-41 confirmed that MCM-41 templates are removed using DBD plasma so that C–H stretching and bending vibrations disappeared completely after 75 min. Also, the oxidation of nitrogen species in the organic template was observed by bands appearing at a wavenumber of about 1384 cm–1 from 15 to 60 min.
Figure 12
Figure 12. (a) Infrared image of the sample during the template removal process using DBD. Reproduced from ref (77). [Liu, Y.; Pan, Y.-x.; Kuai, P.; Liu, C.-j. Template Removal from ZSM-5 Zeolite Using Dielectric-Barrier Discharge Plasma. Catal. Lett.2010, 135 (3), 241–245]. Copyright 2010, Springer. (b) FT-IR spectra of MCM-41 during the detemplating process using DBD plasma. (c) Color changes of the samples during the template removal using DBD. Panels (b) and (c) were reproduced from ref (75). [Liu, Y.; Wang, Z.; Liu, C.-j. Mechanism of template removal for the synthesis of molecular sieves using dielectric barrier discharge. Catal. Today2015, 256, 137–141]. Copyright 2015, Elsevier.
2.2. Chemical Methods
2.2.1. Solvent Extraction
Template extraction using solvents is a common method for template removal, (106−121) as shown in Figure 13. de Ávila et al. (107) used different solvents such as water, acetonitrile, dichloromethane, ethanol, acetone, and methanol to eliminate the template from SBA-15 pores. The results indicated that water had the lowest effect on the template extraction, and the amount of remained P123 template was about 45.9% which was almost the same as the not-extracted one. Among studied solvents, however, methanol has the highest efficiency to remove the template. After template extraction using methanol, SBA-15 possessed about 10.3% of P123, and the result was in agreement with the amount of C of about 4.8% obtained from elemental analysis. The SBET, VT, and pore diameter of SBA-15 extracted with methanol were 703 m2 g–1, 0.995 cm3 g–1, and 15.2 nm, respectively. Moreover, the effect of extraction time on template removal was investigated using the aforementioned solvents. The results indicated that less extraction time of about 6 h is enough to remove the template when methanol was used as the extraction solvent in comparison to other solvents with a longer extraction time of up to 48 h to complete the template extraction. Chun et al. (122) used several solvents for extraction of pluronic F-127 such as methanol, ethanol, acetone, n-hexane, and iso-propanol. It was found that when methanol was employed as the solvent extraction, the highest efficiency of 78.8% was obtained. The above-mentioned results indicate that methanol has a better performance to remove the templates among polar and nonpolar solvents. A mixture of HCl and ethanol was reported for extractions of P123 and CTABr from SBA-15 (123,124) and MCM-48, (125) respectively. Sulfuric acid (H2SO4) was used to extract F-127 and P123 from a mesostructured polymer–silica composite (126) and SBA-15, (124) respectively, and also a mixture of H2SO4 and sodium hydroxide (NaOH) was utilized for removal of a P123 copolymer from SBA-15. (124) To generate mesopores and micropores in SBA-15, Schüth et al. (127) used H2SO4 under reflux at 95 °C for 24 h to partially remove a P123 copolymer from as-synthesized SBA-15 followed by calcination to decompose the occluded poly(ethylene oxide) chains in the silica matrix and to create micropores. The authors demonstrated that the ether cleavage by sulfuric acid at quite a low temperature resulted in the formation of mesopores due to the elimination of the PO groups. Following a thermal treatment in air at 200 °C to produce micropores, the EO chains, which are less accessible to the acid, may be destroyed. Thus, SBA-15 material with superior properties than the traditional calcined SBA-15 material has resulted from such acid and low-temperature treatments (larger mesopore size, larger micropore volume). However, this process is time consuming and requires two stages to remove the template from as-synthesized SBA-15.
Figure 13
Figure 13. Schematic of solvent extraction technique.
Grudzien et al. (128) used a combination of solvent extraction (ethanol/HCl) and temperature-controlled calcination to remove F-127 from SBA-16. Their results showed that SBA-16 has a higher SBET, VT and pore diameter and less framework shrinkage when the template was removed using this combination method in comparison to calcination alone, although the carbon percentage of the latter one was less than the former one. A mixture of ethanol/HCl with a molar ratio of (1:1) was used to remove mixed anionic surfactants such as sodium dodecyl benzenesulfonate (SDBS) and sodium dodecyl sulfate (SDS) from mesoporous silica materials. (129) The pore size distribution showed two narrow and broad peaks located at 10.3 and 30.7 nm, respectively. Samples had a low SBET of 217 m2 g–1. The formation of large pores indicates that a mixed anionic surfactant could be removed from the pores during solvent extraction. The mixture of ethanol–HCl was also used to remove CTAB from SBA-1 synthesized by cocondensation of TEOS and phenyltriethoxysilane (PhTES). (114) When the TEOS/PhTES molar ratio was (7:1), SBA-1 exhibited SBET and VT of 980 m2 g–1 and 0.47 cm3 g–1, respectively. The SBET and VT values were reduced when this ratio was reduced. The TGA data, on the other hand, revealed that surfactant remained in the pores of SBA-1, particularly at lower TEOS/PhTES molar ratios. The same result was reported for mesoporous silica material grafted by aminopropyltriethoxysilane (APS). (130)
Another study showed the removal of SDS using the mixture of HCl and acetonitrile so that 89% of SDS was removed as conformed by elemental analysis. (131) Yokoi et al. (132) used the mixture of HCl and acetonitrile to remove the SDBS, SDS, and lauric acid sodium salt (LAS) anionic surfactants from pores. The elemental analysis results showed that 88%, 89%, and 91% of SDBS, SDS, and LAS surfactants were removed, respectively, following the solvent extraction at room temperature for 2 h. The final powder was unstable when SDBS was used as a surfactant upon the solvent extraction. Also, the extracted samples had a lower SBET than calcined counterparts due to the retention of aminopropyl moieties on the surface.
Rahman et al. (133) used 5 wt % aqueous dimethyl sulfoxide (DMSO) solution to remove the template from mesoporous silica synthesized using sodium silicate as a silica source from bagasse ash. The sample extracted by a 5 wt % aqueous DMSO solution showed a typical type IV isotherm with an H2 type of hysteresis indicating the mesoporosity of the obtained material. The extracted sample exhibited a higher SBET of 656 m2 g–1 than the calcined sample, which had an SBET of 486 m2 g–1 at pH 3. The process of template removal has a substantial impact on the pore volume. The pore volume of silica obtained during solvent extraction was approximately 0.8 cm3 g–1, while that obtained through calcination was around 0.2 cm3 g–1. For solvent extraction, the pore diameter increases dramatically as the pH rises, but it remains relatively constant for calcination. The pore diameter was around 4 nm for calcination, and it varies from 3 nm at pH 2 to 18 nm at pH 7 for solvent extraction.
Solvent extraction was employed to remove dual templates of F-127 and P123 from SBA-16 functionalized by carboxyethylsilanetriol sodium salt (CES) using 8 wt % H2SO4 solutions. (118) After solvent extraction, the sample had SBET and VT of 575 m2 g–1 and 0.71 cm3 g–1, respectively, and exhibited a sharp diffraction peak with a higher intensity in comparison to as-synthesized counterpart. Also, after acid extraction, the TEM image demonstrated the presence of distinctive pores of ordered mesoporous silica. Although these findings show that acid extortion is a viable strategy for removing the template from surface-functionalized mesoporous silica materials, template removal takes a longer duration of 24 h. (118)
Zhou et al. (134) used solvent extraction with acetonitrile in an autoclave at 90 °C to remove IL as a template from mesoporous silica, namely, 1-butyl-3-methyl-imidazolium-tetrafluoroborate, [C4mim]BF4. The FT-IR revealed that imidazolium ν(C–H) stretching region (3200–3000 cm–1) of the IL vanishes completely. The sample had SBET and VT of 801 m2 g–1 and 1.27 cm3 g–1, respectively. These results indicate the effectiveness of solvent extraction in IL removal from the pores. Although IL was removed completely, the extraction was repeated several times, and a high volume of solvent was used.
The solvent extraction method is more advantageous than the calcination method because more silanol groups can be preserved, and shrinkage of pores is not significant after template extraction. However, the solvent extraction method is far from practical application. From the economic and environmental perspectives, this method is not beneficial due to a large volume consumption of organic solvent and the required high energy for solvent recovery. Above all, the template may not be completely removed even when the extraction treatment is repeated several times.
2.2.2. Chemical Oxidation
H2O2 treatment is based on an advanced oxidation process where the surfactant decomposition happens by in situ HO• generation. The Fenton-based oxidation process is frequently applied for HO• generation taking place in the presence of H2O2 and some metal ions (such as Ni, Fe, Bi, Cr, and Zn). H2O2 treatment catalyzed by Fe was applied to remove the template of MCM-41 (135) and zeolite beta. (136,137) Later, Zhang et al. (138) used H2O2 for the generation of HO• catalyzed by Fe cations to eliminate the template of SBA-15 at 70 °C for 7 h. The following reactions show the template removal using H2O2 catalyzed by Fe3+ and Fe2+ cations. In reaction 5, HO• radicals oxidize the organic template entrapped within the structure; finally, mesoporous material is obtained, and H2O and CO2 are generated (reaction 5).
(1)
(2)
(3)
(4)
(5)
The results showed that the carbon content of materials was significantly reduced to 0.4% and even more reduction to 0.2% when the template of SBA-15 was extracted by ethanol and then H2O2 treatment catalyzed by Fe cations. However, the carbon content of calcined SBA-15 was 0.1%. The SBA-15 treated by H2O2 had a higher silanol value of 44% than that of the calcined counterpart with a 30% silanol value determined by 29Si NMR. Also, template removal using H2O2 increased SBET and VT of SBA-15 compared to conventional calcination. (138) Zhang and Melián-Cabrera (139) reported similar results. In their study, the effects of secondary treatments such as direct drying, hydrothermal treatment, and solvent exchange were investigated on the structural and textural properties of SBA-15.
On the other hand, this process has two main disadvantages of a long time for template removal and the limitation of mesoporous silica for desired application because of the existence of metal ions in the silica framework. Also, CO2 is generated after completing the process, as mentioned above. It was reported that H2O2 has enough power to eliminate the template for pores of MCM-41 in the presence or absence of metal ions (Fe3+) with a significantly shorter reaction time (1 h). (140) Later, Barczak (108) used the H2O2 treatment method without a Fenton reaction to remove the P123 copolymer from pores of SBA-15 at 108 °C for 3 h, and the results were compared with extraction and calcination methods. The carbon content of SBA-15 treated by H2O2 was 0.6% which is comparable with the results stated by Zhang et al. (138) with the Fenton reaction. Figure 14(a) displays the scanning electron microscope (SEM) images of SBA-15 treated by different methods. As can be seen, the SBA-15 materials had the same morphology of parallel hexagonal cylinders with a “sausage-like” shape. As displayed in Figure 14(b), the N2 adsorption–desorption isotherms of SBA-15 materials showed a type IV isotherm according to the IUPAC classification associated with their mesoporous structure with hysteresis loops. Also, the results showed that SBA-15 treated by H2O2 exhibited a higher SBET of 953 than those treated by extraction (688 m2 g–1) and calcination (726 m2 g–1). Moreover, from SAXRD patterns shown in Figure 14(c), it was found that the framework shrinkage is significantly reduced through H2O2 treatment and extraction; however, the first sharp reflection and the other two weak reflections were less intense and shifted toward higher values indicating the occurrence of framework shrinkage during calcination. As seen in Figure 14(c), two minor reflections were resolved well, and their intensities were higher for SBA-15 treated by H2O2 than that treated by calcination indicating a better organization obtained by surfactant removal via H2O2 treatment. Therefore, these results confirm that H2O2 treatment is an effective method to eliminate the most anchored poly(oxypropylene) blocks remaining with only very small amounts of the template in the pores. In another interesting effort done by Yang et al., (141) the template was removed using H2O2 in the crystallization process. The coupling of the crystallization process and hydrothermal oxidation with H2O2 facilitates further condensation and slight framework shrinkage. The hydrothermal stability of materials was investigated using boiling water for 72 h under reflux. Their results showed that the sample treated by H2O2 could maintain about 86% of its specific surface, while the sample without H2O2 treatment had a less ordered structure and preserved only 24% of its specific surface area.
Figure 14
Figure 14. Characterization of SBA-15 materials treated by different methods: SBA–P, as-synthesized SBA-15; SBA–C, SBA-15 treated by calcination; SBA–E, SBA-15 treated by extraction; and SBA–H, SBA-15 treated by H2O2. (a)–(c) SEM images. (d) N2 adsorption–desorption isotherms. (e) SAXRD patterns. Reproduced from ref (108). [Barczak, M. Template removal from mesoporous silicas using different methods as a tool for adjusting their properties. New J. Chem.2018, 42 (6), 4182–4191]. Copyright 2018, Royal Society of Chemistry.
Lu et al. (142) used a chemical oxidation method at a low temperature of 60 or 90 °C with a duration of 4 or 24 h for template removal from SBA-15 using a potassium permanganate (KMnO4)–H2SO4 solution as an oxidizer. This method was efficient for the purification of carbon nanotubes from amorphous carbons. (143) According to the findings, the temperature and reaction time have great effects on the formation of manganese oxide on the exterior surface of SBA-15. The reaction between the template and KMnO4 is mainly controlled by temperature so that there is manganese oxide on the exterior surface at low temperature, while there is no deposition of manganese oxide on SBA-15 at higher temperatures (60 or 90 °C). Regarding the effect of reaction time, if the temperature is low, for example, room temperature, the reaction time should be longer. The SBA-15 treated by chemical oxidation at 90 °C for 24 h had a higher SBET, VT, and pore diameter of 940 m2 g–1, 1.42 cm3 g–1, and 9.8 nm, respectively, indicating better textual properties in comparison to calcined SBA-15. Compared with calcined SBA-15 with a0 of 10.5 nm, the SBA-15 treated by KMnO4 had a0 = 11.8 nm, indicating less of a shrinkage structure during KMnO4 treatment compared to calcination. Ding et al. (144) used HNO3 oxidation to remove the P123 copolymer from SBA-15 at 100 °C for 12 h. Through this method, block copolymer P123 is easily oxidized into small molecules, such as formaldehyde, formic acid, acetaldehyde, acetic acid, and CO2. The SBET, VT, and BJH pore size values for SBA-15 treated by HNO3 oxidation were 714.6 m2 g–1, 1.30 cm3 g–1, and 6.79 nm, respectively, while those for calcined SBA-15 were 723.8 m2 g–1, 0.86 cm3 g–1, and 5.36 nm, respectively. Moreover, the positions of the diffraction peaks of the SBA-15 treated by HNO3 oxidation were basically the same as those of as-synthesized SBA-15, while the positions of the diffraction peaks of calcined SBA-15 are obviously shifted to a high angle. This indicates less shrinkage of framework during HNO3 oxidation treatment compared to calcination. The result showed that the removing ratio of the template of SBA-15 is 82.5%. The advantage of HNO3 oxidation treatment over KMnO4–H2SO4 solution treatment is that the reduction product can be easily removed by washing, therefore, avoiding the use of KMnO4 or other metal oxidants in the process of oxidizing the template.
2.2.3. Ionic Liquid (IL) Treatment
The IL treatment is the last method used for template removal, as shown in Figure 15. The idea of using IL for template removal comes from biomass delignification. To increase the accessibility of enzymes to cellulose and in turn improve the hydrolysis process, removal of lignin as an organic polymer is necessary. Wang and Yang (145) used IL 1-butyl-3-methylimidazolium chloride ([C4mim]Cl) to eliminate the P123 template from as-synthesized SBA-15 at 120 °C for 12 h and compared the results with conventional calcination at 500 °C for 6 h. The results revealed that the SBA-15 treated by calcination and IL showed BJH pore size distributions of 6.4 and 7.5 nm, respectively. This indicates that using IL treatment resulted in less shrinkage of the mesoporous framework structure compared to calcination. The TGA results showed that the P123 template was removed at least 92%, demonstrating that treatment was effective. Moreover, more silanol groups were retained in the SBA-15 framework treated by IL in comparison to that treated by calcination so that silanol numbers of SBA-15 treated by IL and calcination were 5.1 and 3.0 OH nm–2, respectively. Moreover, SBET and VT of SBA-15 treated by IL were 835.5 m2 g–1 and 1.09 cm3 g–1, respectively, which were comparable with the calcined counterpart. The template removal mechanism through IL treatment is similar to that of cellulose dissolution in ILs. The hydrogen bonds between the template P123 and the silanol groups on the surface are likely disrupted and broken by using IL so that the treated SBA-15 has a higher surface hydroxyl group density. The template removal at the low temperature of 120 °C and recovery of IL and P123 templates are the main advantages of this method. The disadvantages of this method might be the challenging synthesis route, potential toxicity, high cost, and required purification.
Figure 15
Figure 15. Schematic of IL treatment technique.
3. Challenges and Perspectives
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Mesoporous silica materials have attracted a lot of attention in recent decades due to their highly tunable textural and chemical characteristics, and they have been used as adsorbents and catalyst supports in a range of applications. Template removal is the most important and last step in the preparation of mesoporous silica materials, and it has a great effect on the final properties of desired materials. Calcination under an air atmosphere at a high temperature of 550 °C for more than 5 h is the common method to obtain porosity. Despite its great effectiveness at removing templates, calcination has several drawbacks, including structural shrinkage, reduced silanol concentrations, production of huge volumes of CO2, and the inability to recover or reuse expensive organic templates. Many efforts have been reported in the literature to develop alternative methods to calcination. Herein, we have reviewed the developed approaches to remove various types of templates, as shown in Table 4. The advantages and disadvantages of template removal methods are presented in Table 4. Most of these methods are effective to remove the template from the pores by preserving high silanol density with less shrinkage and possibly a higher micropore volume. However, due to the inability to recover or reuse the template, CO2 emissions at the end of the process, and particularly the requirement of a complicated and expensive apparatus for template removal, it is unlikely that these developed technologies will be used on a large scale in the next years.
Table 4. Comparing Different Template Removal Methods
| Template removal method | Advantages | Disadvantages | ref |
|---|---|---|---|
| Physical method | |||
| Calcination | Highly template removal efficiency | Conducting at high temperature, significant framework shrinkage, reduction of silanol concentrations, generation of large amounts of CO2 and toxic gases, and inability to recover or reuse templates | (33−39) |
| SC–CO2 extraction | High template removal efficiency in the presence of solvents, preserving high silanol concentration, and possible recovery or reuse of template | Equipment limitation, using cosolvents to enhance template removal efficiency, and difficulties to achieve the appropriate temperature, pressure, and CO2 flow speed | (35,36,43−47) |
| Microwave-assisted treatment | High template removal efficiency, quick template removal, less energy consumption, and less framework shrinkage | Emission of CO2 and toxic gases, inability to recover or reuse the surfactant, use of solvents for assisting the template removal process, and equipment limitation | (49,50) |
| Ultrasonic-assisted treatment | High template removal efficiency, preserving high silanol concentration, less framework shrinkage, and possible recovery or reuse of template | Ineffective to remove the template completely at low temperature in some cases, and required organic solvents | (60−62) |
| Ozone treatment | High template removal efficiency and less carbon content | Emission of CO2 and toxic gases, longer reaction time in some cases, equipment limitation, and inability to recover or reuse the surfactant | (52,68−70) |
| Plasma technology | High template removal efficiency, operation under ambient conditions, preserving high silanol concentration, less framework shrinkage, and less exposure time | Emission of CO2 and toxic gases, inability to recover or reuse the surfactant, equipment limitation, inability to recover or reuse the surfactant, higher carbon content compared to calcination, required greater electrical voltage, and deposition of solid byproducts on the reactor’s inner surface and electrodes | (74−80) |
| Chemical methods | |||
| Solvent extraction | Preserving high silanol concentration, less framework shrinkage, and possible recovery or reuse of template | Less template removal efficiency and large volume consumption of organic solvent | (106−118) |
| Chemical oxidation | High template removal efficiency, high silanol concentration, and less framework shrinkage | Longer reaction time, the existence of metal ions in the framework (if Fenton reagents used), generation of CO2, and inability to recover or reuse the surfactant | (108, 135, 138−141) |
| IL treatment | High template removal efficiency, high concentration of surface silanols, less framework shrinkage, required a low temperature of 120 °C, and possible recovery of template | Challenging synthesis route, potential toxicity, high cost, and required purification | (145) |
To remove the template from nonfunctionalized mesoporous silica materials, calcination is a preferred option in the laboratory regardless of its disadvantages. For many desired applications, mesoporous silica materials are functionalized with organic groups, for example, an amino group, via grafting and co-condensation methods. In such cases, calcination is no longer an option due to the elimination of the functional group along with the template, and the template is usually removed using a solvent extraction technique to preserve functional groups. Despite the fact that the process and apparatus are simple and the template might be recovered, removing the template through the solvent extraction approach is not good enough and requires a large amount of solvent and a lengthy time, so it is not the preferred method from environmental and economical perspectives.
For high template removal efficiency and a high silanol density, a combination of two or three methods is frequently utilized instead of high-temperature calcination alone. For instance, the template is removed first via solvent extraction and then calcination at a low temperature. The combination approach, on the other hand, comes at an additional expense and takes longer.
Because of several advantages such as ease of use, high template removal efficiency, less framework shrinkage, maintaining a high silanol density on the surface, template recovery, and no equipment limitations, we believe that IL treatment could be considered a potential approach for template removal. But still, some questions need to be answered, such as whether IL can effectively remove various types of surfactants (nonionic, cationic, and anionic) from various mesoporous silica materials. Furthermore, the template removal conditions need to be optimized by studying various factors such as, for example, solid to liquid ratio of the sample/IL, temperature, reaction time, ane stirring rate.
Despite the fact that there is relatively little evidence in the literature, IL treatment may attract researchers’ interests in the near future. But, bearing in mind that ILs suffer several disadvantages including potential toxicity, the creation of large amounts of waste, availability and cost issues, purification and complex reaction steps, poor biodegradability, and high viscosity which may limit their use in large-scale industrial applications, it is essential to find promising solvents as alternatives to IL for template removal.
Deep eutectic solvents (DESs), also known as IL analogues, have emerged as possible alternatives to ILs. DESs are composed of two or more components, namely, hydrogen bond acceptor (HBA) and hydrogen bond donor (HBD), which can associate with each other through hydrogen bonding interactions. (103,146−158) DESs share the same properties as ILs but enjoy several advantages over ILs: (1) They can be used without purification. (2) Their preparation is easy. (3) They have low cost, good renewability, and low toxicity.
Many types of ILs and DESs have been utilized for biomass delignifcation which are effective to break hydrogen bonds within the cellulose. Among DESs, acid-based DES, base DES, polyalocohol-based DES, and phenolic-based DES have been used for biomass delignifcation. (159,160) Among these DESs, choline chloride-oxalic acid (1:1) showed an excellent performance to remove lignin. As reported by Zhang et al., (161) biomass pretreatment with acid-based DESs such as choline chloride (ChCl)-oxalic acid (Ox) (1:1) removed 98.5% of lignin by stirring at 90 °C for 24 h. Moreover, their results showed that polyalocohol-based DES, ChCl-ethylene glycol (EG) (1:2), can remove about 87.6% of the lignin from corncob biomass. Also, the performance of IL or DES treatment in template removal is the same as that in biomass delignifcation. The DES can break the hydrogen bonding between hydroxyl groups on the surface of virgin mesoporous silica materials and the template at a low temperature leading to retaining a high silanol density on the surface as well. Due to the tunable properties of DESs, it is possible to prepare task-specific DES or ternary DES to enhance template removal efficiency. Therefore, as an alternative to IL treatment and future works, DES treatment is proposed for template removal from mesoporous silica materials.
4. Conclusions
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Template removal is a crucial step in the synthesis of mesoporous silica materials. In the present study, we have discussed several methods to remove a variety of templates such as nonionic, cationic, and anionic surfactants as well as IL from different types of mesoporous silica materials. Among physical and chemical methods discussed here, calcination and solvent extortion methods are widely used for template removal. However, it is frequently noted that thermal calcination at high temperatures for many hours has some drawbacks, including framework shrinkage, lower silanol content, and the burning off of costly templates, which results in CO2 and hazardous gas emissions. The latter method also necessitates a large volume of solvent and a long time, and it is inefficient in effectively removing the template. Therefore, to mitigate the problems related to conventional methods, many physical and chemical methods have been utilized for template removal. The literature survey indicates that the majority of the developed methods can efficiently remove templates while preserving the high silanol content at mild conditions. However, when these new methods for template removal were implemented, certain major issues remained that may limit their practical applicability: (1) Costly templates cannot be recovered or reused. (2) CO2 and hazardous gas are produced at the end of the process. (3) The equipment has limitations. Among the developed methods, IL treatment showed an excellent performance in template removal without suffering the above-mentioned problems.
Author Information
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- Ming Zhao - School of Environment, Tsinghua University, Beijing 100084, China; Research Institute for Environmental Innovation (Suzhou), Tsinghua, Suzhou 215263, China;
https://orcid.org/0000-0002-5801-5593;
Biographies
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Hosein Ghaedi
Hosein Ghaedi was born in the Iranian city of Chahvarz in the province of Fars in the year 1984. He is a Ph.D. candidate in Environmental Science and Engineering at Tsinghua University’s School of Environment (Beijing, China), where he is supervised by Prof. Ming Zhao. He earned his M.Sc. in Chemical Engineering from Malaysia’s Universiti Teknologi Petronas (UTP). His study focuses on utilizing deep eutectic solvents toward green synthesis and functionalization of mesoporous silica materials for CO2 capture.
Ming Zhao
Dr. Ming Zhao is an Associate Professor of the School of Environment, Tsinghua University. He is the founder of the LBC Group (Lab for Bio-resource & Carbon-mitigation Technologies). He obtained his Ph.D. in Chemical Engineering from the University of Sydney in 2010. He joined Tsinghua University after the completion of his work at the Imperial College London in 2014. Dr. Zhao and his group possess expertise in thermo-chemical conversion of biomass (wastes) into clean energy and value-added chemicals and CO2 capture and utilization. The LBC Group has published 90+ peer-reviewed articles in recent years. Dr. Zhao also maintains linkage to the industry, and one of his gasification technologies has been commercialized for gaseous fuel production from solid wastes.
Acknowledgments
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Hosein Ghaedi and Ming Zhao are grateful for the support of the National Key Research and Development Program of China (2018YFC1901300).
| SBA | Santa Barbara Amorphous |
| MCM | Mobil Composition of Matter |
| KIT | Korean Advanced Institute of Science and Technology |
| ZSM-5 | Zeolite Socony Mobil-5 |
| P123 | Poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) |
| F-127 | Poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) |
| CTABr | Cetyltrimethylammonium bromide |
| CTEABr | Cetyltriethylammonium bromide |
| SDBS | Sodium dodecyl benzenesulfonate |
| SDS | Sodium dodecyl sulfate |
| LAS | Lauric acid sodium |
| TEOS | Tetraethyl orthosilicate |
| PhTES | Phenyltriethoxysilane |
| APS | Aminopropyltriethoxysilane |
| CES | Carboxyethylsilanetriol sodium salt |
| HO• | Hydroxyl radicals |
| UV | Ultraviolet |
| SCF | Supercritical fluid |
| SC–CO2 | Suppercritical CO2 |
| BJH | Barett–Joyner–Halenda |
| HCl | Hydrochloric acid |
| H2SO4 | Sulfuric acid |
| HNO3 | Nitric acid |
| PrSO3H | Propylsulfonic acid |
| H2O2 | Hydrogen peroxide |
| DMSO | Dimethyl sulfoxide |
| KMnO4 | Potassium permanganate |
| IL | Ionic liquid |
| [C4mim]Cl | 1-Butyl-3-methylimidazolium chloride |
| [C4mim]BF4 | 1-Butyl-3-methyl-imidazolium-tetrafluoroborate |
| THF | Tetrahydrofuran |
| VOC | Volatile organic compound |
| VT | Total pore volume |
| SBET | BET specific surface area |
| a0 | Unit cell parameter |
| NMR | Nuclear magnetic resonance |
| SAXRD | Small-angle X-ray diffraction |
| FT-IR | Fourier transform infrared spectroscopy |
| SEM | Scanning electron microscope |
| TEM | Transmission electron microscopy |
| TGA | Thermogravimetric analysis |
| GC-MS | Gas chromatography–mass spectrometry |
| NTP | Nonthermal plasma |
| DBD | Dielectric barrier discharge |
| SDBD | Single dielectric-barrier discharge |
| DDBD | Double dielectric-barrier discharge |
| GD | Glow discharge |
References
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This article references 161 other publications.
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- 7Wang, F.; Jiang, L.; Wang, J.; Zhang, Z. Catalytic Conversion of Fructose and 5-Hydroxymethylfurfural into 2,5-Diformylfuran over SBA-15 Supported Ruthenium Catalysts. Energy Fuels 2016, 30 (7), 5885– 5892, DOI: 10.1021/acs.energyfuels.6b01148Google Scholar7Catalytic Conversion of Fructose and 5-Hydroxymethylfurfural into 2,5-Diformylfuran over SBA-15 Supported Ruthenium CatalystsWang, Fan; Jiang, Liang; Wang, Junmei; Zhang, ZehuiEnergy & Fuels (2016), 30 (7), 5885-5892CODEN: ENFUEM; ISSN:0887-0624. (American Chemical Society)The mesoporous SBA-15 was prepd. and used to graft biimidazole groups, which were used to anchor Ru3+ to give rise to a new ruthenium catalyst (SBA-15-Biimidazole-Ru). The structure of the SBA-15-Biimidazole-Ru catalyst was well characterized and used for the aerobic oxidn. of 5-hydroxymethylfurfural (HMF) into 2,5-diformylfuran (DFF). Several important parameters were studied and found that the reaction solvent and oxygen pressure showed a crucial role in the activity of the as-prepd. SBA-15-Biimidazole-Ru catalyst. HMF conversion of 96.9% and DFF yield of 88.7% were achieved after 11 h at 110° under 15 bar oxygen pressure. One important characteristic of the SBA-15-Biimidazole-Ru catalyst is that it was very stable without loss of its catalytic activity during the recycling expts., which was due to the strong interaction between the Ru3+ and the Biimidazole groups on the surface of SBA-15. Finally, the direct conversion of fructose into DFF was also performed using Amberlyst 15 and SBA-15-Biimidazole-Ru as two binary catalysts. The dehydration of fructose over Amberlyst 15 catalyst and the subsequent oxidn. of HMF over SBA-15-Biimidazole-Ru catalyst afforded DFF with an overall yield of 72.4%.
- 8Wang, L.; Diao, Z.; Tian, Y.; Xiong, Z.; Liu, G. Catalytic Cracking of Endothermic Hydrocarbon Fuels over Ordered Meso-HZSM-5 Zeolites with Al-MCM-41 Shells. Energy Fuels 2016, 30 (9), 6977– 6983, DOI: 10.1021/acs.energyfuels.6b01160Google Scholar8Catalytic Cracking of Endothermic Hydrocarbon Fuels over Ordered Meso-HZSM-5 Zeolites with Al-MCM-41 ShellsWang, Li; Diao, Zhenheng; Tian, Yajie; Xiong, Zhongqiang; Liu, GuozhuEnergy & Fuels (2016), 30 (9), 6977-6983CODEN: ENFUEM; ISSN:0887-0624. (American Chemical Society)Ordered meso-HZSM-5 zeolites with Al-MCM-41 shells were synthesized by a surfacant-directed encapsulating process. It was found that ordered meso-HZSM-5, which was used as a core, could be synthesized using a designed amphiphilic organosilane as a surfactant and that the mesopore size of the MCM-41 shell can be adjusted from 2.5-3 to 4.5-10 nm by changing the structures of alkyltrimethylammonium bromide and the trimethylbenzene amt. Catalytic cracking performances of supercrit. n-dodecane (500 °C and 4 MPa) show that ordered meso-HZSM-5 zeolites with Al-MCM-41 shells of 4.5-10 nm exhibit a 28% higher catalytic activity and a 25% lower deactivation rate compared to the conventional HZSM-5 zeolites. With an increasing mesopore size of the MCM-41 shell, the acid sites accessibility increased gradually and, thus, led to enhanced catalytic activity and decreased secondary reaction ability. In addn., ordered hierarchical zeolites show a well connection of ordered mesopores between the core and shell, which could also lead to the enhanced acid site accessibility.
- 9Perumal, T.; Mangesh, V. L.; Perumal, S. K.; Arumugam, R.; Subramanian, N.; Subramanian, S.; Kannan, S. Isomerization of Alkanes over Ionic Liquids Supported on SBA-15. Energy Fuels 2020, 34 (11), 14620– 14632, DOI: 10.1021/acs.energyfuels.0c02331Google Scholar9Isomerization of Alkanes over Ionic Liquids Supported on SBA-15Perumal, Tamizhdurai; Mangesh, V. L.; Perumal, Santhana Krishnan; Arumugam, Ramesh; Subramanian, Narayanan; Subramanian, Sakthinathan; Kannan, ShanthiEnergy & Fuels (2020), 34 (11), 14620-14632CODEN: ENFUEM; ISSN:0887-0624. (American Chemical Society)Exploring the catalytic efficiency of ionic liq. supported on mesoporous material as heterogeneous organ catalysts for example, 1-Ethyl-3-methylimidazolium triflate and 1-ethyl-3-methylimidazolium chloride + AlCl3 (different ratio) immobilized on SBA-15 that contains 0.5% platinum, with regard to isomerization of n-pentane and n-hexane, along with com. light naphtha feed conversion reactions. The prepd. materials were characterized by several instrumental methods, which include temp.-programmed desorption to evaluate acid strength. The reactions were performed in a fixed-bed stainless steel reactor having high pressure by the down-flow method. This valuable novel isomerization reaction was strongly influenced by many key parameters, for instance, temp., pressure, wt. hourly space velocity, and flow rate of H2, which are discussed in detail. The Pt/EMIM-AlCl4(1:1)20/SBA-15 ionic liq. catalyst showed superior catalytic performance out of the four-catalyst system examd. toward the above reactions, which is undoubtedly due to its significant turnover frequencies values of 8.6 s-1 and 8.5 s-1 and specific reaction rates values of 8.01 x 10-4 mol g-1 s-1 and 8.00 x 10-4 mol g-1 s-1 for n-pentane and n-hexane correspondingly. The order of catalytic activity is Pt/EMIM-AlCl4(1:1)20/SBA-15 > Pt-EMIM-Tf/SBA-15 > Pt/EMIM-Al2Cl7(1:2)20/SBA-15 > Pt-EMIM-Al2Cl7(1:2)30/SBA-15.
- 10Lv, Y.; Wang, X.; Gao, D.; Ma, X.; Li, S.; Wang, Y.; Song, G.; Duan, A.; Chen, G. Hierarchically Porous ZSM-5/SBA-15 Zeolite: Tuning Pore Structure and Acidity for Enhanced Hydro-Upgrading of FCC Gasoline. Ind. Eng. Chem. Res. 2018, 57 (42), 14031– 14043, DOI: 10.1021/acs.iecr.8b02952Google Scholar10Hierarchically Porous ZSM-5/SBA-15 Zeolite: Tuning Pore Structure and Acidity for Enhanced Hydro-Upgrading of FCC GasolineLv, Yipin; Wang, Xilong; Gao, Daowei; Ma, Xinlong; Li, Shuna; Wang, Yong; Song, Guolong; Duan, Aijun; Chen, GuozhuIndustrial & Engineering Chemistry Research (2018), 57 (42), 14031-14043CODEN: IECRED; ISSN:0888-5885. (American Chemical Society)The pore structure and acid sites of the catalysts are demonstrated as the main factors for the hydro-upgrading of fluid catalytic cracking (FCC) gasoline. Herein, we report a general synthesis of ZSM-5/SBA-15 composite zeolites with tunable pore structure and acid sites. The effects of the pore structure and acid sites of these catalysts on their hydro-upgrading performance were systematically investigated. The platelet CoMo/AZS-PL (CoMo/ZS-PL-γ-Al2O3) catalyst with the short mesochannels, appropriate Co-Mo-S phase, and suitable acidity exhibited the excellent preservation ability of research octane no. (RON) and hydrodesulfurization (HDS) performance, which was better than those of CoMo/AZS-SR (CoMo/ZS-SR-γ-Al2O3), CoMo/AZS-HP (CoMo/ZS-HP-γ-Al2O3), and CoMo/AZS-LR (CoMo/ZS-LR-γ-Al2O3) catalysts. The relationship between the physicochem. properties (acidity, morphol., pore structure, and sulfided active metal) of the catalysts and their isomerization (ISO), aromatization (ARO), as well as HDS abilities were explored in detail.
- 11Mulu, E.; M’Arimi, M. M.; Ramkat, R. C. A review of recent developments in application of low cost natural materials in purification and upgrade of biogas. Renewable and Sustainable Energy Reviews 2021, 145, 111081, DOI: 10.1016/j.rser.2021.111081Google Scholar11A review of recent developments in application of low cost natural materials in purification and upgrade of biogasMulu, Elshaday; M'Arimi, Milton M.; Ramkat, Rose C.Renewable & Sustainable Energy Reviews (2021), 145 (), 111081CODEN: RSERFH; ISSN:1364-0321. (Elsevier Ltd.)A review. The main contaminants in biogas namely carbon dioxide, hydrogen sulfide, and siloxanes limit its application esp. in engines by reducing energy d. and causing corrosion on machine parts. Furthermore, the carbon dioxide in biogas contributes highly to global warming. Therefore, biogas should be upgraded to increase its safe application. Most com. methods of biogas cleaning are expensive for small and medium scale digesters. There is no review documentation detailing the usage of natural materials in the purifn. of biogas. The aim of the current study was to systematically and critically review recent developments in the applications of natural materials in the purifn. and upgrade of biogas. Documented literature indicate that the low-cost natural adsorbents have potential in purifn. of biogas. The adsorption capacity of biogas contaminants for most materials can be enhanced by phys. and chem. activation. The two mechanisms through which these material eliminate carbon dioxide in biogas namely surface adsorption and wet carbonation process have been discussed. In addn., the study looked at the factors that affect the removal of carbon dioxide from biogas using natural materials. The adsorption capacity of biogas contaminants for different natural and modified materials were reviewed. Furthermore, a summary of the merits and demerits of different natural adsorbents for biogas purifn. is presented. Future studies should investigate the methane loss during upgrading process using low-cost adsorbents. Comparative investigations of the process cost-effectiveness of using natural materials to upgrade biogas should be carried out to det. their suitability against the com. processes.
- 12Melde, B. J.; Johnson, B. J.; Charles, P. T. Mesoporous Silicate Materials in Sensing. Sensors 2008, 8 (8), 5202, DOI: 10.3390/s8085202Google Scholar12Mesoporous silicate materials in sensingMelde, Brian J.; Johnson, Brandy J.; Charles, Paul T.Sensors (2008), 8 (8), 5202-5228CODEN: SENSC9; ISSN:1424-8220. (Molecular Diversity Preservation International)A review. Mesoporous silicas, esp. those exhibiting ordered pore systems and uniform pore diams., have shown great potential for sensing applications in recent years. Morphol. control grants them versatility in the method of deployment whether as bulk powders, monoliths, thin films, or embedded in coatings. High surface areas and pore sizes >2 nm make them effective as adsorbent coatings for humidity sensors. The pore networks also provide the potential for immobilization of enzymes within the materials. Functionalization of materials by silane grafting or through co-condensation of silicate precursors can be used to provide mesoporous materials with a variety of fluorescent probes as well as surface properties that aid in selective detection of specific analytes. This review will illustrate how mesoporous silicas were applied to sensing changes in relative humidity, changes in pH, metal cations, toxic industrial compds., volatile org. compds., small mols. and ions, nitroenergetic compds., and biol. relevant mols.
- 13Méndez, F. J.; Franco-López, O. E.; Bokhimi, X.; Solís-Casados, D. A.; Escobar-Alarcón, L.; Klimova, T. E. Dibenzothiophene hydrodesulfurization with NiMo and CoMo catalysts supported on niobium-modified MCM-41. Applied Catalysis B: Environmental 2017, 219, 479– 491, DOI: 10.1016/j.apcatb.2017.07.079Google Scholar13Dibenzothiophene hydrodesulfurization with NiMo and CoMo catalysts supported on niobium-modified MCM-41Mendez, Franklin J.; Franco-Lopez, Oscar E.; Bokhimi, Xim; Solis-Casados, Dora A.; Escobar-Alarcon, Luis; Klimova, Tatiana E.Applied Catalysis, B: Environmental (2017), 219 (), 479-491CODEN: ACBEE3; ISSN:0926-3373. (Elsevier B.V.)In the present work, we studied the effect of the addn. of niobium to CoMo/MCM-41 and NiMo/MCM-41 catalysts on their characteristics and performance in the hydrodesulfurization of dibenzothiophene. The MCM-41 support was synthesized at room temp. according to a well-known procedure. The metal species (Nb, Mo, Ni or Co) were deposited by successive impregnation using aq. solns. of the corresponding metal salts. MCM-41 and Nb-contg. MCM-41 supports were characterized by X-ray diffraction, N2 physisorption, FT-Raman spectroscopy, XPS, UV-vis diffuse reflectance spectroscopy and SEM. The CoMo and NiMo catalysts in oxide state, in addn. to the above techniques, were characterized by temp.-programmed redn. and the sulfided catalysts were characterized by high resoln. transmission electron microscopy. The results show that the incorporation of small amts. of Nb (3-5 wt.%) increased the catalytic activity of both NiMo and CoMo catalysts in dibenzothiophene hydrodesulfurization and affected their selectivity. The effect of Nb on the selectivities of the NiMo and CoMo catalysts was different: for the NiMo catalysts, Nb increased selectivity towards the HYD route, whereas for the CoMo catalysts, it increased selectivity towards the DDS route. The anal. of the effect of Nb on the catalysts' selectivity was performed based on the kinetic consts. calcd. for the different steps of the DBT HDS network.
- 14Tanimu, A.; Abdel-Azeim, S.; Ganiyu, S. A.; Alhooshani, K. Experimental and Theoretical Investigation of the Synergy Effect of Zr and Ce on the Catalytic Efficiency of NiMoS Grafted on SBA-15 for Oil Hydrodesulfurization. Energy Fuels 2021, 35 (3), 2579– 2589, DOI: 10.1021/acs.energyfuels.0c03461Google Scholar14Experimental and Theoretical Investigation of the Synergy Effect of Zr and Ce on the Catalytic Efficiency of NiMoS Grafted on SBA-15 for Oil HydrodesulfurizationTanimu, Abdulkadir; Abdel-Azeim, Safwat; Ganiyu, Saheed A.; Alhooshani, KhalidEnergy & Fuels (2021), 35 (3), 2579-2589CODEN: ENFUEM; ISSN:0887-0624. (American Chemical Society)In this study, the synergy effect of biheteroatoms (ZrOx and CeOy) and a Ni promoter on the catalytic performance of MoS2 crystallites grafted on SBA-15 silica for the hydrodesulfurization (HDS) of dibenzothiophene (DBT) in diesel was investigated. The pyridine-Fourier transform IR (py-FTIR) spectroscopy, ammonia temp.-programmed desorption (NH3-TPD), and XPS analyses revealed that the surface acidity, no. of active sites, and the dispersion of MoS2 crystallites increased significantly with the incorporation of ZrOx and CeOy on SBA-15 than other supported catalysts evaluated. The ZrOx-CeOy-SBA-15-supported NiMo catalyst could remove 59% of DBT in diesel spiked with 1000 ppm of DBT after 1 h of reaction and up to 96% of DBT after 5 h of reaction. D. functional theory (DFT) simulations further gave interesting insights; a thin-film model of SBA-15 decorated with Zr and Ce indicates that the metal sites induced a strong hydrogen bond network leading to higher surface stability. Furthermore, Ce grafted on SBA-15 enhanced the adsorption of water mols. that increases the Bronsted acid sites and subsequently improved its catalytic efficiency. DFT simulation of thiophene HDS showed a stepwise rupture of thiophene C-S bonds with the second C-S bond breaking as the plausible rate-detg. step.
- 15Wang, X.; Shi, Y.; Gao, S.; Xu, C.; Zhao, Z.; Wang, G.; Fu, S.; Duan, A.; Gao, D. Hierarchically Porous β/SBA-16 Composites: Tuning Pore Structure and Acidity for Enhanced Isomerization Performance in Hydrodesulfurization of Dibenzothiophene and 4,6-Dimethyldibenzothiophene. Energy Fuels 2020, 34 (1), 769– 777, DOI: 10.1021/acs.energyfuels.9b03627Google Scholar15Hierarchically Porous β/SBA-16 Composites: Tuning Pore Structure and Acidity for Enhanced Isomerization Performance in Hydrodesulfurization of Dibenzothiophene and 4,6-DimethyldibenzothiopheneWang, Xilong; Shi, Yu; Gao, Shanbin; Xu, Chunming; Zhao, Zhen; Wang, Gang; Fu, Siyuan; Duan, Aijun; Gao, DaoweiEnergy & Fuels (2020), 34 (1), 769-777CODEN: ENFUEM; ISSN:0887-0624. (American Chemical Society)β/SBA-16 (BS) materials were fabricated using β-nanoclusters through self-assembly hydrothermal crystn. approach; subsequently, the corresponding NiMo/BS catalysts were synthesized. The influence of HCl concn. on the physicochem. properties of the composite support and the corresponding catalyst was investigated by a series of characterization methods. The hydrodesulfurization (HDS) performances were evaluated under the conditions of T = 340°C, PH2 = 4 MPa, and H2/oil (vol./vol.) = 200 by adopting dibenzothiophene (DBT) and 4,6-dimethyldibenzothiophene (4,6-DMDBT) as probe reactants. The results indicated that NiMo/BS-1.5 prepd. under the HCl concn. of 1.5 mol L-1 exhibited the superior HDS performance due to its well-ordered shape and pore channel, high sulfidation degree, moderate acidity, and suitable metal-support interaction (MSI). In addn., the potential HDS reaction networks for DBT and 4,6-DMDBT of series NiMo/BS were presented.
- 16Ganiyu, S. A.; Alhooshani, K. Catalytic Performance of NiMoS Supported on (Zr)SBA-15 for Hydrodesulfurization of Diesel: Insight into a One-Step Calcination and Reduction Strategy during Sulfidation. Energy Fuels 2019, 33 (4), 3047– 3056, DOI: 10.1021/acs.energyfuels.8b04536Google Scholar16Catalytic Performance of NiMoS Supported on (Zr)SBA-15 for Hydrodesulfurization of Diesel: Insight into a One-Step Calcination and Reduction Strategy during SulfidationGaniyu, Saheed A.; Alhooshani, KhalidEnergy & Fuels (2019), 33 (4), 3047-3056CODEN: ENFUEM; ISSN:0887-0624. (American Chemical Society)We report, herein, the catalytic efficiency and activity of a facilely synthesized sulfided NiMo hydrodesulfurization (HDS) catalyst supported on (Zr)-SBA-15 by one-step calcination and redn. heat treatment prior to sulfidation. Zr-SBA-15-Mo is prepd. by a direct synthesis approach, followed by the confinement of Ni into the as-synthesized Zr-SBA-15-Mo without calcination, to generate more dispersion and active sites of metal oxides for an efficient sulfidation process. The HDS performance of these catalysts was evaluated and compared to that of the catalysts prepd. by the sequential calcination and redn. approach prior to sulfidation for HDS of dibenzothiophene (DBT) and dimethyldibenzothiophene (DMDBT) in com. diesel at 350 °C in batch reactor mode. Structural and morphol. properties related to catalytic activity have been obtained by means of spectroscopy (X-ray diffraction (XRD), Raman, pyridine-Fourier transform IR (FTIR), temp.-programmed desorption (TPD), microscopy (SEM)), and N2 physisorption. The characterization and investigations from XRD, Raman, pyridine-FTIR, and TPD revealed that avoiding multiple heat treatment in designing HDS catalysts provides more coordinative unsatd. active sites necessary for better catalyst performance and stability. In addn., the textural properties (sp. surface area, pore size, and vol.) that allow easy diffusion of reactant mols. are better preserved. The activity of the sulfided NiMo catalysts prepd. by one-step heat treatment is 9-16% higher for DBT and 11-13% higher for DMDBT at 1 h reaction time compared to that of the catalysts prepd. by sequential calcination and redn. before sulfidation. The catalysts prepd. by this heat treatment approach have desulfurization efficiencies of 99 and 84% for DBT and DMDBT, resp.
- 17Zheng, P.; Hu, D.; Meng, Q.; Liu, C.; Wang, X.; Fan, J.; Duan, A.; Xu, C. Influence of Support Acidity on the HDS Performance over β-SBA-16 and Al-SBA-16 Substrates: A Combined Experimental and Theoretical Study. Energy Fuels 2019, 33 (2), 1479– 1488, DOI: 10.1021/acs.energyfuels.8b04133Google Scholar17Influence of Support Acidity on the HDS Performance over β-SBA-16 and Al-SBA-16 Substrates: A Combined Experimental and Theoretical StudyZheng, Peng; Hu, Di; Meng, Qian; Liu, Cong; Wang, Xilong; Fan, Jiyuan; Duan, Aijun; Xu, ChunmingEnergy & Fuels (2019), 33 (2), 1479-1488CODEN: ENFUEM; ISSN:0887-0624. (American Chemical Society)A novel composite material β-SBA-16 is successfully synthesized and utilized as the support for the development of hydrodesulfurization (HDS) catalyst. The supports and the corresponding catalysts were characterized by a variety of techniques involving X-ray diffraction, N2 physisorption, 27Al NMR, Raman, pyridine IR, X-ray photoelectron spectra, and high-resoln. transmission electron microscopy. The activity evaluation results displayed that the NiMo/β-SBA-16 catalyst possessed the highest dibenzothiophene HDS efficiency of 97.3% at wt. hourly space velocity of 20 h-1 compared with the catalysts supported on the Al-modified SBA-16 and the conventional Al2O3. Furthermore, the HDS efficiency of NiMo/β-SBA-16 is almost 1.5 times that of the other two catalysts at 150 h-1, which was considered to be closely linked to the acidic properties of the supports. Correspondingly, the results of pyridine IR exhibited that NiMo/β-SBA-16 possessed larger amts. of total acidity and higher B/L acidities ratio. Furthermore, d. functional theory calcns. were performed to explore the Bronsted acid strength generated by the incorporation of β seeds or Al atoms. The calcn. results indicated that Si atoms located in the 5- or 6-membered rings of β-zeolite were more easily substituted by Al atoms, and the generated Si-OH-Al group played an important role in providing stronger Bronsted acid sites. Therefore, both exptl. and theor. results have shown that the incorporation of β seeds contributed more to produce the Bronsted acid sites of SBA-16 materials.
- 18Wu, M.; Li, Q.; Wang, X.; Mi, J. Structure Characteristics and Hot-Coal-Gas Desulfurization Properties of Zn-Based Sorbents Supported on Mesoporous Silica with Different Pore-Arrangement Patterns: A Comparison Study. Energy Fuels 2021, 35 (3), 2456– 2467, DOI: 10.1021/acs.energyfuels.0c03794Google Scholar18Structure Characteristics and Hot-Coal-Gas Desulfurization Properties of Zn-Based Sorbents Supported on Mesoporous Silica with Different Pore-Arrangement Patterns: A Comparison StudyWu, Mengmeng; Li, Qiaochun; Wang, Xiaowen; Mi, JieEnergy & Fuels (2021), 35 (3), 2456-2467CODEN: ENFUEM; ISSN:0887-0624. (American Chemical Society)Ordered mesoporous MCM-41 (two-dimensional (2D) hexagonal pore arrangement) and MCM-48 (three-dimensional (3D) cubic channel arrangement) with similar pore sizes and surface areas were selected for comparison when used as support for Zn-based sorbents for hot coal gas desulfurization. Compared to that of Zn/M48 (MCM-48-supported desulfurizer), the adsorption capacity of Zn/M41 (MCM-41-supported sorbent) increases by 24.4-56.3%. The initial reaction rate consts. of Zn/M41 are 1-13 times greater than those of Zn/M48. These are correlated to the structural features of sorbents. Zn/M41 has a large wall thickness of the framework, suggesting higher thermal stability. Furthermore, the sorbent particles and ZnO grains in Zn/M41 are both smaller in size, which facilitates contact between H2S and ZnO. Addnl., Zn/M41 possesses a large surface area and pore vol., beneficial for the diffusion of H2S through sorbents. The anal. of the atm. effects reveals that there is a stronger synergistic effect of CO and H2 on desulfurization over Zn/M41.
- 19Akopyan, A.; Polikarpova, P.; Gul, O.; Anisimov, A.; Karakhanov, E. Catalysts Based on Acidic SBA-15 for Deep Oxidative Desulfurization of Model Fuels. Energy Fuels 2020, 34 (11), 14611– 14619, DOI: 10.1021/acs.energyfuels.0c02008Google Scholar19Catalysts Based on Acidic SBA-15 for Deep Oxidative Desulfurization of Model FuelsAkopyan, Argam; Polikarpova, Polina; Gul, Olesya; Anisimov, Alexander; Karakhanov, EduardEnergy & Fuels (2020), 34 (11), 14611-14619CODEN: ENFUEM; ISSN:0887-0624. (American Chemical Society)Acidic SBA-15 modified by molybdenum oxide has been synthesized. These materials were characterized by low nitrogen adsorption/desorption, Fourier transform IR spectroscopy, transmission electron microscopy, NH3 temp.-programmed desorption, NMR, and XRD techniques. In this work, the activity of acidic Al-SBA-15 modified with molybdenum oxide in the oxidn. of sulfur-contg. compds. was investigated for the first time. It was shown that the SBA-15 support contg. aluminum allows to significantly increase the catalytic activity of molybdenum oxide. The main factors affecting the process consisting of catalyst dosage, temp., reaction time, oxidant dosage were investigated in detail. In the presence of synthesized catalysts, dibenzothiophene can be completely oxidized in 30 min. These catalysts retain their activity in DBT oxidn. for 10 cycles.
- 20Polikarpova, P.; Akopyan, A.; Shigapova, A.; Glotov, A.; Anisimov, A.; Karakhanov, E. Oxidative Desulfurization of Fuels Using Heterogeneous Catalysts Based on MCM-41. Energy Fuels 2018, 32 (10), 10898– 10903, DOI: 10.1021/acs.energyfuels.8b02583Google Scholar20Oxidative Desulfurization of Fuels Using Heterogeneous Catalysts Based on MCM-41Polikarpova, Polina; Akopyan, Argam; Shigapova, Anastasia; Glotov, Aleksandr; Anisimov, Alexander; Karakhanov, EduardEnergy & Fuels (2018), 32 (10), 10898-10903CODEN: ENFUEM; ISSN:0887-0624. (American Chemical Society)Mesoporous silicas of MCM-41 type modified by transition metal oxides, such as molybdenum, vanadium, and tungsten, were synthesized. These materials were characterized by low-temp. nitrogen adsorption/desorption, Fourier transform IR spectroscopy, X-ray spectral fluorescence anal., and transmission electron microscopy techniques and applied for the removal of sulfur compds. in model and real fuels by oxidative desulfurization. The catalysts obtained were tested under optimal conditions. Dibenzothiophene was removed completely, and sulfur removal in gasoline and diesel fractions could reach 91 and 63%, resp. These catalysts retain their activity in gasoline fraction desulfurization for 5 cycles.
- 21Rao, N.; Wang, M.; Shang, Z.; Hou, Y.; Fan, G.; Li, J. CO2 Adsorption by Amine-Functionalized MCM-41: A Comparison between Impregnation and Grafting Modification Methods. Energy Fuels 2018, 32 (1), 670– 677, DOI: 10.1021/acs.energyfuels.7b02906Google Scholar21CO2 Adsorption by Amine-Functionalized MCM-41: A Comparison between Impregnation and Grafting Modification MethodsRao, Na; Wang, Mei; Shang, Ziming; Hou, Yanwen; Fan, Guozhi; Li, JianfenEnergy & Fuels (2018), 32 (1), 670-677CODEN: ENFUEM; ISSN:0887-0624. (American Chemical Society)Modifications by impregnation and grafting are commonly used for the prepn. of amine-functionalized MCM-41. A comprehensive evaluation of the advantages and disadvantages of the two methods was performed in this work. MCM-41 was synthesized by the hydrothermal method, setting the amine-loading mass fraction at 40, 50, and 60 wt %. Three amine-modified adsorbents were prepd. by impregnating polyethylenimine (PEI), and the three other adsorbents were prepd. by grafting 3-aminopropyltriethoxysilane (APTS) onto MCM-41. The as-prepd. adsorbents were characterized by X-ray diffraction, Fourier transform IR spectroscopy, SEM, thermogravimetric anal., and N2 adsorption-desorption techniques. CO2 adsorption capacities were measured, and the exptl. data were fitted with adsorption kinetic models. The cyclic stability of the adsorbents prepd. by the two kinds of amine-modified methods was compared using the cyclic adsorption-desorption expts. The characterization results showed that the target adsorbents were prepd. successfully. The thermal stability of the adsorbents modified by grafting was better than the thermal stability of the adsorbents modified by the impregnation. Maximum CO2 adsorption capacities of 3.53 mmol g-1 (50% PEI-MCM-41) and 2.41 mmol g-1 (50% APTS-MCM-41) could be reached at 25 °C and 1 atm, which were 4.7 and 3.2 times greater than that of MCM-41. The Avrami model fitted the exptl. data well, indicating a variety of interactions between the adsorbents and CO2. CO2 adsorption capacity after 5 adsorption-desorption cycles decreased by 14.22 and 5.19% for the adsorbents prepd. by impregnation and grafting, resp. It was concluded that MCM-41 modified by impregnation and grafting followed the same kinetic model. The absorbents modified by impregnation showed higher CO2 adsorption capacity and amine-loading efficiency, while those prepd. by grafting had better thermal and cyclic stabilities.
- 22Kishor, R.; Ghoshal, A. K. Polyethylenimine Functionalized As-Synthesized KIT-6 Adsorbent for Highly CO2/N2 Selective Separation. Energy Fuels 2016, 30 (11), 9635– 9644, DOI: 10.1021/acs.energyfuels.6b02082Google Scholar22Polyethylenimine Functionalized As-Synthesized KIT-6 Adsorbent for Highly CO2/N2 Selective SeparationKishor, Rupak; Ghoshal, Aloke KumarEnergy & Fuels (2016), 30 (11), 9635-9644CODEN: ENFUEM; ISSN:0887-0624. (American Chemical Society)The present study targeted the synthesis of CO2 adsorbent by impregnation of DETA, TEPA, PEHA, and polyethylenimine in KIT-6 with a confiscated structure directing agent in min. time and energy. The adsorbents were characterized and revealed the influence of polyethylenimine with CO2 at a wide range of temps. An examn. by TGA confirmed that PluronicP123 present in adsorbent enhances its thermal stability and acts as a carrier for CO2 to the inner layer of polyethylenimine during adsorption. CO2 sorption capacity of the adsorbent was found to be dependent on the polyethylenimine loading, temp., pressure, and the surfactant PluronicP123. At higher temps., adsorbents showed a pos. impact for CO2 adsorption; however, a neg. effect was exhibited in amine efficiency. The sorption capacity decreased with increasing the mol. wt. of polyethylenimine following the order PEI-25K (66 mg CO2/g) < PEI-800 (114 mg CO2/g) < TEPA (124 mg CO2/g) < PEHA (139 mg CO2/g) at 75 °C. However, 60 wt % PEHA impregnated KIT-6 showed the stable sorption capacity of 170-184 mg CO2/g at 90-105 °C and 1 bar.
- 23Du, H.; Ma, L.; Liu, X.; Zhang, F.; Yang, X.; Wu, Y.; Zhang, J. A Novel Mesoporous SiO2Material with MCM-41 Structure from Coal Gangue: Preparation, Ethylenediamine Modification, and Adsorption Properties for CO2 Capture. Energy Fuels 2018, 32 (4), 5374– 5385, DOI: 10.1021/acs.energyfuels.8b00318Google Scholar23A Novel Mesoporous SiO2 Material with MCM-41 Structure from Coal Gangue: Preparation, Ethylenediamine Modification, and Adsorption Properties for CO2 CaptureDu, Hong; Ma, Liang; Liu, Xiaoyao; Zhang, Fei; Yang, Xinyu; Wu, Yu; Zhang, JianbinEnergy & Fuels (2018), 32 (4), 5374-5385CODEN: ENFUEM; ISSN:0887-0624. (American Chemical Society)A novel mesoporous SiO2 material (M-SiO2) with MCM-41 structure was readily fabricated from the inexpensive coal gangue via a hydrothermal reaction in the presence of cetyltrimethylammonium bromide (CTAB) for CO2 capture. On the basis of orthogonal exptl. results, the optimum conditions for the prepn. of M-SiO2 were identified as follows: the SiO32- leaching of 21 g/L from coal gangue, the CTAB concn. of 0.25 mol/L, the HCl concn. of 2.5 mol/L, the hydrothermal temp. of 393.15 K, and the hydrothermal time of 20 h. Under the optimum condition, the M-SiO2 exhibited an adsorption capability of 9.61 mg/g to 8% CO2 at 298.15 K. To further improve the CO2 adsorption performance, the M-SiO2 was chem. modified using ethylenediamine (EDA), and the optimum conditions for the modification of M-SiO2 were identified as follows: the impregnation time of 10 h, the drying temp. of 343.15 K, and the ratio of EDA/M-SiO2 = 2:1. Under the optimum conditions, the adsorption capability of EDA-modified M-SiO2 (EDA-M-SiO2) was increased by 83.5 mg/g. The obtained M-SiO2 and EDA-M-SiO2 were systemically characterized by N2 adsorption-desorption isotherms, thermogravimetric anal., Fourier transform IR spectroscopy, SEM, transmission electron microscopy, and X-ray diffraction measurements techniques. The anal. results indicated that the M-SiO2 was mainly composed of O and Si in the form of SiO2 with a sp. surface area of 156 m2/g, and part of M-SiO2 exhibited a structure similar to MCM-41. Moreover, the mechanisms of EDA modification and CO2 adsorption were investigated and discussed in detail.
- 24Chen, H.; Liang, Z.; Yang, X.; Zhang, Z.; Zhang, Z. Experimental Investigation of CO2 Capture Capacity: Exploring Mesoporous Silica SBA-15 Material Impregnated with Monoethanolamine and Diethanolamine. Energy Fuels 2016, 30 (11), 9554– 9562, DOI: 10.1021/acs.energyfuels.6b01298Google Scholar24Experimental Investigation of CO2 Capture Capacity: Exploring Mesoporous Silica SBA-15 Material Impregnated with Monoethanolamine and DiethanolamineChen, Hongwei; Liang, Zhanwei; Yang, Xin; Zhang, Ze; Zhang, ZhiyuanEnergy & Fuels (2016), 30 (11), 9554-9562CODEN: ENFUEM; ISSN:0887-0624. (American Chemical Society)A series of efficient adsorbents were prepd. by impregnating mesoporous silica SBA-15 with different amts. of monoethanolamine (MEA) and diethanolamine (DEA) in order to improve CO2 capture capacity. The textural properties of pure and modified mesoporous SBA-15 materials were characterized by X-ray diffraction characterization, transmission electron microscopy, N2 adsorption-desorption test, and thermogravimetric anal. When the ratio of DEA to SBA-15 is below 2, these mols. loaded on the support are relatively far away from satg. and allow the accessibility of CO2 mols. to the inner adsorption sites. Further increasing of the amine loading would reduce opportunities of CO2 to contact with internal amino sites, because the amine was covered in a multilayer form or even caking form on the SBA-15 pore surface. The similar performance was obsd. for MEA. Therefore, the adsorption capacity of CO2 increases with the amt. of DEA or MEA content, but when the amt. of MEA or DEA loaded on the mesoporous SBA-15 is further increased, the CO2 capture is influenced by the packing effect on the mesoporous hexagonal silica. Temp. effect on adsorption was also studied in the range of 30-90 °C, showing that, with the increase of temp., the adsorptive amts. of adsorbents lessened gradually from the highest values at 30 °C since the thermodynamically controlled process. The mesoporous SBA-15 material impregnated with MEA or DEA can provide a perspective to further explore effective adsorbents for CO2 capture.
- 25Ye, C.-P.; Wang, R.-N.; Gao, X.; Li, W.-Y. CO2 Capture Performance of Supported Phosphonium Dual Amine-Functionalized Ionic Liquids@MCM-41. Energy Fuels 2020, 34 (11), 14379– 14387, DOI: 10.1021/acs.energyfuels.0c02547Google Scholar25CO2 Capture Performance of Supported Phosphonium Dual Amine-Functionalized Ionic Liquids@MCM-41Ye, Cui-Ping; Wang, Rui-Nan; Gao, Xia; Li, Wen-YingEnergy & Fuels (2020), 34 (11), 14379-14387CODEN: ENFUEM; ISSN:0887-0624. (American Chemical Society)To screen the efficient media for CO2 capture of flue gas from power plants, a strategy for improving the CO2 capture capacity by dual functionalized ionic liqs. (ILs) with multiple active sites is proposed. Three phosphonium dual functionalized ILs ([aP4443][2-Np], [aP4443][2-Op], and [aP4443][Triz]) have been prepd. The sorption capacities of the synthesized ILs under pure CO2 atmosphere and the supported ILs under different loading amts. from 10 to 50%, temps. of 30-80°C, and CO2 partial pressure varied from 10 to 15% were detd. Fourier transform IR (FTIR) spectroscopy was applied to reveal the interaction between CO2 and ILs, and the pseudo-second-order model and the intraparticle diffusion model were used for a better understanding of the CO2 adsorption behavior. The results showed that a high capacity up to 1.88 mol of CO2/mol of IL for [aP4443][2-Np] is achieved, and 30% IL-MCM-41 can reach 3.19 mmol/g with excellent reversibility under the atm. of CO2:N2 (15%:85%) at 30°C and 0.1 MPa. Raising the temp. or decreasing the CO2 concn. is not conducive to improving the CO2 capacity. FTIR spectroscopy demonstrated that the amino and hydroxyl react with CO2 to form NHCOO- or CO3-. Combined with the activation energy calcn., the kinetic anal. revealed that the CO2 capture of supported ILs is an internal diffusion controlled phys. adsorption.
- 26Zhang, W.; Li, Y.; Li, Y.; Gao, E.; Cao, G.; Bernards, M. T.; He, Y.; Shi, Y. Enhanced SO2 Resistance of Tetraethylenepentammonium Nitrate Protic Ionic Liquid-Functionalized SBA-15 during CO2 Capture from Flue Gas. Energy Fuels 2020, 34 (7), 8628– 8634, DOI: 10.1021/acs.energyfuels.0c01074Google Scholar26Enhanced SO2 Resistance of Tetraethylenepentammonium Nitrate Protic Ionic Liquid-Functionalized SBA-15 during CO2 Capture from Flue GasZhang, Wei; Li, Yu; Li, Younan; Gao, Erhao; Cao, Guanghan; Bernards, Matthew T.; He, Yi; Shi, YaoEnergy & Fuels (2020), 34 (7), 8628-8634CODEN: ENFUEM; ISSN:0887-0624. (American Chemical Society)Post-combustion carbon capture using amine-based adsorbents is a highly competitive approach to control CO2 emissions from fossil fuel-fired power plants. However, it is well known that amine-based adsorbents suffer from long-term stability issues due to amine poisoning by flue gas contaminants. Minor contaminants, such as SO2, can preferably react with amine sites to form irreversible sulfonamides. This work investigated the effect of nitrates on the SO2 resistance of tetraethylenepentammonium nitrate protic ionic liq.-functionalized SBA-15 for CO2 capture. The tetraethylenepentamine-functionalized SBA-15 without nitrates was prepd. as the control. The CO2 adsorption capacity was measured over multiple capture cycles in the presence of 500 ppm SO2. The CO2 capture capacities of the sorbent without nitrates decreased by 1.48 mmol g-1 (50.3%) over 11 capture cycles. After introducing nitrates into the sorbent, the CO2 adsorption capacities only decreased by 0.55 mmol g-1 (21.8%). In addn., the nitrates restricted the reaction between amine groups and SO2 leading to reversible sulfonamide products. The significant improvement in SO2 resistance was further explained with d. functional theory (DFT) calcns., which revealed that the binding energy and net charge transfer between SO2 and amine groups were decreased after introducing the nitrate group into the amine. To further investigate the regenerability and structural stability of tetraethylenepentammonium nitrate-functionalized SBA-15 for CO2 capture under realistic conditions, the long-term operating performance was evaluated in a gas mixt. of 150 ppm SO2, 150 ppm NO, 100% RH, 15% CO2, and balance N2. The CO2 adsorption capacities and the structural properties of nitrate-contg. sorbents were nearly unchanged over eight adsorption/regeneration cycles.
- 27Zhang, W.; Gao, E.; Li, Y.; Bernards, M. T.; Li, Y.; Cao, G.; He, Y.; Shi, Y. Synergistic Enhancement of CO2 Adsorption Capacity and Kinetics in Triethylenetetrammonium Nitrate Protic Ionic Liquid Functionalized SBA-15. Energy Fuels 2019, 33 (9), 8967– 8975, DOI: 10.1021/acs.energyfuels.9b01872Google Scholar27Synergistic Enhancement of CO2 Adsorption Capacity and Kinetics in Triethylenetetrammonium Nitrate Protic Ionic Liquid Functionalized SBA-15Zhang, Wei; Gao, Erhao; Li, Yu; Bernards, Matthew T.; Li, Younan; Cao, Guanghan; He, Yi; Shi, YaoEnergy & Fuels (2019), 33 (9), 8967-8975CODEN: ENFUEM; ISSN:0887-0624. (American Chemical Society)A series of triethylenetetrammonium nitrate protic ionic liq. (TNPIL) functionalized, highly ordered mesoporous SBA-15 mol. sieves with different loadings have been synthesized via impregnation. The CO2 capture performance of the hybrid sorbents was evaluated under conditions mimicking a combustion flue gas (15% CO2) over the temp. range of 298-348 K. The breakthrough expts. revealed that the sieves with 66% mass loadings of TNPIL (S15-66TNPIL) exhibited the highest CO2 adsorption capacity of 2.12 mmol g-1 at 333 K, representing a dramatic enhancement compared to the bare support (883%). The intraparticle diffusion model anal. of the hybrid sorbents demonstrated that S15-66TNPIL had the fastest CO2 uptake rate of 131 × 10-3 mmol g-1 s-0.5 in the rate-controlling stage. This was almost 5 times higher than that of the bare support alone and is a significant improvement over other IL-functionalized and amine-modified support systems. This can be attributed to the synergistic effects of the high affinity between the TNPIL and CO2 and the fast diffusion rate from the distribution of TNPIL across the support with a large surface area. In addn., S15-66TNPIL exhibited a great regeneration capacity. The Fourier transform-IR spectroscopy anal. coupled with isosteric heat and d. functional theory simulations revealed that the adsorption state is dominated by chemisorption, and the CO2 preferentially interacts with the primary amine -N(3)H2 to form carbamate based on the high binding energy. Therefore, this novel TNPIL-supported system represents a promising candidate for CO2 capture and recovery applications.
- 28Venkateshwaran, S.; Partheeban, T.; Sasidharan, M.; Senthil Kumar, S. M. Mesoporous Silica Template-Assisted Synthesis of 1T-MoS2 as the Anode for Li-Ion Battery Applications. Energy Fuels 2021, 35 (3), 2683– 2691, DOI: 10.1021/acs.energyfuels.0c03296Google Scholar28Mesoporous Silica Template-Assisted Synthesis of 1T-MoS2 as the Anode for Li-Ion Battery ApplicationsVenkateshwaran, Selvaraj; Partheeban, Thamodaran; Sasidharan, Manickam; Senthil Kumar, Sakkarapalayam MurugesanEnergy & Fuels (2021), 35 (3), 2683-2691CODEN: ENFUEM; ISSN:0887-0624. (American Chemical Society)The development of the MoS2-based catalyst is receiving more attention in recent years, esp. with enriched metallic (1T) phase because of their improvized electrocatalytic behavior. However, the formation of MoS2 with the enriched 1T phase is still hampered because the most stable one is 2H phase. Till date, the most adopted technique to synthesize 1T-MoS2 is the alkali metal exfoliation, but the usage of undesirable org. medium and pyrophoric alkali metal ions is the main setback to this technique. On the other hand, low extent of the 1T phase and lack of reproducibility are issues with aq. medium synthesis of 1T-MoS2. Here, in contrast, the SBA-15 template-assisted technique has been used for the formation of 1T-MoS2 with 90% phase enrichment. As a proof-of-concept, the as-synthesized 1T-MoS2 is investigated as anode materials in the Li-ion battery and they delivered a high initial specific capacity of 1100 mA h g-1 at the 0.1 C rate in the potential window of 0.005-3.0 V and showed a capacity of 700 mA h g-1 with 80% capacity retention after 50 cycles. Investigation of power capability of 1T-MoS2 at high applied current of 1 C rate produced a stable specific capacity of 551 mA h g-1 after 100 cycles. The impressive electrochem. Li+ ion storage property of 1T-MoS2 is attributed to its good elec. cond., fast Li+ ion, and electron conduction owing to its 2D-networked flower-like structure. Moreover, this facile approach is highly useful for the selective enrichment of the 1T phase in other 2D-layered materials that can be used for energy storage and conversion devices.
- 29Subagyono, R. R. D. J. N.; Marshall, M.; Jackson, W. R.; Auxilio, A. R.; Fei, Y.; Chaffee, A. L. Upgrading Microalgal Biocrude Using NiMo/Al-SBA-15 as a Catalyst. Energy Fuels 2020, 34 (4), 4618– 4631, DOI: 10.1021/acs.energyfuels.9b04171Google Scholar29Upgrading Microalgal Biocrude Using NiMo/Al-SBA-15 as a CatalystSubagyono, R. R. Dirgarini J. N.; Marshall, Marc; Jackson, W. Roy; Auxilio, Anthony R.; Fei, Yi; Chaffee, Alan L.Energy & Fuels (2020), 34 (4), 4618-4631CODEN: ENFUEM; ISSN:0887-0624. (American Chemical Society)Biocrude from Chlorococcum sp. algae was hydrotreated in batch autoclaves in the presence and absence of Al-SBA-15 supports and NiMo/Al-SBA-15 catalysts with different Si/Al ratios and hence different acidities. Reaction time (0-15 min), temp. (425-500°C), and H2 pressure (3-9 MPa cold) were varied. The nitrogen content of the biocrude was approx. halved in all of the reactions, regardless of temp., H2 pressure, or the presence of the support/catalyst. Product aromaticity increased with reaction temp. The presence of the supports, esp. those of lower acidity, decreased product yields (CH2Cl2 solubles and hydrocarbon gases) due to severe coking. Incorporation of NiMo introduced a pressure dependence of the product yield. For 425°C reactions, NiMo could more than make up for the coking effect of the support, increasing the product yield to up to 65 wt % (6-9 MPa H2 (cold)) and the proportion of liq. products in the kerosene-boiling-point range (C12-C17). Higher-acidity supports gave higher product yields, and their superiority was maintained when NiMo was incorporated.
- 30Meng, Q.; Duan, A.; Chi, K.; Zhao, Z.; Liu, J.; Zheng, P.; Wang, B.; Liu, C.; Hu, D.; Jia, Y. Synthesis of Titanium Modified Three-Dimensional KIT-5 Mesoporous Support and Its Application of the Quinoline Hydrodenitrogenation. Energy Fuels 2019, 33 (6), 5518– 5528, DOI: 10.1021/acs.energyfuels.9b00520Google Scholar30Synthesis of Titanium Modified Three-Dimensional KIT-5 Mesoporous Support and Its Application of the Quinoline HydrodenitrogenationMeng, Qian; Duan, Aijun; Chi, Kebin; Zhao, Zhen; Liu, Jian; Zheng, Peng; Wang, Bo; Liu, Cong; Hu, Di; Jia, YuanzhenEnergy & Fuels (2019), 33 (6), 5518-5528CODEN: ENFUEM; ISSN:0887-0624. (American Chemical Society)A series of Ti-KIT-5 materials with different ratios of Si/Ti were synthesized and employed as the supports to prep. the NiMo catalysts. All the modified supports and catalysts were measured by means of small-angle and wide-angle XRD, N2 isotherm absorption-desorption, FTIR, XPS, Py-IR, and HRTEM techniques. The small-angle XRD and N2 anal. characterization proved that the modified Ti-KT-x materials maintained the orderly mesoporous structure and displayed the larger pore size than the pure support. Addnl., results from the FTIR and XPS spectra demonstrated that Ti species were successfully embedded into the framework of KIT-5 material. It was noted that the introduction of suitable Ti species increased the amt. of acid sites and promoted well distribution of the active metals. The hydrodenitrogenation performances of the NiMo/Ti-KT-x catalysts were evaluated under the reaction conditions of a H2 pressure of 4 MPa, a WHSV of 10 h-1, and different temps. ranging from 340 to 400 °C. The modified NiMo/Ti-KIT-5 catalysts showed the higher catalytic activities than NiMo/KIT-5 catalyst, which was attributed to the larger pore size, more acid sites, and sulfide active metal species. Moreover, the NiMo/Ti-KT-20 catalyst showed the highest hydrodenitrogenation efficiencies (81.56%).
- 31Gutta, N.; Velisoju, V. K.; Tardio, J.; Patel, J.; Satyanarayana, L.; Sarma, A. V. S.; Akula, V. CH4 Cracking over the Cu–Ni/Al-MCM-41 Catalyst for the Simultaneous Production of H2 and Highly Ordered Graphitic Carbon Nanofibers. Energy Fuels 2019, 33 (12), 12656– 12665, DOI: 10.1021/acs.energyfuels.9b02819Google Scholar31CH4 Cracking over the Cu-Ni/Al-MCM-41 Catalyst for the Simultaneous Production of H2 and Highly Ordered Graphitic Carbon NanofibersGutta, Naresh; Velisoju, Vijay Kumar; Tardio, James; Patel, Jim; Satyanarayana, Lanka; Sarma, Akella V. S.; Akula, VenugopalEnergy & Fuels (2019), 33 (12), 12656-12665CODEN: ENFUEM; ISSN:0887-0624. (American Chemical Society)The Cu-Ni bimetallic catalysts dispersed on various silica supports were examd. for catalytic cracking of CH4 to produce pure H2 with near zero COx emissions and fine quality carbon nanofibers. The 27Al MAS NMR spectra of Al contg. MCM-41 samples revealed the existence of framework and extra framework decorated Al species. Insertion of Al species into the framework of MCM-41, significantly improved the accessible active surface Ni sites, which was confirmed from the simultaneous H2 and N2O pulse titrn. techniques. NH3 TPD measurements demonstrated a high ratio of moderate and strong acid sites upon Al insertion into the silica matrix. The framework tetrahedral Al in MCM-41 stabilized the surface Cu-Ni alloy sites and protected from the sintering and fragmentation of Ni consequently enhanced the H2 yields of 270 Nm3/(molNi)-1 were obtained with Si/Al ratio = 150 with catalyst. The better performance of the Cu-Ni/Al-MCM-41 (Si/Al = 150) was rationalized using the physicochem. characteristics of the catalyst analyzed by XRD, H2-TPR, BET - surface area, 27Al and 29Si MAS NMR, NH3-TPD, XPS, TEM, H2 and/or N2O titrn. and Raman spectroscopic techniques.
- 32Gutta, N.; Velisoju, V. K.; Chatla, A.; Boosa, V.; Tardio, J.; Patel, J.; Akula, V. Promotional Effect of Cu and Influence of Surface Ni–Cu Alloy for Enhanced H2 Yields from CH4 Decomposition over Cu-Modified Ni Supported on MCM-41 Catalyst. Energy Fuels 2018, 32 (3), 4008– 4015, DOI: 10.1021/acs.energyfuels.7b03363Google Scholar32Promotional Effect of Cu and Influence of Surface Ni-Cu Alloy for Enhanced H2 Yields from CH4 Decomposition over Cu-Modified Ni Supported on MCM-41 CatalystGutta, Naresh; Velisoju, Vijay Kumar; Chatla, Anjaneyulu; Boosa, Venu; Tardio, James; Patel, Jim; Akula, VenugopalEnergy & Fuels (2018), 32 (3), 4008-4015CODEN: ENFUEM; ISSN:0887-0624. (American Chemical Society)Catalysts based on MCM-41 decorated with 35-70 nm diam. Ni particles were tested for the prodn. of hydrogen by catalytic decompn. of methane (CDM). About 122 N m3 (molNi)-1 hydrogen yield was achieved over a catalyst comprised of optimized Ni loading of 50 wt % Ni/MCM-41. The H2 yield increased dramatically to 204 N m3 (molNi)-1, upon modification with 10 wt % Cu. The presence of Cu, in contact to Ni, appeared to reduce the sintering and coking of the active Ni sites, which enhanced the longevity of the catalyst. Raman anal. of the catalysts recovered after CDM expts. revealed that doping of Cu to Ni/MCM-41 enhanced the graphitic carbon deposition over the catalyst. All of the samples (Ni and Ni-Cu-modified MCM-41) were characterized by H2 chemisorption, SEM/TEM, XPS, XRD, H2-TPR, N2O titrn., and Raman spectroscopy to examine the bulk and surface properties of the catalysts.
- 33Hung, C.; Bai, H.; Karthik, M. Ordered mesoporous silica particles and Si-MCM-41 for the adsorption of acetone: A comparative study. Sep. Purif. Technol. 2009, 64 (3), 265– 272, DOI: 10.1016/j.seppur.2008.10.020Google Scholar33Ordered mesoporous silica particles and Si-MCM-41 for the adsorption of acetone: A comparative studyHung, Chinte; Bai, Hsunling; Karthik, ManiSeparation and Purification Technology (2009), 64 (3), 265-272CODEN: SPUTFP; ISSN:1383-5866. (Elsevier B.V.)This study compares the surface properties and the acetone adsorption potentials of mesoporous silica particles (MSPs) and Si-MCM-41. The Si-MCM-41 and MSPs are synthesized, resp. by hydrothermal method and evapn.-induced self-assembly (EISA) method. The results show that the surface area and pore diam. of MSPs are similar to those of Si-MCM-41. But the synthesis of Si-MCM-41 frequently requires longer time and tedious procedure as compared to that of MSPs. The bulk d. of MSPs is 3.0-5.0 times higher than that of Si-MCM-41. The mass-based acetone adsorption capacities of these two materials are almost similar. This implies that MSPs have a higher vol.-based acetone adsorption capacity than Si-MCM-41 so that less space is required for volatile org. compds. (VOCs) adsorption using MSPs as the adsorbent. The pressure drops of both powder and pellet forms of MSPs are also smaller than those of Si-MCM-41 for adsorbing the same amt. of acetone. In addn., as compared to com. H-ZSM-5 zeolite, both MSPs and Si-MCM-41 reveal better performances on the regeneration ability. As a result, both MSPs and Si-MCM-41 show high adsorption/desorption potential but the MSPs are better as novel adsorbents in terms of overall engineering consideration.
- 34Basso, A. M.; Nicola, B. P.; Bernardo-Gusmão, K.; Pergher, S. B. C. Tunable Effect of the Calcination of the Silanol Groups of KIT-6 and SBA-15 Mesoporous Materials. Applied Sciences 2020, 10 (3), 970, DOI: 10.3390/app10030970Google Scholar34Tunable effect of the calcination of the silanol groups of KIT-6 and SBA-15 mesoporous materialsBasso, Adriano M.; Nicola, Bruna P.; Bernardo-Gusmao, Katia; Pergher, Sibele B. C.Applied Sciences (2020), 10 (3), 970CODEN: ASPCC7; ISSN:2076-3417. (MDPI AG)The calcination process is a crucial step during SBA-15 and KIT-6 synthesis. It is used to completely remove the org. template and condense silanol groups, and it allows the detn. of the textural and phys. properties of these materials, depending on the adopted conditions. Moreover, calcination influences the no. of silanols available on the surface of the material. The concn. of silanols is important if these materials were synthesized for use in adsorption or functionalization. To understand and optimize the silanol groups of SBA-15 and KIT-6, in this study, the temp. and time calcination parameters were varied. The expts. were performed at 300, 400, and 500 °C for 300, 400, and 500 min. The results show that the ideal temp. to preserve the silanol groups is 300 °C, but to optimize the textural properties, it is better to calcine these mol. sieves at 400 °C. A calcination for 10 h did not give better results than a calcination for 5 h, demonstrating that the former duration is excessive for use.
- 35Huang, L.; Kawi, S.; Poh, C.; Hidajat, K.; Ng, S. C. Extraction of cationic surfactant templates from mesoporous materials by CH3OH-modified CO2 supercritical fluid. Talanta 2005, 66 (4), 943– 951, DOI: 10.1016/j.talanta.2004.12.057Google Scholar35Extraction of cationic surfactant templates from mesoporous materials by CH3OH-modified CO2 supercritical fluidHuang, L.; Kawi, S.; Poh, C.; Hidajat, K.; Ng, S. C.Talanta (2005), 66 (4), 943-951CODEN: TLNTA2; ISSN:0039-9140. (Elsevier B.V.)Extn. of cationic surfactant templates from MCM-41, MCM-48, SBA-1 and SBA-3 has been conducted using CH3OH-modified CO2 supercrit. fluid. The supercrit. fluid extn. (SFE) has been integrated with thermogravimetry (TG), X-ray diffraction (XRD) and N2 adsorption-desorption to evaluate extn. efficiency and structural stability of mesoporous materials. Expts. of optimization indicate that the conditions of 90 bar, 85 °C, CH3OH/CO2 = 0.1/1.0 mL/min and 3 h are most suitable for the SFE of cationic templates. 76-95% of the cationic templates can be extd. from the mesoporous materials. XRD and N2 adsorption-desorption studies illustrate that SFE possesses some advantages over calcination in maintaining mesoporous uniformity and structural stability when used to remove templates. The impact of curing on mesoporous structure is also dealt with.
- 36Huang, Z.; Huang, L.; Shen, S. C.; Poh, C. C.; Hidajat, K.; Kawi, S.; Ng, S. C. High quality mesoporous materials prepared by supercritical fluid extraction: effect of curing treatment on their structural stability. Microporous Mesoporous Mater. 2005, 80 (1), 157– 163, DOI: 10.1016/j.micromeso.2004.12.016Google Scholar36High quality mesoporous materials prepared by supercritical fluid extraction: effect of curing treatment on their structural stabilityHuang, Z.; Huang, L.; Shen, S. C.; Poh, C. C.; Hidajat, K.; Kawi, S.; Ng, S. C.Microporous and Mesoporous Materials (2005), 80 (1-3), 157-163CODEN: MIMMFJ; ISSN:1387-1811. (Elsevier B.V.)Mesoporous mol. sieves like SBA-1, SBA-3, MCM-41 and MCM-48 are generally synthesized by using a quaternary ammonium surfactant as a structure-directing agent to form a porous SiO2 framework. The used templating agent is conventionally removed for producing mesopores by calcination at high temp. Supercrit. fluid extn. (SFE) was employed to remove org. templates from these materials. More than 80% of the templating agent can be successfully removed by using this technique. Among these materials, SBA-3 was obsd. to experience the collapse of mesoporous structures upon the SFE process. Thus, the authors proposed pre-SFE thermal aging as a curing treatment method and found that it has significantly improved the mesoporous structural stability of SBA-3. In the meantime, this curing method has lead to these SFE-processed materials with better ordered mesoporous structures, such as SBA-3 having sp. surface area as large as 1670 m2/g.
- 37Krawiec, P.; Kockrick, E.; Simon, P.; Auffermann, G.; Kaskel, S. Platinum-Catalyzed Template Removal for the in Situ Synthesis of MCM-41 Supported Catalysts. Chem. Mater. 2006, 18 (11), 2663– 2669, DOI: 10.1021/cm052830nGoogle Scholar37Platinum-Catalyzed Template Removal for the in Situ Synthesis of MCM-41 Supported CatalystsKrawiec, Piotr; Kockrick, Emanuel; Simon, Paul; Auffermann, Gudrun; Kaskel, StefanChemistry of Materials (2006), 18 (11), 2663-2669CODEN: CMATEX; ISSN:0897-4756. (American Chemical Society)Platinum-contg. MCM-41 was synthesized in a one step approach. In this new procedure, the swelling agent (toluene) was used as a transport medium to inject the Pt precursor, Pt(acetylacetonate)2, directly into the inner core of the surfactant micelles. A 1 wt % metal loading was achieved without the loss of pore ordering, while samples with 2 wt % loading showed a less ordered structure. A total of 80-100% of the Pt precursor was incorporated in the porous host matrix depending on the precursor concn. and final loading. During the calcination process, platinum acts as a catalyst for the oxidative removal of the surfactant mols., allowing one to decrease the calcination temp. significantly. The calcined material had a high surface area (1000-1200 m2 g-1). Platinum particles could be detected using transmission electron microscopy confirming also the absence of large particles outside the mesopore system. The in situ approach was also applied to prep. other metal/MCM-41 or oxide/MCM-41 materials such as Pd/MCM-41 and V2O5/MCM-41. Both of them showed a high degree of guest incorporation and no significant decrease in surface area. In situ incorporation of metals into SBA-15 resulted in a lower Pt incorporation in the final material (50-60%) and a disordered pore structure, even for low Pt loading (1 wt %). The accessibility of the metallic particles for catalytic reactions was demonstrated using the hydrogenation of cinnamic acid as a model reaction. The highest specific reaction rates were obsd. for Pd supported on MCM-41 and were comparable to that of com. available Pd/carbon catalysts.
- 38Zaleski, R.; Wawryszczuk, J.; Borówka, A.; Goworek, J.; Goworek, T. Temperature changes of the template structure in MCM-41 type materials; positron annihilation studies. Microporous Mesoporous Mater. 2003, 62 (1), 47– 60, DOI: 10.1016/S1387-1811(03)00389-5Google Scholar38Temperature changes of the template structure in MCM-41 type materials; positron annihilation studiesZaleski, Radoslaw; Wawryszczuk, Jan; Borowka, Anna; Goworek, Jacek; Goworek, TomaszMicroporous and Mesoporous Materials (2003), 62 (1-2), 47-60CODEN: MIMMFJ; ISSN:1387-1811. (Elsevier Science B.V.)The lifetime spectra of positrons annihilating in MCM-41 ordered silica were measured as a function of temp. It was found that in alkyltrimethylammonium templates degrdn. in vacuum begins at 380-400 K, that consists in breaking the long micelle cylinders, rise of gaps between the fragments and finally pore evacuation. The latter process is not completed and particularly in C12TAB the spectrum component belonging to fragmented template preserves its high intensity up to 520 K (the highest temp. in our expt.). The pore surface area over 1000 m2/g is achieved already at temps. about 490 K. The lifetime of the longest-lived component indicates that practically all ortho-positronium atoms leave the pores before annihilation.
- 39Ryczkowski, J.; Goworek, J.; Gac, W.; Pasieczna, S.; Borowiecki, T. Temperature removal of templating agent from MCM-41 silica materials. Thermochim. Acta 2005, 434 (1), 2– 8, DOI: 10.1016/j.tca.2004.12.020Google Scholar39Temperature removal of templating agent from MCM-41 silica materialsRyczkowski, J.; Goworek, J.; Gac, W.; Pasieczna, S.; Borowiecki, T.Thermochimica Acta (2005), 434 (1-2), 2-8CODEN: THACAS; ISSN:0040-6031. (Elsevier B.V.)Temp.-programmed desorption coupled with mass spectrometry, FTIR spectroscopy with photoacoustic (PA) detector were applied to investigate org. template degrdn. during thermal treatment of as-prepd. MCM-41 silica. Micelle-templated silica was prepd. using C18 trimethylammonium bromide. The processes accompanying the template transformations were investigated in argon flow and mixed oxygen-helium atm. Template removal appears to be completely different in the inert gas atm. and at the presence of oxygen. The results obtained for as-prepd. sample were compared with those for calcined sample in air and addnl. thermally treated in oxygen flow. Spectroscopic data indicate the presence of a variety of chem. species on silica surface after template removal. Addnl. oxidn. of calcined sample leads to elimination of most org. functional groups and increase of siloxane bridges as a product of surface silanols condensation.
- 40Goworek, J.; Kierys, A.; Kusak, R. Isothermal template removal from MCM-41 in hydrogen flow. Microporous Mesoporous Mater. 2007, 98 (1), 242– 248, DOI: 10.1016/j.micromeso.2006.09.011Google Scholar40Isothermal template removal from MCM-41 in hydrogen flowGoworek, Jacek; Kierys, Agnieszka; Kusak, RyszardMicroporous and Mesoporous Materials (2007), 98 (1-3), 242-248CODEN: MIMMFJ; ISSN:1387-1811. (Elsevier B.V.)Thermal evacuation of template surfactant from MCM-41 in hydrogen atm. was studied. Micelle templated SiO2 was prepd. using hexadecyltrimethylammonium bromide. The mechanism of template removal appears to be completely different in hydrogen as compared to calcination in air. It seems that moderate heating of as-synthesized MCM-41 (up to ∼250°) in hydrogen stream for ∼15 h is effective and simple method of template removal leaving no pure C residues on SiO2 surface. Adsorption properties of partially evacuated MCM-41 samples were tested using gas chromatog. Products of template degrdn. were analyzed using GC-MS technique. The main products of template degrdn. at 250° in hydrogen flow are hexadecene and hexadecane-N,N-dimethylamine. Concn. of surface silanols for MCM-41 calcined and thermally treated in hydrogen flow was studied by NMR technique.
- 41Camel, V.; Tambuté, A.; Caude, M. Analytical-scale supercritical fluid extraction: a promising technique for the determination of pollutants in environmental matrices. J. Chromatogr. A 1993, 642 (1), 263– 281, DOI: 10.1016/0021-9673(93)80093-NGoogle ScholarThere is no corresponding record for this reference.
- 42Hawthorne, S. B. Analytical-scale supercritical fluid extraction. Anal. Chem. 1990, 62 (11), 633A– 642A, DOI: 10.1021/ac00210a722Google Scholar42Analytical-scale supercritical fluid extractionHawthorne, Steven B.Analytical Chemistry (1990), 62 (11), 633A-636A, 638A-642ACODEN: ANCHAM; ISSN:0003-2700.A review with 57 refs. The selection of supercrit. fluids, prediction of optimal conditions, development and availability of app. and techniques, and applications (both off-line and online, i.e. combined with GC and supercrit.-fluid chromatog.) are covered.
- 43Huang, Z.; Luan, D. Y.; Shen, S. C.; Hidajat, K.; Kawi, S. Supercritical fluid extraction of the organic template from synthesized porous materials: effect of pore size. Journal of Supercritical Fluids 2005, 35 (1), 40– 48, DOI: 10.1016/j.supflu.2004.11.001Google Scholar43Supercritical fluid extraction of the organic template from synthesized porous materials: effect of pore sizeHuang, Z.; Luan, D.-Y.; Shen, S.-C.; Hidajat, K.; Kawi, S.Journal of Supercritical Fluids (2005), 35 (1), 40-48CODEN: JSFLEH; ISSN:0896-8446. (Elsevier B.V.)Supercrit. fluid extn. was evaluated for removing surfactants from freshly synthesized mol. sieve powders possessing different pore sizes. In study, MeOH- or H2O-enhanced supercrit. CO2 extn. was carried out on as-synthesized microporous and mesoporous material powders. Very high surfactant recovery (over 80%) could be achieved from large pore-sized mesoporous materials by using the SFE method, while the surfactant recovery is rather low from small pore-sized microporous zeolite materials. Supercrit. fluid extn. technol. may provide a potential method for large-scale prodn. of mesoporous materials with effective surfactant recovery that is extremely efficient.
- 44Lu, X.-B.; Zhang, W.-H.; Xiu, J.-H.; He, R.; Chen, L.-G.; Li, X. Removal of the Template Molecules from MCM-41 with Supercritical Fluid in a Flow Apparatus. Ind. Eng. Chem. Res. 2003, 42 (3), 653– 656, DOI: 10.1021/ie020422cGoogle Scholar44Removal of the Template Molecules from MCM-41 with Supercritical Fluid in a Flow ApparatusLu, Xiao-Bing; Zhang, Wen-Hua; Xiu, Jing-Hai; He, Ren; Chen, Lu-Guang; Li, XiaoIndustrial & Engineering Chemistry Research (2003), 42 (3), 653-656CODEN: IECRED; ISSN:0888-5885. (American Chemical Society)Supercrit. CO2 modified with a methanol/dichloromethane mixt. was used to quant. remove the template mols. (cetyltrimethylammonium bromide) from the pores of as-synthesized pure siliceous MCM-41 in a flow app. The resulting mesoporous MCM-41 materials, characterized by powder x-ray diffraction, nitrogen adsorption, and high-resoln. transmission electron microscopy, exhibited higher surface areas, larger pores, and narrower pore size distributions than those obtained by conventional calcination at high temp. The removed template retained its structures and properties and could be reused in the synthesis of MCM-41 materials.
- 45van Grieken, R.; Calleja, G.; Stucky, G. D.; Melero, J. A.; García, R. A.; Iglesias, J. Supercritical Fluid Extraction of a Nonionic Surfactant Template from SBA-15 Materials and Consequences on the Porous Structure. Langmuir 2003, 19 (9), 3966– 3973, DOI: 10.1021/la026970cGoogle Scholar45Supercritical Fluid Extraction of a Nonionic Surfactant Template from SBA-15 Materials and Consequences on the Porous StructureVan Grieken, Rafael; Calleja, Guillermo; Stucky, Galen D.; Melero, Juan A.; Garcia, Rafael A.; Iglesias, JoseLangmuir (2003), 19 (9), 3966-3973CODEN: LANGD5; ISSN:0743-7463. (American Chemical Society)SBA-15 mesoporous materials were synthesized using the method reported by Zhao et al. Surfactant was removed from as-made materials by means of different techniques: thermal treatment under air atm., solvent washing at different temps., and supercrit. CO2 extn. in the presence and absence of cosolvents. The structure of resulting materials was characterized using conventional techniques: nitrogen and argon adsorption measurements, powder X-ray diffraction (XRD), thermogravimetric anal. (TGA), IR spectroscopy (FT-IR), and 29Si MAS NMR. The efficiency of surfactant removal using CO2 under supercrit. conditions is similar to that obtained by means of solvent washing under reflux but shows some improvements in the presence of cosolvents. Mesoscopic properties of mild-temp. solvent extd. SBA-15 materials depend on the efficiency of the surfactant removal and the use of supercrit. CO2 as solvent. Likewise, the size and vol. of the complementary microporosity detected in the treated materials is closely related to the strategy of removal of hydrophilic poly(ethylene oxide) chains of the triblock copolymer template occluded within the siliceous walls of the SBA-15 mesophase during the synthesis.
- 46Huang, Z.; Li, J.-h.; Li, H.-s.; Teng, L.-j.; Kawi, S.; Lai, M. W. Effects of polar modifiers on supercritical extraction efficiency for organic template removal from mesoporous MCM-41 materials. The. J. Supercrit. Fluids 2013, 82, 96– 105, DOI: 10.1016/j.supflu.2013.06.012Google Scholar46Effects of polar modifiers on supercritical extraction efficiency for organic template removal from mesoporous MCM-41 materialsHuang, Zhen; Li, Jing-huan; Li, Hui-shan; Teng, Li-jun; Kawi, S.; Lai, M. W.Journal of Supercritical Fluids (2013), 82 (), 96-105CODEN: JSFLEH; ISSN:0896-8446. (Elsevier B.V.)The application of polar modifiers usually can make supercrit. CO2 extn. more attractive in various potential applications. In this work, several polar modifiers have been examd. for the extn. of the template cetyltrimethylammonium bromide (CTMABr) from newly synthesized MCM-41 mesoporous materials, and the modifier content, modifier identity and the sample matrix on supercrit. CO2 extn. efficiency are then evaluated. The results show that the polar modifiers employed have strong influences on the template extn. efficiencies and this could be interpreted rather well in terms of soly. parameter and polarity of the modifiers. Methanol, water and acidic methanol are found to result in very high efficiencies of more than 85% for the pure siliceous samples while relatively good extn. efficiencies of 60-80% for aluminum incorporated samples, and the difference is due to that the org. template could form stronger interactions with the Al species than the silanol groups. Nitrogen adsorption/desorption and X-ray diffraction results confirmed that the polar modifiers have strong influences on the final mesoporous structure of the MCM-41 materials and with methanol modified supercrit. CO2 extn. the resultant materials possess well-ordered mesostructure and much better structural properties like higher pore vol. and sp. surface area.
- 47Huang, Z.; Xu, L.; Li, J.-H.; Kawi, S.; Goh, A. H. Organic template removal from hexagonal mesoporous silica by means of methanol-enhanced CO2 extraction: Effect of temperature, pressure and flow rate. Sep. Purif. Technol. 2011, 77 (1), 112– 119, DOI: 10.1016/j.seppur.2010.11.029Google Scholar47Organic template removal from hexagonal mesoporous silica by means of methanol-enhanced CO2 extraction: Effect of temperature, pressure and flow rateHuang, Zhen; Xu, Li; Li, Jing-Huan; Kawi, S.; Goh, A. H.Separation and Purification Technology (2011), 77 (1), 112-119CODEN: SPUTFP; ISSN:1383-5866. (Elsevier B.V.)Supercrit. fluid extn. was evaluated for removing the amine surfactant from hexagonal mesoporous silica materials. In this study, methanol-enhanced supercrit. CO2 extn. was carried out on freshly synthesized materials by a dynamic method. Expts. were performed at pressure ranging from 10.0 to 25.0 MPa, temp. from 45 to 105°, CO2 flow rate from 0.45 to 4.5 mL/min, and methanol flow rate from 0.05 to 0.5 mL/min. The influence of these parameters on the extn. was evaluated in terms of the surfactant recovery. By using this method up to 96% of the total amine surfactant used is extd. out of as-synthesized mesoporous materials within 1 h extn. whereas only 78% of the surfactant can be removed by liq. ethanol extn. The materials processed by supercrit. CO2 extn. are found to possess better structural properties as reflected by the x-ray diffraction anal. and N2 adsorption results, and thus have higher thermal and hydrothermal stability than those obtained by liq. ethanol extn. or high temp. calcination.
- 48Chen, L.; Jiang, S.; Wang, R.; Zhang, Z.; Qiu, S. A novel, efficient and facile method for the template removal from mesoporous materials. Chemical Research in Chinese Universities 2014, 30 (6), 894– 899, DOI: 10.1007/s40242-014-4202-zGoogle Scholar48A novel, efficient and facile method for the template removal from mesoporous materialsChen, Lu; Jiang, Shang; Wang, Runwei; Zhang, Zongtao; Qiu, ShilunChemical Research in Chinese Universities (2014), 30 (6), 894-899CODEN: CRCUED; ISSN:1005-9040. (Jilin University)A new catalytic-oxidn. method was adopted to remove the templates from SBA-15 and MCM-41 mesoporous materials via Fenton-like techniques under microwave irradn. The mesoporous silica materials were treated with different Fenton agents based on the template's property and textural property. The samples were characterized by powder X-ray diffraction(XRD) measurement, N2 adsorption-desorption isotherms, IR spectroscopy, 29Si MAS NMR and thermo gravimetric anal.(TGA). The results reveal that this is an efficient and facile approach to the thorough template-removal from mesoporous silica materials, as well as to offering products with more stable structures, higher BET surface areas, larger pore vols. and larger quantity of silanol groups.
- 49Tian, B.; Liu, X.; Yu, C.; Gao, F.; Luo, Q.; Xie, S.; Tu, B.; Zhao, D. Microwave assisted template removal of siliceous porous materials. Chem. Commun. 2002, (11), 1186– 1187, DOI: 10.1039/b202180cGoogle Scholar49Microwave assisted template removal of siliceous porous materialsTian, Bozhi; Liu, Xiaoying; Yu, Chengzhong; Gao, Feng; Luo, Qian; Xie, Songhai; Tu, Bo; Zhao, DongyuanChemical Communications (Cambridge, United Kingdom) (2002), (11), 1186-1187CODEN: CHCOFS; ISSN:1359-7345. (Royal Society of Chemistry)Org. templates of meso- and macro-porous siliceous materials can be completely removed within minutes by microwave digestion, resulting in highly ordered inorg. frameworks with higher surface areas, larger pore vols., lower structural shrinkage and richer silanol groups compared with those from conventional template removal methods.
- 50Lai, T.-L.; Shu, Y.-Y.; Lin, Y.-C.; Chen, W.-N.; Wang, C.-B. Rapid removal of organic template from SBA-15 with microwave assisted extraction. Mater. Lett. 2009, 63 (20), 1693– 1695, DOI: 10.1016/j.matlet.2009.05.014Google Scholar50Rapid removal of organic template from SBA-15 with microwave assisted extractionLai, Teh-Long; Shu, Youn-Yuen; Lin, Ya-Chu; Chen, Wan-Ning; Wang, Chen-BinMaterials Letters (2009), 63 (20), 1693-1695CODEN: MLETDJ; ISSN:0167-577X. (Elsevier B.V.)The removal of surfactant templates from the pores of as-prepd. SBA-15 was studied by means of microwave assisted extn. (MAE). Occluded surfactant mols. within SBA-15 were completely removed within 6 min by the MAE method, resulting in frameworks with higher surface area, lower structural shrinkage and richer silanol groups than that of thermocalcined samples. The MAE sample exhibited larger surface area (ca. 1000 m2/g-1) than the sample treated by thermocalcining (ca. 560 m2/g-1). As detd. the enrichment of PAHs on MAE with calcined samples by online solid-phase extn. HPLC, the MAE sample possessed more enrichment and lower detection limit than the calcined sample.
- 51Li, X.; Yin, H.; Zhang, J.; Liu, J.; Chen, G. Effect of organic template removal approaches on physiochemical characterization of Ni/Al-SBA-15 and eugenol hydrodeoxygenation. J. Solid State Chem. 2020, 282, 121063, DOI: 10.1016/j.jssc.2019.121063Google Scholar51Effect of organic template removal approaches on physiochemical characterization of Ni/Al-SBA-15 and eugenol hydrodeoxygenationLi, Xiangping; Yin, Han; Zhang, Jianguang; Liu, Juping; Chen, GuanyiJournal of Solid State Chemistry (2020), 282 (), 121063CODEN: JSSCBI; ISSN:0022-4596. (Elsevier B.V.)Template removing approaches can significantly impact the physiochem. properties of mesoporous mol. sieve materials. In order to better understand the relationship between template removing approaches and the properties of Ni/Al-SBA-15, four kinds of template removing approaches were introduced to remove the org. template from Al-SBA-15, resp. The structural characteristics of these materials were analyzed by transmission electron microscopy (TEM), SEM (SEM), X-ray fluorescence (XRF), powder X-ray diffraction (XRD), N2-sorption, Fourier transform IR spectra (FT-IR), IR spectra of pyridine adsorption (Py-FTIR), magic angle spinning-NMR (MAS-NMR), XPS and gas chromatog.-mass spectrometry (GC-MS). Ni/Al-SBA-15 of which the org. template was removed by two-step calcination method had the max. sp. surface area (619 m2/g). In contrast, Ni/Al-SBA-15 of which the org. template was removed using solvent extn. approaches had the lowest sp. surface area (555 m2/g). The mesopore diam. of Ni/Al-SBA-15, using elec. heating digestion method to remove the template, was significantly increased and the wall thickness was significantly decreased to 11.62 nm in comparison with the other samples. The selectivity of products during the process of eugenol hydrodeoxygenation was investigated. High hydrocarbons were obtained during catalytic hydrodeoxygenation over Ni/Al-SBA-15 of which the org. template was removed by using solvent extn. approaches. Compared with direct calcination process, two-step calcination was more effective in removing template and the corresponding catalyst was much more suitable for the hydrodeoxygenation process.
- 52López-Pérez, L.; López-Martínez, M.-A.; Djanashvili, K.; Góra-Marek, K.; Tarach, K. A.; Borges, M. E.; Melián-Cabrera, I. Process Intensification of Mesoporous Material’s Synthesis by Microwave-Assisted Surfactant Removal. ACS Sustainable Chem. Eng. 2020, 8 (45), 16814– 16822, DOI: 10.1021/acssuschemeng.0c05438Google Scholar52Process intensification of mesoporous material's synthesis by microwave-assisted surfactant removalLopez-Perez, Lidia; Lopez-Martinez, Marco-Antonio; Djanashvili, Kristina; Gora-Marek, Kinga; Tarach, Karolina A.; Borges, Maria Emma; Melian-Cabrera, IgnacioACS Sustainable Chemistry & Engineering (2020), 8 (45), 16814-16822CODEN: ASCECG; ISSN:2168-0485. (American Chemical Society)Mesoporous materials are of vital importance for use in sepn., adsorption, and catalysis. The first step in their prepn. consists of synthesizing an org.-inorg. hybrid in which a structuring directing agent (SDA, normally a surfactant) is used to provide the desired porosity. The most common method to eliminate the SDA, and generate the porosity, is high-temp. calcination. Such a process is energy-intensive and slow. In this study, we investigated alternative nonthermal surfactant removal methods on a soft MCM-41 material, aiming at reducing the processing time and temp., while maximizing the material's properties. The choice of a soft MCM-41 is crit. since it is hydrothermally unstable, whereas the SDA removal is troublesome. Microwave processing yielded outstanding performance in terms of surfactant removal, structural preservation, and textural features; the surfactant was fully removed, the hexagonal structure was preserved, and the surface was highly rich in Si-OH groups. It is suggested that H2O2 is the dominant oxidant. In terms of the process features, the processing time is significantly reduced, 14 h (calcination) vs. 5 min (microwaves), and the applied temp. is much lower. The energy savings were estd. to be 72% lower as compared to calcination; therefore, this approach contributes to the process intensification of a very relevant material's prodn. Microwave processing of MCM-41 yielded outstanding performance in terms of surfactant removal, structural preservation, and textural characteristics, with improved processing features.
- 53Qiao, S. Z.; Liu, J.; Max Lu, G. Q. Chapter 21 - Synthetic Chemistry of Nanomaterials. In Modern Inorganic Synthetic Chemistry, Second ed.; Xu, R.; Xu, Y., Eds.; Elsevier: Amsterdam, 2017; pp 613– 640.Google ScholarThere is no corresponding record for this reference.
- 54Perelshtein, I.; Perkas, N.; Gedanken, A. Chapter 3 - Making the Hospital a Safer Place by the Sonochemical Coating of Textiles by Antibacterial Nanoparticles. In Surface Chemistry of Nanobiomaterials; Grumezescu, A. M., Ed.; William Andrew Publishing, 2016; pp 71– 105.Google ScholarThere is no corresponding record for this reference.
- 55Suslick, K. S.; Hammerton, D. A.; Cline, R. E. Sonochemical hot spot. J. Am. Chem. Soc. 1986, 108 (18), 5641– 5642, DOI: 10.1021/ja00278a055Google Scholar55Sonochemical hot spotSuslick, Kenneth S.; Hammerton, David A.; Cline, Raymond E., Jr.Journal of the American Chemical Society (1986), 108 (18), 5641-2CODEN: JACSAT; ISSN:0002-7863.The chem. effects of ultrasound result from acoustic cavitation: the creation, expansion, and implosive collapse of bubbles in ultrasonically irradiated liqs. We have used the sonochem. ligand substitution rates of volatile metal carbonyls to establish the site of sonochem. reactions and fluid that there are two regions of sonochem. reactivity: one corresponding to the gas phase within the collapsing cavity, and the second to a thin liq. layer immediately surrounding the collapsing cavity. Furthermore, we have detd. exptl. the effective temp. in each reaction zone, through the use of comparative rate thermometry. The gas and liq. phase reaction zones have effective temps. of 5200°K and 1900°K, resp. Using a simple thermal conduction model, the liq. reaction zone is estd. to be ≈200 nm thick and to have a lifetime of less than 2 μsec.
- 56Moradi, E.; Rahimi, R.; Safarifard, V. Sonochemically synthesized microporous metal–organic framework representing unique selectivity for detection of Fe3+ ions. Polyhedron 2019, 159, 251– 258, DOI: 10.1016/j.poly.2018.11.062Google Scholar56Sonochemically synthesized microporous metal-organic framework representing unique selectivity for detection of Fe3+ ionsMoradi, Ehsan; Rahimi, Rahmatollah; Safarifard, VahidPolyhedron (2019), 159 (), 251-258CODEN: PLYHDE; ISSN:0277-5387. (Elsevier Ltd.)Synthesis of metal-org. framework (MOF) materials via ultrasound (US) irradn. involves shorter reaction times and offers enhanced control of particle size and morphol. compared to conventional elec. heating. Here, we report the exploration of highly luminescent three-dimensional microporous metal-org. framework, [Zn2(oba)2(bpy)], (1; H2oba = 4,4'-oxybis(benzoic acid); bpy = 4,4'-bipyridine) synthesized by sonochem. for highly selective and sensitive detection of Fe3+ in MeOH soln. via a fluorescence quenching mechanism. Fluorescence titrn. expts. reveal that 1 is highly selective for Fe3+ ion with a response time of <2 min and the limit of detection (LOD) reaches a low level of 0.3μM (17 ppb). The luminescence is completely quenched in 100μM MeOH soln. of Fe3+. Furthermore, the static quenching const. is calcd. to be upper than 58 000 M-1 by the fluorescence titrn. expt. in low concn. of Fe3+. No interferences from 250μM As3+, Cd2+, Zn2+, Co2+, Ni2+, Cu2+, Pb2+, Mn2+ and Al3+ were found for the detection of Fe3+. Importantly, 1 can be cycled at least four times without loss of emission signals, which suggests that the functionalized 1 is a promising luminescent probe for selectively sensing of Fe3+ ions.
- 57Bang, J. H.; Suslick, K. S. Applications of Ultrasound to the Synthesis of Nanostructured Materials. Adv. Mater. 2010, 22 (10), 1039– 1059, DOI: 10.1002/adma.200904093Google Scholar57Applications of ultrasound to the synthesis of nanostructured materialsBang, Jin Ho; Suslick, Kenneth S.Advanced Materials (Weinheim, Germany) (2010), 22 (10), 1039-1059CODEN: ADVMEW; ISSN:0935-9648. (Wiley-VCH Verlag GmbH & Co. KGaA)A review. Recent advances in nanostructured materials have been led by the development of new synthetic methods that provide control over size, morphol., and nano/microstructure. The utilization of high intensity ultrasound offers a facile, versatile synthetic tool for nanostructured materials that are often unavailable by conventional methods. The primary phys. phenomena assocd. with ultrasound that are relevant to materials synthesis are cavitation and nebulization. Acoustic cavitation (the formation, growth, and implosive collapse of bubbles in a liq.) creates extreme conditions inside the collapsing bubble and serves as the origin of most sonochem. phenomena in liqs. or liq.-solid slurries. Nebulization (the creation of mist from ultrasound passing through a liq. and impinging on a liq.-gas interface) is the basis for ultrasonic spray pyrolysis (USP) with subsequent reactions occurring in the heated droplets of the mist. In both cases, there are examples of phase-sepd. attoliter microreactors: for sonochem., it is a hot gas inside bubbles isolated from one another in a liq., while for USP it is hot droplets isolated from one another in a gas. Cavitation-induced sonochem. provides a unique interaction between energy and matter, with hot spots inside the bubbles of ∼5000 K, pressures of ∼1000 bar, heating and cooling rates of > 1010 K s-1; these extraordinary conditions permit access to a range of chem. reaction space normally not accessible, which allows for the synthesis of a wide variety of unusual nanostructured materials. Complementary to cavitational chem., the microdroplet reactors created by USP facilitate the formation of a wide range of nanocomposites. In this review, the fundamental principles are summarized of both synthetic methods and recent development in the applications of ultrasound in nanostructured materials synthesis.
- 58Hinman, J. J.; Suslick, K. S., Nanostructured Materials Synthesis Using Ultrasound. In Sonochemistry: From Basic Principles to Innovative Applications; Colmenares, J. C., Chatel, G., Eds.; Springer International Publishing: Cham, 2017; pp 59– 94.Google ScholarThere is no corresponding record for this reference.
- 59Xu, H.; Zeiger, B. W.; Suslick, K. S. Sonochemical synthesis of nanomaterials. Chem. Soc. Rev. 2013, 42 (7), 2555– 2567, DOI: 10.1039/C2CS35282FGoogle Scholar59Sonochemical synthesis of nanomaterialsXu, Hangxun; Zeiger, Brad W.; Suslick, Kenneth S.Chemical Society Reviews (2013), 42 (7), 2555-2567CODEN: CSRVBR; ISSN:0306-0012. (Royal Society of Chemistry)A review with 92 refs. on sonochem. synthesis of nanomaterials and sonochem. decompn. of volatile organometallic precursors in high-boiling solvents produces nanostructured materials in various forms with high catalytic activities. High intensity ultrasound can be used for the prodn. of novel materials and provides an unusual route to known materials without bulk high temps., high pressures, or long reaction times. Several phenomena are responsible for sonochem. and specifically the prodn. or modification of nanomaterials during ultrasonic irradn. The most notable effects are consequences of acoustic cavitation (the formation, growth, and implosive collapse of bubbles), and can be categorized as primary sonochem. (gas-phase chem. occurring inside collapsing bubbles), secondary sonochem. (soln.-phase chem. occurring outside the bubbles), and phys. modifications (caused by high-speed jets or shock waves derived from bubble collapse). This tutorial review provides examples of how the chem. and phys. effects of high intensity ultrasound can be exploited for the prepn. or modification of a wide range of nanostructured materials.
- 60Jabariyan, S.; Zanjanchi, M. A. A simple and fast sonication procedure to remove surfactant templates from mesoporous MCM-41. Ultrason. Sonochem. 2012, 19 (5), 1087– 1093, DOI: 10.1016/j.ultsonch.2012.01.012Google Scholar60A simple and fast sonication procedure to remove surfactant templates from mesoporous MCM-41Jabariyan, Shaghayegh; Zanjanchi, Mohammad A.Ultrasonics Sonochemistry (2012), 19 (5), 1087-1093CODEN: ULSOER; ISSN:1350-4177. (Elsevier B.V.)Demonstrated is a sonication procedure for the removal of structure-directing micellar templates from mesoporous MCM-41. The method uses a 28 KHz ultrasound in an alc. solvent for disrupting micellar aggregation of the surfactant mols., cetyltrimethylammonium bromide, which have filled the pores of the as-prepd. MCM-41. The majority (93%) of the surfactant mols. are removed out from the powder MCM-41 within a 15 min one-step sonication at a moderate temp. of 40°. The structural and textural characterization techniques reveal that the resulted surfactant-free MCM-41 exhibits higher features compared to that of those obtained using the conventional calcinations approaches. The surfactant mols. are released into alc. and can be recovered for reuse. This study provides an easy, cost-effective, mild, and useful method for template removal from mesoporous materials at conventional conditions.
- 61Zanjanchi, M. A.; Jabariyan, S. Application of ultrasound and methanol for rapid removal of surfactant from MCM-41. J. Serb. Chem. Soc. 2014, 79 (1), 25– 38, DOI: 10.2298/JSC130112056AGoogle Scholar61Application of ultrasound and methanol for the rapid removal of surfactant from MCM-41 molecular sieveZanjanchi, Mohammad A.; Jabariyan, ShaghayeghJournal of the Serbian Chemical Society (2014), 79 (1), 25-38CODEN: JSCSEN; ISSN:0352-5139. (Serbian Chemical Society)Ultrasound waves were successfully applied for the removal of the template from mesoporous MCM-41 mol. sieve. The method uses 28 KHz ultrasound irradn. in a methanol solvent for disrupting the micellar aggregation of the surfactant mols., cetyltrimethylammonium bromide, which fill the pores of as-synthesized MCM-41. After 15 min sonication at the moderate temp. of 40 °C, the majority of surfactant mols. had been removed from powder MCM-41. The template removal rate using ultrasound irradn. (15 min) is faster than the rate obtained via thermal calcination. In addn., a perfect hexagonal pore structure was obtained after template removal using ultrasound irradn., according to characterization using X-ray diffraction (XRD) and nitrogen adsorption analyses, while high temps. during calcination cause shrinkage that affected the surface properties of the materials. In the present procedure, the surfactant mols. are released into methanol and can be recovered for reuse. The effectiveness of the sonication-prepd. MCM-41 as an adsorbent was confirmed by the adsorption of methylene blue (MB).
- 62Pirez, C.; Wilson, K.; Lee, A. F. An energy-efficient route to the rapid synthesis of organically-modified SBA-15 via ultrasonic template removal. Green Chem. 2014, 16 (1), 197– 202, DOI: 10.1039/C3GC40474AGoogle Scholar62An energy-efficient route to the rapid synthesis of organically-modified SBA-15 via ultrasonic template removalPirez, Cyril; Wilson, Karen; Lee, Adam F.Green Chemistry (2014), 16 (1), 197-202CODEN: GRCHFJ; ISSN:1463-9262. (Royal Society of Chemistry)A low energy route for the removal of Pluronic P123 surfactant template during the synthesis of SBA-15 mesoporous silica is explored. The conventional reflux of the hybrid inorg.-org. intermediate formed during co-condensation routes to Pr-SO3H-SBA-15 is slow, utilizes large solvent vols., and requires 24 h to remove ∼90% of the org. template. In contrast, room temp. ultrasonication in a small methanol vol. achieves the same degree of template extn. in only 5 min, with a 99.9% energy saving and 90% solvent redn., without compromising the textural, acidic or catalytic properties of the resultant Pr-SO3H-SBA-15.
- 63Li, F.; Xie, C.; Cheng, Z.; Xia, H. Ultrasound responsive block copolymer micelle of poly(ethylene glycol)–poly(propylene glycol) obtained through click reaction. Ultrason. Sonochem. 2016, 30, 9– 17, DOI: 10.1016/j.ultsonch.2015.11.023Google Scholar63Ultrasound responsive block copolymer micelle of poly(ethylene glycol)-poly(propylene glycol) obtained through click reactionLi, Fayong; Xie, Chuan; Cheng, Zhengang; Xia, HeshengUltrasonics Sonochemistry (2016), 30 (), 9-17CODEN: ULSOER; ISSN:1350-4177. (Elsevier B.V.)The well-defined amphiphilic poly(ethylene glycol)-block-poly(propylene glycol) copolymer contg. 1, 2, 3-triazole moiety and multiple ester bonds (PEG-click-PPG) was prepd. by click reaction strategy. The PEG-click-PPG copolymer can self-assemble into spherical micelles in aq. soln. It is found that high intensity focused ultrasound (HIFU) can open the copolymer PEG-click-PPG micelles and trigger the release of the payload in the micelle. The multiple ester bonds introduced in the junction point of the copolymer chain through click reactions were cleaved under HIFU, and leads to the disruption of the copolymer micelle and fast release of loaded cargo. The click reaction provides a convenient way to construct ultrasound responsive copolymer micelles with weak bonds.
- 64Husseini, G. A.; Pitt, W. G. Micelles and nanoparticles for ultrasonic drug and gene delivery. Adv. Drug Delivery Rev. 2008, 60 (10), 1137– 1152, DOI: 10.1016/j.addr.2008.03.008Google Scholar64Micelles and nanoparticles for ultrasonic drug and gene deliveryHusseini, Ghaleb A.; Pitt, William G.Advanced Drug Delivery Reviews (2008), 60 (10), 1137-1152CODEN: ADDREP; ISSN:0169-409X. (Elsevier B.V.)A review. Drug delivery research employing micelles and nanoparticles has expanded in recent years. Of particular interest is the use of these nanovehicles that deliver high concns. of cytotoxic drugs to diseased tissues selectively, thus reducing the agent's side effects on the rest of the body. Ultrasound, traditionally used in diagnostic medicine, is finding a place in drug delivery in connection with these nanoparticles. In addn. to their noninvasive nature and the fact that they can be focused on targeted tissues, acoustic waves have been credited with releasing pharmacol. agents from nanocarriers, as well as rendering cell membranes more permeable. In this article, we summarize new technologies that combine the use of nanoparticles with acoustic power both in drug and gene delivery. Ultrasonic drug delivery from micelles usually employs polyether block copolymers and has been found effective in vivo for treating tumors. Ultrasound releases drug from micelles, most probably via shear stress and shock waves from the collapse of cavitation bubbles. Liq. emulsions and solid nanoparticles are used with ultrasound to deliver genes in vitro and in vivo. The small packaging allows nanoparticles to extravasate into tumor tissues. Ultrasonic drug and gene delivery from nanocarriers has tremendous potential because of the wide variety of drugs and genes that could be delivered to targeted tissues by fairly non-invasive means.
- 65Xuan, J.; Pelletier, M.; Xia, H.; Zhao, Y. Ultrasound-Induced Disruption of Amphiphilic Block Copolymer Micelles. Macromol. Chem. Phys. 2011, 212 (5), 498– 506, DOI: 10.1002/macp.201000624Google Scholar65Ultrasound-Induced Disruption of Amphiphilic Block Copolymer MicellesXuan, Juan; Pelletier, Maxime; Xia, Hesheng; Zhao, YueMacromolecular Chemistry and Physics (2011), 212 (5), 498-506CODEN: MCHPES; ISSN:1022-1352. (Wiley-VCH Verlag GmbH & Co. KGaA)Ultrasound-induced disruption of PEO-b-PTHPMA, PEO-b-PIBMA, PEO-b-PTHFEMA, and PEO-b-PMMA block copolymer micelles in aq. soln. was investigated. Fluorescence change of loaded NR, DLS, IR, AFM, and SEM show that those micelles could be disrupted differently by 1.1 MHz high-intensity focused ultrasound beams. The micelles of PEO-b-PIBMA and PEO-b-PTHPMA appear to be more sensitive to ultrasound irradn., resulting in a more severe micellar disruption, and IR spectra show evidence of ultrasound-induced chem. reactions, most likely hydrolysis. PEO-b-PMMA appear to resist HIFU irradn. better, and IR anal. found no evidence of chem. reactions. This study provides new evidence for the prospect of ultrasound-responsive BCP micelles for controlled delivery applications.
- 66Hozumi, A.; Yokogawa, Y.; Kameyama, T.; Hiraku, K.; Sugimura, H.; Takai, O.; Okido, M. Photocalcination of Mesoporous Silica Films Using Vacuum Ultraviolet Light. Adv. Mater. 2000, 12 (13), 985– 987, DOI: 10.1002/1521-4095(200006)12:13<985::AID-ADMA985>3.0.CO;2-#Google Scholar66Photocalcination of mesoporous silica films using vacuum ultraviolet lightHozumi, Atsushi; Yokogawa, Yoshiyuki; Kameyama, Tetsuya; Hiraku, Katsumasa; Sugimura, Hiroyuki; Takai, Osamu; Okido, MasazumiAdvanced Materials (Weinheim, Germany) (2000), 12 (13), 985-987CODEN: ADVMEW; ISSN:0935-9648. (Wiley-VCH Verlag GmbH)A method was developed for eliminating template surfactant mols. from mesoporous silica at room temp. The method is based on photochem. decompn. of org.mols. under irradn. with a vacuum-UV (172 nm) light. Thus, cetyltrimethylammonium chloride mols. were eliminated from mesoporous silica films on silicon substrates coated with n-octadecyltrimethoxysilane self-assembled monolayers. Photocalcination at room temp. for 3 h eliminated surfactant mols. as effectively as a std. 1 h calcination at 573 K, however, the latter method strongly reduced the no.of silanol groups on the film surface. X-ray diffractometry showed that photocalcination caused much less damage and distortion to the film than the thermal calcination process.
- 67Ha, C.-S.; Park, S. S. General Synthesis and Physico-chemical Properties of Mesoporous Materials. In Periodic Mesoporous Organosilicas: Preparation, Properties and Applications; Ha, C.-S.; Park, S. S., Eds.; Springer Singapore: Singapore, 2019; pp 15– 85.Google ScholarThere is no corresponding record for this reference.
- 68Keene, M. T. J.; Denoyel, R.; Llewellyn, P. L. Ozone treatment for the removal of surfactant to form MCM-41 type materials. Chem. Commun. 1998, 20, 2203– 2204, DOI: 10.1039/a806118aGoogle ScholarThere is no corresponding record for this reference.
- 69Büchel, G.; Denoyel, R.; Llewellyn, P. L.; Rouquerol, J. In situ surfactant removal from MCM-type mesostructures by ozone treatment. J. Mater. Chem. 2001, 11 (2), 589– 593, DOI: 10.1039/b005297nGoogle ScholarThere is no corresponding record for this reference.
- 70Joshi, H.; Jalalpoor, D.; Ochoa-Hernández, C.; Schmidt, W.; Schüth, F. Ozone Treatment: A Versatile Tool for the Postsynthesis Modification of Porous Silica-Based Materials. Chem. Mater. 2018, 30 (24), 8905– 8914, DOI: 10.1021/acs.chemmater.8b04113Google Scholar70Ozone Treatment: A Versatile Tool for the Postsynthesis Modification of Porous Silica-Based MaterialsJoshi, Hrishikesh; Jalalpoor, Daniel; Ochoa-Hernandez, Cristina; Schmidt, Wolfgang; Schueth, FerdiChemistry of Materials (2018), 30 (24), 8905-8914CODEN: CMATEX; ISSN:0897-4756. (American Chemical Society)Facile synthesis of silica-based functional materials at low temps. has remained a challenge in materials science. To this end, we demonstrate the use of a gaseous ozone stream, generated via an elec. discharge method, as a versatile tool for the postsynthesis modification of silica-based functional nanomaterials. First, a parametric study is conducted with a mesoporous model material to obtain basic insights into the reaction of the orgs. with ozone. The study is then extended to a no. of distinct silica-based inorg. materials. The scope of ozone treatment can be broadly classified into three categories: (a) elimination of templates or structure directing agents (SDAs) from materials with pore sizes ranging from 0.5 to 10 nm, (b) selective transformation of org. groups functionalized on the mesoporous silica, and (c) simultaneous elimination of intermediate polymeric shells and template from the outer shells to obtain yolk-shell type materials. Each material studied here requires different parameters (temp., time, and concn. of ozone) depending on its phys. and chem. properties which have been carefully examd. Overall, the study demonstrates the potential of ozone treatment in tailoring functional materials at low temp. and provides vital insights into the reaction of ozone with silica-based materials. The study shows that gaseous ozone treatment is not limited to only one type of materials but can be applied to many systems, and we are convinced that the methodol. can be applied to a multitude of org.-inorg. systems way beyond the scope of materials presented here.
- 71Vogna, D.; Marotta, R.; Napolitano, A.; d’Ischia, M. Advanced Oxidation Chemistry of Paracetamol. UV/H2O2-Induced Hydroxylation/Degradation Pathways and 15N-Aided Inventory of Nitrogenous Breakdown Products. The. J. Org. Chem. 2002, 67 (17), 6143– 6151, DOI: 10.1021/jo025604vGoogle Scholar71Advanced Oxidation Chemistry of Paracetamol. UV/H2O2-Induced Hydroxylation/Degradation Pathways and 15N-Aided Inventory of Nitrogenous Breakdown Products.Vogna, Davide; Marotta, Raffaele; Napolitano, Alessandra; d'Ischia, MarcoJournal of Organic Chemistry (2002), 67 (17), 6143-6151CODEN: JOCEAH; ISSN:0022-3263. (American Chemical Society)The advanced oxidn. chem. of the antipyretic drug paracetamol (1) with the UV/H2O2 system was investigated by an integrated methodol. based on 15N-labeling and GC-MS, HPLC, and 2D 1H, 13C, and 15N NMR anal. Main degrdn. pathways derived from three hydroxylation steps, leading to 1,4-hydroquinone/1,4-benzoquinone, 4-acetylaminocatechol and, to a much lesser extent, 4-acetylaminoresorcine. Oxidn. of the primary arom. intermediates, viz. 4-acetylaminocatechol, 1,4-hydroquinone, 1,4-benzoquinone, and 1,2,4-benzenetriol, resulted in a series of nitrogenous and non-nitrogenous degrdn. products. The former included N-acetylglyoxylamide, acetylaminomalonic acid, acetylaminohydroxymalonic acid, acetylaminomaleic acid, diastereoisomeric 2-acetylamino-3-hydroxybutanedioic acids, 2-acetylaminobutenedioic acid, 3-acetylamino-4-hydroxy-2-pentenedioic acid, and 2,4-dihydroxy-3-acetylamino-2-pentenedioic acid, as well as two muconic and hydroxymuconic acid derivs. 15N NMR spectra revealed the accumulation since the early stages of substantial amts. of acetamide and oxalic acid monoamide. These results provide the first insight into the advanced oxidn. chem. of a 4-aminophenol deriv. by the UV/H2O2 system, and highlight the investigative potential of integrated GC-MS/NMR methodologies based on 15N-labeling to track degrdn. pathways of nitrogenous species.
- 72Cater, S. R.; Stefan, M. I.; Bolton, J. R.; Safarzadeh-Amiri, A. UV/H2O2 Treatment of Methyl tert-Butyl Ether in Contaminated Waters. Environ. Sci. Technol. 2000, 34 (4), 659– 662, DOI: 10.1021/es9905750Google Scholar72UV/H2O2 Treatment of Methyl tert-Butyl Ether in Contaminated WatersCater, Stephen R.; Stefan, Mihaela I.; Bolton, James R.; Safarzadeh-Amiri, AliEnvironmental Science and Technology (2000), 34 (4), 659-662CODEN: ESTHAG; ISSN:0013-936X. (American Chemical Society)Me tert-Bu ether (MTBE) is a pollutant often found in groundwaters contaminated by gasoline spills or from leaking underground storage tanks. This study examines the UV/H2O2 advanced oxidn. technol. to det. its effectiveness in the treatment of MTBE. The degrdn. of MTBE followed pseudo-1st-order kinetics, and hence the figure-of-merit elec. energy per order (EEO) is appropriate for estg. the elec. energy efficiency. The EEO values depended on the concns. of MTBE, H2O2, and other components, such as benzene, toluene, and xylenes (BTX). This study shows that MTBE can be treated easily and effectively with the UV/H2O2 process with EEO 0.2-7.5 KWh/m3/order, depending on the initial concns. of MTBE and H2O2. The treatment efficiency of 10 mg/L MTBE is not adversely affected by the presence of low concns. of BTX (<2 mg/L); however, the degrdn. efficiency is significantly decreased at BTX >2 mg/L. A kinetic model, based on the initial rates of degrdn., provides good predictions of the EEO for a variety of conditions.
- 73Xiao, L.; Li, J.; Jin, H.; Xu, R. Removal of organic templates from mesoporous SBA-15 at room temperature using UV/dilute H2O2. Microporous Mesoporous Mater. 2006, 96 (1), 413– 418, DOI: 10.1016/j.micromeso.2006.07.019Google Scholar73Removal of organic templates from mesoporous SBA-15 at room temperature using UV/dilute H2O2Xiao, Liping; Li, Jiyang; Jin, Hongxiao; Xu, RurenMicroporous and Mesoporous Materials (2006), 96 (1-3), 413-418CODEN: MIMMFJ; ISSN:1387-1811. (Elsevier B.V.)A new UV/dil. H2O2 method was developed to remove org. templates from mesoporous silica SBA-15. This method combines UV irradn. and dil. H2O2 treatment, allowing complete removal of the org. templates in 3-4 h at room temp. Effects of two important factors, pH value and initial H2O2 concn., were investigated to search for the optimum condition of template removal. Detailed characterizations of the samples treated by UV/dil. H2O2 method in comparison with other methods are performed with the aid of powder x-ray diffraction (XRD), thermogravimetric anal. (TGA), FTIR, solid-state 29Si NMR spectra, and N2 adsorption. The final product resulted from UV/dil. H2O2 treatment has well-defined structure with perfect pore quality. This study provides an easy, cheap, mild and useful method for template removal from mesoporous materials at room temp.
- 74Aumond, T.; Pinard, L.; Batiot-Dupeyrat, C.; Sachse, A. Non-thermal plasma: A fast and efficient template removal approach allowing for new insights to the SBA-15 structure. Microporous Mesoporous Mater. 2020, 296, 110015, DOI: 10.1016/j.micromeso.2020.110015Google Scholar74Non-thermal plasma: A fast and efficient template removal approach allowing for new insights to the SBA-15 structureAumond, Thibaud; Pinard, Ludovic; Batiot-Dupeyrat, Catherine; Sachse, AlexanderMicroporous and Mesoporous Materials (2020), 296 (), 110015CODEN: MIMMFJ; ISSN:1387-1811. (Elsevier B.V.)Non-thermal plasma has revealed as fast and efficient strategy for the complete elimination of template mols. from SBA-15 materials. Through comparing the textural properties of a set of SBA-15 materials obtained by classical calcination and non-thermal plasma treatment new insights to the SBA-15 structure could be revealed. As such, a third type of microporosity could be disclosed by the use of non-thermal plasma for SBA-15 synthesized at 60°C. Addnl., starting from a synthesis temp. of 100°C, template elimination through non-thermal plasma allows for preserving native textural properties of as-synthesized SBA-15. The developed alternative treatment combines the advantages of improved textural properties and higher silanol d., hence making the strategy very promising for superior applications of SBA-15 materials.
- 75Liu, Y.; Wang, Z.; Liu, C.-j. Mechanism of template removal for the synthesis of molecular sieves using dielectric barrier discharge. Catal. Today 2015, 256, 137– 141, DOI: 10.1016/j.cattod.2015.03.009Google Scholar75Mechanism of template removal for the synthesis of molecular sieves using dielectric barrier dischargeLiu, Yuan; Wang, Zhao; Liu, Chang-junCatalysis Today (2015), 256 (Part_1), 137-141CODEN: CATTEA; ISSN:0920-5861. (Elsevier B.V.)The mechanism of dielec.-barrier discharge (DBD) plasma template removal is investigated. The study confirms that dissocn. of template mol. by active species (like electrons and excited oxygen species) and oxidn. of radicals (from the dissocn.) by active oxygen species (like ozone and excited oxygen species) are the mechanism of the DBD plasma enhanced template removal. The thermal image confirms that the DBD plasma template removal is conducted under temp. around 125°C. The thermal effect can be ignored. The present study is leading to a unique way for the syntheses of various micro- and meso-porous materials.
- 76Liu, Y.; Pan, Y.; Wang, Z.-J.; Kuai, P.; Liu, C.-J. Facile and fast template removal from mesoporous MCM-41 molecular sieve using dielectric-barrier discharge plasma. Catal. Commun. 2010, 11 (6), 551– 554, DOI: 10.1016/j.catcom.2009.12.017Google Scholar76Facile and fast template removal from mesoporous MCM-41 molecular sieve using dielectric-barrier discharge plasmaLiu, Yuan; Pan, Yunxiang; Wang, Zhou-Jun; Kuai, Pingyu; Liu, Chang-JunCatalysis Communications (2010), 11 (6), 551-554CODEN: CCAOAC; ISSN:1566-7367. (Elsevier B.V.)Dielec.-barrier discharge (DBD) plasma, initiated at ambient condition, was applied for removing template from the mesoporous MCM-41 mol. sieve. The template removal rate using DBD plasma is 8 times higher than the rate via thermal calcination. A perfect hexagonal pore structure was obtained after the template removal using the plasma, according to the characterization using the x-ray diffraction, TEM, and N2 adsorption analyses. The effectiveness of the plasma prepd. mesoporous MCM-41 mol. sieve as the catalyst support was confirmed using the Suzuki reaction with Pd as the active species.
- 77Liu, Y.; Pan, Y.-x.; Kuai, P.; Liu, C.-j. Template Removal from ZSM-5 Zeolite Using Dielectric-Barrier Discharge Plasma. Catal. Lett. 2010, 135 (3), 241– 245, DOI: 10.1007/s10562-010-0290-7Google Scholar77Template Removal from ZSM-5 Zeolite using Dielectric-Barrier Discharge PlasmaLiu, Yuan; Pan, Yun-Xiang; Kuai, Ping-Yu; Liu, Chang-JunCatalysis Letters (2010), 135 (3-4), 241-245CODEN: CALEER; ISSN:1011-372X. (Springer)A dielec.-barrier discharge (DBD) plasma technique was successfully applied for template removal from ZSM-5 zeolite. The rate for template removal using DBD is about eight times higher than that using the conventional thermal calcination. During the template removal using DBD, the highest temp. of the sample is ∼125°. As such, the thermal effect on the sample during the DBD template removal is not significant. This made the structure changes of ZSM-5 zeolite during the template removal less dramatic than that using thermal calcination.
- 78Yuan, M.-H.; Wang, L.; Yang, R. T. Glow Discharge Plasma-Assisted Template Removal of SBA-15 at Ambient Temperature for High Surface Area, High Silanol Density, and Enhanced CO2 Adsorption Capacity. Langmuir 2014, 30 (27), 8124– 8130, DOI: 10.1021/la501794zGoogle Scholar78Glow Discharge Plasma-Assisted Template Removal of SBA-15 at Ambient Temperature for High Surface Area, High Silanol Density, and Enhanced CO2 Adsorption CapacityYuan, Min-Hao; Wang, Lifeng; Yang, Ralph T.Langmuir (2014), 30 (27), 8124-8130CODEN: LANGD5; ISSN:0743-7463. (American Chemical Society)Glow discharge plasma was successfully applied for effective removal of the org. template P-123 from SBA-15 ordered mesoporous SiO2 at near-room-temp. (<50°) and in a short operation time (2 h). The as-made SBA-15 treated with glow discharge exhibited a larger surface area of 1025 m2 g-1 with larger pores and microspore vol. as compared with that of conventional calcination (550° and 5 h, 827 m2 g-1). In addn. to less structural shrinkage, the plasma-prepd. SBA-15 showed significantly increased silanol d. from 5.4 to 6.6-7.6 mmol g-1, which led directly to higher amine loading from 1.8 to 3.0 mmol g-1. Consequently, the plasma-treated sample showed 77% more CO2 capacity and 60% higher CO2/N2 selectivity than the conventionally treated sample at 0.15 bar and 25°. The advantage of using glow discharge plasma for low-temp. template removal for achieving enhanced performance for CO2 adsorption is clearly demonstrated.
- 79Maesen, T. L. M.; Kouwenhoven, H. W.; van Bekkum, H.; Sulikowski, B.; Klinowski, J. Template removal from molecular sieves by low-temperature plasma calcination. J. Chem. Soc., Faraday Trans. 1990, 86 (23), 3967– 3970, DOI: 10.1039/ft9908603967Google Scholar79Template removal from molecular sieves by low-temperature plasma calcinationMaesen, Theo L. M.; Kouwenhoven, Herman W.; Van Bekkum, Herman; Sulikowski, Bogdan; Klinowski, JacekJournal of the Chemical Society, Faraday Transactions (1990), 86 (23), 3967-70CODEN: JCFTEV; ISSN:0956-5000.The oxidative removal of templates from crystals of MFI- and TON-type zeolites using low-temp. O plasma at 370 K was investigated. This treatment removes Pr4N+ inside 5 μm lengths of channels in the completely siliceous MFI structure (silicalite), and Et2NH to a depth of ≤70 μm in the channels of the completely siliceous TON structure. Substitution of B, Al, or Fe into the framework of silicalite obstructs the removal of Pr4N+, but complete decompn. of the template can be accomplished in small samples of [Si,B]-MFI. A comparison of plasma calcination with thermal calcination in air indicates that the release of B into extra-framework positions upon either treatment is caused by the slow desorption of H2O at the calcination temp.
- 80Wang, L.; Yao, J.; Wang, Z.; Jiao, H.; Qi, J.; Yong, X.; Liu, D. Fast and low-temperature elimination of organic templates from SBA-15 using dielectric barrier discharge plasma. Plasma Science and Technology 2018, 20 (10), 101001, DOI: 10.1088/2058-6272/aad547Google Scholar80Fast and low-temperature elimination of organic templates from SBA-15 using dielectric barrier discharge plasmaWang, Lin; Yao, Junkang; Wang, Zheng; Jiao, Hongqiao; Qi, Jing; Yong, Xiaojing; Liu, DianhuaPlasma Science & Technology (Bristol, United Kingdom) (2018), 20 (10), 101001/1-101001/5CODEN: PSTHC3; ISSN:1009-0630. (IOP Publishing Ltd.)Org. templates P-123 of mesoporous SBA-15 can be effectively removed in a few minutes (4 min) by using the dielec.-barrier discharge plasma technique at ambient pressure and low gas temp. (around 130°C). The mesoporous SBA-15 was characterized by FT-IR, 29Si solid sate NMR, TEM, XRD, TGA and N2 adsorption / desorption isotherms. The as-made SBA-15 treated with DBD plasma exhibited a larger surface area of 790 m2 · g-1 with larger pores and microspore vol. than samples prepd. by using the conventional thermal calcination method (550°C and 5 h, 660 m2 · g-1). In addn. to less shrinkage of the silica framework, the DBD-prepd. SBA-15 showed significantly increased wt. loss of 8.3% about 200°C as compared with that of conventional calcination (5.5%), which is attributed mainly to the dehydroxylation by condensation of silanol groups.
- 81Khataee, A.; Sajjadi, S.; Hasanzadeh, A.; Vahid, B.; Joo, S. W. One-step preparation of nanostructured martite catalyst and graphite electrode by glow discharge plasma for heterogeneous electro-Fenton like process. Journal of Environmental Management 2017, 199, 31– 45, DOI: 10.1016/j.jenvman.2017.04.095Google Scholar81One-step preparation of nanostructured martite catalyst and graphite electrode by glow discharge plasma for heterogeneous electro-Fenton like processKhataee, Alireza; Sajjadi, Saeed; Hasanzadeh, Aliyeh; Vahid, Behrouz; Joo, Sang WooJournal of Environmental Management (2017), 199 (), 31-45CODEN: JEVMAW; ISSN:0301-4797. (Elsevier Ltd.)Natural Martite ore particles and graphite were modified by a.c. (AC) glow discharge plasma to form nanostructured catalyst and cathode electrode for using in the heterogeneous-electro Fenton-like (Het-EF-like) process. The performance of the plasma-treated martite (PTM) and graphite electrode (PTGE) was studied for the treatment of paraquat herbicide in a batch system. 85.78% Degrdn. efficiency for 20 mg L-1 paraquat was achieved in the modified process under desired operational conditions (i.e. current intensity of 300 mA, catalyst amt. of 1 g L-1, pH = 6, and background electrolyte (Na2SO4) concn. of 0.05 mol L-1) which was higher than the 41.03% for the unmodified one after 150 min of treatment. The ecofriendly modification of the martite particles and the graphite electrode, no chem. needed, low leached iron and milder operational pH were the main privileges of plasma utilization. Moreover, the degrdn. efficiency through the process was not declined after five repeated cycles at the optimized conditions, which proved the stability of the nanostructured PTM and PTGE in the long-term usage. The archived results exhibit this method is the first example of high efficient, cost-effective, and environment-friendly method for generation of nanostructured samples.
- 82Bazaka, K.; Baranov, O.; Cvelbar, U.; Podgornik, B.; Wang, Y.; Huang, S.; Xu, L.; Lim, J. W. M.; Levchenko, I.; Xu, S. Oxygen plasmas: a sharp chisel and handy trowel for nanofabrication. Nanoscale 2018, 10 (37), 17494– 17511, DOI: 10.1039/C8NR06502KGoogle Scholar82Oxygen plasmas: a sharp chisel and handy trowel for nanofabricationBazaka, K.; Baranov, O.; Cvelbar, U.; Podgornik, B.; Wang, Y.; Huang, S.; Xu, L.; Lim, J. W. M.; Levchenko, I.; Xu, S.Nanoscale (2018), 10 (37), 17494-17511CODEN: NANOHL; ISSN:2040-3372. (Royal Society of Chemistry)Although extremely chem. reactive, oxygen plasmas feature certain properties that make them attractive not only for material removal via etching and sputtering, but also for driving and sustaining nucleation and growth of various nanostructures in plasma bulk and on plasma-exposed surfaces. In this minireview, a no. of representative examples is used to demonstrate key mechanisms and unique capabilities of oxygen plasmas and how these can be used in present-day nano-fabrication. In addn. to modification and functionalisation processes typical for oxygen plasmas, their ability to catalyze the growth of complex nanoarchitectures is emphasized. Two types of technologies based on oxygen plasmas, namely surface treatment without a change in the size and shape of surface features, as well as direct growth of oxide structures, are used to better illustrate the capabilities of oxygen plasmas as a powerful process environment. Future applications and possible challenges for the use of oxygen plasmas in nanofabrication are discussed.
- 83Wang, Z.-j.; Xie, Y.; Liu, C.-j. Synthesis and Characterization of Noble Metal (Pd, Pt, Au, Ag) Nanostructured Materials Confined in the Channels of Mesoporous SBA-15. J. Phys. Chem. C 2008, 112 (50), 19818– 19824, DOI: 10.1021/jp805538jGoogle Scholar83Synthesis and Characterization of Noble Metal (Pd, Pt, Au, Ag) Nanostructured Materials Confined in the Channels of Mesoporous SBA-15Wang, Zhou-jun; Xie, Yongbing; Liu, Chang-junJournal of Physical Chemistry C (2008), 112 (50), 19818-19824CODEN: JPCCCK; ISSN:1932-7447. (American Chemical Society)Highly dispersed metal (Pd, Pt) nanoparticles and uniformly distributed metal (Au, Ag) nanowires were synthesized in ordered mesoporous silica SBA-15 via conventional incipient wetness impregnation followed by novel glow discharge plasma redn. N2 adsorption-desorption isotherms and the low-angle XRD patterns indicate that the parent ordered mesoporous structure was well-maintained during the synthesis process. The wide-angle XRD patterns and transmission electron microscope images demonstrate that spherical Pd and Pt nanoparticles as well as rodlike Au and Ag nanowires were fabricated within the channels of SBA-15. The diams. of the metal nanoparticles and the metal nanowires were effectively controlled by the mesopores of the SBA-15 host. The population of the metal nanoparticles and the length of the metal nanowires can be tuned by the metal loading amt. In particular, the novel plasma redn. at ambient temp. is green, economical, and nontime-consuming, showing great advantages over the traditional hydrogen redn. at elevated temp. This very simple synthesis method using plasma redn. will be very promising as a general technique for the prepn. of metal nanostructured materials confined in the host architectures.
- 84Mamdouh, W.; Li, Y.; Shawky, S. M.; Azzazy, H. M. E.; Liu, C.-J. Influence of “Glow Discharge Plasma” as an External Stimulus on the Self-Assembly, Morphology and Binding Affinity of Gold Nanoparticle-Streptavidin Conjugates. International Journal of Molecular Sciences 2012, 13 (6), 6534, DOI: 10.3390/ijms13066534Google Scholar84Influence of "glow discharge plasma" as an external stimulus on the self-assembly, morphology and binding affinity of gold nanoparticle-streptavidin conjugatesMamdouh, Wael; Li, Yingzhi; Shawky, Sherif M.; Azzazy, Hassan M. E.; Liu, Chang-JunInternational Journal of Molecular Sciences (2012), 13 (), 6534-6547CODEN: IJMCFK; ISSN:1422-0067. (MDPI AG)In this study, we investigate the influence of glow discharge plasma (GDP) on the self-assembly, morphol. and binding affinity of streptavidin coated gold nanoparticles (Au-NP-SV) and biotinylated antibody (bAb) adsorbed on a highly oriented pyrolytic graphite (HOPG) substrate. Atomic force microscope (AFM) was used to image the pre- and post-GDP treated samples. The anal. of the AFM images showed a considerable change in the aggregation and morphol. of Au-NP-conjugates after treatment with GDP. To our knowledge, this is the first report on using GDP to enhance and speed-up the aggregation (sintering) of adsorbed NP biomol. conjugates. These results show a promising route that could be generalized for other NPs and their conjugates. It can also be considered as an alternative and cheap aggregation method for controlling the binding affinity of biomol. species on different surfaces with interesting applications.
- 85Guo, Q.; With, P.; Liu, Y.; Gläser, R.; Liu, C.-j. Carbon template removal by dielectric-barrier discharge plasma for the preparation of zirconia. Catal. Today 2013, 211, 156– 161, DOI: 10.1016/j.cattod.2013.02.032Google Scholar85Carbon template removal by dielectric-barrier discharge plasma for the preparation of zirconiaGuo, Qiuting; With, Patrick; Liu, Yuan; Glaser, Roger; Liu, Chang-junCatalysis Today (2013), 211 (), 156-161CODEN: CATTEA; ISSN:0920-5861. (Elsevier B.V.)A novel 'micro-combustion', initiated by active oxygen species within dielec. barrier discharge (DBD), has been developed and employed for the removal of a carbon exotemplate for the fabrication of zirconia (ZrO2). The micro-combustion is operated at atm. pressure and relatively low gas temp. (less than 150 °C) with a high template removal rate. The material characterization shows that mesoporous ZrO2 with a broad pore size distribution between 3 and 40 nm has been produced. The obtained ZrO2 exhibits a monoclinic lattice structure, normally generated at temps. over 1000 °C. The DBD-made ZrO2 has been applied as the support for the prepn. of Pd/ZrO2 catalyst, which shows a high activity for selective oxidn. of benzyl alc.
- 86Wang, B.; Chen, B.; Sun, Y.; Xiao, H.; Xu, X.; Fu, M.; Wu, J.; Chen, L.; Ye, D. Effects of dielectric barrier discharge plasma on the catalytic activity of Pt/CeO2 catalysts. Applied Catalysis B: Environmental 2018, 238, 328– 338, DOI: 10.1016/j.apcatb.2018.07.044Google Scholar86Effects of dielectric barrier discharge plasma on the catalytic activity of Pt/CeO2 catalystsWang, Bangfen; Chen, Bingxu; Sun, Yuhai; Xiao, Hailin; Xu, Xiaoxin; Fu, Mingli; Wu, Junliang; Chen, Limin; Ye, DaiqiApplied Catalysis, B: Environmental (2018), 238 (), 328-338CODEN: ACBEE3; ISSN:0926-3373. (Elsevier B.V.)CeO2 nanorod was synthesized by a hydrothermal method and impregnated with Pt to synthesize Pt/CeO2 catalysts, which were modified by dielec. barrier discharge plasma. The modified CeO2 and Pt/CeO2 were characterized by XRD, STEM, N2 adsorption/desorption, CO pulse chemisorption, XPS, H2-TPR, O2-TPD and UV-Raman spectroscopy techniques. After the plasma treatment, the T90 value of (Pt/CeO2)-P catalyst decreased from 287 °C to 208 °C for toluene oxidn. This significantly changed activity of catalyst indicated that plasma has greatly impacted its performance. More and larger notches on surface and broken fragments were found from STEM anal. In addn., smaller Pt particle size and higher dispersion of nanoparticles was found on (Pt/CeO2)-P, which was characterized by CO pulse chemisorption and TEM anal. In addn., Pt/(CeO2-P) and (Pt/CeO2)-P possessed higher concn. of oxygen vacancies and Ce3+, which was obsd. by UV-Raman spectroscopy and XPS. Moreover, according to TPR results, the interaction between Pt and CeO2 was obviously strengthened, which led to a lower redn. temp. after plasma treatment. After plasma treatment, the (Pt/CeO2)-P presented the highest activity due to it possessing the highest TOFPt and TOFov values of 9.88 × 10-4 s-1 and 9.49 × 10-5 s-1, resp., and lower activation energies of 63.8 kJ mol-1. Furthermore, the toluene conversion of (Pt/CeO2)-P without significantly decreasing for working at least 50 h and under 9.6 vol% water vapor.
- 87Li, Y.; Wang, W.; Wang, F.; Di, L.; Yang, S.; Zhu, S.; Yao, Y.; Ma, C.; Dai, B.; Yu, F. Enhanced Photocatalytic Degradation of Organic Dyes via Defect-Rich TiO2 Prepared by Dielectric Barrier Discharge Plasma. Nanomaterials 2019, 9 (5), 720, DOI: 10.3390/nano9050720Google Scholar87Enhanced photocatalytic degradation of organic dyes via defect-rich TiO2 prepared by dielectric barrier discharge plasmaLi, Yanqin; Wang, Wei; Wang, Fu; Di, Lanbo; Yang, Shengchao; Zhu, Shengjie; Yao, Yongbin; Ma, Cunhua; Dai, Bin; Yu, FengNanomaterials (2019), 9 (5), 720CODEN: NANOKO; ISSN:2079-4991. (MDPI AG)The dye wastewater produced in the printing and dyeing industry causes serious harm to the natural environment. TiO2 usually shows photocatalytic degrdn. of dye under the irradn. ultravilet light rather than visible light. In this work, a large no. of oxygen vacancies and Ti3+ defects were generated on the surface of the TiO2 nanoparticles via Ar plasma. Compared with pristine TiO2 nanoparticles, the as-obtained Ar plasma-treated TiO2 (Ar-TiO2) nanoparticles make the energy band gap reduce from 3.21 eV to 3.17 eV and exhibit enhanced photocatalytic degrdn. of org. dyes. The Ar-TiO2 obtained exhibited excellent degrdn. properties of methyl orange (MO); the degrdn. rate under sunlight irradn. was 99.6% in 30 min, and the photocatalytic performance was about twice that of the original TiO2 nanoparticles (49%). The degrdn. rate under visible light (λ > 400 nm) irradn. was 89% in 150 min, and the photocatalytic performance of the Ar-TiO2 was approaching ∼4 times higher than that of the original TiO2 nanoparticles (23%). Ar-TiO2 also showed good degrdn. performance in degrading rhodamine B (Rho B) and methylene blue (MB). We believe that this plasma strategy provides a new method for improving the photocatalytic activity of other metal oxides.
- 88Das, P.; Ojah, N.; Kandimalla, R.; Mohan, K.; Gogoi, D.; Dolui, S. K.; Choudhury, A. J. Surface modification of electrospun PVA/chitosan nanofibers by dielectric barrier discharge plasma at atmospheric pressure and studies of their mechanical properties and biocompatibility. Int. J. Biol. Macromol. 2018, 114, 1026– 1032, DOI: 10.1016/j.ijbiomac.2018.03.115Google Scholar88Surface modification of electrospun PVA/chitosan nanofibers by dielectric barrier discharge plasma at atmospheric pressure and studies of their mechanical properties and biocompatibilityDas, Punamshree; Ojah, Namita; Kandimalla, Raghuram; Mohan, Kiranjyoti; Gogoi, Dolly; Dolui, Swapan Kumar; Choudhury, Arup JyotiInternational Journal of Biological Macromolecules (2018), 114 (), 1026-1032CODEN: IJBMDR; ISSN:0141-8130. (Elsevier B.V.)In this paper, surface of electrospun PVA/Cs nanofibers is modified using dielec. barrier discharge (DBD) plasma and the relationship between the obsd. mech. properties and biocompatibility of the nanofibers and plasma-induced surface properties is discussed. Plasma treatment of electrospun PVA/Cs nanofibers is carried out with both inert (argon, Ar) and reactive (oxygen, O2) gases at atm. pressure. Incorporation of oxygen-contg. polar functional groups on the surface of Ar-plasma treated (PVA/Cs/Ar) and O2-plasma treated (PVA/Cs/O2) nanofibers and increase in surface roughness contribute to the improvement of surface wettability and the decrease of contact angle with water of the nanofibers. Both PVA/Cs/Ar and PVA/Cs/O2 nanofibers show high tensile strength (11.6-15.6%) and Young's modulus (33.8-37.3%) as compared to the untreated one. Exptl. results show that in terms of haemolytic activity the PVA/Cs/Ar and PVA/Cs/O2 nanofibers do not cause structural changes of blood cells and meet the biocompatibility requirements for blood-contacting polymeric materials. MTT cell viability results further reveals improvement in biocompatibility of PVA/Cs nanofibers after Ar and O2 plasma treatment. The results suggest that DBD plasma treated electrospun PVA/Cs nanofibers have the potential to be used as wound dressing and scaffolds for tissue engineering.
- 89Xu, X. Dielectric barrier discharge ─ properties and applications. Thin Solid Films 2001, 390 (1), 237– 242, DOI: 10.1016/S0040-6090(01)00956-7Google Scholar89Dielectric barrier discharge - properties and applicationsXu, X.Thin Solid Films (2001), 390 (1,2), 237-242CODEN: THSFAP; ISSN:0040-6090. (Elsevier Science S.A.)A review with 14 refs. Dielec. barrier discharge (DBD) is a typical non-equil. high-pressure ac gas discharge. Recently, two types of DBD arrangements are developed; vol. discharge (VD) and surface discharge (SD). Such devices are beneficial for industrial acceptance, since vacuum can be got rid of and devices operated in atm. pressure region. DBD is an excellent source of ideal energetic electrons with 1-10 eV and high d. Its unique advantage is to generate low excited at. and mol. species, free radicals and excimers with several eV energy. In this paper, the properties of microdischarge in DBD are discussed with their simulation. Due to its attractive characteristics, DBD is recently widely studied for potential industrial applications. Ozone generators, excimer radiation sources, free radical generation and their applications in pollution control and monitor are also discussed.
- 90Hashim, S. A.; Samsudin, F. N. D. b.; Wong, C. S.; Abu Bakar, K.; Yap, S. L.; Mohd. Zin, M. F. Non-thermal plasma for air and water remediation. Arch. Biochem. Biophys. 2016, 605, 34– 40, DOI: 10.1016/j.abb.2016.03.032Google Scholar90Non-thermal plasma for air and water remediationHashim, Siti Aiasah; Samsudin, Farah Nadia Dayana binti; Wong, Chiow San; Abu Bakar, Khomsaton; Yap, Seong Ling; Mohd. Zin, Mohd. FaizArchives of Biochemistry and Biophysics (2016), 605 (), 34-40CODEN: ABBIA4; ISSN:0003-9861. (Elsevier B.V.)A modular typed dielec. barrier discharge (DBD) device is designed and tested for air and water remediation. The module is made of a no. of DBD tubes that can be arranged in series or parallel. Each of the DBD tubes comprises inner electrode enclosed with dielec. barrier and arranged as such to provide a gap for the passage of gases. Non-thermal plasma generated in the gap effectively creates gaseous chem. reactions. Its efficacy in the remediation of gas stream contg. high NOx, similar to diesel emission and wastewater contg. latex, are presented. A six tubes DBD module has successfully removed more than 80% of nitric oxide from the gas stream. In another arrangement, oxygen was fed into a two tubes DBD to generate ozone for treatment of wastewater. Samples of wastewater were collected from a treatment pond of a rubber vulcanization pilot plant. The water pollution load was evaluated by the COD and biol. oxygen demand (BOD5) values. Preliminary results showed some improvement (about 13%) on the COD after treatment and at the same time had increased the BOD5 by 42%. This results in higher BOD5/COD ratio after ozonation which indicate better biodegradability of the wastewater.
- 91Zhang, C.; Sun, Y.; Yu, Z.; Zhang, G.; Feng, J. Simultaneous removal of Cr(VI) and acid orange 7 from water solution by dielectric barrier discharge plasma. Chemosphere 2018, 191, 527– 536, DOI: 10.1016/j.chemosphere.2017.10.087Google Scholar91Simultaneous removal of Cr(VI) and acid orange 7 from water solution by dielectric barrier discharge plasmaZhang, Chunxiao; Sun, Yabing; Yu, Zhongqing; Zhang, Guyu; Feng, JingweiChemosphere (2018), 191 (), 527-536CODEN: CMSHAF; ISSN:0045-6535. (Elsevier Ltd.)A feasibility study was conducted for simultaneous removal of hexavalent chromium (Cr(VI)) and azo dye acid orange 7 (AO7) by the dielec. barrier discharge (DBD) plasma. The results showed that there was a synergistic effect between Cr(VI) redn. and AO7 degrdn. The presence of Cr(VI) enhanced the degrdn. efficiency of AO7. Meanwhile, the removal efficiency of Cr(VI) also increased in the presence of AO7. Under acidic conditions (pH = 3.0), the redn. efficiency of Cr(VI) was higher (approx. 94%). However, the presence of Cr(VI) diminished the effect of pH on the AO7 degrdn. efficiency. By increasing the input voltage from 80 to 120 V, the removal efficiencies of Cr(VI) and AO7 were observably increased from 54% to 88% and 62% to 89%, resp. Adding org. matters inhibited the degrdn. of AO7 and promoted the redn. of Cr(VI). The addn. of Cu(II), Co(II), Ni(II), Mn(II) and Fe(III) could inhibit the Cr(VI) redn., but not significantly affect the degrdn. of AO7. The degrdn. intermediates of AO7 were identified by LC-MS/MS system and a possible degrdn. pathway was proposed. This study showed that the DBD plasma can simultaneously remove Cr(VI) and AO7, which provided a new idea for the actual wastewater treatment.
- 92Sang, W.; Cui, J.; Feng, Y.; Mei, L.; Zhang, Q.; Li, D.; Zhang, W. Degradation of aniline in aqueous solution by dielectric barrier discharge plasma: Mechanism and degradation pathways. Chemosphere 2019, 223, 416– 424, DOI: 10.1016/j.chemosphere.2019.02.029Google Scholar92Degradation of aniline in aqueous solution by dielectric barrier discharge plasma: Mechanism and degradation pathwaysSang, Wenjiao; Cui, Jiaqi; Feng, Yijie; Mei, Longjie; Zhang, Qian; Li, Dong; Zhang, WanjunChemosphere (2019), 223 (), 416-424CODEN: CMSHAF; ISSN:0045-6535. (Elsevier Ltd.)The degrdn. of aniline soln. using the dielec. barrier discharge (DBD) plasma was studied in this paper. The results indicated that the initial concn. of aniline, applied voltage and initial pH value affected the removal efficiency of aniline significantly. After 12 min with DBD plasma treatment, 90.2% removal efficiency was achieved at aniline concn. of 100 mg L-1 with an applied voltage of 3.0 kV and pH 8.43. The removal efficiency decreased with the presence of radical scavengers, indicating that hydroxyl radical plays a key role in the degrdn. process. The removal efficiency increased obviously when Fe2+ was added. Addnl., the intermediate products generated in the degrdn. process of aniline were analyzed by some anal. techniques, including total org. carbon anal., UV-visible spectroscopy, Fourier Transform IR spectroscopy, Gas Chromatog.-Mass Spectrometer, etc. The results showed that the degrdn. of aniline was mainly due to the strong oxidizing capacity of hydroxyl radical produced by the DBD plasma system. Based on the intermediate products identified in the study, the possible degrdn. mechanism and pathways were proposed.
- 93Iervolino, G.; Vaiano, V.; Palma, V. Enhanced removal of water pollutants by dielectric barrier discharge non-thermal plasma reactor. Sep. Purif. Technol. 2019, 215, 155– 162, DOI: 10.1016/j.seppur.2019.01.007Google Scholar93Enhanced removal of water pollutants by dielectric barrier discharge non-thermal plasma reactorIervolino, Giuseppina; Vaiano, Vincenzo; Palma, VincenzoSeparation and Purification Technology (2019), 215 (), 155-162CODEN: SPUTFP; ISSN:1383-5866. (Elsevier B.V.)In this work it was studied the removal efficiency of several water pollutants (methylene blue, phenol, paracetamol, caffeine and ceftriaxone) by dielec. barrier discharge (DBD) non-thermal plasma (NTP) reactor. The results evidenced that using oxygen as process gas in the DBD reactor and 20 kV of applied voltage, the complete degrdn. and mineralization of methylene blue and ceftriaxone was achieved after only 5 min of treatment time, while 15 min were required for the complete degrdn. and mineralization, of phenol and paracetamol, and 25 min for the caffeine. In addn., kinetic evaluations evidenced that, for each pollutant, the degrdn. and mineralization occurred at the same rates, underling that the pollutants are selectively converted to carbon dioxide. For this reason, the results obtained in the present work were significantly better than those reported in the current literature about the use of non-thermal technol. in the removal of org. pollutants from aq. solns.
- 94Yuan, D.; Wang, Z.; He, Y.; Xie, S.; Lin, F.; Zhu, Y.; Cen, K. Ozone Production with Dielectric Barrier Discharge from Air: The Influence of Pulse Polarity. Ozone: Science & Engineering 2018, 40 (6), 494– 502, DOI: 10.1080/01919512.2018.1476127Google Scholar94Ozone Production with Dielectric Barrier Discharge from Air: The Influence of Pulse PolarityYuan, Dingkun; Wang, Zhihua; He, Yong; Xie, Songru; Lin, Fawei; Zhu, Yanqun; Cen, KefaOzone: Science & Engineering (2018), 40 (6), 494-502CODEN: OZSEDS; ISSN:0191-9512. (Taylor & Francis, Inc.)This research aims to study the effects of different pulse modes of the power supply on ozone prodn. from air. Single pos., neg. as well as the bipolar voltage pulses (pos.-neg. and neg.-pos.) with a repetition rate of 300 Hz have been applied to coaxial dielec. barrier discharge arrangement. Results reveal that at fixed specific input energy (SIE), which is defined as the ratio of power to gas flow rate, the ozone generation efficiencies for different pulse modes are in the sequence of pos. > pos.-neg. > neg.-pos. >neg., and the difference between pos. and pos.-neg. pulse becomes considerable with SIE higher than 500 J/L. Results also reveal that the max. NO2 concn. is obtained at 400 J/L. Moreover, utilizing bipolar pulse can reduce N2O prodn. with SIEs higher than 250 J/L and hinder NO2 prodn. with SIEs higher than 350 J/L.
- 95Zylka, P. Evaluation of Ozone Generation in Volume Spiral-Tubular Dielectric Barrier Discharge Source. Energies 2020, 13 (5), 1199, DOI: 10.3390/en13051199Google Scholar95Evaluation of ozone generation in volume spiral-tubular dielectric barrier discharge sourceZylka, PawelEnergies (Basel, Switzerland) (2020), 13 (5), 1199CODEN: ENERGA; ISSN:1996-1073. (MDPI AG)Ozone, due to its high reactivity cannot be stockpiled, and thus requires to be generated on-demand. The paper reports on lab. studies of O3 generation in a vol. dielec. barrier discharge (DBD) tubular flow-through system with a coaxial-spiral electrode arrangement. Its performance is exptl. verified and compared to a com. surface DBD O3 source fitted with a three-electrode floating supply arrangement. The presented vol. DBD design is capable of steadily producing up to 4180 ppmv O3 at 1 Nl/min unprocessed atm. air intake and 10 kV 1.6 kHz sinusoidal high voltage supply corresponding to 67 g/kWh O3 prodn. yield increasing to 93 g/kWh at 100 Nl/min air intake. The effects of high voltage supply tuning are also investigated and discussed together with finite element method simulation results.
- 96Zeng, Y. X.; Wang, L.; Wu, C. F.; Wang, J. Q.; Shen, B. X.; Tu, X. Low temperature reforming of biogas over K-, Mg- and Ce-promoted Ni/Al2O3 catalysts for the production of hydrogen rich syngas: Understanding the plasma-catalytic synergy. Applied Catalysis B: Environmental 2018, 224, 469– 478, DOI: 10.1016/j.apcatb.2017.10.017Google Scholar96Low temperature reforming of biogas over K-, Mg- and Ce-promoted Ni/Al2O3 catalysts for the production of hydrogen rich syngas: Understanding the plasma-catalytic synergyZeng, Y. X.; Wang, L.; Wu, C. F.; Wang, J. Q.; Shen, B. X.; Tu, X.Applied Catalysis, B: Environmental (2018), 224 (), 469-478CODEN: ACBEE3; ISSN:0926-3373. (Elsevier B.V.)Plasma-catalytic biogas reforming over Ni-X/Al2O3 catalyst (X = K, Mg and Ce) has been carried out in a coaxial dielec. barrier discharge (DBD) plasma reactor. Three different process modes plasma-alone, catalysis-alone and plasma-catalysis were investigated to get new insights into the synergistic effect resulted from the interaction of the plasma with the promoted Ni catalysts. Compared to the biogas reforming using either plasma-alone or catalysis-alone mode at the same temp. (160°), the combination of the plasma with the Ni-based catalysts exhibited a low temp. synergistic effect, as evidenced from the much higher reforming performance of the plasma-catalytic process compared to that of the sum of the individual processes (plasma-alone and catalysis-alone). The addn. of promoters (K, Mg, and Ce) into the Ni/Al2O3 catalyst enhanced the conversion of CH4, the yield of H2 and the energy efficiency of the plasma process. In this study, the behavior of K, Mg and Ce promoters in the low temp. plasma-catalytic biogas reforming was clearly different from that in high temp. thermal catalytic process in terms of the conversion of CH4 and carbon deposition, which could be ascribed to the temp.-dependent character of the promoters. In the plasma-catalytic biogas reforming, the Ni-K/Al2O3 catalyst showed the best performance, enhancing the conversion of both CO2 and CH4, the yield of H2, CO and C2-C4 alkanes and the energy efficiency of the plasma process. The highest conversion of CO2 (22.8%) and CH4 (31.6%) was achieved by placing the K-promoted catalyst in the plasma reforming process. The Mg-promoted catalyst remarkably increased the H2/CO molar ratio in the gas products (up to 2.2) due to the decreased CO2 conversion. In addn., compared to the un-promoted Ni/Al2O3 catalyst, although the use of the promoted catalysts increased the carbon deposition on the surface of the spent catalysts by 22-26%, the total amt. of deposited carbon was still less than that reported in high temp. catalytic dry reforming processes. More than 80% of the increased carbonaceous species was in the form of reactive carbon species, which can be easily oxidized by CO2 and O atoms and maintain the stability of the catalysts during the reforming reaction.
- 97Wang, Y.; Yu, F.; Zhu, M.; Ma, C.; Zhao, D.; Wang, C.; Zhou, A.; Dai, B.; Ji, J.; Guo, X. N-Doping of plasma exfoliated graphene oxide via dielectric barrier discharge plasma treatment for the oxygen reduction reaction. Journal of Materials Chemistry A 2018, 6 (5), 2011– 2017, DOI: 10.1039/C7TA08607EGoogle Scholar97N-Doping of plasma exfoliated graphene oxide via dielectric barrier discharge plasma treatment for the oxygen reduction reactionWang, Yiqing; Yu, Feng; Zhu, Mingyuan; Ma, Cunhua; Zhao, Dan; Wang, Chao; Zhou, Amin; Dai, Bin; Ji, Junyi; Guo, XuhongJournal of Materials Chemistry A: Materials for Energy and Sustainability (2018), 6 (5), 2011-2017CODEN: JMCAET; ISSN:2050-7496. (Royal Society of Chemistry)Nitrogen doped plasma exfoliated graphene oxide (N-PEGO) was obtained by fast and effective dielec. barrier discharge (DBD) plasma technol. The plasma treatment could provide a burst open and high-energy electron/ion collision mechanism for doping and exfoliation. Ammonium carbonate was previously inserted into the interlayer of GO powder, and the rapid release of the NH3 and CO2 gases during DBD plasma treatment could exfoliate the GO powder into few-layer PEGO (<4 layers). Moreover, the plasma treatment also introduced the nitrogen dopant (5.26 at%), which is proven to be an efficient strategy to enhance the performance of oxygen redn. reaction (ORR) electrocatalysts. The resulting N-PEGO showed a high onset potential comparable to that of com. Pt/C, i.e., 0.89 V vs. reversible hydrogen electrode (RHE) and good electrocatalysis stability towards the ORR. This fast and effective one-step doping and exfoliation strategy demonstrated a new industrial-scale N-doped graphene fabrication technique.
- 98Zhang, H.; Li, K.; Shu, C.; Lou, Z.; Sun, T.; Jia, J. Enhancement of styrene removal using a novel double-tube dielectric barrier discharge (DDBD) reactor. Chem. Eng. J. 2014, 256, 107– 118, DOI: 10.1016/j.cej.2014.06.105Google Scholar98Enhancement of styrene removal using a novel double-tube dielectric barrier discharge (DDBD) reactorZhang, Hongbo; Li, Kan; Shu, Chenhua; Lou, Ziyang; Sun, Tonghua; Jia, JinpingChemical Engineering Journal (Amsterdam, Netherlands) (2014), 256 (), 107-118CODEN: CMEJAJ; ISSN:1385-8947. (Elsevier B.V.)A novel double-tube dielec. barrier discharge (DDBD) reactor was used to degrade styrene. This DDBD reactor contained 2 discharge zones with 1 power supply, an outer tube zone with low discharge energy, and an inner tube zone with high discharge energy. Gas first flowed into the outer tube zone, then into the inner tube zone, then flows out from the inner tube zone. Compared to traditional single-tube dielec. barrier discharge (SDBD) reactors, the DDBD reactor has these advantages: energy utilization efficiency can be improved because the low bond energy groups in styrene can be destroyed first in the outer discharge zone by weak discharge energy and the high bond energy groups, e.g., arom. rings, can be destroyed in the inner discharge zone by high discharge energy; high mineralization efficiency results in no oil-like byproducts aggregated on the reactor surface; and the double dielec. layers are protected from penetration. The outer and inner tube diam. were optimized and the DDBD reactor with a 25 mm outer tube and 6 mm inner tube displayed the best styrene mineralization efficiency. Compared to a SDBD reactor with the same outer tube diam., CO and CO2 selectivities were improved by 40% with a 2000 mg/m3 styrene concn. and an applied voltage of 11 kV. There was no any oil-like byproducts obsd. aggregated on outer tube wall, inner tube outlet, and the electrode after 6 h treatment. Applied voltage, O2 content, discharge length, and relative humidity were optimized in this work and O3 and NOx byproducts were detected and discussed.
- 99Mustafa, M. F.; Fu, X.; Liu, Y.; Abbas, Y.; Wang, H.; Lu, W. Volatile organic compounds (VOCs) removal in non-thermal plasma double dielectric barrier discharge reactor. J. Hazard. Mater. 2018, 347, 317– 324, DOI: 10.1016/j.jhazmat.2018.01.021Google Scholar99Volatile organic compounds (VOCs) removal in non-thermal plasma double dielectric barrier discharge reactorMustafa, Muhammad Farooq; Fu, Xindi; Liu, Yanjun; Abbas, Yawar; Wang, Hongtao; Lu, WenjingJournal of Hazardous Materials (2018), 347 (), 317-324CODEN: JHMAD9; ISSN:0304-3894. (Elsevier B.V.)Non-thermal plasma (NTP) an emerging technol. to treat volatile org. compds. (VOCs) present in unhygienic point source air streams. In present study, double dielec. barrier discharge (DDBD) reactors were used for the first time to evaluate the removal efficiency of VOCs mixt. of different nature at const. exptl. conditions (input power 16-65.8 W, VOCs mixt. feeding rate 1-6 L/min, 100-101 ppm inlet concn. of individual VOC). Reactor A and B with discharge gap at 6 mm and 3 mm resp., were used in current study. When treated at an input power of 53.7 W with gas feeding rate of 1 L/min in DDBD reactor A, removal efficiency of the VOCs were: tetrachloroethylene (100%), toluene (100%), trichloroethylene (100%), benzene (100%), Et acetate (100%) and carbon disulfide (88.30%); whereas in reactor B, the removal efficiency of all VOCs were 100%. Plasma-catalyst (Pt-Sn/Al2O3, BaTiO3 and HZSM-5) synergistic effect on VOCs removal efficiency was also investigated. Highest removal efficiency i.e 100% was obsd. for each compd. with BaTiO3 and HZSM-5 at an input power 65.8 W. However, integrating NTP with BaTiO3 and HZSM-5 leads to enhanced removal performance of VOCs mixt. with high activity, increase in energy efficiency and suppression of unwanted byproducts.
- 100Abbas, Y.; Lu, W.; Wang, Q.; Dai, H.; Liu, Y.; Fu, X.; Pan, C.; Ghaedi, H.; Cheng, F.; Wang, H. Remediation of pyrene contaminated soil by double dielectric barrier discharge plasma technology: Performance optimization and evaluation. Environ. Pollut. 2020, 260, 113944, DOI: 10.1016/j.envpol.2020.113944Google Scholar100Remediation of pyrene contaminated soil by double dielectric barrier discharge plasma technology: Performance optimization and evaluationAbbas, Yawar; Lu, Wenjing; Wang, Qian; Dai, Huixing; Liu, Yanting; Fu, Xindi; Pan, Chao; Ghaedi, Hosein; Cheng, Feng; Wang, HongtaoEnvironmental Pollution (Oxford, United Kingdom) (2020), 260 (), 113944CODEN: ENPOEK; ISSN:0269-7491. (Elsevier Ltd.)Polycyclic arom. hydrocarbons (PAHs) in soil are not only detrimental to environment but also to human health. Double dielec. barrier discharge (DDBD) plasma reactor used for the remediation of pyrene contaminated soil was studied. The performance of DDBD reactor was optimized with influential parameters including applied voltage, type of carrier gas, air feeding rate as well as pyrene initial concn. The anal. of variance (ANOVA) results showed that input energy had a great effect on pyrene remediation efficiency followed by pyrene initial concn., while, the effect of air feeding rate was insignificant. More specifically, the remediation efficiency of pyrene under air, nitrogen and argon as carrier gas were approx. 79.7, 40.7 and 38.2% resp. Pyrene remediation efficiency is favored at high level of applied voltages and low level of pyrene initial concn. (10 mgkg-1) and air feeding rate (0.85 L/min). Moreover, computation of the energy efficiency of the DDBD system disclosed that an optimal applied voltage (35.8 kV) and higher initial pyrene concn. (200 mgkg-1) favored the high energy efficiency. A regression model predicting pyrene remediation under DDBD plasma condition was developed using the data from a face-centered central composite design (FCCD) expt. Finally, the residual toxicity anal. depicted that the respiratory activity increased more than 21 times (from 0.04 to 0.849 mg O2 g-1) with a pyrene remediation efficiency of 81.1%. The study demonstrated the DDBD plasma technol. is a promising method not only for high efficiency of pyrene remediation, but also recovering biol. function without changing the phys.-chem. properties of soil.
- 101Mu, R.; Liu, Y.; Li, R.; Xue, G.; Ognier, S. Remediation of pyrene-contaminated soil by active species generated from flat-plate dielectric barrier discharge. Chem. Eng. J. 2016, 296, 356– 365, DOI: 10.1016/j.cej.2016.03.106Google Scholar101Remediation of pyrene-contaminated soil by active species generated from flat-plate dielectric barrier dischargeMu, Ruiwen; Liu, Yanan; Li, Rui; Xue, Gang; Ognier, StephanieChemical Engineering Journal (Amsterdam, Netherlands) (2016), 296 (), 356-365CODEN: CMEJAJ; ISSN:1385-8947. (Elsevier B.V.)Soil polluted with pyrene was remediated using a dielec. barrier discharge (DBD) plasma reactor at atm. pressure. Influencing factors, including treatment time, discharge voltage, electrode gap, gas flow rate, initial pyrene concn., and pH of the soil, were studied. Exptl. results showed that pyrene degrdn. efficiency was influenced on a small scale by soil pH: the pyrene removal rate reached 76% in alk. condition (pH 11.69), i.e., 8% higher than in neutral conditions (pH 7.76) and 13.7% higher than in acidic conditions (pH 5.67). The removal of pyrene increased as the applied voltage increased and the electrode gap decreased. The optimal airflow rate was 1.0 L/min. The more pyrene that was coated on soil particles the higher was the energy efficiency, but the plasma penetrating pyrene layers faded by ∼25% when the layers doubled. Optical emission spectrometer (OES), FTIR and GC-MS data indicated that the excited at. N, at. O and NOx were abundant in the plasma, and that the active species contg. O and N both contributed to the decompn. of pollutants. The possible pyrene degrdn. pathway is suggested. The exptl. results showed that the DBD technique was able to effectively degrade pyrene over a broad pH range.
- 102Aggelopoulos, C. A.; Hatzisymeon, M.; Tataraki, D.; Rassias, G. Remediation of ciprofloxacin-contaminated soil by nanosecond pulsed dielectric barrier discharge plasma: Influencing factors and degradation mechanisms. Chem. Eng. J. 2020, 393, 124768, DOI: 10.1016/j.cej.2020.124768Google Scholar102Remediation of ciprofloxacin-contaminated soil by nanosecond pulsed dielectric barrier discharge plasma: Influencing factors and degradation mechanismsAggelopoulos, C. A.; Hatzisymeon, M.; Tataraki, D.; Rassias, G.Chemical Engineering Journal (Amsterdam, Netherlands) (2020), 393 (), 124768CODEN: CMEJAJ; ISSN:1385-8947. (Elsevier B.V.)The continuous release of antibiotics in soil environment poses a serious threat for soil and water quality and consequently human health. However, research efforts focused on the effective remediation of antibiotic-polluted soil are still very limited. In this study, a nanosecond pulsed dielec. barrier discharge (nsp-DBD) plasma system was used for the first time to remediate soil contaminated by ciprofloxacin which is one of the most widely used, persistent and genotoxic antibiotics. Various cold atm. plasma (CAP) operating parameters were investigated and optimized. The optimal moisture content and air flow rate were detd. at 5% and 1.0 L min-1, resp. Ciprofloxacin degrdn. increased with pulse voltage and pulse repetition rate and decreased with higher initial concns. in the soil. At optimal conditions (pulse voltage 17.4 kV, pulse frequency 200 Hz), ciprofloxacin was completely degraded (∼99%) in soil, at very short nsp-DBD treatment time (∼3 min), with the corresponding energy efficiency being 4.6 mg/kJ. The relative distribution and identity of major ciprofloxacin degradants generated was detd. by UPLC-MS anal. This led to the generation of a degrdn. map that is consistent with hydroxyl radical-driven successive hydrogen atom abstractions and hydroxyl radical recombination events at the onset of the process followed by singlet oxygen mediated degrdn. Interestingly, the degrdn. pattern obsd. under nsp-DBD conditions shares several aspects with the in-vivo metabolic profile of ciprofloxacin.
- 103Ghaedi, H.; Ayoub, M.; Sufian, S.; Lal, B.; Uemura, Y. Thermal stability and FT-IR analysis of Phosphonium-based deep eutectic solvents with different hydrogen bond donors. J. Mol. Liq. 2017, 242, 395– 403, DOI: 10.1016/j.molliq.2017.07.016Google Scholar103Thermal stability and FT-IR analysis of Phosphonium-based deep eutectic solvents with different hydrogen bond donorsGhaedi, Hosein; Ayoub, Muhammad; Sufian, Suriati; Lal, Bhajan; Uemura, YoshimitsuJournal of Molecular Liquids (2017), 242 (), 395-403CODEN: JMLIDT; ISSN:0167-7322. (Elsevier B.V.)Recently, deep eutectic solvent (DES), a relatively new type of solvent, has received a considerable amt. of attention from researchers in different fields of research. DESs have a high potential to be an alternative to ionic liqs. (ILs) and traditional solvents. It is important the knowledge of thermal stability and interaction of functional groups on both salt as a hydrogen bond acceptor (HBA) and hydrogen bond donor (HBD) in order to use of DESs as alternative solvents for numerous industrial applications. In this work, four DESs have been selected with the same salt but four different HBDs. Salt was allyltriphenyl phosphonium bromide (ATPPB) and HBDs were glycerol (GL), ethylene glycol (EG), diethylene glycol (DEG) and triethylene glycol (TEG). DESs were prepd. easily into the same molar ratio of 1:4 salt to HBDs. Fourier transform IR spectroscopy (FT-IR) as an effective technique was conducted to gain information about hydrogen-bonding and vibration modes as well as investigate the functional groups of DESs. Finally, the thermal stability of DESs was studied under nitrogen at a temp. range of 30 to 800°C.
- 104Pootawang, P.; Saito, N.; Takai, O. Solution plasma for template removal in mesoporous silica: pH and discharge time varying characteristics. Thin Solid Films 2011, 519 (20), 7030– 7035, DOI: 10.1016/j.tsf.2011.01.213Google Scholar104Solution plasma for template removal in mesoporous silica: pH and discharge time varying characteristicsPootawang, Panuphong; Saito, Nagahiro; Takai, OsamuThin Solid Films (2011), 519 (20), 7030-7035CODEN: THSFAP; ISSN:0040-6090. (Elsevier B.V.)The evaluation of the ability of soln. plasma process, SPP, depending on the pH of the discharge soln. and discharge time for template removal in mesoporous silica was described. In the synthesis of mesoporous silica, ternary surfactant system contg. tri-block copolymer EO20PO69EO20 (P123), sodium dodecylbenzene sulfonate (SDBS), and 1,1,2,2,3,3,4,4,4-nonafluoro-1-Bu sulfonate (NFBS) was chem. used for synthesis under acid condition via sol-gel method then SPP was employed for template removal. The ordered 2D hexagonal arrangement was obsd. by the evidence of high resoln. TEM and the diffraction mode of X-ray. The efficiency of SPP depending on the pH of the discharge soln. and discharge time was scientifically demonstrated as a function of BET surface area. In the case of pH dependence, it was achieved that the ability of template removal in acid and base solns. was clearly higher than those of such results in neutral soln. In the term of discharge time, moreover, the percentage of template removal comparing in the result of BET surface area increased as the increase in discharge time.
- 105Pootawang, P.; Saito, N.; Takai, O. Solution Plasma Process for Template Removal in Mesoporous Silica Synthesis. Jpn. J. Appl. Phys. 2010, 49 (12), 126202, DOI: 10.1143/JJAP.49.126202Google Scholar105Solution plasma process for template removal in mesoporous silica synthesisPootawang, Panuphong; Saito, Nagahiro; Takai, OsamuJapanese Journal of Applied Physics (2010), 49 (12), 126202/1-126202/7CODEN: JJAPB6 ISSN:. (Japan Society of Applied Physics)The plasma discharge in aq. soln. was scientifically studied and applied to template removal in mesoporous silica synthesis. Highly dispersed spherical mesoporous silica particles were synthesized by the ternary surfactant system contg. the Pluronic P123 copolymer (EO20PO69EO20), sodium dodecylbenzene sulfonate, and 1,1,2,2,3,3,4,4,4-nonafluoro-1-butane sulfonate, via the sol-gel method in acid solns. The soln. plasma process (SPP), instead of conventional thermal calcinations, was used to remove the template. The mechanism of the removal of the org. template occurred via oxidn. by the hydroxyl radicals generated during discharge. The transformation of a mesopore structure from a disordered wormlike structure to a hexagonally arranged structure was obsd. by X-ray diffraction anal. and was confirmed by transmission electron microscopy. The results of the thermal anal. and functional group identification of mesoporous silica after SPP showed evidence of org. template removal. The surface area calcd. using the Brunauer-Emmett-Teller (BET) theory and the mean pore diam. results could be used to evaluate the plasma efficiency, demonstrating that this method does not affect the pore size in the case of discharge in a soln. of pH 3 compared with the results of thermal calcination. Hence, SPP was proved to be highly efficient for org. template removal, exhibiting short consumption time and less contamination.
- 106Lu, B.; Kawamoto, K. A novel approach for synthesizing ordered mesoporous silica SBA-15. Mater. Res. Bull. 2012, 47 (6), 1301– 1305, DOI: 10.1016/j.materresbull.2012.03.020Google Scholar106A novel approach for synthesizing ordered mesoporous silica SBA-15Lu, Baowang; Kawamoto, KatsuyaMaterials Research Bulletin (2012), 47 (6), 1301-1305CODEN: MRBUAC; ISSN:0025-5408. (Elsevier Ltd.)Ordered SBA-15 with a high sp. surface area, large pore size and pore vol. could be synthesized at a short time (overnight) without further calcination. During the SBA-15 synthesis process, TEOS hydrolysis, the condensation of the silica species and the decompn. of the Pluronic P123 template were completed by using sulfuric acid. The decompd. Pluronic P123 could be completely exacted by solvent after synthesis. SBA-15 had high hydrothermal stability.
- 107de Ávila, S. G.; Silva, L. C. C.; Matos, J. R. Optimisation of SBA-15 properties using Soxhlet solvent extraction for template removal. Microporous Mesoporous Mater. 2016, 234, 277– 286, DOI: 10.1016/j.micromeso.2016.07.027Google Scholar107Optimisation of SBA-15 properties using Soxhlet solvent extraction for template removalde Avila, Simone G.; Silva, Luis Carlos C.; Matos, Jivaldo R.Microporous and Mesoporous Materials (2016), 234 (), 277-286CODEN: MIMMFJ; ISSN:1387-1811. (Elsevier B.V.)Surfactants are utilized as templates in the synthesis of mesoporous materials. Normally, they are removed using a calcination process, however, careful removal is necessary to conserve the properties of the material. This work proposed surfactant removal from SBA-15 mesoporous silica using a Soxhlet extractor and different solvents. The thermal decompn. of the template was studied in order to understand the process of calcination of SBA-15. The results show that the calcination process influences the properties of the material. All of the utilized solvents enabled the removal of template. Some solvents such as water, acetonitrile and dichloromethane promoted template removal primarily from the surface of the material and others such as ethanol, acetone and methanol promoted the removal of template from within the porous silica. All samples were calcined after the extn. process, however the properties of the resulting materials were different. The greater the template removal, the greater was the surface area and pore size of the materials. Increased pore size caused decreased wall thickness. Methanol was the best of the studied solvents in terms of template removal. The extn. time required was studied and 6 h was necessary to complete the process. Soxhlet extn. is not efficient for the complete removal of template from mesoporous materials. However, the reduced quantity of template in the matrix means that less aggressive calcination is required, and therefore the properties of the mesoporous material can be preserved.
- 108Barczak, M. Template removal from mesoporous silicas using different methods as a tool for adjusting their properties. New J. Chem. 2018, 42 (6), 4182– 4191, DOI: 10.1039/C7NJ04642AGoogle Scholar108Template removal from mesoporous silicas using different methods as a tool for adjusting their propertiesBarczak, MariuszNew Journal of Chemistry (2018), 42 (6), 4182-4191CODEN: NJCHE5; ISSN:1144-0546. (Royal Society of Chemistry)Removal of the surfactant template is the final step in the synthesis of silica-based mesoporous materials. This step influences the properties of the final sample, including porosity, surface chem., and ordering. Three methods: (1) calcination, (2) extn., and (3) treatment with hydrogen peroxide are applied to remove the polymeric template from 2 types of mesoporous materials: ordered SBA-15 and silica nanorings. The 3 above-mentioned methods lead to materials with different properties as indicated by nitrogen sorption measurements, elemental anal., FTIR, NMR, and electron microscopy. The content of carbon in the final samples also differs testifying to variations in the efficiency of template removal. The detemplating scheme influences not only the structural and chem. properties but also the adsorption performance of the materials. The adsorption uptakes of L-histidine vary largely depending on the no. of silanol groups remaining on the surface after detemplation. Thus, template removal should be considered not only as the last necessary step in the synthesis of mesoporous silicas but also as a tool for tailoring the properties of the final structures.
- 109Gao, F.; Lu, Q.; Liu, X.; Yan, Y.; Zhao, D. Controlled Synthesis of Semiconductor PbS Nanocrystals and Nanowires Inside Mesoporous Silica SBA-15 Phase. Nano Lett. 2001, 1 (12), 743– 748, DOI: 10.1021/nl0156383Google Scholar109Controlled Synthesis of Semiconductor PbS Nanocrystals and Nanowires Inside Mesoporous Silica SBA-15 PhaseGao, Feng; Lu, Qingyi; Liu, Xiaoying; Yan, Yushan; Zhao, DongyuanNano Letters (2001), 1 (12), 743-748CODEN: NALEFD; ISSN:1530-6984. (American Chemical Society)A new flexible approach is developed to fabricate uniform nanocrystals and nanowires of binary compd. semiconductor PbS inside the channels of mesoporous silica SBA-15. The approach combines functionalization of the channel surface with thiol groups, absorption of Pb2+, and heating in N2 atmosphere at high temp. The sep. introduction of thiol groups and Pb2+ makes the loading of a binary compd. efficient and as easy as the loading of a single element. The nanocrystals are uniform and their sizes (5 nm) are consistent with the diam. of mesoporous SBA-15. The diam. of the PbS nanowires is about 6 nm and the length is several hundred nanometers. TEM images first intuitively confirm the formation of binary sulfide nanocrystals and nanowires dispersing uniformly inside the channels of mesoporous SBA-15. The key for transition from nanocrystals to nanowires is to increase the amt. of the Si-OH group on the channel surface of SBA-15, and ethanol extn. proves to be effective to keep large amt. of Si-OH groups during removing of the block copolymer. A massive blue shift is obsd. in photoluminescence spectra, and this clearly shows the quantum size effects of the PbS nanocrystals and nanowires.
- 110Aguado, J.; Arsuaga, J. M.; Arencibia, A.; Lindo, M.; Gascón, V. Aqueous heavy metals removal by adsorption on amine-functionalized mesoporous silica. J. Hazard. Mater. 2009, 163 (1), 213– 221, DOI: 10.1016/j.jhazmat.2008.06.080Google Scholar110Aqueous heavy metals removal by adsorption on amine-functionalized mesoporous silicaAguado, Jose; Arsuaga, Jesus M.; Arencibia, Amaya; Lindo, Montana; Gascon, VictoriaJournal of Hazardous Materials (2009), 163 (1), 213-221CODEN: JHMAD9; ISSN:0304-3894. (Elsevier B.V.)Amino functional mesoporous silica SBA-15 materials have been prepd. to develop efficient adsorbents of heavy metals in wastewater. Functionalization with amino groups has been carried out by using two independent methods, grafting and co-condensation. Three org. moieties have been selected to incorporate the active amino sites: aminopropyl (H2N-(CH2)3-), [2-aminoethylamino]-Pr (H2N-(CH2)2-NH-(CH2)3-), and [(2-aminoethylamino)-ethylamino]-Pr (H2N-(CH2)2-NH-(CH2)2-NH-(CH2)3-). Materials have been characterized by XRD, nitrogen sorption measurements and chem. anal. We have found that all materials preserve the mesoscopic order and exhibit suitable textural properties and nitrogen contents to act as potential adsorbents. Metal removal from aq. soln. has been examd. for Cu(II), Ni(II), Pb(II), Cd(II), and Zn(II); adsorption performances of materials prepd. by the two functionalization methods have been compared. In addn., copper adsorption process has been thoroughly studied from both kinetic and equil. points of view for some selected materials. Aq. Cu(II) adsorption rates show that the overall process is fast and the time evolution can be successfully reproduced with a pseudo-second-order kinetic model. Whole copper adsorption isotherms have been obtained at 25°. Significant max. adsorption capacities have been found with excellent behavior at low concn.
- 111Lu, F.; Wu, S.-H.; Hung, Y.; Mou, C.-Y. Size Effect on Cell Uptake in Well-Suspended, Uniform Mesoporous Silica Nanoparticles. Small 2009, 5 (12), 1408– 1413, DOI: 10.1002/smll.200900005Google Scholar111Size effect on cell uptake in well-suspended, uniform mesoporous silica nanoparticlesLu, Fang; Wu, Si-Han; Hung, Yann; Mou, Chung-YuanSmall (2009), 5 (12), 1408-1413CODEN: SMALBC; ISSN:1613-6810. (Wiley-VCH Verlag GmbH & Co. KGaA)The size of it: Mesoporous silica nanoparticles (MSNs) of controlled size in the range 30 to 280 nm are obtained by adjusting the pH of the reaction soln. The uptake of fluorescein-labeled MSNs (green, see image) by HeLa cells is size dependent, with max. uptake at a nanoparticle size of 50 nm.
- 112Laghaei, M.; Sadeghi, M.; Ghalei, B.; Dinari, M. The effect of various types of post-synthetic modifications on the structure and properties of MCM-41 mesoporous silica. Prog. Org. Coat. 2016, 90, 163– 170, DOI: 10.1016/j.porgcoat.2015.10.007Google Scholar112The effect of various types of post-synthetic modifications on the structure and properties of MCM-41 mesoporous silicaLaghaei, Milad; Sadeghi, Morteza; Ghalei, Behnam; Dinari, MohammadProgress in Organic Coatings (2016), 90 (), 163-170CODEN: POGCAT; ISSN:0300-9440. (Elsevier B.V.)MCM-41 mesoporous silicas synthesized by hydrothermal method were subsequently modified by 3-aminopropyltrimethoxysilane (APTMS) and trimethylchlorosilane (TMCS) via two different grafting methods, i.e. attaching functional groups with or without solvent. The post-synthetic modification, grafting, was applied due to its flexibility for the introduction of functional moieties into the favorite locations of the particles. The primary purpose of this study was to evaluate the effects of grafting methods as well as organosilanes on the modified MCM-41 particles. To achieve this aim, the obtained materials were investigated by various techniques including Fourier transform IR spectroscopy (FTIR), X-ray diffraction (XRD), N2 adsorption-desorption, transmission electron microscope (TEM), dynamic light scattering (DLS) and thermogravimetric anal. (TGA) to examine the functional groups, crystallinity, surface area, morphol., particle size distribution and amts. of functional groups, resp. The results confirmed that the spherical MCM-41 particles were successfully functionalized by APTMS and TMCS. Moreover, the surface area and av. pore diams. of the particles were affected by the inherent properties of organosilanes such as their side chains and catalytic behaviors. In addn. to the type of organosilanes, the grafting methods due to the various interactions between different components such as the surfactant, organosilane and acid had a tremendous impact on the modification process.
- 113Cheng, S.; Wang, X.; Chen, S.-Y. Applications of Amine-functionalized Mesoporous Silica in Fine Chemical Synthesis. Top. Catal. 2009, 52 (6), 681– 687, DOI: 10.1007/s11244-009-9216-2Google Scholar113Applications of Amine-functionalized Mesoporous Silica in Fine Chemical SynthesisCheng, Soofin; Wang, Xueguang; Chen, Shih-YuanTopics in Catalysis (2009), 52 (6-7), 681-687CODEN: TOCAFI; ISSN:1022-5528. (Springer)SBA-15 silica contg. homogeneously distributed amine-functional groups and of fiber or platelet morphol. was prepd. through a modified co-condensation method using P123 copolymer as template under acidic condition. Synthetic factors which led to well-ordered mesoporous materials with high loadings of various amine groups were discussed. The resultant mesoporous materials were efficient base catalysts in Knoevenagel and Claisen-Schmidt addn. reactions. The activities over SBA-15 materials with different amino-functional groups are compared. Moreover, the advantage of ordered large mesopores of SBA-15 in catalyzing liq. phase reactions was demonstrated, and the reaction rate could be further increased when SBA-15 was with platelet morphol. and short mesochannels.
- 114Gokulakrishnan, N.; Karbowiak, T.; Bellat, J. P.; Vonna, L.; Saada, M.-A.; Paillaud, J. L.; Soulard, M.; Patarin, J.; Parmentier, J. Improved hydrophobicity of inorganic–organic hybrid mesoporous silica with cage-like pores. Colloids Surf., A 2013, 421, 34– 43, DOI: 10.1016/j.colsurfa.2012.11.066Google Scholar114Improved hydrophobicity of inorganic-organic hybrid mesoporous silica with cage-like poresGokulakrishnan, Narasimhan; Karbowiak, Thomas; Bellat, Jean Pierre; Vonna, Laurent; Saada, Mohamed-Ali; Paillaud, Jean Louis; Soulard, Michel; Patarin, Joel; Parmentier, JulienColloids and Surfaces, A: Physicochemical and Engineering Aspects (2013), 421 (), 34-43CODEN: CPEAEH; ISSN:0927-7757. (Elsevier B.V.)Hydrophobic ordered mesoporous silica particles with cage-like pores (SBA-1 type) were prepd. through co-condensation of phenyltriethoxysilane (PhTES) and tetraethylorthosilicate (TEOS) at different TEOS/PhTES molar ratios. It is shown that the hydrophobic character of the particles is enhanced by increasing the Ph loading (decreasing the TEOS/PhTES molar ratio) and that it could be further enhanced by subsequent trimethylsilyl (TMS) grafting on remaining silanol groups (TMS-PhSBA-1 sample). This increase of hydrophobicity has been evidenced on the internal surface (mesoporosity) of the particles using water adsorption and, on the external surface of the particles (in the form of a pellet) using contact angle measurements. Interestingly, a high hysteresis was measured on the most hydrophobic sample (TMS-PhSBA-1), both on its internal surface during high pressure intrusion/extrusion of liq. water and on its external surface using advancing/receding contact angle measurements. This hydrophobic/hydrophilic behavior is explained by surface silanol sites, first shielded by hydrophobic org. moieties and, which subsequently trap water mols. within the porosity or on the external surface after a forced contact with liq. water. The absence of water extrusion (bumper behavior) of this material is then related both to the presence of silanol sites and to the restricted aperture of the cage-like pore morphol.
- 115Gao, J.; Wu, S.; Tan, F.; Tian, H.; Liu, J.; Lu, G. Q. M. Nanoengineering of amino - functionalized mesoporous silica nanospheres as nanoreactors. Progress in Natural Science: Materials International 2018, 28 (2), 242– 245, DOI: 10.1016/j.pnsc.2018.01.015Google Scholar115Nanoengineering of amino - functionalized mesoporous silica nanospheres as nanoreactorsGao, Jinsuo; Wu, Shouchun; Tan, Feng; Tian, Hao; Liu, Jian; Lu, G. Q. MaxProgress in Natural Science: Materials International (2018), 28 (2), 242-245CODEN: PNSMBB ISSN:. (Elsevier B.V.)Selective functionalization of mesoporous silica nanospheres (MSNs) is crucial for nanoengineering of MSNs. Herein, we have combined "surface-protected etching strategy" and "cationic surfactant assisted etching strategy" to prep. functionalized MSNs with externally attached amino groups. The externally attached NH2 groups endow the catalysts with excellent catalytic performance for nitroaldol reaction between nitromethane and benzaldehyde. In addn., those NH2-MSNs can also be used to support gold nanoparticles, which display very good catalytic performance for redn. of 4-nitrophenol. It can be envisioned that the synthesis protocol developed in this work could also be extended to nanoengineered MSNs, which provides opportunities for nanoreactors design.
- 116Wang, J.; Zheng, S.; Liu, J.; Xu, Z. Tannic acid adsorption on amino-functionalized magnetic mesoporous silica. Chem. Eng. J. 2010, 165 (1), 10– 16, DOI: 10.1016/j.cej.2010.08.066Google Scholar116Tannic acid adsorption on amino-functionalized magnetic mesoporous silicaWang, Jiahong; Zheng, Shourong; Liu, Jingliang; Xu, ZhaoyiChemical Engineering Journal (Amsterdam, Netherlands) (2010), 165 (1), 10-16CODEN: CMEJAJ; ISSN:1385-8947. (Elsevier B.V.)Amino-functionalized magnetic mesoporous silica (magMCM-41-NH2) was prepd. and adsorption of org. pollutant tannic acid (TA) from aq. soln. on the resulting material was studied. The adsorbent was characterized by elemental anal., XRD, TEM, N2 adsorption-desorption, IR spectroscopy, Zeta potential measurements and vibration sample magnetometer (VSM). Characterization results showed that magMCM-41-NH2 had ordered mesoporous structure with amino group content of 4.57%, BET surface area of 668 m2/g and the pore vol. of 0.525 cm3/g. Batch adsorption tests indicated that magMCM-41-NH2 adsorbent exhibited high adsorption affinity towards aq. TA with a max. adsorption capacity of 510.2 mg/g. The Freundlich model could fit the adsorption isotherm of TA over magMCM-41-NH2 very well, implying that adsorption process is heterogeneous. TA adsorption on magMCM-41-NH2 could be well described by the pseudo-second-order kinetics. Adsorption of TA on the adsorbent is strongly dependent on pH and ionic strength, suggesting that electrostatic interaction played a crucial role in TA adsorption. XPS anal. confirmed the formation of complex compd. between TA and surface amino groups of magMCM-41-NH2 upon adsorption.
- 117Ghorbani, M.; Nowee, S. M.; Ramezanian, N.; Raji, F. A new nanostructured material amino functionalized mesoporous silica synthesized via co-condensation method for Pb(II) and Ni(II) ion sorption from aqueous solution. Hydrometallurgy 2016, 161, 117– 126, DOI: 10.1016/j.hydromet.2016.02.002Google Scholar117A new nanostructured material amino functionalized mesoporous silica synthesized via co-condensation method for Pb(II) and Ni(II) ion sorption from aqueous solutionGhorbani, Masoomeh; Nowee, Seyyed Mostafa; Ramezanian, Navid; Raji, FoadHydrometallurgy (2016), 161 (), 117-126CODEN: HYDRDA; ISSN:0304-386X. (Elsevier B.V.)In this investigation, MCM-41/N-(3-trimethoxysilyl)-propyl)diethylenetriamine (MCM-41/TMSPDETA) adsorbent was prepd. via co-condensation method and characterized by FTIR, BET, XRD, TEM, SEM and DLS anal. techniques. Expts. were carried out to investigate the influence of different sorption parameters, such as pH, adsorbent dosage, contact time, initial concn. of heavy metal ions and soln. temp. in a batch system. Optimum conditions of sorption expts. were obtained at 20 °C with the pH of 6.0 and contact time of 60 min for Pb(II) and 120 min for Ni(II). The pseudo-first-order, the pseudo-second-order and intraparticle diffusion models have been used to analyze the sorption kinetic results. The sorption process was found to be well described by the pseudo-second-order rate model. The Langmuir and Freundlich isotherms have been used to describe the equil. sorption; the adsorption data obeyed the Langmuir isotherm. The max. capacity of the nanosorbent was 77.52 and 58.47 mg g-1 for Pb (II) and Ni (II) ions, resp. In order to verify the nature of sorption processes as phys. or chem., the equil. data were also fitted to the Dubinin-Radushkevitch (D-R) model. Based on D-R isotherm results, the values of mean free energy were 13.36 and 9.13 kJ mol-1 for Pb(II) and Ni(II) sorption, resp. These values of E (kJ mol-1) indicating chem. sorption for both metal ions. The selectivity order of lead and nickel sorption onto the adsorbent was Pb(II) > Ni(II).
- 118Wu, H.-C.; Chen, T.-C.; Budi, C. S.; Huang, P.-H.; Chen, C.-S.; Kao, H.-M. Confinement of Pt nanoparticles in cage-type mesoporous silica SBA-16 as efficient catalysts for toluene oxidation: the effect of carboxylic groups on the mesopore surface. Catalysis Science & Technology 2019, 9 (24), 6852– 6862, DOI: 10.1039/C9CY01787AGoogle Scholar118Confinement of Pt nanoparticles in cage-type mesoporous silica SBA-16 as efficient catalysts for toluene oxidation: the effect of carboxylic groups on the mesopore surfaceWu, Hung-Chi; Chen, Tse-Ching; Budi, Canggih Setya; Huang, Pin-Hsuan; Chen, Ching-Shiun; Kao, Hsien-MingCatalysis Science & Technology (2019), 9 (24), 6852-6862CODEN: CSTAGD; ISSN:2044-4753. (Royal Society of Chemistry)In this work, 3D cage-type mesoporous silica SBA-16, which is functionalized either with or without -COOH groups, is used to support Pt nanoparticles (NPs) and then applied for toluene oxidn. The -COOH functionalized SBA-16 exhibits higher affinity towards Pt4+ species, and as a result highly dispersed and nanosized Pt nanoparticles are formed in comparison to the case of its counterpart pure silica SBA-16 without -COOH groups. When pure SBA-16 without -COOH is used as the support, Pt NPs are formed outside the mesopores of SBA-16, resulting in larger Pt NPs. The catalytic activity for toluene oxidn. over Pt nanoparticles deposited on SBA-16 with -COOH is significantly higher than that on pure SBA-16. The intermediate species, reaction mechanisms and active sites in the course of toluene oxidn. are probed by in situ IR spectroscopy of CO and toluene adsorption. The Pt nanoparticles confined in the cage-type mesopores of SBA-16 with -COOH can induce the breakage of the strong C-C bonding between Ph and Me groups to form CO and carbonyl intermediates, and thus enhance the catalytic activity for toluene oxidn. The defect sites of Pt particles on SBA-16 with -COOH may play a role in the adsorption and decompn. of toluene. The low reducibility of Pt on SBA-16 results in a poor ability to degrade toluene, thus leading to a low catalytic rate for toluene oxidn.
- 119Suteewong, T.; Sai, H.; Lee, J.; Bradbury, M.; Hyeon, T.; Gruner, S. M.; Wiesner, U. Ordered mesoporous silica nanoparticles with and without embedded iron oxide nanoparticles: structure evolution during synthesis. J. Mater. Chem. 2010, 20 (36), 7807– 7814, DOI: 10.1039/c0jm01002bGoogle Scholar119Ordered mesoporous silica nanoparticles with and without embedded iron oxide nanoparticles: structure evolution during synthesisSuteewong, Teeraporn; Sai, Hiroaki; Lee, Jinwoo; Bradbury, Michelle; Hyeon, Taeghwan; Gruner, Sol M.; Wiesner, UlrichJournal of Materials Chemistry (2010), 20 (36), 7807-7814CODEN: JMACEP; ISSN:0959-9428. (Royal Society of Chemistry)This work reports on the structural evolution during room temp. synthesis of hexagonally ordered mesoporous silica nanoparticles with and without embedded iron oxide particles. Oleic acid-capped iron oxide nanoparticles are synthesized and transferred to an aq. phase using the cationic surfactant, hexadecyltrimethylammonium bromide (CTAB). MCM-41 type silica and composite nanoparticles are fabricated via sol-gel synthesis. Aliquots are taken from the soln. during synthesis to capture the particle formation process. TEM and Small Angle x-ray Scattering (SAXS) reveal a transition from a disordered to an ordered structure in both synthesis systems. Along with the evolution of structure, iron oxide nanoparticles acting as seeds at the early stages are relocated from the particle centers to the edges. Nitrogen sorption measurements for iron oxide-embedded mesoporous nanoparticles indicate surface areas as high as for the mesoporous silica nanoparticles without iron oxide.
- 120Karimi, S.; Heydari, M. Voltammetric mixture analysis of tyrosine and tryptophan using carbon paste electrode modified by newly synthesized mesoporous silica nanoparticles and clustering of variable-partial least square: Efficient strategy for template extraction in mesoporous silica nanoparticle synthesis. Sens. Actuators, B 2018, 257, 1134– 1142, DOI: 10.1016/j.snb.2017.11.014Google Scholar120Voltammetric mixture analysis of tyrosine and tryptophan using carbon paste electrode modified by newly synthesized mesoporous silica nanoparticles and clustering of variable-partial least squareKarimi, Sadegh; Heydari, MaryamSensors and Actuators, B: Chemical (2018), 257 (), 1134-1142CODEN: SABCEB; ISSN:0925-4005. (Elsevier B.V.)A sensitive, selective and efficient sensor based on carbon paste electrode modified by newly synthesized mesoporous silica nanoparticles (MSNs/CPE) is proposed for electrochem. detn. of tyrosine (Tyr) and tryptophan (Trp). In the proposed synthesis procedure of MSN, a weak acid such as NH4NO3 has been used in the washing stage, instead of strong acid, HCl. Brunauer-Emmett-Teller, BET, and Barrett-Joyner-Halenda (BJH) analyses confirms that the creation of cavities in MSN was happen more efficiently when NH4NO3 was applied respect to HCl procedure. Moreover, the obtained result shows the superiority of proposed approach compared with the unmodified carbon paste electrode, CPE; reported result for com. SiO2 modified electrode, SiO2/CPE, and also MSN/CPE by HCl procedure, such that the oxidn. peak current improved significantly for both amino acids. After optimization of exptl. parameters, the oxidn. peak current of Trp was linear over a concn. range of 0.05-600μM with a detection limit of 1.13 × 10-8 M. Similarly, the concn. range for Tyr, based on oxidn. peak current, was in the range from 0.3-600μM with limit of detection 4.97 × 10-8 M. Finally, since the differential pulse voltammetric peaks of Trp and Tyr has severe overlapping degree, the clustering of variables concept based PLS has been used as an efficient variable selection algorithm for simultaneous detn. of Tyr and Trp. The results demonstrated that the variable clustering combined with PLS can split the voltammogram spectra into useful and redundant ones and then based on informative cluster, stable model can be reached. Anal. of artificial urine as a real sample, confirms the potential ability of the proposed method for simultaneous detn. of these amino acids.
- 121Zhang, J.; Li, X.; Rosenholm, J. M.; Gu, H.-c. Synthesis and characterization of pore size-tunable magnetic mesoporous silica nanoparticles. J. Colloid Interface Sci. 2011, 361 (1), 16– 24, DOI: 10.1016/j.jcis.2011.05.038Google Scholar121Synthesis and characterization of pore size-tunable magnetic mesoporous silica nanoparticlesZhang, Jixi; Li, Xu; Rosenholm, Jessica M.; Gu, Hong-chenJournal of Colloid and Interface Science (2011), 361 (1), 16-24CODEN: JCISA5; ISSN:0021-9797. (Elsevier B.V.)Magnetic mesoporous silica nanoparticles (M-MSNs) are emerging as one of the most appealing candidates for theranostic carriers. Herein, a simple synthesis method of M-MSNs with a single Fe3O4 nanocrystal core and a mesoporous shell with radially aligned pores was elaborated using tetra-Et orthosilicate (TEOS) as silica source, cationic surfactant CTAB as template, and 1,3,5-triisopropylbenzene (TMB)/decane as pore swelling agents. Due to the special localization of TMB during the synthesis process, the pore size was increased with added TMB amt. within a limited range, while further employment of TMB lead to severe particle coalescence and not well-developed pore structure. On the other hand, when a proper amt. of decane was jointly incorporated with limited amts. of TMB, effective pore expansion of M-MSNs similar to that of analogous mesoporous silica nanoparticles was realized. The resultant M-MSN materials possessed smaller particle size (about 40-70 nm in diam.), tunable pore sizes (3.8-6.1 nm), high surface areas (700-1100 m2/g), and large pore vols. (0.44-1.54 cm3/g). We also demonstrate their high potential in conventional DNA loading. Maximum loading capacity of salmon sperm DNA (375 mg/g) was obtained by the use of the M-MSN sample with the largest pore size of 6.1 nm.
- 122Chun, B.-S.; Pendleton, P.; Badalyan, A.; Park, S.-Y. Mesoporous silica synthesis in sub- and supercritical carbon dioxide. Korean J. Chem. Eng. 2010, 27 (3), 983– 990, DOI: 10.1007/s11814-010-0130-xGoogle Scholar122Mesoporous silica synthesis in sub- and supercritical carbon dioxideChun, Byung-Soo; Pendleton, Phillip; Badalyan, Alexander; Park, Sun-YoungKorean Journal of Chemical Engineering (2010), 27 (3), 983-990CODEN: KJCHE6; ISSN:0256-1115. (Korean Institute of Chemical Engineers)Mesoporous silicas were synthesized from sodium silicate (Na2Si3O7) and tetraethylorthosilicate (TEOS) with Pluronic F127 (polyethylene oxide-polypropylene oxide-polyethylene oxide, EO106PO70EO106) triblock copolymer using sub- and supercrit. carbon dioxide (SubCO2 and SCO2) resp., as solvents. Templates were removed using liq. carbon dioxide (LCO2) and SCO2. The most efficient template removal was achieved by LCO2 - 92.7% (wt./wt.), followed by LCO2 with ethanol entrainer - 85.6% (wt./wt.), and by methanol - 78.8% (wt./wt.). The best efficiency of template removal by SCO2 was 50.7%. Values of sp. surface areas, ABET, were increased by 10% with the increase of an aging time from 6 to 24 h for Na2Si3O7-based silicas at aq. prepn. conditions, whereas the use of SCO2 reduced this value by 19.4%. Tor TEOS-based silicas synthesized using SCO2, ABET values increased by 3.8 times. Application of SCO2 for synthesis of TEOS-based silicas resulted in higher mesopore vols. of 0.719 and 1.241 mL/g with an av. mesopore width varying from 3.4 to 3.9 nm. Although Na2Si3O7-based silicas have almost similar mesopore width range, their mesopore vols. were 7 times less than those for TEOS-based silicas. Formation of mesopores in Na2Si3O7- and TEOS-based silicas was at the expense of micropores when prepd. in SCO2.
- 123Gunathilake, C.; Jaroniec, M. Mesoporous Organosilica with Amidoxime Groups for CO2 Sorption. ACS Appl. Mater. Interfaces 2014, 6 (15), 13069– 13078, DOI: 10.1021/am5028742Google Scholar123Mesoporous Organosilica with Amidoxime Groups for CO2 SorptionGunathilake, Chamila; Jaroniec, MietekACS Applied Materials & Interfaces (2014), 6 (15), 13069-13078CODEN: AAMICK; ISSN:1944-8244. (American Chemical Society)Incorporation of basic species such as amine-contg. groups into porous materials is a well-established strategy for achieving high uptake of acidic mols. such as CO2. This work reports a successful use of the aforementioned strategy for the development of ordered mesoporous organosilica (OMO) with amidoxime groups for CO2 sorption. These materials were prepd. by two-step process involving: (1) synthesis of OMO with cyanopropyl groups by co-condensation of (3-cyanopropyl)triethoxysilane and tetraethylorthosilicate in the presence of Pluronic P123 triblock copolymer under acidic conditions, and (2) conversion of cyanopropyl groups into amidoxime upon treatment with hydroxylamine hydrochloride under suitable conditions. The resulting series of amidoxime-contg. OMO was prepd. and used for CO2 sorption at low (25 °C) and elevated (60, 120 °C) temps. These sorbents exhibited relatively high adsorption capacity at ambient conditions (25 °C, 1 atm) and remarkable high sorption uptake (∼3 mmol/g) at 60 and 120 °C. This high CO2 uptake at elevated temps. by amidoxime-contg. OMO sorbent makes it a noticeable material for CO2 capture.
- 124Tsoncheva, T.; Rosenholm, J.; Linden, M.; Ivanova, L.; Minchev, C. Iron and copper oxide modified SBA-15 materials as catalysts in methanol decomposition: Effect of copolymer template removal. Applied Catalysis A: General 2007, 318, 234– 243, DOI: 10.1016/j.apcata.2006.11.008Google Scholar124Iron and copper oxide modified SBA-15 materials as catalysts in methanol decomposition: Effect of copolymer template removalTsoncheva, Tanya; Rosenholm, Jessica; Linden, Mika; Ivanova, Lyubomira; Minchev, ChristoApplied Catalysis, A: General (2007), 318 (), 234-243CODEN: ACAGE4; ISSN:0926-860X. (Elsevier B.V.)Several SBA-15 type mesoporous silicas, where different means of surfactant removal were used, were modified by copper and iron oxide, and tested as catalyst for methanol decompn. The materials were thoroughly characterized by nitrogen physisorption, x-ray diffraction, Moessbauer spectroscopy and temp. programmed redn. with hydrogen. The different means of template removal results in SBA-15 materials different in mesopore size and degree of microporosity. These parameters have a strong influence on the reductive and catalytic properties of the obtained composite materials.
- 125Ji, H.; Fan, Y.; Jin, W.; Chen, C.; Xu, N. Synthesis of Si-MCM-48 membrane by solvent extraction of the surfactant template. J. Non-Cryst. Solids 2008, 354 (18), 2010– 2016, DOI: 10.1016/j.jnoncrysol.2007.11.011Google Scholar125Synthesis of Si-MCM-48 membrane by solvent extraction of the surfactant templateJi, Hua; Fan, Yiqun; Jin, Wanqin; Chen, Changlin; Xu, NanpingJournal of Non-Crystalline Solids (2008), 354 (18), 2010-2016CODEN: JNCSBJ; ISSN:0022-3093. (Elsevier B.V.)Mesoporous MCM-48 SiO2 membranes were synthesized on porous supports under hydrothermal conditions, using tetra-Et orthosilicate (TEOS) as SiO2 source, cetyltrimethylammonium bromide (CTAB) as template surfactant. Then the templates were removed by solvent extn. instead of calcination. The results of the TG and FTIR showed that the solvent of 1 M HCl/EtOH soln. was feasible to ext. the templates in the MCM-48 materials and over 90% of the templates were extd. at room temp. for 24 h. The results of XRD, SEM indicated that the MCM-48 membranes were prepd. on the porous supports and extn. did not destroy the mesostructure of the MCM-48. The compactness of the extd. MCM-48 membrane was evaluated by the permeation of single gas (N2 and H2) with transmembrane pressure of 60-220 kPa. The permeance of N2 was independent of the transmembrane pressure and the ideal sepn. factor was ∼3.45. All the method, solvent extn. to remove surfactant template, is more effective to synthesize high quality MCM-48 membranes than calcination.
- 126Zhuang, X.; Qian, X.; Lv, J.; Wan, Y. An alternative method to remove PEO–PPO–PEO template in organic–inorganic mesoporous nanocomposites by sulfuric acid extraction. Appl. Surf. Sci. 2010, 256 (17), 5343– 5348, DOI: 10.1016/j.apsusc.2009.12.074Google Scholar126An alternative method to remove PEO-PPO-PEO template in organic-inorganic mesoporous nanocomposites by sulfuric acid extractionZhuang, Xin; Qian, Xufang; Lv, Jiahui; Wan, YingApplied Surface Science (2010), 256 (17), 5343-5348CODEN: ASUSEE; ISSN:0169-4332. (Elsevier B.V.)Sulfuric acid is used as an extn. agent to remove PEO-PPO-PEO templates in the org.-inorg. mesoporous nanocomposites from the triconstituent co-assembly which includes the low-polymd. phenolic resins, TEOS and triblock copolymer F127. The XRD and TEM results show well ordered mesostructure after extn. with sulfuric acid. As followed from the N2 sorption isotherms the extd. composites possess high surface areas (332-367 m2/g), large pore vols. (0.66-0.78 cm3/g), and large pore sizes (about 10.7 nm). The FT-IR anal. reveals almost complete elimination of triblock copolymer F127, and the maintenance of org. groups. This method shows potentials in removing templates from nanocomposites contg. functional moieties.
- 127Yang, C.-M.; Zibrowius, B.; Schmidt, W.; Schüth, F. Consecutive Generation of Mesopores and Micropores in SBA-15. Chem. Mater. 2003, 15 (20), 3739– 3741, DOI: 10.1021/cm031109jGoogle Scholar127Consecutive Generation of Mesopores and Micropores in SBA 15Yang, Chia-Min; Zibrowius, Bodo; Schmidt, Wolfgang; Schueth, FerdiChemistry of Materials (2003), 15 (20), 3739-3741CODEN: CMATEX; ISSN:0897-4756. (American Chemical Society)The authors provide a method for the consecutive generation of mesopores and micropores in SBA 15 through ether cleavage and subsequent thermal treatment at 200 °C. The mesopores are 1st vacated by partial decompn. of the template via ether cleavage by H2SO4. The occluded poly(ethylene oxide) chains in the SiO2 matrix, which are less accessible to the acid, can be decompd. subsequently by thermal treatment in air to create micropores. In addn., because the entire process is based on reactions at low temps., the resulting SBA 15 has larger mesopores and a greater micropore vol., which is also beneficial for certain applications.
- 128Grudzien, R. M.; Grabicka, B. E.; Jaroniec, M. Effective method for removal of polymeric template from SBA-16 silica combining extraction and temperature-controlled calcination. J. Mater. Chem. 2006, 16 (9), 819– 823, DOI: 10.1039/B515975JGoogle Scholar128Effective method for removal of polymeric template from SBA-16 silica combining extraction and temperature-controlled calcinationGrudzien, Rafal M.; Grabicka, Bogna E.; Jaroniec, MietekJournal of Materials Chemistry (2006), 16 (9), 819-823CODEN: JMACEP; ISSN:0959-9428. (Royal Society of Chemistry)An effective method for the removal of polymeric template, which combines extn. and temp.-controlled calcination, is proposed to obtain high pore vol. and large pore size ordered mesoporous silicas, SBA-16 (Im3m symmetry group), synthesized in the presence of sodium chloride at low acid concns. using poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (Pluronic F127) as a structure directing agent and tetraethylorthosilicate as a silica source. The aforementioned materials were characterized by small angle X-ray powder diffraction, nitrogen adsorption, high resoln. thermogravimetry and elemental anal.
- 129Gai, F.; Zhou, T.; Chu, G.; Li, Y.; Liu, Y.; Huo, Q.; Akhtar, F. Mixed anionic surfactant-templated mesoporous silica nanoparticles for fluorescence detection of Fe3+. Dalton Transactions 2016, 45 (2), 508– 514, DOI: 10.1039/C5DT03052HGoogle Scholar129Mixed anionic surfactant-templated mesoporous silica nanoparticles for fluorescence detection of Fe3+Gai, Fangyuan; Zhou, Tianlei; Chu, Guang; Li, Ye; Liu, Yunling; Huo, Qisheng; Akhtar, FaridDalton Transactions (2016), 45 (2), 508-514CODEN: DTARAF; ISSN:1477-9226. (Royal Society of Chemistry)This work demonstrates a method for the synthesis of large pore mesoporous silica nanoparticles (MSNs) with a pore diam. of 10.3 nm and a particle diam. of ∼50 nm based on the incorporation of mixed anionic surfactants sodium dodecyl benzenesulfonate (SDBS) and sodium dodecyl sulfate (SDS) as the template in the synthesis process. The dispersity, morphol., pore structure and size of mesoporous nanoparticles were adjusted by changing the molar ratio of two anionic surfactants, the concn. of the co-structure-directing agent (3-aminopropyltrimethoxysilane) and the reaction temp. The results of synthesis expts. suggested that the formation of large pore MSNs involved a nucleation and growth process. MSNs were post-grafted with a Schiff base moiety for fluorescence sensing of Fe3+ in water. The applicability of functionalized MSNs was demonstrated by selective fluorescence detection of Fe3+ in aq. media.
- 130Zheng, J.; Tian, X.; Sun, Y.; Lu, D.; Yang, W. pH-sensitive poly(glutamic acid) grafted mesoporous silica nanoparticles for drug delivery. Int. J. Pharm. 2013, 450 (1), 296– 303, DOI: 10.1016/j.ijpharm.2013.04.014Google Scholar130pH-sensitive poly(glutamic acid) grafted mesoporous silica nanoparticles for drug deliveryZheng, Jin; Tian, Xuejiao; Sun, Yangfei; Lu, Daru; Yang, WuliInternational Journal of Pharmaceutics (Amsterdam, Netherlands) (2013), 450 (1-2), 296-303CODEN: IJPHDE; ISSN:0378-5173. (Elsevier B.V.)PH-sensitive poly(l-glutamic acid) grafted mesoporous silica nanoparticles (MSN-PLGA) were prepd. by the surface-initiated N-carboxyanhydride polymn. method. The resultant MSN-PLGA was well dispersed in aq. medium and showed high drug loading efficiency, superior stability, and significantly higher drug release rates. The cumulative release of doxorubicin hydrochloride (DOX) from DOX-loaded MSN-PLGA (DOX@MSN-PLGA) was pH-dependent and the release rate was much higher at pH 5.5 than that at pH 7.4. The cytotoxicity results indicated that the blank MSN-PLGA was biocompatible and the DOX@MSN-PLGA had potent in vitro cytotoxicity effect similar to free DOX. Overall, these results demonstrate that MSN-PLGA is a promising platform to build pH controlled drug delivery systems for cancer therapy.
- 131Yokoi, T.; Yoshitake, H.; Tatsumi, T. Synthesis of Anionic-Surfactant-Templated Mesoporous Silica Using Organoalkoxysilane-Containing Amino Groups. Chem. Mater. 2003, 15 (24), 4536– 4538, DOI: 10.1021/cm034499iGoogle Scholar131Synthesis of anionic-surfactant-templated mesoporous silica using organoalkoxysilane-containing amino groupsYokoi, Toshiyuki; Yoshitake, Hideaki; Tatsumi, TakashiChemistry of Materials (2003), 15 (24), 4536-4538CODEN: CMATEX; ISSN:0897-4756. (American Chemical Society)Mesoporous silica was prepd. by dissolving sodium dodecyl sulfate in a water-ethanol mixt. (molar ratio 9:1), adding 3-aminopropyltriethoxysilane and tetra-Et orthosilicate, stirring for 1 h and ambient temp., and keeping statically at 373 K for 2 days. The resulting white ppt. was filtered, washed in deionized water and dried in air at 373 K. The anionic templating route suggests a structural control by functional groups in inorg. precursors for the formation of mesoporous metal oxides.
- 132Yokoi, T.; Yoshitake, H.; Tatsumi, T. Synthesis of mesoporous silica by using anionic surfactant. In Studies in Surface Science and Catalysis; van Steen, E., Claeys, I. M., Callanan, L. H., Eds.; Elsevier: 2004; Vol. 154, pp 519– 527.Google ScholarThere is no corresponding record for this reference.
- 133Rahman, N. A.; Widhiana, I.; Juliastuti, S. R.; Setyawan, H. Synthesis of mesoporous silica with controlled pore structure from bagasse ash as a silica source. Colloids Surf., A 2015, 476, 1– 7, DOI: 10.1016/j.colsurfa.2015.03.018Google Scholar133Synthesis of mesoporous silica with controlled pore structure from bagasse ash as a silica sourceRahman, Nanik Astuti; Widhiana, Ika; Juliastuti, Sri Rachmania; Setyawan, HeruColloids and Surfaces, A: Physicochemical and Engineering Aspects (2015), 476 (), 1-7CODEN: CPEAEH; ISSN:0927-7757. (Elsevier B.V.)Mesoporous silica with controlled pore structure was prepd. from bagasse ash as a silica source. The silica in the bagasse ash was dissolved by NaOH soln. to produce sodium silicate precursor for the mesoporous silica, with or without polyethylene glycol (PEG) template. Without the PEG template, the pore structure was greatly influenced by the pH and the presence of Na+ ions. The porous silica produced in the presence of Na+ possessed higher surface area and pore diam. than those produced in the absence of Na+. The surface area and pore diam. reached approx. 525 m2 g-1 and 18 nm, resp., when the gelation pH was 3. When the gelation pH was increased, the surface area decreased while the pore diam. increased. The use of PEG template increased significantly the surface area, which reached approx. 656 m2 g-1 when the template was removed by solvothermal extn. Calcination at high temp. caused a densification of pore structure resulting a smaller surface area, pore diam. and pore vol. The pore diam. for all cases was greater than 4 nm, indicating that the silicas were mesoporous.
- 134Zhou, Y.; Schattka, J. H.; Antonietti, M. Room-Temperature Ionic Liquids as Template to Monolithic Mesoporous Silica with Wormlike Pores via a Sol–Gel Nanocasting Technique. Nano Lett. 2004, 4 (3), 477– 481, DOI: 10.1021/nl025861fGoogle Scholar134Room-Temperature Ionic Liquids as Template to Monolithic Mesoporous Silica with Wormlike Pores via a Sol-Gel Nanocasting TechniqueZhou, Yong; Schattka, Jan H.; Antonietti, MarkusNano Letters (2004), 4 (3), 477-481CODEN: NALEFD; ISSN:1530-6984. (American Chemical Society)This paper reports a novel room-temp. ionic liq. (RTIL), 1-Butyl-3-methyl-imidazolium-tetrafluoroborate ([C4mim]+BF4-), as template to monolithic mesoporous silica with wormhole framework via a convenient nanocasting technique. In contrast with the applied liq. crystal self-assembly of long-chain surfactants on the prepn. of mesoporous nanostructures, a new so-called hydrogen bond-co-π-π stack mechanism was proposed to be responsible for the present self-assembly of the RTIL in the reaction system for the formation of the wormlike mesopore, in which both the hydrogen bonds formed between the [BF4]- and silano group of silica gel and the π-π stack interaction of the neighboring imidazolium rings play crucial roles in the formation of the wormhole framework of mesporous silica. The proposed hydrogen bond-co-π-π stack mechanism with the RTIL as template may open a new pathway to prep. mesoporous materials.
- 135Pérez, L. L.; Ortiz-Iniesta, M. J.; Zhang, Z.; Agirrezabal-Telleria, I.; Santes, M.; Heeres, H. J.; Melián-Cabrera, I. Detemplation of soft mesoporous silica nanoparticles with structural preservation. Journal of Materials Chemistry A 2013, 1 (15), 4747– 4753, DOI: 10.1039/c3ta01240aGoogle Scholar135Detemplation of soft mesoporous silica nanoparticles with structural preservationPerez, Lidia Lopez; Ortiz-Iniesta, Maria J.; Zhang, Zheng; Agirrezabal-Telleria, Iker; Santes, Martijn; Heeres, Hero Jan; Melian-Cabrera, IgnacioJournal of Materials Chemistry A: Materials for Energy and Sustainability (2013), 1 (15), 4747-4753CODEN: JMCAET; ISSN:2050-7496. (Royal Society of Chemistry)A mild protocol that allows the template removal of soft un-aged silica nanoparticles was investigated. After oxidizing the org. template by Fenton chem., a good structural preservation is only achieved when the material is equilibrated and dried in a low-surface tension solvent. This avoids excessive capillary stress induced by the high surface tension of water, a major component in the Fenton reaction medium. The Fenton reaction should be carried out under mild conditions as well; otherwise the sample deteriorates by extensive hydrolysis, and capillary stress, and the structural ordering diminishes severely. The authors propose employing 10 ppm Fe concn. at 70°C for 24 h for the cetyltrimethylammonium bromide template. The proposed protocol involves two steps resulting in an overall significantly higher pore vol. attributed to the wider pores and limited particle agglomeration, while the calcined counterpart evidences aggregation and loss of the hexagonal ordering. N-BuOH exchange is unnecessary when the mesophase is stabilized by ageing, as the structure resists the water capillary stress.
- 136Melián-Cabrera, I.; Kapteijn, F.; Moulijn, J. A. Room temperature detemplation of zeolites through H2O2-mediated oxidation. Chem. Commun. 2005, 21, 2744– 2746, DOI: 10.1039/b502167gGoogle ScholarThere is no corresponding record for this reference.
- 137Melián-Cabrera, I.; Kapteijn, F.; Moulijn, J. A. One-pot catalyst preparation: combined detemplating and Fe ion-exchange of BEA through Fenton’s chemistry. Chem. Commun. 2005, (16), 2178– 2180, DOI: 10.1039/B500291EGoogle Scholar137One-pot catalyst preparation: combined detemplating and Fe ion-exchange of BEA through Fenton's chemistryMelian-Cabrera, I.; Kapteijn, F.; Moulijn, J. A.Chemical Communications (Cambridge, United Kingdom) (2005), (16), 2178-2180CODEN: CHCOFS; ISSN:1359-7345. (Royal Society of Chemistry)BEA zeolite has been simultaneously detemplated and Fe-exchanged by treating the parent zeolite with a Fenton's-type reagent (Fe3+-H2O2) at low temp. This one-pot process simplifies and speeds up considerably the prepn. route. The catalyst shows excellent performance on N2O decompn. compared to conventionally prepd. Fe-BEA.
- 138Zhang, Z.; Santangelo, D. L.; ten Brink, G.; Kooi, B. J.; Moulijn, J. A.; Melián-Cabrera, I. On the drug adsorption capacity of SBA-15 obtained from various detemplation protocols. Mater. Lett. 2014, 131, 186– 189, DOI: 10.1016/j.matlet.2014.05.173Google Scholar138On the drug adsorption capacity of SBA-15 obtained from various detemplation protocolsZhang, Zheng; Santangelo, Diana L.; ten Brink, Gert; Kooi, Bart J.; Moulijn, Jacob A.; Melian-Cabrera, IgnacioMaterials Letters (2014), 131 (), 186-189CODEN: MLETDJ; ISSN:0167-577X. (Elsevier B.V.)The effect of the mild detemplation method, based on Fenton chem. (with and without previous solvent extn.), and calcination was evaluated by the drug uptake capacity of SBA-15 materials. A no. of characterization techniques were applied for evaluation and comparison of the materials properties such as TGA, CNH, N2 physisorption and 29Si NMR. The mild Fenton detemplation method rendered a nearly pristine SBA-15 without structural shrinkage, low residual template, improved surface area, pore vol. and silanol concn. The drug (ibuprofen) adsorption expts. were carried out by soln. immersion in powdery form. The mild detemplated samples experienced an enhanced uptake that could be explained by the enhanced d. of silanols (mmol/g), originated from the absence of calcination in the Fenton approaches.
- 139Zhang, Z.; Melián-Cabrera, I. Modifying the Hierarchical Porosity of SBA-15 via Mild-Detemplation Followed by Secondary Treatments. The. J. Phys. Chem. C 2014, 118 (49), 28689– 28698, DOI: 10.1021/jp5096213Google Scholar139Modifying the Hierarchical Porosity of SBA-15 via Mild-Detemplation Followed by Secondary TreatmentsZhang, Zheng; Melian-Cabrera, IgnacioJournal of Physical Chemistry C (2014), 118 (49), 28689-28698CODEN: JPCCCK; ISSN:1932-7447. (American Chemical Society)Fenton-chem.-based detemplation combined with secondary treatments offers options to tune the hierarchical porosity of SBA-15. This approach has been studied on a series of SBA-15 mesophases and has been compared to the conventional calcination. The as-synthesized and detemplated materials were studied with regard to their template content (TGA, CHN), structure (SAXS, TEM), surface hydroxylation (Blin-Carteret's approach), and texture (high-resoln. argon physisorption). Fenton detemplation achieves 99% of template removal, leading to highly hydroxylated materials. The structure is better preserved when a secondary treatment is applied after the Fenton oxidn., due to the intense capillary forces during drying in water. Two successful approaches are presented: drying in a low-surface-tension solvent (such as n-BuOH) and a hydrothermal stabilization to further condense the structure and make it structurally more robust. Both approaches give rise to remarkably low structural shrinkage, lower than calcination and the direct water-dried Fenton. Interestingly, the derived textural features are remarkably different. The n-BuOH exchange route gives rise to highly hierarchical structures with enhanced interconnecting pores and the highest surface areas. The hydrothermal stabilization produces large-pore SBA-15 structures with high pore vol., intermediate interconnectivity, and minimal micropores. Therefore, the hierarchical texture can be fine-tuned in these two fashions while the template is removed under mild conditions.
- 140Kecht, J.; Bein, T. Oxidative removal of template molecules and organic functionalities in mesoporous silica nanoparticles by H2O2 treatment. Microporous Mesoporous Mater. 2008, 116 (1), 123– 130, DOI: 10.1016/j.micromeso.2008.03.027Google Scholar140Oxidative removal of template molecules and organic functionalities in mesoporous silica nanoparticles by H2O2 treatmentKecht, Johann; Bein, ThomasMicroporous and Mesoporous Materials (2008), 116 (1-3), 123-130CODEN: MIMMFJ; ISSN:1387-1811. (Elsevier)The H2O2-mediated oxidn. of cetyltrimethylammonium (CTA) template inside the channels of mesoporous silica is investigated. Furthermore, the influence of H2O2 on the decompn. of various functional groups inserted by co-condensation is examd. The resulting oxidized products are compared to materials obtained by extn. in acidic ethanolic media. The concept of oxidative template removal is then transferred to colloidal suspensions contg. mesoporous silica nanoparticles. By using phenyltriethoxysilane as a co-condensation agent, it is possible to control the size and shape of such nanosized porous hosts. The optimized H2O2 treatment is applied in order to produce suspensions of unfunctionalized mesoporous silica nanoparticles with accessible pores and controlled morphologies by a quick and efficient one-pot reaction.
- 141Yang, L. M.; Wang, Y. J.; Luo, G. S.; Dai, Y. Y. Simultaneous removal of copolymer template from SBA-15 in the crystallization process. Microporous Mesoporous Mater. 2005, 81 (1), 107– 114, DOI: 10.1016/j.micromeso.2005.01.023Google Scholar141Simultaneous removal of copolymer template from SBA-15 in the crystallization processYang, L. M.; Wang, Y. J.; Luo, G. S.; Dai, Y. Y.Microporous and Mesoporous Materials (2005), 81 (1-3), 107-114CODEN: MIMMFJ; ISSN:1387-1811. (Elsevier B.V.)The triblock copolymer templates were successfully removed from as-synthesized mesoporous mol. sieve SBA-15 by a new treatment process with H2O2 as oxidizing agent, and the process couples the crystn. process into one step to make the synthesis process compact. The effect of operation conditions on removal efficiency was studied, including treating time and temp., H2O2 concn., and the quantity ratio of H2O2 to org. templates. The prepd. mesoporous SBA-15 materials by the new process, characterized by XRD, N adsorption and desorption, TEM, SEM, IR spectroscopy (FTIR), and hydrothermal stability expts., exhibited higher surface areas, larger micropore vols., more uniform particle sizes and higher d. of silanol groups on the pore wall than those obtained by conventional methods. Also, the removal of templates in the crystn. process facilitates a further condensation and mild shrinkage of the SiO2 framework, and rearrangement of the materials, which prevents the hydrothermally treated SBA-15 materials from shrinking significantly during subsequent calcination and makes them show higher hydrothermal stabilities.
- 142Lu, A.-H.; Li, W.-C.; Schmidt, W.; Schüth, F. Low temperature oxidative template removal from SBA-15 using MnO4– solution and carbon replication of the mesoporous silica product. J. Mater. Chem. 2006, 16 (33), 3396– 3401, DOI: 10.1039/B607542HGoogle Scholar142Low temperature oxidative template removal from SBA-15 using MnO4- solution and carbon replication of the mesoporous silica productLu, An-Hui; Li, Wen-Cui; Schmidt, Wolfgang; Schueth, FerdiJournal of Materials Chemistry (2006), 16 (33), 3396-3401CODEN: JMACEP; ISSN:0959-9428. (Royal Society of Chemistry)We report a new method of low temp. removal of template from SBA-15 by KMnO4 chem. oxidn. Using this silica as template, mesoporous carbon with thick pore walls and relatively small mesopores can be cast. The results from XRD and nitrogen sorption show that the silica obtained after surfactant removal has high surface area, high pore vol. and good structural ordering. The obtained carbon replica also shows good structural ordering as reflected from XRD and TEM characterizations. EDX anal. shows that no residue of potassium and manganese in the carbon sample can be detected, indicating the complete removal of such species during the washing step. Interestingly, the anal. of the micropore vol. based on the DFT method shows that these carbon replicas have a large fraction of micropores with respect to the total pore vol. These micropore rich carbon materials could be candidates as mol. sieve type adsorbents and catalyst supports.
- 143Hiura, H.; Ebbesen, T. W.; Tanigaki, K. Opening and purification of carbon nanotubes in high yields. Adv. Mater. 1995, 7 (3), 275– 276, DOI: 10.1002/adma.19950070304Google Scholar143Opening and purification of carbon nanotubes in high yieldsHiura, Hidefumi; Ebbesen, Thomas W.; Tanigaki, KatsumiAdvanced Materials (Weinheim, Germany) (1995), 7 (3), 275-6CODEN: ADVMEW; ISSN:0935-9648. (VCH)C nanotubes, produced by the C arc discharge synthesis method, were opened and purified by treating them with a mixt. of H2SO4 and KMnO4. The method, useful for gram quantities of purified product, gave yields of 40%. The obtained nanotubes were examd. with XPS.
- 144Ding, Z.; Chen, J.; Guo, Yu; Xuzhong, G. Study on Removing Organic Template from SBA-15 by HNO3 Oxidation Treatment. Bulletin of the Chinese Ceramic Society 2009, 28, 80– 84Google ScholarThere is no corresponding record for this reference.
- 145Wang, Y.; Yang, R. T. Template Removal from SBA-15 by Ionic Liquid for Amine Grafting: Applications to CO2 Capture and Natural Gas Desulfurization. ACS Sustainable Chem. Eng. 2020, 8 (22), 8295– 8304, DOI: 10.1021/acssuschemeng.0c01941Google Scholar145Template Removal from SBA-15 by Ionic Liquid for Amine Grafting: Applications to CO2 Capture and Natural Gas DesulfurizationWang, Yiren; Yang, Ralph T.ACS Sustainable Chemistry & Engineering (2020), 8 (22), 8295-8304CODEN: ASCECG; ISSN:2168-0485. (American Chemical Society)A new ionic liq. treatment method has been developed for removing the org. template from mesoporous silica SBA-15. Compared with conventional template removal by air calcination, the novel ionic liq. treatment method efficiently removed the org. template at a low temp. and preserved the surface silanol groups. The significantly increased silanol d. led to higher amine loadings on amine grafted SBA-15. Consequently, the ionic liq. treated sample showed 63% more CO2 capacity at conditions relevant to CO2 capture from flue gas. Moreover, the ionic liq. treated sample exhibited significantly higher capacities for H2S capture from natural gas as well as CO2 adsorption capacities for direct air capture which were nearly 3 times higher than the conventionally treated sample. The adsorbent stability, the isosteric heats of adsorption, and the effect of moisture were also investigated for the ionic liq. treated sample. The mechanism of template removal by ionic liq. is discussed, and the feasibility of recovery/reuse of the ionic liq. and the template is shown. A novel template removal method using ionic liq. is developed to enhance selective adsorption capacities of CO2 and H2S by amine grafted SBA-15.
- 146Ghaedi, H.; Akbari, S.; Zhou, H.; Wang, W.; Zhao, M. Excess Properties of and Simultaneous Effects of Important Parameters on CO2 Solubility in Binary Mixture of Water-Phosphonium Based-Deep Eutectic Solvents: Taguchi Method. Energy Fuels 2022, na, DOI: 10.1021/acs.energyfuels.1c03623Google ScholarThere is no corresponding record for this reference.
- 147Ghaedi, H.; Kalhor, P.; Zhao, M.; Clough, P. T.; Anthony, E. J.; Fennell, P. S. Potassium carbonate-based ternary transition temperature mixture (deep eutectic analogues) for CO2 absorption: Characterizations and DFT analysis. Frontiers of Environmental Science & Engineering 2022, 16 (7), 92, DOI: 10.1007/s11783-021-1500-9Google Scholar147Potassium carbonate-based ternary transition temperature mixture (deep eutectic analogues) for CO2 absorption: Characterizations and DFT analysisGhaedi, Hosein; Kalhor, Payam; Zhao, Ming; Clough, Peter T.; Anthony, Edward J.; Fennell, Paul S.Frontiers of Environmental Science & Engineering (2022), 16 (7), 92CODEN: FESECJ; ISSN:2095-221X. (Higher Education Press)Abstr.: Is it possible to improve CO2 soly. in potassium carbonate (K2CO3)-based transition temp. mixts. (TTMs). To assess this possibility, a ternary transition-temp. mixt. (TTTM) was prepd. by using a hindered amine, 2-amino-2-methyl-1,3-propanediol (AMPD). Fourier transform IR spectroscopy (FT-IR) was employed to detect the functional groups including hydroxyl, amine, carbonate ion, and aliph. functional groups in the prepd. solvents. From thermogravimetric anal. (TGA), it was found that the addn. of AMPD to the binary mixt. can increase the thermal stability of TTTM. The viscosity findings showed that TTTM has a higher viscosity than TTM while their difference was decreased by increasing temp. In addn., Eyring's abs. rate theory was used to compute the activation parameters (ΔG*, ΔH*, and ΔS*). The CO2 soly. in liqs. was measured at a temp. of 303.15 K and pressures up to 1.8 MPa. The results disclosed that the CO2 soly. of TTTM was improved by the addn. of AMPD. At the pressure of about 1.8 MPa, the CO2 mole fractions of TTM and TTTM were 0.1697 and 0.2022, resp. To confirm the exptl. data, d. functional theory (DFT) was employed. From the DFT anal., it was found that the TTTM + CO2 system has higher interaction energy (|ΔE|) than the TTM + CO2 system indicating the higher CO2 affinity of the former system. This study might help scientists to better understand and to improve CO2 soly. in these types of solvents by choosing a suitable amine as HBD and finding the best combination of HBA and HBD. [graphic not available: see fulltext].
- 148Ghaedi, H.; Zhao, M.; Clough, P. T.; Anthony, E. J.; Fennell, P. S. High CO2 absorption in new amine based-transition-temperature mixtures (deep eutectic analogues) and reporting thermal stability, viscosity and surface tension: Response surface methodology (RSM). J. Mol. Liq. 2020, 316, 113863, DOI: 10.1016/j.molliq.2020.113863Google Scholar148High CO2 absorption in new amine based-transition-temperature mixtures (deep eutectic analogues) and reporting thermal stability, viscosity and surface tension: Response surface methodology (RSM)Ghaedi, Hosein; Zhao, Ming; Clough, Peter T.; Anthony, Edward J.; Fennell, Paul S.Journal of Molecular Liquids (2020), 316 (), 113863CODEN: JMLIDT; ISSN:0167-7322. (Elsevier B.V.)To study CO2 capture potential, three types of transition-temp. mixts. (TTMs) were prepd. by mixing ethyltriphenylphosphonium bromide (MTPPB) as a hydrogen bond acceptor (HBA) and n-Me diethanolamine (MDEA) as a hydrogen bond donor (HBD) in different molar ratios (1:7, 1:10 and 1:16). Fourier transform IR spectroscopy (FT-IR) results showed that TTMs have almost similar spectra to their HBD (MDEA) with different levels of transmittance and exhibit similar behavior. From the exptl. results, it was found that the thermal stability, viscosity and surface tension of TTMs decreased as the concn. of MDEA in the mixt. increased. According to response surface methodol. (RSM) models and anal. of variance (ANOVA), temp. and molar ratio had a great effect on the viscosity and surface tension of TTMs. Finally, it was found that CO2 soly. in TTMs (at 303.15 K at pressure up to 1.35 MPa) was enhanced as the MDEA quantity increased in the mixt. up to 1:10 mol ratio. However, by increasing MDEA concn. to 16:1 mol ratio, there was a decreasing trend in the CO2 soly. data. Also, all TTMs, particularly TTM contg. 10:1 mol MDEA (MTPPB-MDEA 1:10) exhibited an equil. loading capacity approaching 1 mol CO2 per mol solvent at high pressure, revealing their high potential for CO2 capture. A comparison showed that the CO2 soly. in the studied solvents was higher than that of existing deep eutectic solvents (DESs) and other TTMs as well as several ionic liqs. (ILs) to date. To the best of our knowledge, this is the first study to report the CO2 soly. in phosphonium-base TTMs contg. MDEA.
- 149Ghaedi, H.; Zhao, M.; Ayoub, M.; Zahraa, D.; Shariff, A. M.; Inayat, A. Preparation and characterization of amine (N-methyl diethanolamine)-based transition temperature mixtures (deep eutectic analogues solvents). J. Chem. Thermodyn. 2019, 137, 108– 118, DOI: 10.1016/j.jct.2018.12.014Google Scholar149Preparation and characterization of amine (N-methyl diethanolamine)-based transition temperature mixtures (deep eutectic analogues solvents)Ghaedi, Hosein; Zhao, Ming; Ayoub, Muhammad; Zahraa, Diana; Shariff, Azmi Mohd; Inayat, AbrarJournal of Chemical Thermodynamics (2019), 137 (), 108-118CODEN: JCTDAF; ISSN:0021-9614. (Elsevier Ltd.)In this study, three mixts.of methylyltriphenylphosphonium bromide (MTPPB) as hydrogen bond acceptor (HBA) and N-Me diethanolamine (MDEA) as hydrogen bond donor (HBD) component was used to prep.transition temp.mixts.(TTMs) into different mole ratios of 1:7, 1:10 and 1:16 HBA/HBD. Two important physicochem. properties of TTMs such as d.and refractive index were investigated at the atm. pressure and temp. ranges of (293.15-353.15) K and (293.15-343.15) K, resp. The exptl.d.data were used to derive the molar volume, mol.vol., lattice energy and isobaric thermal expansion coeffs. With the help of exptl.refractive index data, the electronic polarization, molar refraction, and free vol.were calcd.at the whole temps. Several empirical equations were used to correlate refractive indexes such as an empirical equation and one-parameter equations (Dale-Gladstone, Eykman, Lorentz-Lorenz, Newton, Arago-Biot, and Oster). Finally, the response surface methodol.(RSM) was applied to evaluate the effects of two main factors such as temp. and mole ratio on the d.and refractive index of TTMs. The results revealed that the molar ratio has almost a higher effect on the studied properties than temp.
- 150Ghaedi, H.; Ayoub, M.; Sufian, S.; Shariff, A. M.; Lal, B.; Wilfred, C. D. Density and refractive index measurements of transition-temperature mixture (deep eutectic analogues) based on potassium carbonate with dual hydrogen bond donors for CO2 capture. The. J. Chem. Thermodyn. 2018, 118, 147– 158, DOI: 10.1016/j.jct.2017.11.008Google Scholar150Density and refractive index measurements of transition-temperature mixture (deep eutectic analogues) based on potassium carbonate with dual hydrogen bond donors for CO2 captureGhaedi, Hosein; Ayoub, Muhammad; Sufian, Suriati; Shariff, Azmi Mohd.; Lal, Bhajan; Wilfred, Cecilia DeviJournal of Chemical Thermodynamics (2018), 118 (), 147-158CODEN: JCTDAF; ISSN:0021-9614. (Elsevier Ltd.)The transition-temp. mixt. (TTM) is a new type of solvent and is known as a tuneable solvent similar to deep eutectic solvent (DES). The new type of solvent called ternary transition-temp. mixt. (TTTM) was prepd. to use for CO2 capture purposes. In this work, TTMs and TTTMs were prepd. with potassium carbonate (PC) as a hydrogen bond acceptor (HBA) and three hydrogen bond donors (HBDs) such as glycerol (GL), ethylene glycol (EG) and 2-amino-2-methyl-1-3-propanediol (AMPD) known as a hindered amine (HA). Binary TTMs were PC-GL with mole ratios 1:10 and 1:16 and PC-EG with the same mole ratios. TTTMs were prepd. by adding AMPD in binary TTMs such as PC-GL-AMPD 1:16:1 and PC-EG-AMPD 1:10:1. The exptl. d. and refractive index of all mixts. were measured at temps. from 293.15 K to 343.15 K with an interval of 5 K. The effect of temp., mole ratio, molar mass and alkyl chain length on the properties was investigated. The molar volumes and isobaric thermal expansion were calcd. using exptl. d. data. The exptl. refractive index values were used to derive the specific refraction, molar refraction, free molar volume, electronic polarization and polarizability at several temps.
- 151Ghaedi, H.; Ayoub, M.; Sufian, S.; Hailegiorgis, S. M.; Murshid, G.; Khan, S. N. Thermal stability analysis, experimental conductivity and pH of phosphonium-based deep eutectic solvents and their prediction by a new empirical equation. J. Chem. Thermodyn. 2018, 116, 50– 60, DOI: 10.1016/j.jct.2017.08.029Google Scholar151Thermal stability analysis, experimental conductivity and pH of phosphonium-based deep eutectic solvents and their prediction by a new empirical equationGhaedi, Hosein; Ayoub, Muhammad; Sufian, Suriati; Hailegiorgis, Sintayehu Mekuria; Murshid, Ghulam; Khan, Saleem NawazJournal of Chemical Thermodynamics (2018), 116 (), 50-60CODEN: JCTDAF; ISSN:0021-9614. (Elsevier Ltd.)Deep eutectic solvents (DESs) are derived from two or more salts as the hydrogen bond acceptors (HBAs) and hydrogen bond donors (HBDs). Because of many unique features, DESs can be a versatile alternative to ionic liqs. and traditional solvents. In this work, DESs were prepd. namely allyltriphenylphosphonium bromide-diethylene glycol (ATPPB-DEG) and allyltriphenylphosphonium bromide-triethylene glycol (ATPPB-TEG) into three mole ratios 1:4, 1:10, and 1:16 salt to HBDs. The thermal stability was comprehensively analyzed under the temp. range of (30-800) °C. The cond. and pH values were detd. within the temp. range of 293.15 K-343.15 K. The results revealed that the amt. and type of HBDs have an effect on these properties. Moreover, the effect of temp. was studied on these properties. As the temp. increases, the cond. values increase while the pH values decrease. Finally, a new empirical equation was applied to correlate the exptl. cond. and pH data. It was found that this equation is powerful and reliable to correlate these properties of DESs.
- 152Ghaedi, H.; Ayoub, M.; Sufian, S.; Hailegiorgis, S. M.; Murshid, G.; Farrukh, S.; Khan, S. N. Experimental and prediction of volumetric properties of aqueous solution of (allyltriphenylPhosphonium bromide─Triethylene glycol) deep eutectic solvents. Thermochim. Acta 2017, 657, 123– 133, DOI: 10.1016/j.tca.2017.09.025Google Scholar152Experimental and prediction of volumetric properties of aqueous solution of (allyltriphenylPhosphonium bromide-Triethylene glycol) deep eutectic solventsGhaedi, Hosein; Ayoub, Muhammad; Sufian, Suriati; Hailegiorgis, Sintayehu Mekuria; Murshid, Ghulam; Farrukh, Sarah; Khan, Saleem NawazThermochimica Acta (2017), 657 (), 123-133CODEN: THACAS; ISSN:0040-6031. (Elsevier B.V.)Deep eutectic solvents (DESs) are derived from two or more salts as the hydrogen bond acceptors (HBAs) and hydrogen bond donors (HBDs). In this work, DES namely allyltriphenylphosphonium bromide- triethylene glycol (ATPPB-TEG) was prepd. by using three molar ratios; i.e.,1:4, 1:10, and 1:16 of salt to HBDs. The volumetric properties of aq. mixt. of DESs, such as d., molar volume, isobaric thermal expansion, apparent molar volume and apparent molar expansibility were reported at several temps. from 293.15 to 343.15 K. A math. equation, namely Jouyban-Acree model (JAM), was used to correlate the exptl. d. and molar volume data. Furthermore, in order to calc. the limiting apparent molar volume values, the apparent molar volume values were fitted into a Redlich-Mayer equation. By applying Hepler equation, it was found that DESs 1:4 and 1:10 are as structure-maker solutes, while DES 1:16 is a structure-breaking solute in aq. solns.
- 153Ghaedi, H.; Ayoub, M.; Sufian, S.; Shariff, A. M.; Murshid, G.; Hailegiorgis, S. M.; Khan, S. N. Density, excess and limiting properties of (water and deep eutectic solvent) systems at temperatures from 293.15K to 343.15K. J. Mol. Liq. 2017, 248, 378– 390, DOI: 10.1016/j.molliq.2017.10.074Google Scholar153Density, excess and limiting properties of (water and deep eutectic solvent) systems at temperatures from 293.15-343.15 KGhaedi, Hosein; Ayoub, Muhammad; Sufian, Suriati; Shariff, Azmi Mohd.; Murshid, Gulam; Hailegiorgis, Sintayehu Mekuria; Khan, Saleem NawazJournal of Molecular Liquids (2017), 248 (), 378-390CODEN: JMLIDT; ISSN:0167-7322. (Elsevier B.V.)Deep eutectic solvents (DESs) are derived from two or more salts as the hydrogen bond acceptors (HBAs) and hydrogen bond donors (HBDs). In this work, DES namely allyltriphenyl phosphonium bromide-diethylene glycol (ATPPB-DEG) was prepd. by using three molar ratios of 1:4, 1:10 and 1:16 salt to HBD. The volumetric properties of aq. DESs, such as d., molar volume, isobaric thermal expansion, apparent molar volume and apparent molar expansibility were reported at several temps. from 293.15 to 343.15 K. A math. equation, so-called Jouyban-Acree model (JAM), was used to correlate the exptl. d. and molar volume data of aq. soln. of DESs with respect to the concn. and temp. The results disclosed that this model is an accurate and reliable model for the prediction of aq. DES properties. The excess properties, such as excess molar volume and excess isobaric thermal expansion were reported and fitted to two different equations. In order to calc. the limiting apparent molar volume values, the apparent molar volume values were fitted into a Redlich-Mayer equation. By applying the Hepler equation, it was found that DESs with molar ratios of 1:4 and 1:10 are as structure-maker solutes, while the DES 1:16 is a structure-breaking solute in aq. solns. at different temps.
- 154Ghaedi, H.; Ayoub, M.; Sufian, S.; Murshid, G.; Farrukh, S.; Shariff, A. M. Investigation of various process parameters on the solubility of carbon dioxide in phosphonium-based deep eutectic solvents and their aqueous mixtures: Experimental and modeling. International Journal of Greenhouse Gas Control 2017, 66, 147– 158, DOI: 10.1016/j.ijggc.2017.09.020Google Scholar154Investigation of various process parameters on the solubility of carbon dioxide in phosphonium-based deep eutectic solvents and their aqueous mixtures: Experimental and modelingGhaedi, Hosein; Ayoub, Muhammad; Sufian, Suriati; Murshid, Ghulam; Farrukh, Sarah; Shariff, Azmi Mohd.International Journal of Greenhouse Gas Control (2017), 66 (), 147-158CODEN: IJGGBW; ISSN:1750-5836. (Elsevier B.V.)This research presents the application of predictive regression model such as quadratic regression for estn. of CO2 soly. in deep eutectic solvents namely allyltriphenylphosphonium bromide-triethylene glycol (ATPPB-TEG) into different molar ratios and their aq. solns. A quadratic regression model was developed after validation and confirmation through several strong approaches. The results disclose that the prediction of developed quadratic regression model is in acceptable agreement with exptl. soly. data. The overall R-squared (R2) and abs. relative error (ARE) values of proposed quadratic regression model were 0.9966 and 0.0725, resp. Moreover, anal. of variance (ANOVA) indicates that pressure is the most significant factor influencing the XCO2. Finally, the signal to noise (S/N) ratio shows that the highest levels for pressure, concn. of DES in mixt., and molar ratio, and lowest level for temp. are the optimal levels of input parameters to obtain the highest CO2 soly. in this system. The developed quadratic regression model and correlation are effective and provide quick, reliable and accurate predictions of CO2 soly. in DESs without carrying out any time consuming, difficult and expensive exptl. measurements. To the best of our knowledge, this is the first time a regression model was developed for prediction of CO2 soly. in DESs and their aq. solns.
- 155Ghaedi, H.; Ayoub, M.; Sufian, S.; Hailegiorgis, S. M.; Krishnan, S. Toxicity of Several Potassium Carbonate and Phosphonium-Based Deep Eutectic Solvents towards Escherichia coli and Listeria monocytogenes Bacteria. J. Environ. Anal Toxicol 2017, 7 (485), 2161– 0525, DOI: 10.4172/2161-0525Google ScholarThere is no corresponding record for this reference.
- 156Ghaedi, H.; Ayoub, M.; Sufian, S.; Shariff, A. M.; Lal, B. The study on temperature dependence of viscosity and surface tension of several Phosphonium-based deep eutectic solvents. J. Mol. Liq. 2017, 241, 500– 510, DOI: 10.1016/j.molliq.2017.06.024Google Scholar156The study on temperature dependence of viscosity and surface tension of several Phosphonium-based deep eutectic solventsGhaedi, Hosein; Ayoub, Muhammad; Sufian, Suriati; Shariff, Azmi Mohd.; Lal, BhajanJournal of Molecular Liquids (2017), 241 (), 500-510CODEN: JMLIDT; ISSN:0167-7322. (Elsevier B.V.)Deep eutectic solvents (DESs) are derived from two or more salts as the hydrogen bond acceptors (HBAs) and hydrogen bond donors (HBDs). In this work, six deep eutectic solvents (DESs) were prepd. namely allyltriphenyl phosphonium bromide- diethylene glycol (ATPPB-DEG) and allyltriphenyl phosphonium bromide - triethylene glycol (ATPPB-TEG) using three molar ratios of 1:4, 1:10 and 1:16 salt to HBDs. The temp. range for exptl. viscosity was from 293.15 to 343.15 K and that of the exptl. surface tension was between 298.15 and 343.15 K. The results disclosed that hydrogen bonding in DESs has a great effect on the properties. Among all DESs with the same components, the DESs with the strong hydrogen bonding in their structures had the higher viscosity and surface tension. Besides, by increasing the temp. and quantity of HBDs in DESs, both of these properties experienced a decreasing trend in the amt. It was found that the mol. wt. of DESs with the same component has an effect on the properties. The higher mol. wt. caused the higher viscosity and surface tension. Further, ATPPB-TEG DESs had the higher viscosity and lower surface tension than ATPPB-DEG DESs because of the higher alkyl chain in their structures. Several models and a new empirical equation were used to correlate the exptl. viscosity data. It was found that there is a well agreement between theor. and exptl. values esp. when the new empirical equation is used. In addn., the activation parameters for all DESs were calcd. using the exptl. viscosity data and application of Eyring's abs. rate theory. The exptl. surface tension was employed to predict the crit. temp., surface entropy and internal surface energy of DESs. Finally, two empirical equations were used for relating the exptl. surface tension to the exptl. viscosity of DESs.
- 157Ghaedi, H.; Ayoub, M.; Sufian, S.; Lal, B.; Shariff, A. M. Measurement and correlation of physicochemical properties of phosphonium-based deep eutectic solvents at several temperatures (293.15K–343.15K) for CO2 capture. J. Chem. Thermodyn. 2017, 113, 41– 51, DOI: 10.1016/j.jct.2017.05.020Google Scholar157Measurement and correlation of physicochemical properties of phosphonium-based deep eutectic solvents at several temperatures (293.15 K-343.15 K) for CO2 captureGhaedi, Hosein; Ayoub, Muhammad; Sufian, Suriati; Lal, Bhajan; Shariff, Azmi Mohd.Journal of Chemical Thermodynamics (2017), 113 (), 41-51CODEN: JCTDAF; ISSN:0021-9614. (Elsevier Ltd.)Recently, deep eutectic solvents (DESs) as the new solvents have received considerable amt. of attention between researchers in different research fields and are under investigation so find out their potential to become a versatile alternative to ionic liqs. (ILs) and traditional solvents. DESs are derived from two or more salts as the hydrogen bond acceptors (HBAs) and hydrogen bond donors (HBDs). Six DESs were synthesized namely allyltriphenylphosphonium bromide- diethylene glycol (ATPPB-DEG) and allyltriphenylphosphonium bromide- triethylene glycol (ATPPB-TEG) using three mole ratios of 1:4, 1:10 and 1:16 salt to HBDs. In this work, we report physicochem. properties of these DESs, which include d., molar volume, isobaric thermal expansion, refractive index, specific refraction, molar refraction, free molar volume, electronic polarization and internal pressure at several temps. from 293.15 K to 343.15 K. Most of these properties are fitted to a linear equation by the method of least-squares using the Levenberg-Marquardt algorithm to derive the corresponding parameters and est. the root mean square error (RMSE) and least squared correlation coeff. (R2).
- 158Ghaedi, H.; Ayoub, M.; Sufian, S.; Shariff, A. M.; Hailegiorgis, S. M.; Khan, S. N. CO2 capture with the help of Phosphonium-based deep eutectic solvents. J. Mol. Liq. 2017, 243, 564– 571, DOI: 10.1016/j.molliq.2017.08.046Google Scholar158CO2 capture with the help of Phosphonium-based deep eutectic solventsGhaedi, Hosein; Ayoub, Muhammad; Sufian, Suriati; Shariff, Azmi Mohd.; Hailegiorgis, Sintayehu Mekuria; Khan, Saleem NawazJournal of Molecular Liquids (2017), 243 (), 564-571CODEN: JMLIDT; ISSN:0167-7322. (Elsevier B.V.)Deep eutectic solvents (DESs) are derived from the concomitant reaction of two or more salts i.e. between hydrogen bond acceptor (HBA) and hydrogen bond donors (HBD) components. In this work, DESs were prepd. namely allyltriphenyl phosphonium bromide-diethylene glycol (ATPPB-DEG) and allyltriphenyl phosphonium bromide-triethylene glycol (ATPPB-TEG) into three molar ratios 1:4, 1:10, and 1:16 salt to HBDs. The carbon dioxide soly. in DESs at temp. of 303.15 K and pressure up to 2 MPa were detd. and reported in terms of mole fraction, CO2 loading and Henry's law consts. Krichevsky-Kasarnovsky equation was used to correlate the soly. data and obtain Henry's law consts. at 303.15 K. Finally, the effects of hydrogen bonding within DESs, molar ratio, molar volume, free vol., ether group and alkyl chain length were investigated based on CO2 soly. in DESs. To the best of our knowledge, this is the first time CO2 soly. in these DESs was studied.
- 159Satlewal, A.; Agrawal, R.; Bhagia, S.; Sangoro, J.; Ragauskas, A. J. Natural deep eutectic solvents for lignocellulosic biomass pretreatment: Recent developments, challenges and novel opportunities. Biotechnol. Adv. 2018, 36, 2032, DOI: 10.1016/j.biotechadv.2018.08.009Google Scholar159Natural deep eutectic solvents for lignocellulosic biomass pretreatment: Recent developments, challenges and novel opportunitiesSatlewal, Alok; Agrawal, Ruchi; Bhagia, Samarthya; Sangoro, Joshua; Ragauskas, Arthur J.Biotechnology Advances (2018), 36 (8), 2032-2050CODEN: BIADDD; ISSN:0734-9750. (Elsevier)Conversion of lignocellulosic biomass to fuels and chems. has attracted immense research and development around the world. Lowering recalcitrance of biomass in a cost-effective manner is a challenge to commercialize biomass-based technologies. Deep eutectic solvents (DESs) are new 'green' solvents that have a high potential for biomass processing because of their low cost, low toxicity, biodegradability, easy recycling and reuse. This article discusses the properties of DESs and recent advances in their application for lignocellulosic biomass processing. The effectiveness of DESs in hydrolyzing lignin-carbohydrate complexes, removing lignin/hemicellulose from biomass as well as their effect on biomass deconstruction, crystallinity and enzymic digestibility have been discussed. Moreover, this review presents recent findings on the compatibility of natural DESs with enzymes and microorganisms.
- 160Tan, Y. T.; Chua, A. S. M.; Ngoh, G. C. Deep eutectic solvent for lignocellulosic biomass fractionation and the subsequent conversion to bio-based products – A review. Bioresour. Technol. 2020, 297, 122522, DOI: 10.1016/j.biortech.2019.122522Google Scholar160Deep eutectic solvent for lignocellulosic biomass fractionation and the subsequent conversion to bio-based products - A reviewTan, Yee Tong; Chua, Adeline Seak May; Ngoh, Gek ChengBioresource Technology (2020), 297 (), 122522CODEN: BIRTEB; ISSN:0960-8524. (Elsevier Ltd.)A review. Since the introduction of deep eutectic solvent (DES) in biomass processing field, the efficiency of DES in lignocellulosic biopolymer model compds.' (cellulose, hemicellulose and lignin) solubilization and conversion was widely recognized. Nevertheless, DES's potential for biorefinery application can be reflected more accurately through their performance in raw lignocellulosic biomass processing rather than model compd. conversion. Therefore, this review examines the studies on raw lignocellulosic biomass fractionation using DES and the subsequent conversion of DES-fractionated products into bio-based products. The review stresses on three key parts: performance of varying types of DESs and pretreatment schemes for biopolymer fractionation, properties and conversion of fractionated saccharides as well as DES-extd. lignin. The prospects and challenges of DES implementation in biomass processing will also be discussed. This review provides a front-to-end view on the DES's performance, starting from pretreatment to DES-fractionated products conversion, which would be helpful in devising a comprehensive biomass utilization process.
- 161Zhang, C.-W.; Xia, S.-Q.; Ma, P.-S. Facile pretreatment of lignocellulosic biomass using deep eutectic solvents. Bioresour. Technol. 2016, 219, 1– 5, DOI: 10.1016/j.biortech.2016.07.026Google Scholar161Facile pretreatment of lignocellulosic biomass using deep eutectic solventsZhang, Cheng-Wu; Xia, Shu-Qian; Ma, Pei-ShengBioresource Technology (2016), 219 (), 1-5CODEN: BIRTEB; ISSN:0960-8524. (Elsevier Ltd.)In this work, three kinds of deep eutectic solvents (DESs) were facilely prepd. and used in the pretreatment of corncob, including monocarboxylic acid/choline chloride, dicarboxylic acid/choline chloride and polyalc./choline chloride. The enhanced delignification and subsequent enzymic hydrolysis efficiency were found to be related to the acid amt., acid strength and the nature of hydrogen bond acceptors. The XRD, SEM and FT-IR results consistently indicated that the structures of corncob were disrupted by the removal of lignin and hemicellulose in the pretreatment process. In addn., the optimal pretreatment temp. and time were 90 °C and 24 h, resp. This study explored the roles of various DESs combinations, pretreatment temp. and time to better utilize the DESs in the pretreatment of lignocellulosic biomass.
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Energy & Fuels
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Abstract
Figure 1
Figure 1. (a) Number of publications for mesoporous silica materials from 2000 to 2021. (b) Applications of mesoporous silica materials in different research fields published on the Web of Science with the keyword of “mesoporous silica material” (accessed December 25, 2021).
Figure 2
Figure 2. Residual carbon content for calcined SBA-15 and KIT-6 at various temperatures and times. Reproduced from ref (34). [Basso, A. M.; Nicola, B. P.; Bernardo-Gusmão, K.; Pergher, S. B. C. Tunable Effect of calcination of the silanol groups of KIT-6 and SBA-15 Mesoporous Materials. Applied Sciences2020, 10 (3), 970]. Copyright 2020, MDPI.
Figure 3
Figure 3. In situ preparation of Pt/mesoporous composite materials using catalytic template removal method. Reproduced from ref (37). [Krawiec, P.; Kockrick, E.; Simon, P.; Auffermann, G.; Kaskel, S. Platinum-Catalyzed Template Removal for the in Situ Synthesis of MCM-41 Supported Catalysts. Chem. Mater.2006, 18 (11), 2663–2669].Copyright 2006, American Chemical Society.
Figure 4
Figure 4. Schematic of SC–CO2 extraction technique.
Figure 5
Figure 5. (a) Schematic of microwave-assisted treatment. (b) Possible mechanism for template removal from MCM-41 and SBA-15 using H2O2 treatment assisted by microwave. Reproduced from ref (48). [Chen, L.; Jiang, S.; Wang, R.; Zhang, Z.; Qiu, S. A novel, efficient and facile method for the template removal from mesoporous materials. Chemical Research in Chinese Universities2014, 30 (6), 894–899]. Copyright 2014, Springer.
Figure 6
Figure 6. (a) Generation of acoustic bubbles by ultrasonic irradiation. (b) Schematic of ultrasonic-assisted treatment.
Figure 7
Figure 7. FT-IR spectra of (a) fresh CTABr-ethanol solution, (b) effluents after 15 min sonication at 40 °C, and (c) effluents after 60 min sonication at 40 °C. Panels (a) and (b) were reproduced from ref (60). [Jabariyan, S.; Zanjanchi, M. A. A simple and fast sonication procedure to remove surfactant templates from mesoporous MCM-41. Ultrason. Sonochem.2012, 19 (5), 1087–1093]. Copyright 2012 Elsevier. (d) UV–vis spectra for the methanol–effluent solutions after sonication at 40 °C and different times. Reproduced from ref (61). [Zanjanchi, M. A.; Jabariyan, S. Application of ultrasound and methanol for rapid removal of surfactant from MCM-41. J. Serb. Chem. Soc.2014, 79 (1), 25–38]. Copyright 2014, Serbian Chemical Society.
Figure 8
Figure 8. (a) Schematic of ozone treatment set up, (b) normalized ATR spectra of samples, and (c) TEM image of SBA-15 treated by H2O2. Reproduced from ref (70). [Joshi, H.; Jalalpoor, D.; Ochoa-Hernández, C.; Schmidt, W.; Schüth, F. Ozone Treatment: A Versatile Tool for the Postsynthesis Modification of Porous Silica-Based Materials. Chem. Mater.2018, 30 (24), 8905–8914]. Copyright 2018, American Chemical Society.
Figure 9
Figure 9. (a) Schematic of GD plasma, (b) loaded sample on a quartz boat placed in the positive column of O2-forming GD, and (c) N2 isotherms and BJH pore size distributions (inset) of SBA-15-C and SBA-15-GD. Reproduced from ref (78). [Yuan, M.-H.; Wang, L.; Yang, R. T. Glow Discharge Plasma-Assisted Template Removal of SBA-15 at Ambient Temperature for High Surface Area, High Silanol Density, and Enhanced CO2 Adsorption Capacity. Langmuir2014, 30 (27), 8124–8130]. Copyright 2014, American Chemical Society.
Figure 10
Figure 10. (a) Schematic of the SDBD apparatus. Reproduced from ref (85). [Guo, Q.; With, P.; Liu, Y.; Gläser, R.; Liu, C.-j. Carbon template removal by dielectric-barrier discharge plasma for the preparation of zirconia. Catal. Today2013, 211, 156–161]. Copyright 2013, Elsevier. (b) FT-IR spectra of samples and (c) N2 sorption–desorption isotherms of the sample treated by calcination and NTP along with their physicochemical properties. Panels (b) and (c) were reproduced from ref (80). [Wang, L.; Yao, J.; Wang, Z.; Jiao, H.; Qi, J.; Yong, X.; Liu, D. Fast and low-temperature elimination of organic templates from SBA-15 using dielectric barrier discharge plasma. Plasma Science and Technology2018, 20 (10), 101001]. Copyright 2018, IOPscience.
Figure 11
Figure 11. Plasma solution process. (A) Scheme image of the solution plasma experimental setup. (B) SAXRD patterns of mesoporous silica discharged in different pHs at fixed 15 min of discharge time: (a) as-synthesized silica, (b) pH 3, (c) pH 7, and (d) pH 11. (C) SAXRD patterns of mesoporous silica discharged at different discharge times in pH 3: (a) as-synthesized silica, (b) 1 min, (c) 5 min, and (d) 15 min. TEM images of mesoporous silica discharged in different pH values at fixed 15 min of discharge time: (D) pH 3, (E) pH 7, and (F) pH 11. Reproduced from ref (104). [Pootawang, P.; Saito, N.; Takai, O. Solution plasma for template removal in mesoporous silica: pH and discharge time varying characteristics. Thin Solid Films2011, 519 (20), 7030–7035]. Copyright 2015, Elsevier.
Figure 12
Figure 12. (a) Infrared image of the sample during the template removal process using DBD. Reproduced from ref (77). [Liu, Y.; Pan, Y.-x.; Kuai, P.; Liu, C.-j. Template Removal from ZSM-5 Zeolite Using Dielectric-Barrier Discharge Plasma. Catal. Lett.2010, 135 (3), 241–245]. Copyright 2010, Springer. (b) FT-IR spectra of MCM-41 during the detemplating process using DBD plasma. (c) Color changes of the samples during the template removal using DBD. Panels (b) and (c) were reproduced from ref (75). [Liu, Y.; Wang, Z.; Liu, C.-j. Mechanism of template removal for the synthesis of molecular sieves using dielectric barrier discharge. Catal. Today2015, 256, 137–141]. Copyright 2015, Elsevier.
Figure 13
Figure 13. Schematic of solvent extraction technique.
Figure 14
Figure 14. Characterization of SBA-15 materials treated by different methods: SBA–P, as-synthesized SBA-15; SBA–C, SBA-15 treated by calcination; SBA–E, SBA-15 treated by extraction; and SBA–H, SBA-15 treated by H2O2. (a)–(c) SEM images. (d) N2 adsorption–desorption isotherms. (e) SAXRD patterns. Reproduced from ref (108). [Barczak, M. Template removal from mesoporous silicas using different methods as a tool for adjusting their properties. New J. Chem.2018, 42 (6), 4182–4191]. Copyright 2018, Royal Society of Chemistry.
Figure 15
Figure 15. Schematic of IL treatment technique.
References
This article references 161 other publications.
- 1Jafari, S.; Derakhshankhah, H.; Alaei, L.; Fattahi, A.; Varnamkhasti, B. S.; Saboury, A. A. Mesoporous silica nanoparticles for therapeutic/diagnostic applications. Biomedicine & Pharmacotherapy 2019, 109, 1100– 1111, DOI: 10.1016/j.biopha.2018.10.1671Mesoporous silica nanoparticles for therapeutic/diagnostic applicationsJafari, Samira; Derakhshankhah, Hossein; Alaei, Loghman; Fattahi, Ali; Varnamkhasti, Behrang Shiri; Saboury, Ali AkbarBiomedicine & Pharmacotherapy (2019), 109 (), 1100-1111CODEN: BIPHEX; ISSN:0753-3322. (Elsevier Masson SAS)A review. Based on unique intrinsic properties of mesoporous silica nanoparticles (MSNs) such as high surface area, large pore size, good biocompatibility and biodegradability, stable aq. dispersion, they have received much attention in the recent decades for their applications as a promising platform in the biomedicine field. These porous structures possess a pore size ranging from 2 to 50 nm which make them excellent candidates for various biomedical applications. Herein, at first we described the common approaches of cargo loading and release processes from MSNs. Then, the intracellular uptake, safety and cytotoxicity aspects of MSNs are discussed as well. This review also highlights the most recent advances in the biomedical applications of MSNs, including 1) MSNs-based carriers, 2) MSNs as bioimaging agents, 3) MSNs-based biosensors, 4) MSNs as therapeutic agents (photodynamic therapy), 5) MSN based quantum dots, 6) MSNs as platforms for upconverting nanoparticles, and 6) MSNs in tissue engineering.
- 2Rahikkala, A.; Pereira, S. A. P.; Figueiredo, P.; Passos, M. L. C.; Araújo, A. R. T. S.; Saraiva, M. L. M. F. S.; Santos, H. A. Mesoporous Silica Nanoparticles for Targeted and Stimuli-Responsive Delivery of Chemotherapeutics: A Review. Advanced Biosystems 2018, 2 (7), 1800020, DOI: 10.1002/adbi.201800020There is no corresponding record for this reference.
- 3Nguyen, T. L.; Choi, Y.; Kim, J. Mesoporous Silica as a Versatile Platform for Cancer Immunotherapy. Adv. Mater. 2019, 31 (34), 1803953, DOI: 10.1002/adma.201803953There is no corresponding record for this reference.
- 4Dinker, M. K.; Kulkarni, P. S. Recent Advances in Silica-Based Materials for the Removal of Hexavalent Chromium: A Review. Journal of Chemical & Engineering Data 2015, 60 (9), 2521– 2540, DOI: 10.1021/acs.jced.5b002924Recent Advances in Silica-Based Materials for the Removal of Hexavalent Chromium: A ReviewDinker, Manish Kumar; Kulkarni, Prashant ShripadJournal of Chemical & Engineering Data (2015), 60 (9), 2521-2540CODEN: JCEAAX; ISSN:0021-9568. (American Chemical Society)A review. Hexavalent chromium [Cr(VI)], one of the most toxic contaminants, is released in the environment due to various anthropogenic activities. Exposure of Cr(VI) can pose a serious threat to the public health as well as flora and fauna. Effective treatment of Cr(VI) is, therefore, very essential from safety, health, and environment points of view. The present review focuses on the development of silica-based materials for the adsorption of Cr(VI) from wastewater. After discussing toxicity issues and general removal methods of Cr(VI), the importance of silica materials are highlighted. The silica has different shapes, sizes, surface areas, and pore diams. and, hence, can play a vital role in designing the adsorbent. They can be modified into org., inorg., polymeric, biol., and ionic liq. based materials. Therefore, they are broadly classified into these five categories. The adsorption isotherms and kinetics of these materials for Cr(VI) are discussed and compared with each other. Future prospects based on the findings of the review article are summarized in the end which mainly emphasizes the importance of biosorbents and ionic liq. immobilized silica materials for the treatment of Cr(VI).
- 5Cashin, V. B.; Eldridge, D. S.; Yu, A.; Zhao, D. Surface functionalization and manipulation of mesoporous silica adsorbents for improved removal of pollutants: a review. Environmental Science: Water Research & Technology 2018, 4 (2), 110– 128, DOI: 10.1039/C7EW00322F5Surface functionalization and manipulation of mesoporous silica adsorbents for improved removal of pollutants: a reviewCashin, Veronica B.; Eldridge, Daniel S.; Yu, Aimin; Zhao, DongyuanEnvironmental Science: Water Research & Technology (2018), 4 (2), 110-128CODEN: ESWRAR; ISSN:2053-1419. (Royal Society of Chemistry)A review. Mesoporous silica (MS) has been one of the most versatile and successful adsorbents for the removal of environmental pollutants in recent years. The extent to which its structural properties can be tailored and the ease with which such morphol. properties can be manipulated are widely acknowledged as major advantages of MS over other adsorbents. In addn. to this, modifications to the surface of MS have also been explored in recent years. When the morphol. and surface functionality of adsorbents are optimized, great improvements in selective adsorption capacities for a wide range of different pollutant types have been achieved. This review article will explore the most common functional groups deposited at adsorbent surfaces, and the reagents and methods used to deposit these groups to the MS surface, for the purpose of increasing the adsorption capacity and/or selectivity for both inorg. and org. wastewater pollutants. A selection of successful surface functionalizations which have been performed on different substrates will also be outlined, to guide future MS surface modifications.
- 6Liang, J.; Liang, Z.; Zou, R.; Zhao, Y. Heterogeneous Catalysis in Zeolites, Mesoporous Silica, and Metal–Organic Frameworks. Adv. Mater. 2017, 29 (30), 1701139, DOI: 10.1002/adma.201701139There is no corresponding record for this reference.
- 7Wang, F.; Jiang, L.; Wang, J.; Zhang, Z. Catalytic Conversion of Fructose and 5-Hydroxymethylfurfural into 2,5-Diformylfuran over SBA-15 Supported Ruthenium Catalysts. Energy Fuels 2016, 30 (7), 5885– 5892, DOI: 10.1021/acs.energyfuels.6b011487Catalytic Conversion of Fructose and 5-Hydroxymethylfurfural into 2,5-Diformylfuran over SBA-15 Supported Ruthenium CatalystsWang, Fan; Jiang, Liang; Wang, Junmei; Zhang, ZehuiEnergy & Fuels (2016), 30 (7), 5885-5892CODEN: ENFUEM; ISSN:0887-0624. (American Chemical Society)The mesoporous SBA-15 was prepd. and used to graft biimidazole groups, which were used to anchor Ru3+ to give rise to a new ruthenium catalyst (SBA-15-Biimidazole-Ru). The structure of the SBA-15-Biimidazole-Ru catalyst was well characterized and used for the aerobic oxidn. of 5-hydroxymethylfurfural (HMF) into 2,5-diformylfuran (DFF). Several important parameters were studied and found that the reaction solvent and oxygen pressure showed a crucial role in the activity of the as-prepd. SBA-15-Biimidazole-Ru catalyst. HMF conversion of 96.9% and DFF yield of 88.7% were achieved after 11 h at 110° under 15 bar oxygen pressure. One important characteristic of the SBA-15-Biimidazole-Ru catalyst is that it was very stable without loss of its catalytic activity during the recycling expts., which was due to the strong interaction between the Ru3+ and the Biimidazole groups on the surface of SBA-15. Finally, the direct conversion of fructose into DFF was also performed using Amberlyst 15 and SBA-15-Biimidazole-Ru as two binary catalysts. The dehydration of fructose over Amberlyst 15 catalyst and the subsequent oxidn. of HMF over SBA-15-Biimidazole-Ru catalyst afforded DFF with an overall yield of 72.4%.
- 8Wang, L.; Diao, Z.; Tian, Y.; Xiong, Z.; Liu, G. Catalytic Cracking of Endothermic Hydrocarbon Fuels over Ordered Meso-HZSM-5 Zeolites with Al-MCM-41 Shells. Energy Fuels 2016, 30 (9), 6977– 6983, DOI: 10.1021/acs.energyfuels.6b011608Catalytic Cracking of Endothermic Hydrocarbon Fuels over Ordered Meso-HZSM-5 Zeolites with Al-MCM-41 ShellsWang, Li; Diao, Zhenheng; Tian, Yajie; Xiong, Zhongqiang; Liu, GuozhuEnergy & Fuels (2016), 30 (9), 6977-6983CODEN: ENFUEM; ISSN:0887-0624. (American Chemical Society)Ordered meso-HZSM-5 zeolites with Al-MCM-41 shells were synthesized by a surfacant-directed encapsulating process. It was found that ordered meso-HZSM-5, which was used as a core, could be synthesized using a designed amphiphilic organosilane as a surfactant and that the mesopore size of the MCM-41 shell can be adjusted from 2.5-3 to 4.5-10 nm by changing the structures of alkyltrimethylammonium bromide and the trimethylbenzene amt. Catalytic cracking performances of supercrit. n-dodecane (500 °C and 4 MPa) show that ordered meso-HZSM-5 zeolites with Al-MCM-41 shells of 4.5-10 nm exhibit a 28% higher catalytic activity and a 25% lower deactivation rate compared to the conventional HZSM-5 zeolites. With an increasing mesopore size of the MCM-41 shell, the acid sites accessibility increased gradually and, thus, led to enhanced catalytic activity and decreased secondary reaction ability. In addn., ordered hierarchical zeolites show a well connection of ordered mesopores between the core and shell, which could also lead to the enhanced acid site accessibility.
- 9Perumal, T.; Mangesh, V. L.; Perumal, S. K.; Arumugam, R.; Subramanian, N.; Subramanian, S.; Kannan, S. Isomerization of Alkanes over Ionic Liquids Supported on SBA-15. Energy Fuels 2020, 34 (11), 14620– 14632, DOI: 10.1021/acs.energyfuels.0c023319Isomerization of Alkanes over Ionic Liquids Supported on SBA-15Perumal, Tamizhdurai; Mangesh, V. L.; Perumal, Santhana Krishnan; Arumugam, Ramesh; Subramanian, Narayanan; Subramanian, Sakthinathan; Kannan, ShanthiEnergy & Fuels (2020), 34 (11), 14620-14632CODEN: ENFUEM; ISSN:0887-0624. (American Chemical Society)Exploring the catalytic efficiency of ionic liq. supported on mesoporous material as heterogeneous organ catalysts for example, 1-Ethyl-3-methylimidazolium triflate and 1-ethyl-3-methylimidazolium chloride + AlCl3 (different ratio) immobilized on SBA-15 that contains 0.5% platinum, with regard to isomerization of n-pentane and n-hexane, along with com. light naphtha feed conversion reactions. The prepd. materials were characterized by several instrumental methods, which include temp.-programmed desorption to evaluate acid strength. The reactions were performed in a fixed-bed stainless steel reactor having high pressure by the down-flow method. This valuable novel isomerization reaction was strongly influenced by many key parameters, for instance, temp., pressure, wt. hourly space velocity, and flow rate of H2, which are discussed in detail. The Pt/EMIM-AlCl4(1:1)20/SBA-15 ionic liq. catalyst showed superior catalytic performance out of the four-catalyst system examd. toward the above reactions, which is undoubtedly due to its significant turnover frequencies values of 8.6 s-1 and 8.5 s-1 and specific reaction rates values of 8.01 x 10-4 mol g-1 s-1 and 8.00 x 10-4 mol g-1 s-1 for n-pentane and n-hexane correspondingly. The order of catalytic activity is Pt/EMIM-AlCl4(1:1)20/SBA-15 > Pt-EMIM-Tf/SBA-15 > Pt/EMIM-Al2Cl7(1:2)20/SBA-15 > Pt-EMIM-Al2Cl7(1:2)30/SBA-15.
- 10Lv, Y.; Wang, X.; Gao, D.; Ma, X.; Li, S.; Wang, Y.; Song, G.; Duan, A.; Chen, G. Hierarchically Porous ZSM-5/SBA-15 Zeolite: Tuning Pore Structure and Acidity for Enhanced Hydro-Upgrading of FCC Gasoline. Ind. Eng. Chem. Res. 2018, 57 (42), 14031– 14043, DOI: 10.1021/acs.iecr.8b0295210Hierarchically Porous ZSM-5/SBA-15 Zeolite: Tuning Pore Structure and Acidity for Enhanced Hydro-Upgrading of FCC GasolineLv, Yipin; Wang, Xilong; Gao, Daowei; Ma, Xinlong; Li, Shuna; Wang, Yong; Song, Guolong; Duan, Aijun; Chen, GuozhuIndustrial & Engineering Chemistry Research (2018), 57 (42), 14031-14043CODEN: IECRED; ISSN:0888-5885. (American Chemical Society)The pore structure and acid sites of the catalysts are demonstrated as the main factors for the hydro-upgrading of fluid catalytic cracking (FCC) gasoline. Herein, we report a general synthesis of ZSM-5/SBA-15 composite zeolites with tunable pore structure and acid sites. The effects of the pore structure and acid sites of these catalysts on their hydro-upgrading performance were systematically investigated. The platelet CoMo/AZS-PL (CoMo/ZS-PL-γ-Al2O3) catalyst with the short mesochannels, appropriate Co-Mo-S phase, and suitable acidity exhibited the excellent preservation ability of research octane no. (RON) and hydrodesulfurization (HDS) performance, which was better than those of CoMo/AZS-SR (CoMo/ZS-SR-γ-Al2O3), CoMo/AZS-HP (CoMo/ZS-HP-γ-Al2O3), and CoMo/AZS-LR (CoMo/ZS-LR-γ-Al2O3) catalysts. The relationship between the physicochem. properties (acidity, morphol., pore structure, and sulfided active metal) of the catalysts and their isomerization (ISO), aromatization (ARO), as well as HDS abilities were explored in detail.
- 11Mulu, E.; M’Arimi, M. M.; Ramkat, R. C. A review of recent developments in application of low cost natural materials in purification and upgrade of biogas. Renewable and Sustainable Energy Reviews 2021, 145, 111081, DOI: 10.1016/j.rser.2021.11108111A review of recent developments in application of low cost natural materials in purification and upgrade of biogasMulu, Elshaday; M'Arimi, Milton M.; Ramkat, Rose C.Renewable & Sustainable Energy Reviews (2021), 145 (), 111081CODEN: RSERFH; ISSN:1364-0321. (Elsevier Ltd.)A review. The main contaminants in biogas namely carbon dioxide, hydrogen sulfide, and siloxanes limit its application esp. in engines by reducing energy d. and causing corrosion on machine parts. Furthermore, the carbon dioxide in biogas contributes highly to global warming. Therefore, biogas should be upgraded to increase its safe application. Most com. methods of biogas cleaning are expensive for small and medium scale digesters. There is no review documentation detailing the usage of natural materials in the purifn. of biogas. The aim of the current study was to systematically and critically review recent developments in the applications of natural materials in the purifn. and upgrade of biogas. Documented literature indicate that the low-cost natural adsorbents have potential in purifn. of biogas. The adsorption capacity of biogas contaminants for most materials can be enhanced by phys. and chem. activation. The two mechanisms through which these material eliminate carbon dioxide in biogas namely surface adsorption and wet carbonation process have been discussed. In addn., the study looked at the factors that affect the removal of carbon dioxide from biogas using natural materials. The adsorption capacity of biogas contaminants for different natural and modified materials were reviewed. Furthermore, a summary of the merits and demerits of different natural adsorbents for biogas purifn. is presented. Future studies should investigate the methane loss during upgrading process using low-cost adsorbents. Comparative investigations of the process cost-effectiveness of using natural materials to upgrade biogas should be carried out to det. their suitability against the com. processes.
- 12Melde, B. J.; Johnson, B. J.; Charles, P. T. Mesoporous Silicate Materials in Sensing. Sensors 2008, 8 (8), 5202, DOI: 10.3390/s808520212Mesoporous silicate materials in sensingMelde, Brian J.; Johnson, Brandy J.; Charles, Paul T.Sensors (2008), 8 (8), 5202-5228CODEN: SENSC9; ISSN:1424-8220. (Molecular Diversity Preservation International)A review. Mesoporous silicas, esp. those exhibiting ordered pore systems and uniform pore diams., have shown great potential for sensing applications in recent years. Morphol. control grants them versatility in the method of deployment whether as bulk powders, monoliths, thin films, or embedded in coatings. High surface areas and pore sizes >2 nm make them effective as adsorbent coatings for humidity sensors. The pore networks also provide the potential for immobilization of enzymes within the materials. Functionalization of materials by silane grafting or through co-condensation of silicate precursors can be used to provide mesoporous materials with a variety of fluorescent probes as well as surface properties that aid in selective detection of specific analytes. This review will illustrate how mesoporous silicas were applied to sensing changes in relative humidity, changes in pH, metal cations, toxic industrial compds., volatile org. compds., small mols. and ions, nitroenergetic compds., and biol. relevant mols.
- 13Méndez, F. J.; Franco-López, O. E.; Bokhimi, X.; Solís-Casados, D. A.; Escobar-Alarcón, L.; Klimova, T. E. Dibenzothiophene hydrodesulfurization with NiMo and CoMo catalysts supported on niobium-modified MCM-41. Applied Catalysis B: Environmental 2017, 219, 479– 491, DOI: 10.1016/j.apcatb.2017.07.07913Dibenzothiophene hydrodesulfurization with NiMo and CoMo catalysts supported on niobium-modified MCM-41Mendez, Franklin J.; Franco-Lopez, Oscar E.; Bokhimi, Xim; Solis-Casados, Dora A.; Escobar-Alarcon, Luis; Klimova, Tatiana E.Applied Catalysis, B: Environmental (2017), 219 (), 479-491CODEN: ACBEE3; ISSN:0926-3373. (Elsevier B.V.)In the present work, we studied the effect of the addn. of niobium to CoMo/MCM-41 and NiMo/MCM-41 catalysts on their characteristics and performance in the hydrodesulfurization of dibenzothiophene. The MCM-41 support was synthesized at room temp. according to a well-known procedure. The metal species (Nb, Mo, Ni or Co) were deposited by successive impregnation using aq. solns. of the corresponding metal salts. MCM-41 and Nb-contg. MCM-41 supports were characterized by X-ray diffraction, N2 physisorption, FT-Raman spectroscopy, XPS, UV-vis diffuse reflectance spectroscopy and SEM. The CoMo and NiMo catalysts in oxide state, in addn. to the above techniques, were characterized by temp.-programmed redn. and the sulfided catalysts were characterized by high resoln. transmission electron microscopy. The results show that the incorporation of small amts. of Nb (3-5 wt.%) increased the catalytic activity of both NiMo and CoMo catalysts in dibenzothiophene hydrodesulfurization and affected their selectivity. The effect of Nb on the selectivities of the NiMo and CoMo catalysts was different: for the NiMo catalysts, Nb increased selectivity towards the HYD route, whereas for the CoMo catalysts, it increased selectivity towards the DDS route. The anal. of the effect of Nb on the catalysts' selectivity was performed based on the kinetic consts. calcd. for the different steps of the DBT HDS network.
- 14Tanimu, A.; Abdel-Azeim, S.; Ganiyu, S. A.; Alhooshani, K. Experimental and Theoretical Investigation of the Synergy Effect of Zr and Ce on the Catalytic Efficiency of NiMoS Grafted on SBA-15 for Oil Hydrodesulfurization. Energy Fuels 2021, 35 (3), 2579– 2589, DOI: 10.1021/acs.energyfuels.0c0346114Experimental and Theoretical Investigation of the Synergy Effect of Zr and Ce on the Catalytic Efficiency of NiMoS Grafted on SBA-15 for Oil HydrodesulfurizationTanimu, Abdulkadir; Abdel-Azeim, Safwat; Ganiyu, Saheed A.; Alhooshani, KhalidEnergy & Fuels (2021), 35 (3), 2579-2589CODEN: ENFUEM; ISSN:0887-0624. (American Chemical Society)In this study, the synergy effect of biheteroatoms (ZrOx and CeOy) and a Ni promoter on the catalytic performance of MoS2 crystallites grafted on SBA-15 silica for the hydrodesulfurization (HDS) of dibenzothiophene (DBT) in diesel was investigated. The pyridine-Fourier transform IR (py-FTIR) spectroscopy, ammonia temp.-programmed desorption (NH3-TPD), and XPS analyses revealed that the surface acidity, no. of active sites, and the dispersion of MoS2 crystallites increased significantly with the incorporation of ZrOx and CeOy on SBA-15 than other supported catalysts evaluated. The ZrOx-CeOy-SBA-15-supported NiMo catalyst could remove 59% of DBT in diesel spiked with 1000 ppm of DBT after 1 h of reaction and up to 96% of DBT after 5 h of reaction. D. functional theory (DFT) simulations further gave interesting insights; a thin-film model of SBA-15 decorated with Zr and Ce indicates that the metal sites induced a strong hydrogen bond network leading to higher surface stability. Furthermore, Ce grafted on SBA-15 enhanced the adsorption of water mols. that increases the Bronsted acid sites and subsequently improved its catalytic efficiency. DFT simulation of thiophene HDS showed a stepwise rupture of thiophene C-S bonds with the second C-S bond breaking as the plausible rate-detg. step.
- 15Wang, X.; Shi, Y.; Gao, S.; Xu, C.; Zhao, Z.; Wang, G.; Fu, S.; Duan, A.; Gao, D. Hierarchically Porous β/SBA-16 Composites: Tuning Pore Structure and Acidity for Enhanced Isomerization Performance in Hydrodesulfurization of Dibenzothiophene and 4,6-Dimethyldibenzothiophene. Energy Fuels 2020, 34 (1), 769– 777, DOI: 10.1021/acs.energyfuels.9b0362715Hierarchically Porous β/SBA-16 Composites: Tuning Pore Structure and Acidity for Enhanced Isomerization Performance in Hydrodesulfurization of Dibenzothiophene and 4,6-DimethyldibenzothiopheneWang, Xilong; Shi, Yu; Gao, Shanbin; Xu, Chunming; Zhao, Zhen; Wang, Gang; Fu, Siyuan; Duan, Aijun; Gao, DaoweiEnergy & Fuels (2020), 34 (1), 769-777CODEN: ENFUEM; ISSN:0887-0624. (American Chemical Society)β/SBA-16 (BS) materials were fabricated using β-nanoclusters through self-assembly hydrothermal crystn. approach; subsequently, the corresponding NiMo/BS catalysts were synthesized. The influence of HCl concn. on the physicochem. properties of the composite support and the corresponding catalyst was investigated by a series of characterization methods. The hydrodesulfurization (HDS) performances were evaluated under the conditions of T = 340°C, PH2 = 4 MPa, and H2/oil (vol./vol.) = 200 by adopting dibenzothiophene (DBT) and 4,6-dimethyldibenzothiophene (4,6-DMDBT) as probe reactants. The results indicated that NiMo/BS-1.5 prepd. under the HCl concn. of 1.5 mol L-1 exhibited the superior HDS performance due to its well-ordered shape and pore channel, high sulfidation degree, moderate acidity, and suitable metal-support interaction (MSI). In addn., the potential HDS reaction networks for DBT and 4,6-DMDBT of series NiMo/BS were presented.
- 16Ganiyu, S. A.; Alhooshani, K. Catalytic Performance of NiMoS Supported on (Zr)SBA-15 for Hydrodesulfurization of Diesel: Insight into a One-Step Calcination and Reduction Strategy during Sulfidation. Energy Fuels 2019, 33 (4), 3047– 3056, DOI: 10.1021/acs.energyfuels.8b0453616Catalytic Performance of NiMoS Supported on (Zr)SBA-15 for Hydrodesulfurization of Diesel: Insight into a One-Step Calcination and Reduction Strategy during SulfidationGaniyu, Saheed A.; Alhooshani, KhalidEnergy & Fuels (2019), 33 (4), 3047-3056CODEN: ENFUEM; ISSN:0887-0624. (American Chemical Society)We report, herein, the catalytic efficiency and activity of a facilely synthesized sulfided NiMo hydrodesulfurization (HDS) catalyst supported on (Zr)-SBA-15 by one-step calcination and redn. heat treatment prior to sulfidation. Zr-SBA-15-Mo is prepd. by a direct synthesis approach, followed by the confinement of Ni into the as-synthesized Zr-SBA-15-Mo without calcination, to generate more dispersion and active sites of metal oxides for an efficient sulfidation process. The HDS performance of these catalysts was evaluated and compared to that of the catalysts prepd. by the sequential calcination and redn. approach prior to sulfidation for HDS of dibenzothiophene (DBT) and dimethyldibenzothiophene (DMDBT) in com. diesel at 350 °C in batch reactor mode. Structural and morphol. properties related to catalytic activity have been obtained by means of spectroscopy (X-ray diffraction (XRD), Raman, pyridine-Fourier transform IR (FTIR), temp.-programmed desorption (TPD), microscopy (SEM)), and N2 physisorption. The characterization and investigations from XRD, Raman, pyridine-FTIR, and TPD revealed that avoiding multiple heat treatment in designing HDS catalysts provides more coordinative unsatd. active sites necessary for better catalyst performance and stability. In addn., the textural properties (sp. surface area, pore size, and vol.) that allow easy diffusion of reactant mols. are better preserved. The activity of the sulfided NiMo catalysts prepd. by one-step heat treatment is 9-16% higher for DBT and 11-13% higher for DMDBT at 1 h reaction time compared to that of the catalysts prepd. by sequential calcination and redn. before sulfidation. The catalysts prepd. by this heat treatment approach have desulfurization efficiencies of 99 and 84% for DBT and DMDBT, resp.
- 17Zheng, P.; Hu, D.; Meng, Q.; Liu, C.; Wang, X.; Fan, J.; Duan, A.; Xu, C. Influence of Support Acidity on the HDS Performance over β-SBA-16 and Al-SBA-16 Substrates: A Combined Experimental and Theoretical Study. Energy Fuels 2019, 33 (2), 1479– 1488, DOI: 10.1021/acs.energyfuels.8b0413317Influence of Support Acidity on the HDS Performance over β-SBA-16 and Al-SBA-16 Substrates: A Combined Experimental and Theoretical StudyZheng, Peng; Hu, Di; Meng, Qian; Liu, Cong; Wang, Xilong; Fan, Jiyuan; Duan, Aijun; Xu, ChunmingEnergy & Fuels (2019), 33 (2), 1479-1488CODEN: ENFUEM; ISSN:0887-0624. (American Chemical Society)A novel composite material β-SBA-16 is successfully synthesized and utilized as the support for the development of hydrodesulfurization (HDS) catalyst. The supports and the corresponding catalysts were characterized by a variety of techniques involving X-ray diffraction, N2 physisorption, 27Al NMR, Raman, pyridine IR, X-ray photoelectron spectra, and high-resoln. transmission electron microscopy. The activity evaluation results displayed that the NiMo/β-SBA-16 catalyst possessed the highest dibenzothiophene HDS efficiency of 97.3% at wt. hourly space velocity of 20 h-1 compared with the catalysts supported on the Al-modified SBA-16 and the conventional Al2O3. Furthermore, the HDS efficiency of NiMo/β-SBA-16 is almost 1.5 times that of the other two catalysts at 150 h-1, which was considered to be closely linked to the acidic properties of the supports. Correspondingly, the results of pyridine IR exhibited that NiMo/β-SBA-16 possessed larger amts. of total acidity and higher B/L acidities ratio. Furthermore, d. functional theory calcns. were performed to explore the Bronsted acid strength generated by the incorporation of β seeds or Al atoms. The calcn. results indicated that Si atoms located in the 5- or 6-membered rings of β-zeolite were more easily substituted by Al atoms, and the generated Si-OH-Al group played an important role in providing stronger Bronsted acid sites. Therefore, both exptl. and theor. results have shown that the incorporation of β seeds contributed more to produce the Bronsted acid sites of SBA-16 materials.
- 18Wu, M.; Li, Q.; Wang, X.; Mi, J. Structure Characteristics and Hot-Coal-Gas Desulfurization Properties of Zn-Based Sorbents Supported on Mesoporous Silica with Different Pore-Arrangement Patterns: A Comparison Study. Energy Fuels 2021, 35 (3), 2456– 2467, DOI: 10.1021/acs.energyfuels.0c0379418Structure Characteristics and Hot-Coal-Gas Desulfurization Properties of Zn-Based Sorbents Supported on Mesoporous Silica with Different Pore-Arrangement Patterns: A Comparison StudyWu, Mengmeng; Li, Qiaochun; Wang, Xiaowen; Mi, JieEnergy & Fuels (2021), 35 (3), 2456-2467CODEN: ENFUEM; ISSN:0887-0624. (American Chemical Society)Ordered mesoporous MCM-41 (two-dimensional (2D) hexagonal pore arrangement) and MCM-48 (three-dimensional (3D) cubic channel arrangement) with similar pore sizes and surface areas were selected for comparison when used as support for Zn-based sorbents for hot coal gas desulfurization. Compared to that of Zn/M48 (MCM-48-supported desulfurizer), the adsorption capacity of Zn/M41 (MCM-41-supported sorbent) increases by 24.4-56.3%. The initial reaction rate consts. of Zn/M41 are 1-13 times greater than those of Zn/M48. These are correlated to the structural features of sorbents. Zn/M41 has a large wall thickness of the framework, suggesting higher thermal stability. Furthermore, the sorbent particles and ZnO grains in Zn/M41 are both smaller in size, which facilitates contact between H2S and ZnO. Addnl., Zn/M41 possesses a large surface area and pore vol., beneficial for the diffusion of H2S through sorbents. The anal. of the atm. effects reveals that there is a stronger synergistic effect of CO and H2 on desulfurization over Zn/M41.
- 19Akopyan, A.; Polikarpova, P.; Gul, O.; Anisimov, A.; Karakhanov, E. Catalysts Based on Acidic SBA-15 for Deep Oxidative Desulfurization of Model Fuels. Energy Fuels 2020, 34 (11), 14611– 14619, DOI: 10.1021/acs.energyfuels.0c0200819Catalysts Based on Acidic SBA-15 for Deep Oxidative Desulfurization of Model FuelsAkopyan, Argam; Polikarpova, Polina; Gul, Olesya; Anisimov, Alexander; Karakhanov, EduardEnergy & Fuels (2020), 34 (11), 14611-14619CODEN: ENFUEM; ISSN:0887-0624. (American Chemical Society)Acidic SBA-15 modified by molybdenum oxide has been synthesized. These materials were characterized by low nitrogen adsorption/desorption, Fourier transform IR spectroscopy, transmission electron microscopy, NH3 temp.-programmed desorption, NMR, and XRD techniques. In this work, the activity of acidic Al-SBA-15 modified with molybdenum oxide in the oxidn. of sulfur-contg. compds. was investigated for the first time. It was shown that the SBA-15 support contg. aluminum allows to significantly increase the catalytic activity of molybdenum oxide. The main factors affecting the process consisting of catalyst dosage, temp., reaction time, oxidant dosage were investigated in detail. In the presence of synthesized catalysts, dibenzothiophene can be completely oxidized in 30 min. These catalysts retain their activity in DBT oxidn. for 10 cycles.
- 20Polikarpova, P.; Akopyan, A.; Shigapova, A.; Glotov, A.; Anisimov, A.; Karakhanov, E. Oxidative Desulfurization of Fuels Using Heterogeneous Catalysts Based on MCM-41. Energy Fuels 2018, 32 (10), 10898– 10903, DOI: 10.1021/acs.energyfuels.8b0258320Oxidative Desulfurization of Fuels Using Heterogeneous Catalysts Based on MCM-41Polikarpova, Polina; Akopyan, Argam; Shigapova, Anastasia; Glotov, Aleksandr; Anisimov, Alexander; Karakhanov, EduardEnergy & Fuels (2018), 32 (10), 10898-10903CODEN: ENFUEM; ISSN:0887-0624. (American Chemical Society)Mesoporous silicas of MCM-41 type modified by transition metal oxides, such as molybdenum, vanadium, and tungsten, were synthesized. These materials were characterized by low-temp. nitrogen adsorption/desorption, Fourier transform IR spectroscopy, X-ray spectral fluorescence anal., and transmission electron microscopy techniques and applied for the removal of sulfur compds. in model and real fuels by oxidative desulfurization. The catalysts obtained were tested under optimal conditions. Dibenzothiophene was removed completely, and sulfur removal in gasoline and diesel fractions could reach 91 and 63%, resp. These catalysts retain their activity in gasoline fraction desulfurization for 5 cycles.
- 21Rao, N.; Wang, M.; Shang, Z.; Hou, Y.; Fan, G.; Li, J. CO2 Adsorption by Amine-Functionalized MCM-41: A Comparison between Impregnation and Grafting Modification Methods. Energy Fuels 2018, 32 (1), 670– 677, DOI: 10.1021/acs.energyfuels.7b0290621CO2 Adsorption by Amine-Functionalized MCM-41: A Comparison between Impregnation and Grafting Modification MethodsRao, Na; Wang, Mei; Shang, Ziming; Hou, Yanwen; Fan, Guozhi; Li, JianfenEnergy & Fuels (2018), 32 (1), 670-677CODEN: ENFUEM; ISSN:0887-0624. (American Chemical Society)Modifications by impregnation and grafting are commonly used for the prepn. of amine-functionalized MCM-41. A comprehensive evaluation of the advantages and disadvantages of the two methods was performed in this work. MCM-41 was synthesized by the hydrothermal method, setting the amine-loading mass fraction at 40, 50, and 60 wt %. Three amine-modified adsorbents were prepd. by impregnating polyethylenimine (PEI), and the three other adsorbents were prepd. by grafting 3-aminopropyltriethoxysilane (APTS) onto MCM-41. The as-prepd. adsorbents were characterized by X-ray diffraction, Fourier transform IR spectroscopy, SEM, thermogravimetric anal., and N2 adsorption-desorption techniques. CO2 adsorption capacities were measured, and the exptl. data were fitted with adsorption kinetic models. The cyclic stability of the adsorbents prepd. by the two kinds of amine-modified methods was compared using the cyclic adsorption-desorption expts. The characterization results showed that the target adsorbents were prepd. successfully. The thermal stability of the adsorbents modified by grafting was better than the thermal stability of the adsorbents modified by the impregnation. Maximum CO2 adsorption capacities of 3.53 mmol g-1 (50% PEI-MCM-41) and 2.41 mmol g-1 (50% APTS-MCM-41) could be reached at 25 °C and 1 atm, which were 4.7 and 3.2 times greater than that of MCM-41. The Avrami model fitted the exptl. data well, indicating a variety of interactions between the adsorbents and CO2. CO2 adsorption capacity after 5 adsorption-desorption cycles decreased by 14.22 and 5.19% for the adsorbents prepd. by impregnation and grafting, resp. It was concluded that MCM-41 modified by impregnation and grafting followed the same kinetic model. The absorbents modified by impregnation showed higher CO2 adsorption capacity and amine-loading efficiency, while those prepd. by grafting had better thermal and cyclic stabilities.
- 22Kishor, R.; Ghoshal, A. K. Polyethylenimine Functionalized As-Synthesized KIT-6 Adsorbent for Highly CO2/N2 Selective Separation. Energy Fuels 2016, 30 (11), 9635– 9644, DOI: 10.1021/acs.energyfuels.6b0208222Polyethylenimine Functionalized As-Synthesized KIT-6 Adsorbent for Highly CO2/N2 Selective SeparationKishor, Rupak; Ghoshal, Aloke KumarEnergy & Fuels (2016), 30 (11), 9635-9644CODEN: ENFUEM; ISSN:0887-0624. (American Chemical Society)The present study targeted the synthesis of CO2 adsorbent by impregnation of DETA, TEPA, PEHA, and polyethylenimine in KIT-6 with a confiscated structure directing agent in min. time and energy. The adsorbents were characterized and revealed the influence of polyethylenimine with CO2 at a wide range of temps. An examn. by TGA confirmed that PluronicP123 present in adsorbent enhances its thermal stability and acts as a carrier for CO2 to the inner layer of polyethylenimine during adsorption. CO2 sorption capacity of the adsorbent was found to be dependent on the polyethylenimine loading, temp., pressure, and the surfactant PluronicP123. At higher temps., adsorbents showed a pos. impact for CO2 adsorption; however, a neg. effect was exhibited in amine efficiency. The sorption capacity decreased with increasing the mol. wt. of polyethylenimine following the order PEI-25K (66 mg CO2/g) < PEI-800 (114 mg CO2/g) < TEPA (124 mg CO2/g) < PEHA (139 mg CO2/g) at 75 °C. However, 60 wt % PEHA impregnated KIT-6 showed the stable sorption capacity of 170-184 mg CO2/g at 90-105 °C and 1 bar.
- 23Du, H.; Ma, L.; Liu, X.; Zhang, F.; Yang, X.; Wu, Y.; Zhang, J. A Novel Mesoporous SiO2Material with MCM-41 Structure from Coal Gangue: Preparation, Ethylenediamine Modification, and Adsorption Properties for CO2 Capture. Energy Fuels 2018, 32 (4), 5374– 5385, DOI: 10.1021/acs.energyfuels.8b0031823A Novel Mesoporous SiO2 Material with MCM-41 Structure from Coal Gangue: Preparation, Ethylenediamine Modification, and Adsorption Properties for CO2 CaptureDu, Hong; Ma, Liang; Liu, Xiaoyao; Zhang, Fei; Yang, Xinyu; Wu, Yu; Zhang, JianbinEnergy & Fuels (2018), 32 (4), 5374-5385CODEN: ENFUEM; ISSN:0887-0624. (American Chemical Society)A novel mesoporous SiO2 material (M-SiO2) with MCM-41 structure was readily fabricated from the inexpensive coal gangue via a hydrothermal reaction in the presence of cetyltrimethylammonium bromide (CTAB) for CO2 capture. On the basis of orthogonal exptl. results, the optimum conditions for the prepn. of M-SiO2 were identified as follows: the SiO32- leaching of 21 g/L from coal gangue, the CTAB concn. of 0.25 mol/L, the HCl concn. of 2.5 mol/L, the hydrothermal temp. of 393.15 K, and the hydrothermal time of 20 h. Under the optimum condition, the M-SiO2 exhibited an adsorption capability of 9.61 mg/g to 8% CO2 at 298.15 K. To further improve the CO2 adsorption performance, the M-SiO2 was chem. modified using ethylenediamine (EDA), and the optimum conditions for the modification of M-SiO2 were identified as follows: the impregnation time of 10 h, the drying temp. of 343.15 K, and the ratio of EDA/M-SiO2 = 2:1. Under the optimum conditions, the adsorption capability of EDA-modified M-SiO2 (EDA-M-SiO2) was increased by 83.5 mg/g. The obtained M-SiO2 and EDA-M-SiO2 were systemically characterized by N2 adsorption-desorption isotherms, thermogravimetric anal., Fourier transform IR spectroscopy, SEM, transmission electron microscopy, and X-ray diffraction measurements techniques. The anal. results indicated that the M-SiO2 was mainly composed of O and Si in the form of SiO2 with a sp. surface area of 156 m2/g, and part of M-SiO2 exhibited a structure similar to MCM-41. Moreover, the mechanisms of EDA modification and CO2 adsorption were investigated and discussed in detail.
- 24Chen, H.; Liang, Z.; Yang, X.; Zhang, Z.; Zhang, Z. Experimental Investigation of CO2 Capture Capacity: Exploring Mesoporous Silica SBA-15 Material Impregnated with Monoethanolamine and Diethanolamine. Energy Fuels 2016, 30 (11), 9554– 9562, DOI: 10.1021/acs.energyfuels.6b0129824Experimental Investigation of CO2 Capture Capacity: Exploring Mesoporous Silica SBA-15 Material Impregnated with Monoethanolamine and DiethanolamineChen, Hongwei; Liang, Zhanwei; Yang, Xin; Zhang, Ze; Zhang, ZhiyuanEnergy & Fuels (2016), 30 (11), 9554-9562CODEN: ENFUEM; ISSN:0887-0624. (American Chemical Society)A series of efficient adsorbents were prepd. by impregnating mesoporous silica SBA-15 with different amts. of monoethanolamine (MEA) and diethanolamine (DEA) in order to improve CO2 capture capacity. The textural properties of pure and modified mesoporous SBA-15 materials were characterized by X-ray diffraction characterization, transmission electron microscopy, N2 adsorption-desorption test, and thermogravimetric anal. When the ratio of DEA to SBA-15 is below 2, these mols. loaded on the support are relatively far away from satg. and allow the accessibility of CO2 mols. to the inner adsorption sites. Further increasing of the amine loading would reduce opportunities of CO2 to contact with internal amino sites, because the amine was covered in a multilayer form or even caking form on the SBA-15 pore surface. The similar performance was obsd. for MEA. Therefore, the adsorption capacity of CO2 increases with the amt. of DEA or MEA content, but when the amt. of MEA or DEA loaded on the mesoporous SBA-15 is further increased, the CO2 capture is influenced by the packing effect on the mesoporous hexagonal silica. Temp. effect on adsorption was also studied in the range of 30-90 °C, showing that, with the increase of temp., the adsorptive amts. of adsorbents lessened gradually from the highest values at 30 °C since the thermodynamically controlled process. The mesoporous SBA-15 material impregnated with MEA or DEA can provide a perspective to further explore effective adsorbents for CO2 capture.
- 25Ye, C.-P.; Wang, R.-N.; Gao, X.; Li, W.-Y. CO2 Capture Performance of Supported Phosphonium Dual Amine-Functionalized Ionic Liquids@MCM-41. Energy Fuels 2020, 34 (11), 14379– 14387, DOI: 10.1021/acs.energyfuels.0c0254725CO2 Capture Performance of Supported Phosphonium Dual Amine-Functionalized Ionic Liquids@MCM-41Ye, Cui-Ping; Wang, Rui-Nan; Gao, Xia; Li, Wen-YingEnergy & Fuels (2020), 34 (11), 14379-14387CODEN: ENFUEM; ISSN:0887-0624. (American Chemical Society)To screen the efficient media for CO2 capture of flue gas from power plants, a strategy for improving the CO2 capture capacity by dual functionalized ionic liqs. (ILs) with multiple active sites is proposed. Three phosphonium dual functionalized ILs ([aP4443][2-Np], [aP4443][2-Op], and [aP4443][Triz]) have been prepd. The sorption capacities of the synthesized ILs under pure CO2 atmosphere and the supported ILs under different loading amts. from 10 to 50%, temps. of 30-80°C, and CO2 partial pressure varied from 10 to 15% were detd. Fourier transform IR (FTIR) spectroscopy was applied to reveal the interaction between CO2 and ILs, and the pseudo-second-order model and the intraparticle diffusion model were used for a better understanding of the CO2 adsorption behavior. The results showed that a high capacity up to 1.88 mol of CO2/mol of IL for [aP4443][2-Np] is achieved, and 30% IL-MCM-41 can reach 3.19 mmol/g with excellent reversibility under the atm. of CO2:N2 (15%:85%) at 30°C and 0.1 MPa. Raising the temp. or decreasing the CO2 concn. is not conducive to improving the CO2 capacity. FTIR spectroscopy demonstrated that the amino and hydroxyl react with CO2 to form NHCOO- or CO3-. Combined with the activation energy calcn., the kinetic anal. revealed that the CO2 capture of supported ILs is an internal diffusion controlled phys. adsorption.
- 26Zhang, W.; Li, Y.; Li, Y.; Gao, E.; Cao, G.; Bernards, M. T.; He, Y.; Shi, Y. Enhanced SO2 Resistance of Tetraethylenepentammonium Nitrate Protic Ionic Liquid-Functionalized SBA-15 during CO2 Capture from Flue Gas. Energy Fuels 2020, 34 (7), 8628– 8634, DOI: 10.1021/acs.energyfuels.0c0107426Enhanced SO2 Resistance of Tetraethylenepentammonium Nitrate Protic Ionic Liquid-Functionalized SBA-15 during CO2 Capture from Flue GasZhang, Wei; Li, Yu; Li, Younan; Gao, Erhao; Cao, Guanghan; Bernards, Matthew T.; He, Yi; Shi, YaoEnergy & Fuels (2020), 34 (7), 8628-8634CODEN: ENFUEM; ISSN:0887-0624. (American Chemical Society)Post-combustion carbon capture using amine-based adsorbents is a highly competitive approach to control CO2 emissions from fossil fuel-fired power plants. However, it is well known that amine-based adsorbents suffer from long-term stability issues due to amine poisoning by flue gas contaminants. Minor contaminants, such as SO2, can preferably react with amine sites to form irreversible sulfonamides. This work investigated the effect of nitrates on the SO2 resistance of tetraethylenepentammonium nitrate protic ionic liq.-functionalized SBA-15 for CO2 capture. The tetraethylenepentamine-functionalized SBA-15 without nitrates was prepd. as the control. The CO2 adsorption capacity was measured over multiple capture cycles in the presence of 500 ppm SO2. The CO2 capture capacities of the sorbent without nitrates decreased by 1.48 mmol g-1 (50.3%) over 11 capture cycles. After introducing nitrates into the sorbent, the CO2 adsorption capacities only decreased by 0.55 mmol g-1 (21.8%). In addn., the nitrates restricted the reaction between amine groups and SO2 leading to reversible sulfonamide products. The significant improvement in SO2 resistance was further explained with d. functional theory (DFT) calcns., which revealed that the binding energy and net charge transfer between SO2 and amine groups were decreased after introducing the nitrate group into the amine. To further investigate the regenerability and structural stability of tetraethylenepentammonium nitrate-functionalized SBA-15 for CO2 capture under realistic conditions, the long-term operating performance was evaluated in a gas mixt. of 150 ppm SO2, 150 ppm NO, 100% RH, 15% CO2, and balance N2. The CO2 adsorption capacities and the structural properties of nitrate-contg. sorbents were nearly unchanged over eight adsorption/regeneration cycles.
- 27Zhang, W.; Gao, E.; Li, Y.; Bernards, M. T.; Li, Y.; Cao, G.; He, Y.; Shi, Y. Synergistic Enhancement of CO2 Adsorption Capacity and Kinetics in Triethylenetetrammonium Nitrate Protic Ionic Liquid Functionalized SBA-15. Energy Fuels 2019, 33 (9), 8967– 8975, DOI: 10.1021/acs.energyfuels.9b0187227Synergistic Enhancement of CO2 Adsorption Capacity and Kinetics in Triethylenetetrammonium Nitrate Protic Ionic Liquid Functionalized SBA-15Zhang, Wei; Gao, Erhao; Li, Yu; Bernards, Matthew T.; Li, Younan; Cao, Guanghan; He, Yi; Shi, YaoEnergy & Fuels (2019), 33 (9), 8967-8975CODEN: ENFUEM; ISSN:0887-0624. (American Chemical Society)A series of triethylenetetrammonium nitrate protic ionic liq. (TNPIL) functionalized, highly ordered mesoporous SBA-15 mol. sieves with different loadings have been synthesized via impregnation. The CO2 capture performance of the hybrid sorbents was evaluated under conditions mimicking a combustion flue gas (15% CO2) over the temp. range of 298-348 K. The breakthrough expts. revealed that the sieves with 66% mass loadings of TNPIL (S15-66TNPIL) exhibited the highest CO2 adsorption capacity of 2.12 mmol g-1 at 333 K, representing a dramatic enhancement compared to the bare support (883%). The intraparticle diffusion model anal. of the hybrid sorbents demonstrated that S15-66TNPIL had the fastest CO2 uptake rate of 131 × 10-3 mmol g-1 s-0.5 in the rate-controlling stage. This was almost 5 times higher than that of the bare support alone and is a significant improvement over other IL-functionalized and amine-modified support systems. This can be attributed to the synergistic effects of the high affinity between the TNPIL and CO2 and the fast diffusion rate from the distribution of TNPIL across the support with a large surface area. In addn., S15-66TNPIL exhibited a great regeneration capacity. The Fourier transform-IR spectroscopy anal. coupled with isosteric heat and d. functional theory simulations revealed that the adsorption state is dominated by chemisorption, and the CO2 preferentially interacts with the primary amine -N(3)H2 to form carbamate based on the high binding energy. Therefore, this novel TNPIL-supported system represents a promising candidate for CO2 capture and recovery applications.
- 28Venkateshwaran, S.; Partheeban, T.; Sasidharan, M.; Senthil Kumar, S. M. Mesoporous Silica Template-Assisted Synthesis of 1T-MoS2 as the Anode for Li-Ion Battery Applications. Energy Fuels 2021, 35 (3), 2683– 2691, DOI: 10.1021/acs.energyfuels.0c0329628Mesoporous Silica Template-Assisted Synthesis of 1T-MoS2 as the Anode for Li-Ion Battery ApplicationsVenkateshwaran, Selvaraj; Partheeban, Thamodaran; Sasidharan, Manickam; Senthil Kumar, Sakkarapalayam MurugesanEnergy & Fuels (2021), 35 (3), 2683-2691CODEN: ENFUEM; ISSN:0887-0624. (American Chemical Society)The development of the MoS2-based catalyst is receiving more attention in recent years, esp. with enriched metallic (1T) phase because of their improvized electrocatalytic behavior. However, the formation of MoS2 with the enriched 1T phase is still hampered because the most stable one is 2H phase. Till date, the most adopted technique to synthesize 1T-MoS2 is the alkali metal exfoliation, but the usage of undesirable org. medium and pyrophoric alkali metal ions is the main setback to this technique. On the other hand, low extent of the 1T phase and lack of reproducibility are issues with aq. medium synthesis of 1T-MoS2. Here, in contrast, the SBA-15 template-assisted technique has been used for the formation of 1T-MoS2 with 90% phase enrichment. As a proof-of-concept, the as-synthesized 1T-MoS2 is investigated as anode materials in the Li-ion battery and they delivered a high initial specific capacity of 1100 mA h g-1 at the 0.1 C rate in the potential window of 0.005-3.0 V and showed a capacity of 700 mA h g-1 with 80% capacity retention after 50 cycles. Investigation of power capability of 1T-MoS2 at high applied current of 1 C rate produced a stable specific capacity of 551 mA h g-1 after 100 cycles. The impressive electrochem. Li+ ion storage property of 1T-MoS2 is attributed to its good elec. cond., fast Li+ ion, and electron conduction owing to its 2D-networked flower-like structure. Moreover, this facile approach is highly useful for the selective enrichment of the 1T phase in other 2D-layered materials that can be used for energy storage and conversion devices.
- 29Subagyono, R. R. D. J. N.; Marshall, M.; Jackson, W. R.; Auxilio, A. R.; Fei, Y.; Chaffee, A. L. Upgrading Microalgal Biocrude Using NiMo/Al-SBA-15 as a Catalyst. Energy Fuels 2020, 34 (4), 4618– 4631, DOI: 10.1021/acs.energyfuels.9b0417129Upgrading Microalgal Biocrude Using NiMo/Al-SBA-15 as a CatalystSubagyono, R. R. Dirgarini J. N.; Marshall, Marc; Jackson, W. Roy; Auxilio, Anthony R.; Fei, Yi; Chaffee, Alan L.Energy & Fuels (2020), 34 (4), 4618-4631CODEN: ENFUEM; ISSN:0887-0624. (American Chemical Society)Biocrude from Chlorococcum sp. algae was hydrotreated in batch autoclaves in the presence and absence of Al-SBA-15 supports and NiMo/Al-SBA-15 catalysts with different Si/Al ratios and hence different acidities. Reaction time (0-15 min), temp. (425-500°C), and H2 pressure (3-9 MPa cold) were varied. The nitrogen content of the biocrude was approx. halved in all of the reactions, regardless of temp., H2 pressure, or the presence of the support/catalyst. Product aromaticity increased with reaction temp. The presence of the supports, esp. those of lower acidity, decreased product yields (CH2Cl2 solubles and hydrocarbon gases) due to severe coking. Incorporation of NiMo introduced a pressure dependence of the product yield. For 425°C reactions, NiMo could more than make up for the coking effect of the support, increasing the product yield to up to 65 wt % (6-9 MPa H2 (cold)) and the proportion of liq. products in the kerosene-boiling-point range (C12-C17). Higher-acidity supports gave higher product yields, and their superiority was maintained when NiMo was incorporated.
- 30Meng, Q.; Duan, A.; Chi, K.; Zhao, Z.; Liu, J.; Zheng, P.; Wang, B.; Liu, C.; Hu, D.; Jia, Y. Synthesis of Titanium Modified Three-Dimensional KIT-5 Mesoporous Support and Its Application of the Quinoline Hydrodenitrogenation. Energy Fuels 2019, 33 (6), 5518– 5528, DOI: 10.1021/acs.energyfuels.9b0052030Synthesis of Titanium Modified Three-Dimensional KIT-5 Mesoporous Support and Its Application of the Quinoline HydrodenitrogenationMeng, Qian; Duan, Aijun; Chi, Kebin; Zhao, Zhen; Liu, Jian; Zheng, Peng; Wang, Bo; Liu, Cong; Hu, Di; Jia, YuanzhenEnergy & Fuels (2019), 33 (6), 5518-5528CODEN: ENFUEM; ISSN:0887-0624. (American Chemical Society)A series of Ti-KIT-5 materials with different ratios of Si/Ti were synthesized and employed as the supports to prep. the NiMo catalysts. All the modified supports and catalysts were measured by means of small-angle and wide-angle XRD, N2 isotherm absorption-desorption, FTIR, XPS, Py-IR, and HRTEM techniques. The small-angle XRD and N2 anal. characterization proved that the modified Ti-KT-x materials maintained the orderly mesoporous structure and displayed the larger pore size than the pure support. Addnl., results from the FTIR and XPS spectra demonstrated that Ti species were successfully embedded into the framework of KIT-5 material. It was noted that the introduction of suitable Ti species increased the amt. of acid sites and promoted well distribution of the active metals. The hydrodenitrogenation performances of the NiMo/Ti-KT-x catalysts were evaluated under the reaction conditions of a H2 pressure of 4 MPa, a WHSV of 10 h-1, and different temps. ranging from 340 to 400 °C. The modified NiMo/Ti-KIT-5 catalysts showed the higher catalytic activities than NiMo/KIT-5 catalyst, which was attributed to the larger pore size, more acid sites, and sulfide active metal species. Moreover, the NiMo/Ti-KT-20 catalyst showed the highest hydrodenitrogenation efficiencies (81.56%).
- 31Gutta, N.; Velisoju, V. K.; Tardio, J.; Patel, J.; Satyanarayana, L.; Sarma, A. V. S.; Akula, V. CH4 Cracking over the Cu–Ni/Al-MCM-41 Catalyst for the Simultaneous Production of H2 and Highly Ordered Graphitic Carbon Nanofibers. Energy Fuels 2019, 33 (12), 12656– 12665, DOI: 10.1021/acs.energyfuels.9b0281931CH4 Cracking over the Cu-Ni/Al-MCM-41 Catalyst for the Simultaneous Production of H2 and Highly Ordered Graphitic Carbon NanofibersGutta, Naresh; Velisoju, Vijay Kumar; Tardio, James; Patel, Jim; Satyanarayana, Lanka; Sarma, Akella V. S.; Akula, VenugopalEnergy & Fuels (2019), 33 (12), 12656-12665CODEN: ENFUEM; ISSN:0887-0624. (American Chemical Society)The Cu-Ni bimetallic catalysts dispersed on various silica supports were examd. for catalytic cracking of CH4 to produce pure H2 with near zero COx emissions and fine quality carbon nanofibers. The 27Al MAS NMR spectra of Al contg. MCM-41 samples revealed the existence of framework and extra framework decorated Al species. Insertion of Al species into the framework of MCM-41, significantly improved the accessible active surface Ni sites, which was confirmed from the simultaneous H2 and N2O pulse titrn. techniques. NH3 TPD measurements demonstrated a high ratio of moderate and strong acid sites upon Al insertion into the silica matrix. The framework tetrahedral Al in MCM-41 stabilized the surface Cu-Ni alloy sites and protected from the sintering and fragmentation of Ni consequently enhanced the H2 yields of 270 Nm3/(molNi)-1 were obtained with Si/Al ratio = 150 with catalyst. The better performance of the Cu-Ni/Al-MCM-41 (Si/Al = 150) was rationalized using the physicochem. characteristics of the catalyst analyzed by XRD, H2-TPR, BET - surface area, 27Al and 29Si MAS NMR, NH3-TPD, XPS, TEM, H2 and/or N2O titrn. and Raman spectroscopic techniques.
- 32Gutta, N.; Velisoju, V. K.; Chatla, A.; Boosa, V.; Tardio, J.; Patel, J.; Akula, V. Promotional Effect of Cu and Influence of Surface Ni–Cu Alloy for Enhanced H2 Yields from CH4 Decomposition over Cu-Modified Ni Supported on MCM-41 Catalyst. Energy Fuels 2018, 32 (3), 4008– 4015, DOI: 10.1021/acs.energyfuels.7b0336332Promotional Effect of Cu and Influence of Surface Ni-Cu Alloy for Enhanced H2 Yields from CH4 Decomposition over Cu-Modified Ni Supported on MCM-41 CatalystGutta, Naresh; Velisoju, Vijay Kumar; Chatla, Anjaneyulu; Boosa, Venu; Tardio, James; Patel, Jim; Akula, VenugopalEnergy & Fuels (2018), 32 (3), 4008-4015CODEN: ENFUEM; ISSN:0887-0624. (American Chemical Society)Catalysts based on MCM-41 decorated with 35-70 nm diam. Ni particles were tested for the prodn. of hydrogen by catalytic decompn. of methane (CDM). About 122 N m3 (molNi)-1 hydrogen yield was achieved over a catalyst comprised of optimized Ni loading of 50 wt % Ni/MCM-41. The H2 yield increased dramatically to 204 N m3 (molNi)-1, upon modification with 10 wt % Cu. The presence of Cu, in contact to Ni, appeared to reduce the sintering and coking of the active Ni sites, which enhanced the longevity of the catalyst. Raman anal. of the catalysts recovered after CDM expts. revealed that doping of Cu to Ni/MCM-41 enhanced the graphitic carbon deposition over the catalyst. All of the samples (Ni and Ni-Cu-modified MCM-41) were characterized by H2 chemisorption, SEM/TEM, XPS, XRD, H2-TPR, N2O titrn., and Raman spectroscopy to examine the bulk and surface properties of the catalysts.
- 33Hung, C.; Bai, H.; Karthik, M. Ordered mesoporous silica particles and Si-MCM-41 for the adsorption of acetone: A comparative study. Sep. Purif. Technol. 2009, 64 (3), 265– 272, DOI: 10.1016/j.seppur.2008.10.02033Ordered mesoporous silica particles and Si-MCM-41 for the adsorption of acetone: A comparative studyHung, Chinte; Bai, Hsunling; Karthik, ManiSeparation and Purification Technology (2009), 64 (3), 265-272CODEN: SPUTFP; ISSN:1383-5866. (Elsevier B.V.)This study compares the surface properties and the acetone adsorption potentials of mesoporous silica particles (MSPs) and Si-MCM-41. The Si-MCM-41 and MSPs are synthesized, resp. by hydrothermal method and evapn.-induced self-assembly (EISA) method. The results show that the surface area and pore diam. of MSPs are similar to those of Si-MCM-41. But the synthesis of Si-MCM-41 frequently requires longer time and tedious procedure as compared to that of MSPs. The bulk d. of MSPs is 3.0-5.0 times higher than that of Si-MCM-41. The mass-based acetone adsorption capacities of these two materials are almost similar. This implies that MSPs have a higher vol.-based acetone adsorption capacity than Si-MCM-41 so that less space is required for volatile org. compds. (VOCs) adsorption using MSPs as the adsorbent. The pressure drops of both powder and pellet forms of MSPs are also smaller than those of Si-MCM-41 for adsorbing the same amt. of acetone. In addn., as compared to com. H-ZSM-5 zeolite, both MSPs and Si-MCM-41 reveal better performances on the regeneration ability. As a result, both MSPs and Si-MCM-41 show high adsorption/desorption potential but the MSPs are better as novel adsorbents in terms of overall engineering consideration.
- 34Basso, A. M.; Nicola, B. P.; Bernardo-Gusmão, K.; Pergher, S. B. C. Tunable Effect of the Calcination of the Silanol Groups of KIT-6 and SBA-15 Mesoporous Materials. Applied Sciences 2020, 10 (3), 970, DOI: 10.3390/app1003097034Tunable effect of the calcination of the silanol groups of KIT-6 and SBA-15 mesoporous materialsBasso, Adriano M.; Nicola, Bruna P.; Bernardo-Gusmao, Katia; Pergher, Sibele B. C.Applied Sciences (2020), 10 (3), 970CODEN: ASPCC7; ISSN:2076-3417. (MDPI AG)The calcination process is a crucial step during SBA-15 and KIT-6 synthesis. It is used to completely remove the org. template and condense silanol groups, and it allows the detn. of the textural and phys. properties of these materials, depending on the adopted conditions. Moreover, calcination influences the no. of silanols available on the surface of the material. The concn. of silanols is important if these materials were synthesized for use in adsorption or functionalization. To understand and optimize the silanol groups of SBA-15 and KIT-6, in this study, the temp. and time calcination parameters were varied. The expts. were performed at 300, 400, and 500 °C for 300, 400, and 500 min. The results show that the ideal temp. to preserve the silanol groups is 300 °C, but to optimize the textural properties, it is better to calcine these mol. sieves at 400 °C. A calcination for 10 h did not give better results than a calcination for 5 h, demonstrating that the former duration is excessive for use.
- 35Huang, L.; Kawi, S.; Poh, C.; Hidajat, K.; Ng, S. C. Extraction of cationic surfactant templates from mesoporous materials by CH3OH-modified CO2 supercritical fluid. Talanta 2005, 66 (4), 943– 951, DOI: 10.1016/j.talanta.2004.12.05735Extraction of cationic surfactant templates from mesoporous materials by CH3OH-modified CO2 supercritical fluidHuang, L.; Kawi, S.; Poh, C.; Hidajat, K.; Ng, S. C.Talanta (2005), 66 (4), 943-951CODEN: TLNTA2; ISSN:0039-9140. (Elsevier B.V.)Extn. of cationic surfactant templates from MCM-41, MCM-48, SBA-1 and SBA-3 has been conducted using CH3OH-modified CO2 supercrit. fluid. The supercrit. fluid extn. (SFE) has been integrated with thermogravimetry (TG), X-ray diffraction (XRD) and N2 adsorption-desorption to evaluate extn. efficiency and structural stability of mesoporous materials. Expts. of optimization indicate that the conditions of 90 bar, 85 °C, CH3OH/CO2 = 0.1/1.0 mL/min and 3 h are most suitable for the SFE of cationic templates. 76-95% of the cationic templates can be extd. from the mesoporous materials. XRD and N2 adsorption-desorption studies illustrate that SFE possesses some advantages over calcination in maintaining mesoporous uniformity and structural stability when used to remove templates. The impact of curing on mesoporous structure is also dealt with.
- 36Huang, Z.; Huang, L.; Shen, S. C.; Poh, C. C.; Hidajat, K.; Kawi, S.; Ng, S. C. High quality mesoporous materials prepared by supercritical fluid extraction: effect of curing treatment on their structural stability. Microporous Mesoporous Mater. 2005, 80 (1), 157– 163, DOI: 10.1016/j.micromeso.2004.12.01636High quality mesoporous materials prepared by supercritical fluid extraction: effect of curing treatment on their structural stabilityHuang, Z.; Huang, L.; Shen, S. C.; Poh, C. C.; Hidajat, K.; Kawi, S.; Ng, S. C.Microporous and Mesoporous Materials (2005), 80 (1-3), 157-163CODEN: MIMMFJ; ISSN:1387-1811. (Elsevier B.V.)Mesoporous mol. sieves like SBA-1, SBA-3, MCM-41 and MCM-48 are generally synthesized by using a quaternary ammonium surfactant as a structure-directing agent to form a porous SiO2 framework. The used templating agent is conventionally removed for producing mesopores by calcination at high temp. Supercrit. fluid extn. (SFE) was employed to remove org. templates from these materials. More than 80% of the templating agent can be successfully removed by using this technique. Among these materials, SBA-3 was obsd. to experience the collapse of mesoporous structures upon the SFE process. Thus, the authors proposed pre-SFE thermal aging as a curing treatment method and found that it has significantly improved the mesoporous structural stability of SBA-3. In the meantime, this curing method has lead to these SFE-processed materials with better ordered mesoporous structures, such as SBA-3 having sp. surface area as large as 1670 m2/g.
- 37Krawiec, P.; Kockrick, E.; Simon, P.; Auffermann, G.; Kaskel, S. Platinum-Catalyzed Template Removal for the in Situ Synthesis of MCM-41 Supported Catalysts. Chem. Mater. 2006, 18 (11), 2663– 2669, DOI: 10.1021/cm052830n37Platinum-Catalyzed Template Removal for the in Situ Synthesis of MCM-41 Supported CatalystsKrawiec, Piotr; Kockrick, Emanuel; Simon, Paul; Auffermann, Gudrun; Kaskel, StefanChemistry of Materials (2006), 18 (11), 2663-2669CODEN: CMATEX; ISSN:0897-4756. (American Chemical Society)Platinum-contg. MCM-41 was synthesized in a one step approach. In this new procedure, the swelling agent (toluene) was used as a transport medium to inject the Pt precursor, Pt(acetylacetonate)2, directly into the inner core of the surfactant micelles. A 1 wt % metal loading was achieved without the loss of pore ordering, while samples with 2 wt % loading showed a less ordered structure. A total of 80-100% of the Pt precursor was incorporated in the porous host matrix depending on the precursor concn. and final loading. During the calcination process, platinum acts as a catalyst for the oxidative removal of the surfactant mols., allowing one to decrease the calcination temp. significantly. The calcined material had a high surface area (1000-1200 m2 g-1). Platinum particles could be detected using transmission electron microscopy confirming also the absence of large particles outside the mesopore system. The in situ approach was also applied to prep. other metal/MCM-41 or oxide/MCM-41 materials such as Pd/MCM-41 and V2O5/MCM-41. Both of them showed a high degree of guest incorporation and no significant decrease in surface area. In situ incorporation of metals into SBA-15 resulted in a lower Pt incorporation in the final material (50-60%) and a disordered pore structure, even for low Pt loading (1 wt %). The accessibility of the metallic particles for catalytic reactions was demonstrated using the hydrogenation of cinnamic acid as a model reaction. The highest specific reaction rates were obsd. for Pd supported on MCM-41 and were comparable to that of com. available Pd/carbon catalysts.
- 38Zaleski, R.; Wawryszczuk, J.; Borówka, A.; Goworek, J.; Goworek, T. Temperature changes of the template structure in MCM-41 type materials; positron annihilation studies. Microporous Mesoporous Mater. 2003, 62 (1), 47– 60, DOI: 10.1016/S1387-1811(03)00389-538Temperature changes of the template structure in MCM-41 type materials; positron annihilation studiesZaleski, Radoslaw; Wawryszczuk, Jan; Borowka, Anna; Goworek, Jacek; Goworek, TomaszMicroporous and Mesoporous Materials (2003), 62 (1-2), 47-60CODEN: MIMMFJ; ISSN:1387-1811. (Elsevier Science B.V.)The lifetime spectra of positrons annihilating in MCM-41 ordered silica were measured as a function of temp. It was found that in alkyltrimethylammonium templates degrdn. in vacuum begins at 380-400 K, that consists in breaking the long micelle cylinders, rise of gaps between the fragments and finally pore evacuation. The latter process is not completed and particularly in C12TAB the spectrum component belonging to fragmented template preserves its high intensity up to 520 K (the highest temp. in our expt.). The pore surface area over 1000 m2/g is achieved already at temps. about 490 K. The lifetime of the longest-lived component indicates that practically all ortho-positronium atoms leave the pores before annihilation.
- 39Ryczkowski, J.; Goworek, J.; Gac, W.; Pasieczna, S.; Borowiecki, T. Temperature removal of templating agent from MCM-41 silica materials. Thermochim. Acta 2005, 434 (1), 2– 8, DOI: 10.1016/j.tca.2004.12.02039Temperature removal of templating agent from MCM-41 silica materialsRyczkowski, J.; Goworek, J.; Gac, W.; Pasieczna, S.; Borowiecki, T.Thermochimica Acta (2005), 434 (1-2), 2-8CODEN: THACAS; ISSN:0040-6031. (Elsevier B.V.)Temp.-programmed desorption coupled with mass spectrometry, FTIR spectroscopy with photoacoustic (PA) detector were applied to investigate org. template degrdn. during thermal treatment of as-prepd. MCM-41 silica. Micelle-templated silica was prepd. using C18 trimethylammonium bromide. The processes accompanying the template transformations were investigated in argon flow and mixed oxygen-helium atm. Template removal appears to be completely different in the inert gas atm. and at the presence of oxygen. The results obtained for as-prepd. sample were compared with those for calcined sample in air and addnl. thermally treated in oxygen flow. Spectroscopic data indicate the presence of a variety of chem. species on silica surface after template removal. Addnl. oxidn. of calcined sample leads to elimination of most org. functional groups and increase of siloxane bridges as a product of surface silanols condensation.
- 40Goworek, J.; Kierys, A.; Kusak, R. Isothermal template removal from MCM-41 in hydrogen flow. Microporous Mesoporous Mater. 2007, 98 (1), 242– 248, DOI: 10.1016/j.micromeso.2006.09.01140Isothermal template removal from MCM-41 in hydrogen flowGoworek, Jacek; Kierys, Agnieszka; Kusak, RyszardMicroporous and Mesoporous Materials (2007), 98 (1-3), 242-248CODEN: MIMMFJ; ISSN:1387-1811. (Elsevier B.V.)Thermal evacuation of template surfactant from MCM-41 in hydrogen atm. was studied. Micelle templated SiO2 was prepd. using hexadecyltrimethylammonium bromide. The mechanism of template removal appears to be completely different in hydrogen as compared to calcination in air. It seems that moderate heating of as-synthesized MCM-41 (up to ∼250°) in hydrogen stream for ∼15 h is effective and simple method of template removal leaving no pure C residues on SiO2 surface. Adsorption properties of partially evacuated MCM-41 samples were tested using gas chromatog. Products of template degrdn. were analyzed using GC-MS technique. The main products of template degrdn. at 250° in hydrogen flow are hexadecene and hexadecane-N,N-dimethylamine. Concn. of surface silanols for MCM-41 calcined and thermally treated in hydrogen flow was studied by NMR technique.
- 41Camel, V.; Tambuté, A.; Caude, M. Analytical-scale supercritical fluid extraction: a promising technique for the determination of pollutants in environmental matrices. J. Chromatogr. A 1993, 642 (1), 263– 281, DOI: 10.1016/0021-9673(93)80093-NThere is no corresponding record for this reference.
- 42Hawthorne, S. B. Analytical-scale supercritical fluid extraction. Anal. Chem. 1990, 62 (11), 633A– 642A, DOI: 10.1021/ac00210a72242Analytical-scale supercritical fluid extractionHawthorne, Steven B.Analytical Chemistry (1990), 62 (11), 633A-636A, 638A-642ACODEN: ANCHAM; ISSN:0003-2700.A review with 57 refs. The selection of supercrit. fluids, prediction of optimal conditions, development and availability of app. and techniques, and applications (both off-line and online, i.e. combined with GC and supercrit.-fluid chromatog.) are covered.
- 43Huang, Z.; Luan, D. Y.; Shen, S. C.; Hidajat, K.; Kawi, S. Supercritical fluid extraction of the organic template from synthesized porous materials: effect of pore size. Journal of Supercritical Fluids 2005, 35 (1), 40– 48, DOI: 10.1016/j.supflu.2004.11.00143Supercritical fluid extraction of the organic template from synthesized porous materials: effect of pore sizeHuang, Z.; Luan, D.-Y.; Shen, S.-C.; Hidajat, K.; Kawi, S.Journal of Supercritical Fluids (2005), 35 (1), 40-48CODEN: JSFLEH; ISSN:0896-8446. (Elsevier B.V.)Supercrit. fluid extn. was evaluated for removing surfactants from freshly synthesized mol. sieve powders possessing different pore sizes. In study, MeOH- or H2O-enhanced supercrit. CO2 extn. was carried out on as-synthesized microporous and mesoporous material powders. Very high surfactant recovery (over 80%) could be achieved from large pore-sized mesoporous materials by using the SFE method, while the surfactant recovery is rather low from small pore-sized microporous zeolite materials. Supercrit. fluid extn. technol. may provide a potential method for large-scale prodn. of mesoporous materials with effective surfactant recovery that is extremely efficient.
- 44Lu, X.-B.; Zhang, W.-H.; Xiu, J.-H.; He, R.; Chen, L.-G.; Li, X. Removal of the Template Molecules from MCM-41 with Supercritical Fluid in a Flow Apparatus. Ind. Eng. Chem. Res. 2003, 42 (3), 653– 656, DOI: 10.1021/ie020422c44Removal of the Template Molecules from MCM-41 with Supercritical Fluid in a Flow ApparatusLu, Xiao-Bing; Zhang, Wen-Hua; Xiu, Jing-Hai; He, Ren; Chen, Lu-Guang; Li, XiaoIndustrial & Engineering Chemistry Research (2003), 42 (3), 653-656CODEN: IECRED; ISSN:0888-5885. (American Chemical Society)Supercrit. CO2 modified with a methanol/dichloromethane mixt. was used to quant. remove the template mols. (cetyltrimethylammonium bromide) from the pores of as-synthesized pure siliceous MCM-41 in a flow app. The resulting mesoporous MCM-41 materials, characterized by powder x-ray diffraction, nitrogen adsorption, and high-resoln. transmission electron microscopy, exhibited higher surface areas, larger pores, and narrower pore size distributions than those obtained by conventional calcination at high temp. The removed template retained its structures and properties and could be reused in the synthesis of MCM-41 materials.
- 45van Grieken, R.; Calleja, G.; Stucky, G. D.; Melero, J. A.; García, R. A.; Iglesias, J. Supercritical Fluid Extraction of a Nonionic Surfactant Template from SBA-15 Materials and Consequences on the Porous Structure. Langmuir 2003, 19 (9), 3966– 3973, DOI: 10.1021/la026970c45Supercritical Fluid Extraction of a Nonionic Surfactant Template from SBA-15 Materials and Consequences on the Porous StructureVan Grieken, Rafael; Calleja, Guillermo; Stucky, Galen D.; Melero, Juan A.; Garcia, Rafael A.; Iglesias, JoseLangmuir (2003), 19 (9), 3966-3973CODEN: LANGD5; ISSN:0743-7463. (American Chemical Society)SBA-15 mesoporous materials were synthesized using the method reported by Zhao et al. Surfactant was removed from as-made materials by means of different techniques: thermal treatment under air atm., solvent washing at different temps., and supercrit. CO2 extn. in the presence and absence of cosolvents. The structure of resulting materials was characterized using conventional techniques: nitrogen and argon adsorption measurements, powder X-ray diffraction (XRD), thermogravimetric anal. (TGA), IR spectroscopy (FT-IR), and 29Si MAS NMR. The efficiency of surfactant removal using CO2 under supercrit. conditions is similar to that obtained by means of solvent washing under reflux but shows some improvements in the presence of cosolvents. Mesoscopic properties of mild-temp. solvent extd. SBA-15 materials depend on the efficiency of the surfactant removal and the use of supercrit. CO2 as solvent. Likewise, the size and vol. of the complementary microporosity detected in the treated materials is closely related to the strategy of removal of hydrophilic poly(ethylene oxide) chains of the triblock copolymer template occluded within the siliceous walls of the SBA-15 mesophase during the synthesis.
- 46Huang, Z.; Li, J.-h.; Li, H.-s.; Teng, L.-j.; Kawi, S.; Lai, M. W. Effects of polar modifiers on supercritical extraction efficiency for organic template removal from mesoporous MCM-41 materials. The. J. Supercrit. Fluids 2013, 82, 96– 105, DOI: 10.1016/j.supflu.2013.06.01246Effects of polar modifiers on supercritical extraction efficiency for organic template removal from mesoporous MCM-41 materialsHuang, Zhen; Li, Jing-huan; Li, Hui-shan; Teng, Li-jun; Kawi, S.; Lai, M. W.Journal of Supercritical Fluids (2013), 82 (), 96-105CODEN: JSFLEH; ISSN:0896-8446. (Elsevier B.V.)The application of polar modifiers usually can make supercrit. CO2 extn. more attractive in various potential applications. In this work, several polar modifiers have been examd. for the extn. of the template cetyltrimethylammonium bromide (CTMABr) from newly synthesized MCM-41 mesoporous materials, and the modifier content, modifier identity and the sample matrix on supercrit. CO2 extn. efficiency are then evaluated. The results show that the polar modifiers employed have strong influences on the template extn. efficiencies and this could be interpreted rather well in terms of soly. parameter and polarity of the modifiers. Methanol, water and acidic methanol are found to result in very high efficiencies of more than 85% for the pure siliceous samples while relatively good extn. efficiencies of 60-80% for aluminum incorporated samples, and the difference is due to that the org. template could form stronger interactions with the Al species than the silanol groups. Nitrogen adsorption/desorption and X-ray diffraction results confirmed that the polar modifiers have strong influences on the final mesoporous structure of the MCM-41 materials and with methanol modified supercrit. CO2 extn. the resultant materials possess well-ordered mesostructure and much better structural properties like higher pore vol. and sp. surface area.
- 47Huang, Z.; Xu, L.; Li, J.-H.; Kawi, S.; Goh, A. H. Organic template removal from hexagonal mesoporous silica by means of methanol-enhanced CO2 extraction: Effect of temperature, pressure and flow rate. Sep. Purif. Technol. 2011, 77 (1), 112– 119, DOI: 10.1016/j.seppur.2010.11.02947Organic template removal from hexagonal mesoporous silica by means of methanol-enhanced CO2 extraction: Effect of temperature, pressure and flow rateHuang, Zhen; Xu, Li; Li, Jing-Huan; Kawi, S.; Goh, A. H.Separation and Purification Technology (2011), 77 (1), 112-119CODEN: SPUTFP; ISSN:1383-5866. (Elsevier B.V.)Supercrit. fluid extn. was evaluated for removing the amine surfactant from hexagonal mesoporous silica materials. In this study, methanol-enhanced supercrit. CO2 extn. was carried out on freshly synthesized materials by a dynamic method. Expts. were performed at pressure ranging from 10.0 to 25.0 MPa, temp. from 45 to 105°, CO2 flow rate from 0.45 to 4.5 mL/min, and methanol flow rate from 0.05 to 0.5 mL/min. The influence of these parameters on the extn. was evaluated in terms of the surfactant recovery. By using this method up to 96% of the total amine surfactant used is extd. out of as-synthesized mesoporous materials within 1 h extn. whereas only 78% of the surfactant can be removed by liq. ethanol extn. The materials processed by supercrit. CO2 extn. are found to possess better structural properties as reflected by the x-ray diffraction anal. and N2 adsorption results, and thus have higher thermal and hydrothermal stability than those obtained by liq. ethanol extn. or high temp. calcination.
- 48Chen, L.; Jiang, S.; Wang, R.; Zhang, Z.; Qiu, S. A novel, efficient and facile method for the template removal from mesoporous materials. Chemical Research in Chinese Universities 2014, 30 (6), 894– 899, DOI: 10.1007/s40242-014-4202-z48A novel, efficient and facile method for the template removal from mesoporous materialsChen, Lu; Jiang, Shang; Wang, Runwei; Zhang, Zongtao; Qiu, ShilunChemical Research in Chinese Universities (2014), 30 (6), 894-899CODEN: CRCUED; ISSN:1005-9040. (Jilin University)A new catalytic-oxidn. method was adopted to remove the templates from SBA-15 and MCM-41 mesoporous materials via Fenton-like techniques under microwave irradn. The mesoporous silica materials were treated with different Fenton agents based on the template's property and textural property. The samples were characterized by powder X-ray diffraction(XRD) measurement, N2 adsorption-desorption isotherms, IR spectroscopy, 29Si MAS NMR and thermo gravimetric anal.(TGA). The results reveal that this is an efficient and facile approach to the thorough template-removal from mesoporous silica materials, as well as to offering products with more stable structures, higher BET surface areas, larger pore vols. and larger quantity of silanol groups.
- 49Tian, B.; Liu, X.; Yu, C.; Gao, F.; Luo, Q.; Xie, S.; Tu, B.; Zhao, D. Microwave assisted template removal of siliceous porous materials. Chem. Commun. 2002, (11), 1186– 1187, DOI: 10.1039/b202180c49Microwave assisted template removal of siliceous porous materialsTian, Bozhi; Liu, Xiaoying; Yu, Chengzhong; Gao, Feng; Luo, Qian; Xie, Songhai; Tu, Bo; Zhao, DongyuanChemical Communications (Cambridge, United Kingdom) (2002), (11), 1186-1187CODEN: CHCOFS; ISSN:1359-7345. (Royal Society of Chemistry)Org. templates of meso- and macro-porous siliceous materials can be completely removed within minutes by microwave digestion, resulting in highly ordered inorg. frameworks with higher surface areas, larger pore vols., lower structural shrinkage and richer silanol groups compared with those from conventional template removal methods.
- 50Lai, T.-L.; Shu, Y.-Y.; Lin, Y.-C.; Chen, W.-N.; Wang, C.-B. Rapid removal of organic template from SBA-15 with microwave assisted extraction. Mater. Lett. 2009, 63 (20), 1693– 1695, DOI: 10.1016/j.matlet.2009.05.01450Rapid removal of organic template from SBA-15 with microwave assisted extractionLai, Teh-Long; Shu, Youn-Yuen; Lin, Ya-Chu; Chen, Wan-Ning; Wang, Chen-BinMaterials Letters (2009), 63 (20), 1693-1695CODEN: MLETDJ; ISSN:0167-577X. (Elsevier B.V.)The removal of surfactant templates from the pores of as-prepd. SBA-15 was studied by means of microwave assisted extn. (MAE). Occluded surfactant mols. within SBA-15 were completely removed within 6 min by the MAE method, resulting in frameworks with higher surface area, lower structural shrinkage and richer silanol groups than that of thermocalcined samples. The MAE sample exhibited larger surface area (ca. 1000 m2/g-1) than the sample treated by thermocalcining (ca. 560 m2/g-1). As detd. the enrichment of PAHs on MAE with calcined samples by online solid-phase extn. HPLC, the MAE sample possessed more enrichment and lower detection limit than the calcined sample.
- 51Li, X.; Yin, H.; Zhang, J.; Liu, J.; Chen, G. Effect of organic template removal approaches on physiochemical characterization of Ni/Al-SBA-15 and eugenol hydrodeoxygenation. J. Solid State Chem. 2020, 282, 121063, DOI: 10.1016/j.jssc.2019.12106351Effect of organic template removal approaches on physiochemical characterization of Ni/Al-SBA-15 and eugenol hydrodeoxygenationLi, Xiangping; Yin, Han; Zhang, Jianguang; Liu, Juping; Chen, GuanyiJournal of Solid State Chemistry (2020), 282 (), 121063CODEN: JSSCBI; ISSN:0022-4596. (Elsevier B.V.)Template removing approaches can significantly impact the physiochem. properties of mesoporous mol. sieve materials. In order to better understand the relationship between template removing approaches and the properties of Ni/Al-SBA-15, four kinds of template removing approaches were introduced to remove the org. template from Al-SBA-15, resp. The structural characteristics of these materials were analyzed by transmission electron microscopy (TEM), SEM (SEM), X-ray fluorescence (XRF), powder X-ray diffraction (XRD), N2-sorption, Fourier transform IR spectra (FT-IR), IR spectra of pyridine adsorption (Py-FTIR), magic angle spinning-NMR (MAS-NMR), XPS and gas chromatog.-mass spectrometry (GC-MS). Ni/Al-SBA-15 of which the org. template was removed by two-step calcination method had the max. sp. surface area (619 m2/g). In contrast, Ni/Al-SBA-15 of which the org. template was removed using solvent extn. approaches had the lowest sp. surface area (555 m2/g). The mesopore diam. of Ni/Al-SBA-15, using elec. heating digestion method to remove the template, was significantly increased and the wall thickness was significantly decreased to 11.62 nm in comparison with the other samples. The selectivity of products during the process of eugenol hydrodeoxygenation was investigated. High hydrocarbons were obtained during catalytic hydrodeoxygenation over Ni/Al-SBA-15 of which the org. template was removed by using solvent extn. approaches. Compared with direct calcination process, two-step calcination was more effective in removing template and the corresponding catalyst was much more suitable for the hydrodeoxygenation process.
- 52López-Pérez, L.; López-Martínez, M.-A.; Djanashvili, K.; Góra-Marek, K.; Tarach, K. A.; Borges, M. E.; Melián-Cabrera, I. Process Intensification of Mesoporous Material’s Synthesis by Microwave-Assisted Surfactant Removal. ACS Sustainable Chem. Eng. 2020, 8 (45), 16814– 16822, DOI: 10.1021/acssuschemeng.0c0543852Process intensification of mesoporous material's synthesis by microwave-assisted surfactant removalLopez-Perez, Lidia; Lopez-Martinez, Marco-Antonio; Djanashvili, Kristina; Gora-Marek, Kinga; Tarach, Karolina A.; Borges, Maria Emma; Melian-Cabrera, IgnacioACS Sustainable Chemistry & Engineering (2020), 8 (45), 16814-16822CODEN: ASCECG; ISSN:2168-0485. (American Chemical Society)Mesoporous materials are of vital importance for use in sepn., adsorption, and catalysis. The first step in their prepn. consists of synthesizing an org.-inorg. hybrid in which a structuring directing agent (SDA, normally a surfactant) is used to provide the desired porosity. The most common method to eliminate the SDA, and generate the porosity, is high-temp. calcination. Such a process is energy-intensive and slow. In this study, we investigated alternative nonthermal surfactant removal methods on a soft MCM-41 material, aiming at reducing the processing time and temp., while maximizing the material's properties. The choice of a soft MCM-41 is crit. since it is hydrothermally unstable, whereas the SDA removal is troublesome. Microwave processing yielded outstanding performance in terms of surfactant removal, structural preservation, and textural features; the surfactant was fully removed, the hexagonal structure was preserved, and the surface was highly rich in Si-OH groups. It is suggested that H2O2 is the dominant oxidant. In terms of the process features, the processing time is significantly reduced, 14 h (calcination) vs. 5 min (microwaves), and the applied temp. is much lower. The energy savings were estd. to be 72% lower as compared to calcination; therefore, this approach contributes to the process intensification of a very relevant material's prodn. Microwave processing of MCM-41 yielded outstanding performance in terms of surfactant removal, structural preservation, and textural characteristics, with improved processing features.
- 53Qiao, S. Z.; Liu, J.; Max Lu, G. Q. Chapter 21 - Synthetic Chemistry of Nanomaterials. In Modern Inorganic Synthetic Chemistry, Second ed.; Xu, R.; Xu, Y., Eds.; Elsevier: Amsterdam, 2017; pp 613– 640.There is no corresponding record for this reference.
- 54Perelshtein, I.; Perkas, N.; Gedanken, A. Chapter 3 - Making the Hospital a Safer Place by the Sonochemical Coating of Textiles by Antibacterial Nanoparticles. In Surface Chemistry of Nanobiomaterials; Grumezescu, A. M., Ed.; William Andrew Publishing, 2016; pp 71– 105.There is no corresponding record for this reference.
- 55Suslick, K. S.; Hammerton, D. A.; Cline, R. E. Sonochemical hot spot. J. Am. Chem. Soc. 1986, 108 (18), 5641– 5642, DOI: 10.1021/ja00278a05555Sonochemical hot spotSuslick, Kenneth S.; Hammerton, David A.; Cline, Raymond E., Jr.Journal of the American Chemical Society (1986), 108 (18), 5641-2CODEN: JACSAT; ISSN:0002-7863.The chem. effects of ultrasound result from acoustic cavitation: the creation, expansion, and implosive collapse of bubbles in ultrasonically irradiated liqs. We have used the sonochem. ligand substitution rates of volatile metal carbonyls to establish the site of sonochem. reactions and fluid that there are two regions of sonochem. reactivity: one corresponding to the gas phase within the collapsing cavity, and the second to a thin liq. layer immediately surrounding the collapsing cavity. Furthermore, we have detd. exptl. the effective temp. in each reaction zone, through the use of comparative rate thermometry. The gas and liq. phase reaction zones have effective temps. of 5200°K and 1900°K, resp. Using a simple thermal conduction model, the liq. reaction zone is estd. to be ≈200 nm thick and to have a lifetime of less than 2 μsec.
- 56Moradi, E.; Rahimi, R.; Safarifard, V. Sonochemically synthesized microporous metal–organic framework representing unique selectivity for detection of Fe3+ ions. Polyhedron 2019, 159, 251– 258, DOI: 10.1016/j.poly.2018.11.06256Sonochemically synthesized microporous metal-organic framework representing unique selectivity for detection of Fe3+ ionsMoradi, Ehsan; Rahimi, Rahmatollah; Safarifard, VahidPolyhedron (2019), 159 (), 251-258CODEN: PLYHDE; ISSN:0277-5387. (Elsevier Ltd.)Synthesis of metal-org. framework (MOF) materials via ultrasound (US) irradn. involves shorter reaction times and offers enhanced control of particle size and morphol. compared to conventional elec. heating. Here, we report the exploration of highly luminescent three-dimensional microporous metal-org. framework, [Zn2(oba)2(bpy)], (1; H2oba = 4,4'-oxybis(benzoic acid); bpy = 4,4'-bipyridine) synthesized by sonochem. for highly selective and sensitive detection of Fe3+ in MeOH soln. via a fluorescence quenching mechanism. Fluorescence titrn. expts. reveal that 1 is highly selective for Fe3+ ion with a response time of <2 min and the limit of detection (LOD) reaches a low level of 0.3μM (17 ppb). The luminescence is completely quenched in 100μM MeOH soln. of Fe3+. Furthermore, the static quenching const. is calcd. to be upper than 58 000 M-1 by the fluorescence titrn. expt. in low concn. of Fe3+. No interferences from 250μM As3+, Cd2+, Zn2+, Co2+, Ni2+, Cu2+, Pb2+, Mn2+ and Al3+ were found for the detection of Fe3+. Importantly, 1 can be cycled at least four times without loss of emission signals, which suggests that the functionalized 1 is a promising luminescent probe for selectively sensing of Fe3+ ions.
- 57Bang, J. H.; Suslick, K. S. Applications of Ultrasound to the Synthesis of Nanostructured Materials. Adv. Mater. 2010, 22 (10), 1039– 1059, DOI: 10.1002/adma.20090409357Applications of ultrasound to the synthesis of nanostructured materialsBang, Jin Ho; Suslick, Kenneth S.Advanced Materials (Weinheim, Germany) (2010), 22 (10), 1039-1059CODEN: ADVMEW; ISSN:0935-9648. (Wiley-VCH Verlag GmbH & Co. KGaA)A review. Recent advances in nanostructured materials have been led by the development of new synthetic methods that provide control over size, morphol., and nano/microstructure. The utilization of high intensity ultrasound offers a facile, versatile synthetic tool for nanostructured materials that are often unavailable by conventional methods. The primary phys. phenomena assocd. with ultrasound that are relevant to materials synthesis are cavitation and nebulization. Acoustic cavitation (the formation, growth, and implosive collapse of bubbles in a liq.) creates extreme conditions inside the collapsing bubble and serves as the origin of most sonochem. phenomena in liqs. or liq.-solid slurries. Nebulization (the creation of mist from ultrasound passing through a liq. and impinging on a liq.-gas interface) is the basis for ultrasonic spray pyrolysis (USP) with subsequent reactions occurring in the heated droplets of the mist. In both cases, there are examples of phase-sepd. attoliter microreactors: for sonochem., it is a hot gas inside bubbles isolated from one another in a liq., while for USP it is hot droplets isolated from one another in a gas. Cavitation-induced sonochem. provides a unique interaction between energy and matter, with hot spots inside the bubbles of ∼5000 K, pressures of ∼1000 bar, heating and cooling rates of > 1010 K s-1; these extraordinary conditions permit access to a range of chem. reaction space normally not accessible, which allows for the synthesis of a wide variety of unusual nanostructured materials. Complementary to cavitational chem., the microdroplet reactors created by USP facilitate the formation of a wide range of nanocomposites. In this review, the fundamental principles are summarized of both synthetic methods and recent development in the applications of ultrasound in nanostructured materials synthesis.
- 58Hinman, J. J.; Suslick, K. S., Nanostructured Materials Synthesis Using Ultrasound. In Sonochemistry: From Basic Principles to Innovative Applications; Colmenares, J. C., Chatel, G., Eds.; Springer International Publishing: Cham, 2017; pp 59– 94.There is no corresponding record for this reference.
- 59Xu, H.; Zeiger, B. W.; Suslick, K. S. Sonochemical synthesis of nanomaterials. Chem. Soc. Rev. 2013, 42 (7), 2555– 2567, DOI: 10.1039/C2CS35282F59Sonochemical synthesis of nanomaterialsXu, Hangxun; Zeiger, Brad W.; Suslick, Kenneth S.Chemical Society Reviews (2013), 42 (7), 2555-2567CODEN: CSRVBR; ISSN:0306-0012. (Royal Society of Chemistry)A review with 92 refs. on sonochem. synthesis of nanomaterials and sonochem. decompn. of volatile organometallic precursors in high-boiling solvents produces nanostructured materials in various forms with high catalytic activities. High intensity ultrasound can be used for the prodn. of novel materials and provides an unusual route to known materials without bulk high temps., high pressures, or long reaction times. Several phenomena are responsible for sonochem. and specifically the prodn. or modification of nanomaterials during ultrasonic irradn. The most notable effects are consequences of acoustic cavitation (the formation, growth, and implosive collapse of bubbles), and can be categorized as primary sonochem. (gas-phase chem. occurring inside collapsing bubbles), secondary sonochem. (soln.-phase chem. occurring outside the bubbles), and phys. modifications (caused by high-speed jets or shock waves derived from bubble collapse). This tutorial review provides examples of how the chem. and phys. effects of high intensity ultrasound can be exploited for the prepn. or modification of a wide range of nanostructured materials.
- 60Jabariyan, S.; Zanjanchi, M. A. A simple and fast sonication procedure to remove surfactant templates from mesoporous MCM-41. Ultrason. Sonochem. 2012, 19 (5), 1087– 1093, DOI: 10.1016/j.ultsonch.2012.01.01260A simple and fast sonication procedure to remove surfactant templates from mesoporous MCM-41Jabariyan, Shaghayegh; Zanjanchi, Mohammad A.Ultrasonics Sonochemistry (2012), 19 (5), 1087-1093CODEN: ULSOER; ISSN:1350-4177. (Elsevier B.V.)Demonstrated is a sonication procedure for the removal of structure-directing micellar templates from mesoporous MCM-41. The method uses a 28 KHz ultrasound in an alc. solvent for disrupting micellar aggregation of the surfactant mols., cetyltrimethylammonium bromide, which have filled the pores of the as-prepd. MCM-41. The majority (93%) of the surfactant mols. are removed out from the powder MCM-41 within a 15 min one-step sonication at a moderate temp. of 40°. The structural and textural characterization techniques reveal that the resulted surfactant-free MCM-41 exhibits higher features compared to that of those obtained using the conventional calcinations approaches. The surfactant mols. are released into alc. and can be recovered for reuse. This study provides an easy, cost-effective, mild, and useful method for template removal from mesoporous materials at conventional conditions.
- 61Zanjanchi, M. A.; Jabariyan, S. Application of ultrasound and methanol for rapid removal of surfactant from MCM-41. J. Serb. Chem. Soc. 2014, 79 (1), 25– 38, DOI: 10.2298/JSC130112056A61Application of ultrasound and methanol for the rapid removal of surfactant from MCM-41 molecular sieveZanjanchi, Mohammad A.; Jabariyan, ShaghayeghJournal of the Serbian Chemical Society (2014), 79 (1), 25-38CODEN: JSCSEN; ISSN:0352-5139. (Serbian Chemical Society)Ultrasound waves were successfully applied for the removal of the template from mesoporous MCM-41 mol. sieve. The method uses 28 KHz ultrasound irradn. in a methanol solvent for disrupting the micellar aggregation of the surfactant mols., cetyltrimethylammonium bromide, which fill the pores of as-synthesized MCM-41. After 15 min sonication at the moderate temp. of 40 °C, the majority of surfactant mols. had been removed from powder MCM-41. The template removal rate using ultrasound irradn. (15 min) is faster than the rate obtained via thermal calcination. In addn., a perfect hexagonal pore structure was obtained after template removal using ultrasound irradn., according to characterization using X-ray diffraction (XRD) and nitrogen adsorption analyses, while high temps. during calcination cause shrinkage that affected the surface properties of the materials. In the present procedure, the surfactant mols. are released into methanol and can be recovered for reuse. The effectiveness of the sonication-prepd. MCM-41 as an adsorbent was confirmed by the adsorption of methylene blue (MB).
- 62Pirez, C.; Wilson, K.; Lee, A. F. An energy-efficient route to the rapid synthesis of organically-modified SBA-15 via ultrasonic template removal. Green Chem. 2014, 16 (1), 197– 202, DOI: 10.1039/C3GC40474A62An energy-efficient route to the rapid synthesis of organically-modified SBA-15 via ultrasonic template removalPirez, Cyril; Wilson, Karen; Lee, Adam F.Green Chemistry (2014), 16 (1), 197-202CODEN: GRCHFJ; ISSN:1463-9262. (Royal Society of Chemistry)A low energy route for the removal of Pluronic P123 surfactant template during the synthesis of SBA-15 mesoporous silica is explored. The conventional reflux of the hybrid inorg.-org. intermediate formed during co-condensation routes to Pr-SO3H-SBA-15 is slow, utilizes large solvent vols., and requires 24 h to remove ∼90% of the org. template. In contrast, room temp. ultrasonication in a small methanol vol. achieves the same degree of template extn. in only 5 min, with a 99.9% energy saving and 90% solvent redn., without compromising the textural, acidic or catalytic properties of the resultant Pr-SO3H-SBA-15.
- 63Li, F.; Xie, C.; Cheng, Z.; Xia, H. Ultrasound responsive block copolymer micelle of poly(ethylene glycol)–poly(propylene glycol) obtained through click reaction. Ultrason. Sonochem. 2016, 30, 9– 17, DOI: 10.1016/j.ultsonch.2015.11.02363Ultrasound responsive block copolymer micelle of poly(ethylene glycol)-poly(propylene glycol) obtained through click reactionLi, Fayong; Xie, Chuan; Cheng, Zhengang; Xia, HeshengUltrasonics Sonochemistry (2016), 30 (), 9-17CODEN: ULSOER; ISSN:1350-4177. (Elsevier B.V.)The well-defined amphiphilic poly(ethylene glycol)-block-poly(propylene glycol) copolymer contg. 1, 2, 3-triazole moiety and multiple ester bonds (PEG-click-PPG) was prepd. by click reaction strategy. The PEG-click-PPG copolymer can self-assemble into spherical micelles in aq. soln. It is found that high intensity focused ultrasound (HIFU) can open the copolymer PEG-click-PPG micelles and trigger the release of the payload in the micelle. The multiple ester bonds introduced in the junction point of the copolymer chain through click reactions were cleaved under HIFU, and leads to the disruption of the copolymer micelle and fast release of loaded cargo. The click reaction provides a convenient way to construct ultrasound responsive copolymer micelles with weak bonds.
- 64Husseini, G. A.; Pitt, W. G. Micelles and nanoparticles for ultrasonic drug and gene delivery. Adv. Drug Delivery Rev. 2008, 60 (10), 1137– 1152, DOI: 10.1016/j.addr.2008.03.00864Micelles and nanoparticles for ultrasonic drug and gene deliveryHusseini, Ghaleb A.; Pitt, William G.Advanced Drug Delivery Reviews (2008), 60 (10), 1137-1152CODEN: ADDREP; ISSN:0169-409X. (Elsevier B.V.)A review. Drug delivery research employing micelles and nanoparticles has expanded in recent years. Of particular interest is the use of these nanovehicles that deliver high concns. of cytotoxic drugs to diseased tissues selectively, thus reducing the agent's side effects on the rest of the body. Ultrasound, traditionally used in diagnostic medicine, is finding a place in drug delivery in connection with these nanoparticles. In addn. to their noninvasive nature and the fact that they can be focused on targeted tissues, acoustic waves have been credited with releasing pharmacol. agents from nanocarriers, as well as rendering cell membranes more permeable. In this article, we summarize new technologies that combine the use of nanoparticles with acoustic power both in drug and gene delivery. Ultrasonic drug delivery from micelles usually employs polyether block copolymers and has been found effective in vivo for treating tumors. Ultrasound releases drug from micelles, most probably via shear stress and shock waves from the collapse of cavitation bubbles. Liq. emulsions and solid nanoparticles are used with ultrasound to deliver genes in vitro and in vivo. The small packaging allows nanoparticles to extravasate into tumor tissues. Ultrasonic drug and gene delivery from nanocarriers has tremendous potential because of the wide variety of drugs and genes that could be delivered to targeted tissues by fairly non-invasive means.
- 65Xuan, J.; Pelletier, M.; Xia, H.; Zhao, Y. Ultrasound-Induced Disruption of Amphiphilic Block Copolymer Micelles. Macromol. Chem. Phys. 2011, 212 (5), 498– 506, DOI: 10.1002/macp.20100062465Ultrasound-Induced Disruption of Amphiphilic Block Copolymer MicellesXuan, Juan; Pelletier, Maxime; Xia, Hesheng; Zhao, YueMacromolecular Chemistry and Physics (2011), 212 (5), 498-506CODEN: MCHPES; ISSN:1022-1352. (Wiley-VCH Verlag GmbH & Co. KGaA)Ultrasound-induced disruption of PEO-b-PTHPMA, PEO-b-PIBMA, PEO-b-PTHFEMA, and PEO-b-PMMA block copolymer micelles in aq. soln. was investigated. Fluorescence change of loaded NR, DLS, IR, AFM, and SEM show that those micelles could be disrupted differently by 1.1 MHz high-intensity focused ultrasound beams. The micelles of PEO-b-PIBMA and PEO-b-PTHPMA appear to be more sensitive to ultrasound irradn., resulting in a more severe micellar disruption, and IR spectra show evidence of ultrasound-induced chem. reactions, most likely hydrolysis. PEO-b-PMMA appear to resist HIFU irradn. better, and IR anal. found no evidence of chem. reactions. This study provides new evidence for the prospect of ultrasound-responsive BCP micelles for controlled delivery applications.
- 66Hozumi, A.; Yokogawa, Y.; Kameyama, T.; Hiraku, K.; Sugimura, H.; Takai, O.; Okido, M. Photocalcination of Mesoporous Silica Films Using Vacuum Ultraviolet Light. Adv. Mater. 2000, 12 (13), 985– 987, DOI: 10.1002/1521-4095(200006)12:13<985::AID-ADMA985>3.0.CO;2-#66Photocalcination of mesoporous silica films using vacuum ultraviolet lightHozumi, Atsushi; Yokogawa, Yoshiyuki; Kameyama, Tetsuya; Hiraku, Katsumasa; Sugimura, Hiroyuki; Takai, Osamu; Okido, MasazumiAdvanced Materials (Weinheim, Germany) (2000), 12 (13), 985-987CODEN: ADVMEW; ISSN:0935-9648. (Wiley-VCH Verlag GmbH)A method was developed for eliminating template surfactant mols. from mesoporous silica at room temp. The method is based on photochem. decompn. of org.mols. under irradn. with a vacuum-UV (172 nm) light. Thus, cetyltrimethylammonium chloride mols. were eliminated from mesoporous silica films on silicon substrates coated with n-octadecyltrimethoxysilane self-assembled monolayers. Photocalcination at room temp. for 3 h eliminated surfactant mols. as effectively as a std. 1 h calcination at 573 K, however, the latter method strongly reduced the no.of silanol groups on the film surface. X-ray diffractometry showed that photocalcination caused much less damage and distortion to the film than the thermal calcination process.
- 67Ha, C.-S.; Park, S. S. General Synthesis and Physico-chemical Properties of Mesoporous Materials. In Periodic Mesoporous Organosilicas: Preparation, Properties and Applications; Ha, C.-S.; Park, S. S., Eds.; Springer Singapore: Singapore, 2019; pp 15– 85.There is no corresponding record for this reference.
- 68Keene, M. T. J.; Denoyel, R.; Llewellyn, P. L. Ozone treatment for the removal of surfactant to form MCM-41 type materials. Chem. Commun. 1998, 20, 2203– 2204, DOI: 10.1039/a806118aThere is no corresponding record for this reference.
- 69Büchel, G.; Denoyel, R.; Llewellyn, P. L.; Rouquerol, J. In situ surfactant removal from MCM-type mesostructures by ozone treatment. J. Mater. Chem. 2001, 11 (2), 589– 593, DOI: 10.1039/b005297nThere is no corresponding record for this reference.
- 70Joshi, H.; Jalalpoor, D.; Ochoa-Hernández, C.; Schmidt, W.; Schüth, F. Ozone Treatment: A Versatile Tool for the Postsynthesis Modification of Porous Silica-Based Materials. Chem. Mater. 2018, 30 (24), 8905– 8914, DOI: 10.1021/acs.chemmater.8b0411370Ozone Treatment: A Versatile Tool for the Postsynthesis Modification of Porous Silica-Based MaterialsJoshi, Hrishikesh; Jalalpoor, Daniel; Ochoa-Hernandez, Cristina; Schmidt, Wolfgang; Schueth, FerdiChemistry of Materials (2018), 30 (24), 8905-8914CODEN: CMATEX; ISSN:0897-4756. (American Chemical Society)Facile synthesis of silica-based functional materials at low temps. has remained a challenge in materials science. To this end, we demonstrate the use of a gaseous ozone stream, generated via an elec. discharge method, as a versatile tool for the postsynthesis modification of silica-based functional nanomaterials. First, a parametric study is conducted with a mesoporous model material to obtain basic insights into the reaction of the orgs. with ozone. The study is then extended to a no. of distinct silica-based inorg. materials. The scope of ozone treatment can be broadly classified into three categories: (a) elimination of templates or structure directing agents (SDAs) from materials with pore sizes ranging from 0.5 to 10 nm, (b) selective transformation of org. groups functionalized on the mesoporous silica, and (c) simultaneous elimination of intermediate polymeric shells and template from the outer shells to obtain yolk-shell type materials. Each material studied here requires different parameters (temp., time, and concn. of ozone) depending on its phys. and chem. properties which have been carefully examd. Overall, the study demonstrates the potential of ozone treatment in tailoring functional materials at low temp. and provides vital insights into the reaction of ozone with silica-based materials. The study shows that gaseous ozone treatment is not limited to only one type of materials but can be applied to many systems, and we are convinced that the methodol. can be applied to a multitude of org.-inorg. systems way beyond the scope of materials presented here.
- 71Vogna, D.; Marotta, R.; Napolitano, A.; d’Ischia, M. Advanced Oxidation Chemistry of Paracetamol. UV/H2O2-Induced Hydroxylation/Degradation Pathways and 15N-Aided Inventory of Nitrogenous Breakdown Products. The. J. Org. Chem. 2002, 67 (17), 6143– 6151, DOI: 10.1021/jo025604v71Advanced Oxidation Chemistry of Paracetamol. UV/H2O2-Induced Hydroxylation/Degradation Pathways and 15N-Aided Inventory of Nitrogenous Breakdown Products.Vogna, Davide; Marotta, Raffaele; Napolitano, Alessandra; d'Ischia, MarcoJournal of Organic Chemistry (2002), 67 (17), 6143-6151CODEN: JOCEAH; ISSN:0022-3263. (American Chemical Society)The advanced oxidn. chem. of the antipyretic drug paracetamol (1) with the UV/H2O2 system was investigated by an integrated methodol. based on 15N-labeling and GC-MS, HPLC, and 2D 1H, 13C, and 15N NMR anal. Main degrdn. pathways derived from three hydroxylation steps, leading to 1,4-hydroquinone/1,4-benzoquinone, 4-acetylaminocatechol and, to a much lesser extent, 4-acetylaminoresorcine. Oxidn. of the primary arom. intermediates, viz. 4-acetylaminocatechol, 1,4-hydroquinone, 1,4-benzoquinone, and 1,2,4-benzenetriol, resulted in a series of nitrogenous and non-nitrogenous degrdn. products. The former included N-acetylglyoxylamide, acetylaminomalonic acid, acetylaminohydroxymalonic acid, acetylaminomaleic acid, diastereoisomeric 2-acetylamino-3-hydroxybutanedioic acids, 2-acetylaminobutenedioic acid, 3-acetylamino-4-hydroxy-2-pentenedioic acid, and 2,4-dihydroxy-3-acetylamino-2-pentenedioic acid, as well as two muconic and hydroxymuconic acid derivs. 15N NMR spectra revealed the accumulation since the early stages of substantial amts. of acetamide and oxalic acid monoamide. These results provide the first insight into the advanced oxidn. chem. of a 4-aminophenol deriv. by the UV/H2O2 system, and highlight the investigative potential of integrated GC-MS/NMR methodologies based on 15N-labeling to track degrdn. pathways of nitrogenous species.
- 72Cater, S. R.; Stefan, M. I.; Bolton, J. R.; Safarzadeh-Amiri, A. UV/H2O2 Treatment of Methyl tert-Butyl Ether in Contaminated Waters. Environ. Sci. Technol. 2000, 34 (4), 659– 662, DOI: 10.1021/es990575072UV/H2O2 Treatment of Methyl tert-Butyl Ether in Contaminated WatersCater, Stephen R.; Stefan, Mihaela I.; Bolton, James R.; Safarzadeh-Amiri, AliEnvironmental Science and Technology (2000), 34 (4), 659-662CODEN: ESTHAG; ISSN:0013-936X. (American Chemical Society)Me tert-Bu ether (MTBE) is a pollutant often found in groundwaters contaminated by gasoline spills or from leaking underground storage tanks. This study examines the UV/H2O2 advanced oxidn. technol. to det. its effectiveness in the treatment of MTBE. The degrdn. of MTBE followed pseudo-1st-order kinetics, and hence the figure-of-merit elec. energy per order (EEO) is appropriate for estg. the elec. energy efficiency. The EEO values depended on the concns. of MTBE, H2O2, and other components, such as benzene, toluene, and xylenes (BTX). This study shows that MTBE can be treated easily and effectively with the UV/H2O2 process with EEO 0.2-7.5 KWh/m3/order, depending on the initial concns. of MTBE and H2O2. The treatment efficiency of 10 mg/L MTBE is not adversely affected by the presence of low concns. of BTX (<2 mg/L); however, the degrdn. efficiency is significantly decreased at BTX >2 mg/L. A kinetic model, based on the initial rates of degrdn., provides good predictions of the EEO for a variety of conditions.
- 73Xiao, L.; Li, J.; Jin, H.; Xu, R. Removal of organic templates from mesoporous SBA-15 at room temperature using UV/dilute H2O2. Microporous Mesoporous Mater. 2006, 96 (1), 413– 418, DOI: 10.1016/j.micromeso.2006.07.01973Removal of organic templates from mesoporous SBA-15 at room temperature using UV/dilute H2O2Xiao, Liping; Li, Jiyang; Jin, Hongxiao; Xu, RurenMicroporous and Mesoporous Materials (2006), 96 (1-3), 413-418CODEN: MIMMFJ; ISSN:1387-1811. (Elsevier B.V.)A new UV/dil. H2O2 method was developed to remove org. templates from mesoporous silica SBA-15. This method combines UV irradn. and dil. H2O2 treatment, allowing complete removal of the org. templates in 3-4 h at room temp. Effects of two important factors, pH value and initial H2O2 concn., were investigated to search for the optimum condition of template removal. Detailed characterizations of the samples treated by UV/dil. H2O2 method in comparison with other methods are performed with the aid of powder x-ray diffraction (XRD), thermogravimetric anal. (TGA), FTIR, solid-state 29Si NMR spectra, and N2 adsorption. The final product resulted from UV/dil. H2O2 treatment has well-defined structure with perfect pore quality. This study provides an easy, cheap, mild and useful method for template removal from mesoporous materials at room temp.
- 74Aumond, T.; Pinard, L.; Batiot-Dupeyrat, C.; Sachse, A. Non-thermal plasma: A fast and efficient template removal approach allowing for new insights to the SBA-15 structure. Microporous Mesoporous Mater. 2020, 296, 110015, DOI: 10.1016/j.micromeso.2020.11001574Non-thermal plasma: A fast and efficient template removal approach allowing for new insights to the SBA-15 structureAumond, Thibaud; Pinard, Ludovic; Batiot-Dupeyrat, Catherine; Sachse, AlexanderMicroporous and Mesoporous Materials (2020), 296 (), 110015CODEN: MIMMFJ; ISSN:1387-1811. (Elsevier B.V.)Non-thermal plasma has revealed as fast and efficient strategy for the complete elimination of template mols. from SBA-15 materials. Through comparing the textural properties of a set of SBA-15 materials obtained by classical calcination and non-thermal plasma treatment new insights to the SBA-15 structure could be revealed. As such, a third type of microporosity could be disclosed by the use of non-thermal plasma for SBA-15 synthesized at 60°C. Addnl., starting from a synthesis temp. of 100°C, template elimination through non-thermal plasma allows for preserving native textural properties of as-synthesized SBA-15. The developed alternative treatment combines the advantages of improved textural properties and higher silanol d., hence making the strategy very promising for superior applications of SBA-15 materials.
- 75Liu, Y.; Wang, Z.; Liu, C.-j. Mechanism of template removal for the synthesis of molecular sieves using dielectric barrier discharge. Catal. Today 2015, 256, 137– 141, DOI: 10.1016/j.cattod.2015.03.00975Mechanism of template removal for the synthesis of molecular sieves using dielectric barrier dischargeLiu, Yuan; Wang, Zhao; Liu, Chang-junCatalysis Today (2015), 256 (Part_1), 137-141CODEN: CATTEA; ISSN:0920-5861. (Elsevier B.V.)The mechanism of dielec.-barrier discharge (DBD) plasma template removal is investigated. The study confirms that dissocn. of template mol. by active species (like electrons and excited oxygen species) and oxidn. of radicals (from the dissocn.) by active oxygen species (like ozone and excited oxygen species) are the mechanism of the DBD plasma enhanced template removal. The thermal image confirms that the DBD plasma template removal is conducted under temp. around 125°C. The thermal effect can be ignored. The present study is leading to a unique way for the syntheses of various micro- and meso-porous materials.
- 76Liu, Y.; Pan, Y.; Wang, Z.-J.; Kuai, P.; Liu, C.-J. Facile and fast template removal from mesoporous MCM-41 molecular sieve using dielectric-barrier discharge plasma. Catal. Commun. 2010, 11 (6), 551– 554, DOI: 10.1016/j.catcom.2009.12.01776Facile and fast template removal from mesoporous MCM-41 molecular sieve using dielectric-barrier discharge plasmaLiu, Yuan; Pan, Yunxiang; Wang, Zhou-Jun; Kuai, Pingyu; Liu, Chang-JunCatalysis Communications (2010), 11 (6), 551-554CODEN: CCAOAC; ISSN:1566-7367. (Elsevier B.V.)Dielec.-barrier discharge (DBD) plasma, initiated at ambient condition, was applied for removing template from the mesoporous MCM-41 mol. sieve. The template removal rate using DBD plasma is 8 times higher than the rate via thermal calcination. A perfect hexagonal pore structure was obtained after the template removal using the plasma, according to the characterization using the x-ray diffraction, TEM, and N2 adsorption analyses. The effectiveness of the plasma prepd. mesoporous MCM-41 mol. sieve as the catalyst support was confirmed using the Suzuki reaction with Pd as the active species.
- 77Liu, Y.; Pan, Y.-x.; Kuai, P.; Liu, C.-j. Template Removal from ZSM-5 Zeolite Using Dielectric-Barrier Discharge Plasma. Catal. Lett. 2010, 135 (3), 241– 245, DOI: 10.1007/s10562-010-0290-777Template Removal from ZSM-5 Zeolite using Dielectric-Barrier Discharge PlasmaLiu, Yuan; Pan, Yun-Xiang; Kuai, Ping-Yu; Liu, Chang-JunCatalysis Letters (2010), 135 (3-4), 241-245CODEN: CALEER; ISSN:1011-372X. (Springer)A dielec.-barrier discharge (DBD) plasma technique was successfully applied for template removal from ZSM-5 zeolite. The rate for template removal using DBD is about eight times higher than that using the conventional thermal calcination. During the template removal using DBD, the highest temp. of the sample is ∼125°. As such, the thermal effect on the sample during the DBD template removal is not significant. This made the structure changes of ZSM-5 zeolite during the template removal less dramatic than that using thermal calcination.
- 78Yuan, M.-H.; Wang, L.; Yang, R. T. Glow Discharge Plasma-Assisted Template Removal of SBA-15 at Ambient Temperature for High Surface Area, High Silanol Density, and Enhanced CO2 Adsorption Capacity. Langmuir 2014, 30 (27), 8124– 8130, DOI: 10.1021/la501794z78Glow Discharge Plasma-Assisted Template Removal of SBA-15 at Ambient Temperature for High Surface Area, High Silanol Density, and Enhanced CO2 Adsorption CapacityYuan, Min-Hao; Wang, Lifeng; Yang, Ralph T.Langmuir (2014), 30 (27), 8124-8130CODEN: LANGD5; ISSN:0743-7463. (American Chemical Society)Glow discharge plasma was successfully applied for effective removal of the org. template P-123 from SBA-15 ordered mesoporous SiO2 at near-room-temp. (<50°) and in a short operation time (2 h). The as-made SBA-15 treated with glow discharge exhibited a larger surface area of 1025 m2 g-1 with larger pores and microspore vol. as compared with that of conventional calcination (550° and 5 h, 827 m2 g-1). In addn. to less structural shrinkage, the plasma-prepd. SBA-15 showed significantly increased silanol d. from 5.4 to 6.6-7.6 mmol g-1, which led directly to higher amine loading from 1.8 to 3.0 mmol g-1. Consequently, the plasma-treated sample showed 77% more CO2 capacity and 60% higher CO2/N2 selectivity than the conventionally treated sample at 0.15 bar and 25°. The advantage of using glow discharge plasma for low-temp. template removal for achieving enhanced performance for CO2 adsorption is clearly demonstrated.
- 79Maesen, T. L. M.; Kouwenhoven, H. W.; van Bekkum, H.; Sulikowski, B.; Klinowski, J. Template removal from molecular sieves by low-temperature plasma calcination. J. Chem. Soc., Faraday Trans. 1990, 86 (23), 3967– 3970, DOI: 10.1039/ft990860396779Template removal from molecular sieves by low-temperature plasma calcinationMaesen, Theo L. M.; Kouwenhoven, Herman W.; Van Bekkum, Herman; Sulikowski, Bogdan; Klinowski, JacekJournal of the Chemical Society, Faraday Transactions (1990), 86 (23), 3967-70CODEN: JCFTEV; ISSN:0956-5000.The oxidative removal of templates from crystals of MFI- and TON-type zeolites using low-temp. O plasma at 370 K was investigated. This treatment removes Pr4N+ inside 5 μm lengths of channels in the completely siliceous MFI structure (silicalite), and Et2NH to a depth of ≤70 μm in the channels of the completely siliceous TON structure. Substitution of B, Al, or Fe into the framework of silicalite obstructs the removal of Pr4N+, but complete decompn. of the template can be accomplished in small samples of [Si,B]-MFI. A comparison of plasma calcination with thermal calcination in air indicates that the release of B into extra-framework positions upon either treatment is caused by the slow desorption of H2O at the calcination temp.
- 80Wang, L.; Yao, J.; Wang, Z.; Jiao, H.; Qi, J.; Yong, X.; Liu, D. Fast and low-temperature elimination of organic templates from SBA-15 using dielectric barrier discharge plasma. Plasma Science and Technology 2018, 20 (10), 101001, DOI: 10.1088/2058-6272/aad54780Fast and low-temperature elimination of organic templates from SBA-15 using dielectric barrier discharge plasmaWang, Lin; Yao, Junkang; Wang, Zheng; Jiao, Hongqiao; Qi, Jing; Yong, Xiaojing; Liu, DianhuaPlasma Science & Technology (Bristol, United Kingdom) (2018), 20 (10), 101001/1-101001/5CODEN: PSTHC3; ISSN:1009-0630. (IOP Publishing Ltd.)Org. templates P-123 of mesoporous SBA-15 can be effectively removed in a few minutes (4 min) by using the dielec.-barrier discharge plasma technique at ambient pressure and low gas temp. (around 130°C). The mesoporous SBA-15 was characterized by FT-IR, 29Si solid sate NMR, TEM, XRD, TGA and N2 adsorption / desorption isotherms. The as-made SBA-15 treated with DBD plasma exhibited a larger surface area of 790 m2 · g-1 with larger pores and microspore vol. than samples prepd. by using the conventional thermal calcination method (550°C and 5 h, 660 m2 · g-1). In addn. to less shrinkage of the silica framework, the DBD-prepd. SBA-15 showed significantly increased wt. loss of 8.3% about 200°C as compared with that of conventional calcination (5.5%), which is attributed mainly to the dehydroxylation by condensation of silanol groups.
- 81Khataee, A.; Sajjadi, S.; Hasanzadeh, A.; Vahid, B.; Joo, S. W. One-step preparation of nanostructured martite catalyst and graphite electrode by glow discharge plasma for heterogeneous electro-Fenton like process. Journal of Environmental Management 2017, 199, 31– 45, DOI: 10.1016/j.jenvman.2017.04.09581One-step preparation of nanostructured martite catalyst and graphite electrode by glow discharge plasma for heterogeneous electro-Fenton like processKhataee, Alireza; Sajjadi, Saeed; Hasanzadeh, Aliyeh; Vahid, Behrouz; Joo, Sang WooJournal of Environmental Management (2017), 199 (), 31-45CODEN: JEVMAW; ISSN:0301-4797. (Elsevier Ltd.)Natural Martite ore particles and graphite were modified by a.c. (AC) glow discharge plasma to form nanostructured catalyst and cathode electrode for using in the heterogeneous-electro Fenton-like (Het-EF-like) process. The performance of the plasma-treated martite (PTM) and graphite electrode (PTGE) was studied for the treatment of paraquat herbicide in a batch system. 85.78% Degrdn. efficiency for 20 mg L-1 paraquat was achieved in the modified process under desired operational conditions (i.e. current intensity of 300 mA, catalyst amt. of 1 g L-1, pH = 6, and background electrolyte (Na2SO4) concn. of 0.05 mol L-1) which was higher than the 41.03% for the unmodified one after 150 min of treatment. The ecofriendly modification of the martite particles and the graphite electrode, no chem. needed, low leached iron and milder operational pH were the main privileges of plasma utilization. Moreover, the degrdn. efficiency through the process was not declined after five repeated cycles at the optimized conditions, which proved the stability of the nanostructured PTM and PTGE in the long-term usage. The archived results exhibit this method is the first example of high efficient, cost-effective, and environment-friendly method for generation of nanostructured samples.
- 82Bazaka, K.; Baranov, O.; Cvelbar, U.; Podgornik, B.; Wang, Y.; Huang, S.; Xu, L.; Lim, J. W. M.; Levchenko, I.; Xu, S. Oxygen plasmas: a sharp chisel and handy trowel for nanofabrication. Nanoscale 2018, 10 (37), 17494– 17511, DOI: 10.1039/C8NR06502K82Oxygen plasmas: a sharp chisel and handy trowel for nanofabricationBazaka, K.; Baranov, O.; Cvelbar, U.; Podgornik, B.; Wang, Y.; Huang, S.; Xu, L.; Lim, J. W. M.; Levchenko, I.; Xu, S.Nanoscale (2018), 10 (37), 17494-17511CODEN: NANOHL; ISSN:2040-3372. (Royal Society of Chemistry)Although extremely chem. reactive, oxygen plasmas feature certain properties that make them attractive not only for material removal via etching and sputtering, but also for driving and sustaining nucleation and growth of various nanostructures in plasma bulk and on plasma-exposed surfaces. In this minireview, a no. of representative examples is used to demonstrate key mechanisms and unique capabilities of oxygen plasmas and how these can be used in present-day nano-fabrication. In addn. to modification and functionalisation processes typical for oxygen plasmas, their ability to catalyze the growth of complex nanoarchitectures is emphasized. Two types of technologies based on oxygen plasmas, namely surface treatment without a change in the size and shape of surface features, as well as direct growth of oxide structures, are used to better illustrate the capabilities of oxygen plasmas as a powerful process environment. Future applications and possible challenges for the use of oxygen plasmas in nanofabrication are discussed.
- 83Wang, Z.-j.; Xie, Y.; Liu, C.-j. Synthesis and Characterization of Noble Metal (Pd, Pt, Au, Ag) Nanostructured Materials Confined in the Channels of Mesoporous SBA-15. J. Phys. Chem. C 2008, 112 (50), 19818– 19824, DOI: 10.1021/jp805538j83Synthesis and Characterization of Noble Metal (Pd, Pt, Au, Ag) Nanostructured Materials Confined in the Channels of Mesoporous SBA-15Wang, Zhou-jun; Xie, Yongbing; Liu, Chang-junJournal of Physical Chemistry C (2008), 112 (50), 19818-19824CODEN: JPCCCK; ISSN:1932-7447. (American Chemical Society)Highly dispersed metal (Pd, Pt) nanoparticles and uniformly distributed metal (Au, Ag) nanowires were synthesized in ordered mesoporous silica SBA-15 via conventional incipient wetness impregnation followed by novel glow discharge plasma redn. N2 adsorption-desorption isotherms and the low-angle XRD patterns indicate that the parent ordered mesoporous structure was well-maintained during the synthesis process. The wide-angle XRD patterns and transmission electron microscope images demonstrate that spherical Pd and Pt nanoparticles as well as rodlike Au and Ag nanowires were fabricated within the channels of SBA-15. The diams. of the metal nanoparticles and the metal nanowires were effectively controlled by the mesopores of the SBA-15 host. The population of the metal nanoparticles and the length of the metal nanowires can be tuned by the metal loading amt. In particular, the novel plasma redn. at ambient temp. is green, economical, and nontime-consuming, showing great advantages over the traditional hydrogen redn. at elevated temp. This very simple synthesis method using plasma redn. will be very promising as a general technique for the prepn. of metal nanostructured materials confined in the host architectures.
- 84Mamdouh, W.; Li, Y.; Shawky, S. M.; Azzazy, H. M. E.; Liu, C.-J. Influence of “Glow Discharge Plasma” as an External Stimulus on the Self-Assembly, Morphology and Binding Affinity of Gold Nanoparticle-Streptavidin Conjugates. International Journal of Molecular Sciences 2012, 13 (6), 6534, DOI: 10.3390/ijms1306653484Influence of "glow discharge plasma" as an external stimulus on the self-assembly, morphology and binding affinity of gold nanoparticle-streptavidin conjugatesMamdouh, Wael; Li, Yingzhi; Shawky, Sherif M.; Azzazy, Hassan M. E.; Liu, Chang-JunInternational Journal of Molecular Sciences (2012), 13 (), 6534-6547CODEN: IJMCFK; ISSN:1422-0067. (MDPI AG)In this study, we investigate the influence of glow discharge plasma (GDP) on the self-assembly, morphol. and binding affinity of streptavidin coated gold nanoparticles (Au-NP-SV) and biotinylated antibody (bAb) adsorbed on a highly oriented pyrolytic graphite (HOPG) substrate. Atomic force microscope (AFM) was used to image the pre- and post-GDP treated samples. The anal. of the AFM images showed a considerable change in the aggregation and morphol. of Au-NP-conjugates after treatment with GDP. To our knowledge, this is the first report on using GDP to enhance and speed-up the aggregation (sintering) of adsorbed NP biomol. conjugates. These results show a promising route that could be generalized for other NPs and their conjugates. It can also be considered as an alternative and cheap aggregation method for controlling the binding affinity of biomol. species on different surfaces with interesting applications.
- 85Guo, Q.; With, P.; Liu, Y.; Gläser, R.; Liu, C.-j. Carbon template removal by dielectric-barrier discharge plasma for the preparation of zirconia. Catal. Today 2013, 211, 156– 161, DOI: 10.1016/j.cattod.2013.02.03285Carbon template removal by dielectric-barrier discharge plasma for the preparation of zirconiaGuo, Qiuting; With, Patrick; Liu, Yuan; Glaser, Roger; Liu, Chang-junCatalysis Today (2013), 211 (), 156-161CODEN: CATTEA; ISSN:0920-5861. (Elsevier B.V.)A novel 'micro-combustion', initiated by active oxygen species within dielec. barrier discharge (DBD), has been developed and employed for the removal of a carbon exotemplate for the fabrication of zirconia (ZrO2). The micro-combustion is operated at atm. pressure and relatively low gas temp. (less than 150 °C) with a high template removal rate. The material characterization shows that mesoporous ZrO2 with a broad pore size distribution between 3 and 40 nm has been produced. The obtained ZrO2 exhibits a monoclinic lattice structure, normally generated at temps. over 1000 °C. The DBD-made ZrO2 has been applied as the support for the prepn. of Pd/ZrO2 catalyst, which shows a high activity for selective oxidn. of benzyl alc.
- 86Wang, B.; Chen, B.; Sun, Y.; Xiao, H.; Xu, X.; Fu, M.; Wu, J.; Chen, L.; Ye, D. Effects of dielectric barrier discharge plasma on the catalytic activity of Pt/CeO2 catalysts. Applied Catalysis B: Environmental 2018, 238, 328– 338, DOI: 10.1016/j.apcatb.2018.07.04486Effects of dielectric barrier discharge plasma on the catalytic activity of Pt/CeO2 catalystsWang, Bangfen; Chen, Bingxu; Sun, Yuhai; Xiao, Hailin; Xu, Xiaoxin; Fu, Mingli; Wu, Junliang; Chen, Limin; Ye, DaiqiApplied Catalysis, B: Environmental (2018), 238 (), 328-338CODEN: ACBEE3; ISSN:0926-3373. (Elsevier B.V.)CeO2 nanorod was synthesized by a hydrothermal method and impregnated with Pt to synthesize Pt/CeO2 catalysts, which were modified by dielec. barrier discharge plasma. The modified CeO2 and Pt/CeO2 were characterized by XRD, STEM, N2 adsorption/desorption, CO pulse chemisorption, XPS, H2-TPR, O2-TPD and UV-Raman spectroscopy techniques. After the plasma treatment, the T90 value of (Pt/CeO2)-P catalyst decreased from 287 °C to 208 °C for toluene oxidn. This significantly changed activity of catalyst indicated that plasma has greatly impacted its performance. More and larger notches on surface and broken fragments were found from STEM anal. In addn., smaller Pt particle size and higher dispersion of nanoparticles was found on (Pt/CeO2)-P, which was characterized by CO pulse chemisorption and TEM anal. In addn., Pt/(CeO2-P) and (Pt/CeO2)-P possessed higher concn. of oxygen vacancies and Ce3+, which was obsd. by UV-Raman spectroscopy and XPS. Moreover, according to TPR results, the interaction between Pt and CeO2 was obviously strengthened, which led to a lower redn. temp. after plasma treatment. After plasma treatment, the (Pt/CeO2)-P presented the highest activity due to it possessing the highest TOFPt and TOFov values of 9.88 × 10-4 s-1 and 9.49 × 10-5 s-1, resp., and lower activation energies of 63.8 kJ mol-1. Furthermore, the toluene conversion of (Pt/CeO2)-P without significantly decreasing for working at least 50 h and under 9.6 vol% water vapor.
- 87Li, Y.; Wang, W.; Wang, F.; Di, L.; Yang, S.; Zhu, S.; Yao, Y.; Ma, C.; Dai, B.; Yu, F. Enhanced Photocatalytic Degradation of Organic Dyes via Defect-Rich TiO2 Prepared by Dielectric Barrier Discharge Plasma. Nanomaterials 2019, 9 (5), 720, DOI: 10.3390/nano905072087Enhanced photocatalytic degradation of organic dyes via defect-rich TiO2 prepared by dielectric barrier discharge plasmaLi, Yanqin; Wang, Wei; Wang, Fu; Di, Lanbo; Yang, Shengchao; Zhu, Shengjie; Yao, Yongbin; Ma, Cunhua; Dai, Bin; Yu, FengNanomaterials (2019), 9 (5), 720CODEN: NANOKO; ISSN:2079-4991. (MDPI AG)The dye wastewater produced in the printing and dyeing industry causes serious harm to the natural environment. TiO2 usually shows photocatalytic degrdn. of dye under the irradn. ultravilet light rather than visible light. In this work, a large no. of oxygen vacancies and Ti3+ defects were generated on the surface of the TiO2 nanoparticles via Ar plasma. Compared with pristine TiO2 nanoparticles, the as-obtained Ar plasma-treated TiO2 (Ar-TiO2) nanoparticles make the energy band gap reduce from 3.21 eV to 3.17 eV and exhibit enhanced photocatalytic degrdn. of org. dyes. The Ar-TiO2 obtained exhibited excellent degrdn. properties of methyl orange (MO); the degrdn. rate under sunlight irradn. was 99.6% in 30 min, and the photocatalytic performance was about twice that of the original TiO2 nanoparticles (49%). The degrdn. rate under visible light (λ > 400 nm) irradn. was 89% in 150 min, and the photocatalytic performance of the Ar-TiO2 was approaching ∼4 times higher than that of the original TiO2 nanoparticles (23%). Ar-TiO2 also showed good degrdn. performance in degrading rhodamine B (Rho B) and methylene blue (MB). We believe that this plasma strategy provides a new method for improving the photocatalytic activity of other metal oxides.
- 88Das, P.; Ojah, N.; Kandimalla, R.; Mohan, K.; Gogoi, D.; Dolui, S. K.; Choudhury, A. J. Surface modification of electrospun PVA/chitosan nanofibers by dielectric barrier discharge plasma at atmospheric pressure and studies of their mechanical properties and biocompatibility. Int. J. Biol. Macromol. 2018, 114, 1026– 1032, DOI: 10.1016/j.ijbiomac.2018.03.11588Surface modification of electrospun PVA/chitosan nanofibers by dielectric barrier discharge plasma at atmospheric pressure and studies of their mechanical properties and biocompatibilityDas, Punamshree; Ojah, Namita; Kandimalla, Raghuram; Mohan, Kiranjyoti; Gogoi, Dolly; Dolui, Swapan Kumar; Choudhury, Arup JyotiInternational Journal of Biological Macromolecules (2018), 114 (), 1026-1032CODEN: IJBMDR; ISSN:0141-8130. (Elsevier B.V.)In this paper, surface of electrospun PVA/Cs nanofibers is modified using dielec. barrier discharge (DBD) plasma and the relationship between the obsd. mech. properties and biocompatibility of the nanofibers and plasma-induced surface properties is discussed. Plasma treatment of electrospun PVA/Cs nanofibers is carried out with both inert (argon, Ar) and reactive (oxygen, O2) gases at atm. pressure. Incorporation of oxygen-contg. polar functional groups on the surface of Ar-plasma treated (PVA/Cs/Ar) and O2-plasma treated (PVA/Cs/O2) nanofibers and increase in surface roughness contribute to the improvement of surface wettability and the decrease of contact angle with water of the nanofibers. Both PVA/Cs/Ar and PVA/Cs/O2 nanofibers show high tensile strength (11.6-15.6%) and Young's modulus (33.8-37.3%) as compared to the untreated one. Exptl. results show that in terms of haemolytic activity the PVA/Cs/Ar and PVA/Cs/O2 nanofibers do not cause structural changes of blood cells and meet the biocompatibility requirements for blood-contacting polymeric materials. MTT cell viability results further reveals improvement in biocompatibility of PVA/Cs nanofibers after Ar and O2 plasma treatment. The results suggest that DBD plasma treated electrospun PVA/Cs nanofibers have the potential to be used as wound dressing and scaffolds for tissue engineering.
- 89Xu, X. Dielectric barrier discharge ─ properties and applications. Thin Solid Films 2001, 390 (1), 237– 242, DOI: 10.1016/S0040-6090(01)00956-789Dielectric barrier discharge - properties and applicationsXu, X.Thin Solid Films (2001), 390 (1,2), 237-242CODEN: THSFAP; ISSN:0040-6090. (Elsevier Science S.A.)A review with 14 refs. Dielec. barrier discharge (DBD) is a typical non-equil. high-pressure ac gas discharge. Recently, two types of DBD arrangements are developed; vol. discharge (VD) and surface discharge (SD). Such devices are beneficial for industrial acceptance, since vacuum can be got rid of and devices operated in atm. pressure region. DBD is an excellent source of ideal energetic electrons with 1-10 eV and high d. Its unique advantage is to generate low excited at. and mol. species, free radicals and excimers with several eV energy. In this paper, the properties of microdischarge in DBD are discussed with their simulation. Due to its attractive characteristics, DBD is recently widely studied for potential industrial applications. Ozone generators, excimer radiation sources, free radical generation and their applications in pollution control and monitor are also discussed.
- 90Hashim, S. A.; Samsudin, F. N. D. b.; Wong, C. S.; Abu Bakar, K.; Yap, S. L.; Mohd. Zin, M. F. Non-thermal plasma for air and water remediation. Arch. Biochem. Biophys. 2016, 605, 34– 40, DOI: 10.1016/j.abb.2016.03.03290Non-thermal plasma for air and water remediationHashim, Siti Aiasah; Samsudin, Farah Nadia Dayana binti; Wong, Chiow San; Abu Bakar, Khomsaton; Yap, Seong Ling; Mohd. Zin, Mohd. FaizArchives of Biochemistry and Biophysics (2016), 605 (), 34-40CODEN: ABBIA4; ISSN:0003-9861. (Elsevier B.V.)A modular typed dielec. barrier discharge (DBD) device is designed and tested for air and water remediation. The module is made of a no. of DBD tubes that can be arranged in series or parallel. Each of the DBD tubes comprises inner electrode enclosed with dielec. barrier and arranged as such to provide a gap for the passage of gases. Non-thermal plasma generated in the gap effectively creates gaseous chem. reactions. Its efficacy in the remediation of gas stream contg. high NOx, similar to diesel emission and wastewater contg. latex, are presented. A six tubes DBD module has successfully removed more than 80% of nitric oxide from the gas stream. In another arrangement, oxygen was fed into a two tubes DBD to generate ozone for treatment of wastewater. Samples of wastewater were collected from a treatment pond of a rubber vulcanization pilot plant. The water pollution load was evaluated by the COD and biol. oxygen demand (BOD5) values. Preliminary results showed some improvement (about 13%) on the COD after treatment and at the same time had increased the BOD5 by 42%. This results in higher BOD5/COD ratio after ozonation which indicate better biodegradability of the wastewater.
- 91Zhang, C.; Sun, Y.; Yu, Z.; Zhang, G.; Feng, J. Simultaneous removal of Cr(VI) and acid orange 7 from water solution by dielectric barrier discharge plasma. Chemosphere 2018, 191, 527– 536, DOI: 10.1016/j.chemosphere.2017.10.08791Simultaneous removal of Cr(VI) and acid orange 7 from water solution by dielectric barrier discharge plasmaZhang, Chunxiao; Sun, Yabing; Yu, Zhongqing; Zhang, Guyu; Feng, JingweiChemosphere (2018), 191 (), 527-536CODEN: CMSHAF; ISSN:0045-6535. (Elsevier Ltd.)A feasibility study was conducted for simultaneous removal of hexavalent chromium (Cr(VI)) and azo dye acid orange 7 (AO7) by the dielec. barrier discharge (DBD) plasma. The results showed that there was a synergistic effect between Cr(VI) redn. and AO7 degrdn. The presence of Cr(VI) enhanced the degrdn. efficiency of AO7. Meanwhile, the removal efficiency of Cr(VI) also increased in the presence of AO7. Under acidic conditions (pH = 3.0), the redn. efficiency of Cr(VI) was higher (approx. 94%). However, the presence of Cr(VI) diminished the effect of pH on the AO7 degrdn. efficiency. By increasing the input voltage from 80 to 120 V, the removal efficiencies of Cr(VI) and AO7 were observably increased from 54% to 88% and 62% to 89%, resp. Adding org. matters inhibited the degrdn. of AO7 and promoted the redn. of Cr(VI). The addn. of Cu(II), Co(II), Ni(II), Mn(II) and Fe(III) could inhibit the Cr(VI) redn., but not significantly affect the degrdn. of AO7. The degrdn. intermediates of AO7 were identified by LC-MS/MS system and a possible degrdn. pathway was proposed. This study showed that the DBD plasma can simultaneously remove Cr(VI) and AO7, which provided a new idea for the actual wastewater treatment.
- 92Sang, W.; Cui, J.; Feng, Y.; Mei, L.; Zhang, Q.; Li, D.; Zhang, W. Degradation of aniline in aqueous solution by dielectric barrier discharge plasma: Mechanism and degradation pathways. Chemosphere 2019, 223, 416– 424, DOI: 10.1016/j.chemosphere.2019.02.02992Degradation of aniline in aqueous solution by dielectric barrier discharge plasma: Mechanism and degradation pathwaysSang, Wenjiao; Cui, Jiaqi; Feng, Yijie; Mei, Longjie; Zhang, Qian; Li, Dong; Zhang, WanjunChemosphere (2019), 223 (), 416-424CODEN: CMSHAF; ISSN:0045-6535. (Elsevier Ltd.)The degrdn. of aniline soln. using the dielec. barrier discharge (DBD) plasma was studied in this paper. The results indicated that the initial concn. of aniline, applied voltage and initial pH value affected the removal efficiency of aniline significantly. After 12 min with DBD plasma treatment, 90.2% removal efficiency was achieved at aniline concn. of 100 mg L-1 with an applied voltage of 3.0 kV and pH 8.43. The removal efficiency decreased with the presence of radical scavengers, indicating that hydroxyl radical plays a key role in the degrdn. process. The removal efficiency increased obviously when Fe2+ was added. Addnl., the intermediate products generated in the degrdn. process of aniline were analyzed by some anal. techniques, including total org. carbon anal., UV-visible spectroscopy, Fourier Transform IR spectroscopy, Gas Chromatog.-Mass Spectrometer, etc. The results showed that the degrdn. of aniline was mainly due to the strong oxidizing capacity of hydroxyl radical produced by the DBD plasma system. Based on the intermediate products identified in the study, the possible degrdn. mechanism and pathways were proposed.
- 93Iervolino, G.; Vaiano, V.; Palma, V. Enhanced removal of water pollutants by dielectric barrier discharge non-thermal plasma reactor. Sep. Purif. Technol. 2019, 215, 155– 162, DOI: 10.1016/j.seppur.2019.01.00793Enhanced removal of water pollutants by dielectric barrier discharge non-thermal plasma reactorIervolino, Giuseppina; Vaiano, Vincenzo; Palma, VincenzoSeparation and Purification Technology (2019), 215 (), 155-162CODEN: SPUTFP; ISSN:1383-5866. (Elsevier B.V.)In this work it was studied the removal efficiency of several water pollutants (methylene blue, phenol, paracetamol, caffeine and ceftriaxone) by dielec. barrier discharge (DBD) non-thermal plasma (NTP) reactor. The results evidenced that using oxygen as process gas in the DBD reactor and 20 kV of applied voltage, the complete degrdn. and mineralization of methylene blue and ceftriaxone was achieved after only 5 min of treatment time, while 15 min were required for the complete degrdn. and mineralization, of phenol and paracetamol, and 25 min for the caffeine. In addn., kinetic evaluations evidenced that, for each pollutant, the degrdn. and mineralization occurred at the same rates, underling that the pollutants are selectively converted to carbon dioxide. For this reason, the results obtained in the present work were significantly better than those reported in the current literature about the use of non-thermal technol. in the removal of org. pollutants from aq. solns.
- 94Yuan, D.; Wang, Z.; He, Y.; Xie, S.; Lin, F.; Zhu, Y.; Cen, K. Ozone Production with Dielectric Barrier Discharge from Air: The Influence of Pulse Polarity. Ozone: Science & Engineering 2018, 40 (6), 494– 502, DOI: 10.1080/01919512.2018.147612794Ozone Production with Dielectric Barrier Discharge from Air: The Influence of Pulse PolarityYuan, Dingkun; Wang, Zhihua; He, Yong; Xie, Songru; Lin, Fawei; Zhu, Yanqun; Cen, KefaOzone: Science & Engineering (2018), 40 (6), 494-502CODEN: OZSEDS; ISSN:0191-9512. (Taylor & Francis, Inc.)This research aims to study the effects of different pulse modes of the power supply on ozone prodn. from air. Single pos., neg. as well as the bipolar voltage pulses (pos.-neg. and neg.-pos.) with a repetition rate of 300 Hz have been applied to coaxial dielec. barrier discharge arrangement. Results reveal that at fixed specific input energy (SIE), which is defined as the ratio of power to gas flow rate, the ozone generation efficiencies for different pulse modes are in the sequence of pos. > pos.-neg. > neg.-pos. >neg., and the difference between pos. and pos.-neg. pulse becomes considerable with SIE higher than 500 J/L. Results also reveal that the max. NO2 concn. is obtained at 400 J/L. Moreover, utilizing bipolar pulse can reduce N2O prodn. with SIEs higher than 250 J/L and hinder NO2 prodn. with SIEs higher than 350 J/L.
- 95Zylka, P. Evaluation of Ozone Generation in Volume Spiral-Tubular Dielectric Barrier Discharge Source. Energies 2020, 13 (5), 1199, DOI: 10.3390/en1305119995Evaluation of ozone generation in volume spiral-tubular dielectric barrier discharge sourceZylka, PawelEnergies (Basel, Switzerland) (2020), 13 (5), 1199CODEN: ENERGA; ISSN:1996-1073. (MDPI AG)Ozone, due to its high reactivity cannot be stockpiled, and thus requires to be generated on-demand. The paper reports on lab. studies of O3 generation in a vol. dielec. barrier discharge (DBD) tubular flow-through system with a coaxial-spiral electrode arrangement. Its performance is exptl. verified and compared to a com. surface DBD O3 source fitted with a three-electrode floating supply arrangement. The presented vol. DBD design is capable of steadily producing up to 4180 ppmv O3 at 1 Nl/min unprocessed atm. air intake and 10 kV 1.6 kHz sinusoidal high voltage supply corresponding to 67 g/kWh O3 prodn. yield increasing to 93 g/kWh at 100 Nl/min air intake. The effects of high voltage supply tuning are also investigated and discussed together with finite element method simulation results.
- 96Zeng, Y. X.; Wang, L.; Wu, C. F.; Wang, J. Q.; Shen, B. X.; Tu, X. Low temperature reforming of biogas over K-, Mg- and Ce-promoted Ni/Al2O3 catalysts for the production of hydrogen rich syngas: Understanding the plasma-catalytic synergy. Applied Catalysis B: Environmental 2018, 224, 469– 478, DOI: 10.1016/j.apcatb.2017.10.01796Low temperature reforming of biogas over K-, Mg- and Ce-promoted Ni/Al2O3 catalysts for the production of hydrogen rich syngas: Understanding the plasma-catalytic synergyZeng, Y. X.; Wang, L.; Wu, C. F.; Wang, J. Q.; Shen, B. X.; Tu, X.Applied Catalysis, B: Environmental (2018), 224 (), 469-478CODEN: ACBEE3; ISSN:0926-3373. (Elsevier B.V.)Plasma-catalytic biogas reforming over Ni-X/Al2O3 catalyst (X = K, Mg and Ce) has been carried out in a coaxial dielec. barrier discharge (DBD) plasma reactor. Three different process modes plasma-alone, catalysis-alone and plasma-catalysis were investigated to get new insights into the synergistic effect resulted from the interaction of the plasma with the promoted Ni catalysts. Compared to the biogas reforming using either plasma-alone or catalysis-alone mode at the same temp. (160°), the combination of the plasma with the Ni-based catalysts exhibited a low temp. synergistic effect, as evidenced from the much higher reforming performance of the plasma-catalytic process compared to that of the sum of the individual processes (plasma-alone and catalysis-alone). The addn. of promoters (K, Mg, and Ce) into the Ni/Al2O3 catalyst enhanced the conversion of CH4, the yield of H2 and the energy efficiency of the plasma process. In this study, the behavior of K, Mg and Ce promoters in the low temp. plasma-catalytic biogas reforming was clearly different from that in high temp. thermal catalytic process in terms of the conversion of CH4 and carbon deposition, which could be ascribed to the temp.-dependent character of the promoters. In the plasma-catalytic biogas reforming, the Ni-K/Al2O3 catalyst showed the best performance, enhancing the conversion of both CO2 and CH4, the yield of H2, CO and C2-C4 alkanes and the energy efficiency of the plasma process. The highest conversion of CO2 (22.8%) and CH4 (31.6%) was achieved by placing the K-promoted catalyst in the plasma reforming process. The Mg-promoted catalyst remarkably increased the H2/CO molar ratio in the gas products (up to 2.2) due to the decreased CO2 conversion. In addn., compared to the un-promoted Ni/Al2O3 catalyst, although the use of the promoted catalysts increased the carbon deposition on the surface of the spent catalysts by 22-26%, the total amt. of deposited carbon was still less than that reported in high temp. catalytic dry reforming processes. More than 80% of the increased carbonaceous species was in the form of reactive carbon species, which can be easily oxidized by CO2 and O atoms and maintain the stability of the catalysts during the reforming reaction.
- 97Wang, Y.; Yu, F.; Zhu, M.; Ma, C.; Zhao, D.; Wang, C.; Zhou, A.; Dai, B.; Ji, J.; Guo, X. N-Doping of plasma exfoliated graphene oxide via dielectric barrier discharge plasma treatment for the oxygen reduction reaction. Journal of Materials Chemistry A 2018, 6 (5), 2011– 2017, DOI: 10.1039/C7TA08607E97N-Doping of plasma exfoliated graphene oxide via dielectric barrier discharge plasma treatment for the oxygen reduction reactionWang, Yiqing; Yu, Feng; Zhu, Mingyuan; Ma, Cunhua; Zhao, Dan; Wang, Chao; Zhou, Amin; Dai, Bin; Ji, Junyi; Guo, XuhongJournal of Materials Chemistry A: Materials for Energy and Sustainability (2018), 6 (5), 2011-2017CODEN: JMCAET; ISSN:2050-7496. (Royal Society of Chemistry)Nitrogen doped plasma exfoliated graphene oxide (N-PEGO) was obtained by fast and effective dielec. barrier discharge (DBD) plasma technol. The plasma treatment could provide a burst open and high-energy electron/ion collision mechanism for doping and exfoliation. Ammonium carbonate was previously inserted into the interlayer of GO powder, and the rapid release of the NH3 and CO2 gases during DBD plasma treatment could exfoliate the GO powder into few-layer PEGO (<4 layers). Moreover, the plasma treatment also introduced the nitrogen dopant (5.26 at%), which is proven to be an efficient strategy to enhance the performance of oxygen redn. reaction (ORR) electrocatalysts. The resulting N-PEGO showed a high onset potential comparable to that of com. Pt/C, i.e., 0.89 V vs. reversible hydrogen electrode (RHE) and good electrocatalysis stability towards the ORR. This fast and effective one-step doping and exfoliation strategy demonstrated a new industrial-scale N-doped graphene fabrication technique.
- 98Zhang, H.; Li, K.; Shu, C.; Lou, Z.; Sun, T.; Jia, J. Enhancement of styrene removal using a novel double-tube dielectric barrier discharge (DDBD) reactor. Chem. Eng. J. 2014, 256, 107– 118, DOI: 10.1016/j.cej.2014.06.10598Enhancement of styrene removal using a novel double-tube dielectric barrier discharge (DDBD) reactorZhang, Hongbo; Li, Kan; Shu, Chenhua; Lou, Ziyang; Sun, Tonghua; Jia, JinpingChemical Engineering Journal (Amsterdam, Netherlands) (2014), 256 (), 107-118CODEN: CMEJAJ; ISSN:1385-8947. (Elsevier B.V.)A novel double-tube dielec. barrier discharge (DDBD) reactor was used to degrade styrene. This DDBD reactor contained 2 discharge zones with 1 power supply, an outer tube zone with low discharge energy, and an inner tube zone with high discharge energy. Gas first flowed into the outer tube zone, then into the inner tube zone, then flows out from the inner tube zone. Compared to traditional single-tube dielec. barrier discharge (SDBD) reactors, the DDBD reactor has these advantages: energy utilization efficiency can be improved because the low bond energy groups in styrene can be destroyed first in the outer discharge zone by weak discharge energy and the high bond energy groups, e.g., arom. rings, can be destroyed in the inner discharge zone by high discharge energy; high mineralization efficiency results in no oil-like byproducts aggregated on the reactor surface; and the double dielec. layers are protected from penetration. The outer and inner tube diam. were optimized and the DDBD reactor with a 25 mm outer tube and 6 mm inner tube displayed the best styrene mineralization efficiency. Compared to a SDBD reactor with the same outer tube diam., CO and CO2 selectivities were improved by 40% with a 2000 mg/m3 styrene concn. and an applied voltage of 11 kV. There was no any oil-like byproducts obsd. aggregated on outer tube wall, inner tube outlet, and the electrode after 6 h treatment. Applied voltage, O2 content, discharge length, and relative humidity were optimized in this work and O3 and NOx byproducts were detected and discussed.
- 99Mustafa, M. F.; Fu, X.; Liu, Y.; Abbas, Y.; Wang, H.; Lu, W. Volatile organic compounds (VOCs) removal in non-thermal plasma double dielectric barrier discharge reactor. J. Hazard. Mater. 2018, 347, 317– 324, DOI: 10.1016/j.jhazmat.2018.01.02199Volatile organic compounds (VOCs) removal in non-thermal plasma double dielectric barrier discharge reactorMustafa, Muhammad Farooq; Fu, Xindi; Liu, Yanjun; Abbas, Yawar; Wang, Hongtao; Lu, WenjingJournal of Hazardous Materials (2018), 347 (), 317-324CODEN: JHMAD9; ISSN:0304-3894. (Elsevier B.V.)Non-thermal plasma (NTP) an emerging technol. to treat volatile org. compds. (VOCs) present in unhygienic point source air streams. In present study, double dielec. barrier discharge (DDBD) reactors were used for the first time to evaluate the removal efficiency of VOCs mixt. of different nature at const. exptl. conditions (input power 16-65.8 W, VOCs mixt. feeding rate 1-6 L/min, 100-101 ppm inlet concn. of individual VOC). Reactor A and B with discharge gap at 6 mm and 3 mm resp., were used in current study. When treated at an input power of 53.7 W with gas feeding rate of 1 L/min in DDBD reactor A, removal efficiency of the VOCs were: tetrachloroethylene (100%), toluene (100%), trichloroethylene (100%), benzene (100%), Et acetate (100%) and carbon disulfide (88.30%); whereas in reactor B, the removal efficiency of all VOCs were 100%. Plasma-catalyst (Pt-Sn/Al2O3, BaTiO3 and HZSM-5) synergistic effect on VOCs removal efficiency was also investigated. Highest removal efficiency i.e 100% was obsd. for each compd. with BaTiO3 and HZSM-5 at an input power 65.8 W. However, integrating NTP with BaTiO3 and HZSM-5 leads to enhanced removal performance of VOCs mixt. with high activity, increase in energy efficiency and suppression of unwanted byproducts.
- 100Abbas, Y.; Lu, W.; Wang, Q.; Dai, H.; Liu, Y.; Fu, X.; Pan, C.; Ghaedi, H.; Cheng, F.; Wang, H. Remediation of pyrene contaminated soil by double dielectric barrier discharge plasma technology: Performance optimization and evaluation. Environ. Pollut. 2020, 260, 113944, DOI: 10.1016/j.envpol.2020.113944100Remediation of pyrene contaminated soil by double dielectric barrier discharge plasma technology: Performance optimization and evaluationAbbas, Yawar; Lu, Wenjing; Wang, Qian; Dai, Huixing; Liu, Yanting; Fu, Xindi; Pan, Chao; Ghaedi, Hosein; Cheng, Feng; Wang, HongtaoEnvironmental Pollution (Oxford, United Kingdom) (2020), 260 (), 113944CODEN: ENPOEK; ISSN:0269-7491. (Elsevier Ltd.)Polycyclic arom. hydrocarbons (PAHs) in soil are not only detrimental to environment but also to human health. Double dielec. barrier discharge (DDBD) plasma reactor used for the remediation of pyrene contaminated soil was studied. The performance of DDBD reactor was optimized with influential parameters including applied voltage, type of carrier gas, air feeding rate as well as pyrene initial concn. The anal. of variance (ANOVA) results showed that input energy had a great effect on pyrene remediation efficiency followed by pyrene initial concn., while, the effect of air feeding rate was insignificant. More specifically, the remediation efficiency of pyrene under air, nitrogen and argon as carrier gas were approx. 79.7, 40.7 and 38.2% resp. Pyrene remediation efficiency is favored at high level of applied voltages and low level of pyrene initial concn. (10 mgkg-1) and air feeding rate (0.85 L/min). Moreover, computation of the energy efficiency of the DDBD system disclosed that an optimal applied voltage (35.8 kV) and higher initial pyrene concn. (200 mgkg-1) favored the high energy efficiency. A regression model predicting pyrene remediation under DDBD plasma condition was developed using the data from a face-centered central composite design (FCCD) expt. Finally, the residual toxicity anal. depicted that the respiratory activity increased more than 21 times (from 0.04 to 0.849 mg O2 g-1) with a pyrene remediation efficiency of 81.1%. The study demonstrated the DDBD plasma technol. is a promising method not only for high efficiency of pyrene remediation, but also recovering biol. function without changing the phys.-chem. properties of soil.
- 101Mu, R.; Liu, Y.; Li, R.; Xue, G.; Ognier, S. Remediation of pyrene-contaminated soil by active species generated from flat-plate dielectric barrier discharge. Chem. Eng. J. 2016, 296, 356– 365, DOI: 10.1016/j.cej.2016.03.106101Remediation of pyrene-contaminated soil by active species generated from flat-plate dielectric barrier dischargeMu, Ruiwen; Liu, Yanan; Li, Rui; Xue, Gang; Ognier, StephanieChemical Engineering Journal (Amsterdam, Netherlands) (2016), 296 (), 356-365CODEN: CMEJAJ; ISSN:1385-8947. (Elsevier B.V.)Soil polluted with pyrene was remediated using a dielec. barrier discharge (DBD) plasma reactor at atm. pressure. Influencing factors, including treatment time, discharge voltage, electrode gap, gas flow rate, initial pyrene concn., and pH of the soil, were studied. Exptl. results showed that pyrene degrdn. efficiency was influenced on a small scale by soil pH: the pyrene removal rate reached 76% in alk. condition (pH 11.69), i.e., 8% higher than in neutral conditions (pH 7.76) and 13.7% higher than in acidic conditions (pH 5.67). The removal of pyrene increased as the applied voltage increased and the electrode gap decreased. The optimal airflow rate was 1.0 L/min. The more pyrene that was coated on soil particles the higher was the energy efficiency, but the plasma penetrating pyrene layers faded by ∼25% when the layers doubled. Optical emission spectrometer (OES), FTIR and GC-MS data indicated that the excited at. N, at. O and NOx were abundant in the plasma, and that the active species contg. O and N both contributed to the decompn. of pollutants. The possible pyrene degrdn. pathway is suggested. The exptl. results showed that the DBD technique was able to effectively degrade pyrene over a broad pH range.
- 102Aggelopoulos, C. A.; Hatzisymeon, M.; Tataraki, D.; Rassias, G. Remediation of ciprofloxacin-contaminated soil by nanosecond pulsed dielectric barrier discharge plasma: Influencing factors and degradation mechanisms. Chem. Eng. J. 2020, 393, 124768, DOI: 10.1016/j.cej.2020.124768102Remediation of ciprofloxacin-contaminated soil by nanosecond pulsed dielectric barrier discharge plasma: Influencing factors and degradation mechanismsAggelopoulos, C. A.; Hatzisymeon, M.; Tataraki, D.; Rassias, G.Chemical Engineering Journal (Amsterdam, Netherlands) (2020), 393 (), 124768CODEN: CMEJAJ; ISSN:1385-8947. (Elsevier B.V.)The continuous release of antibiotics in soil environment poses a serious threat for soil and water quality and consequently human health. However, research efforts focused on the effective remediation of antibiotic-polluted soil are still very limited. In this study, a nanosecond pulsed dielec. barrier discharge (nsp-DBD) plasma system was used for the first time to remediate soil contaminated by ciprofloxacin which is one of the most widely used, persistent and genotoxic antibiotics. Various cold atm. plasma (CAP) operating parameters were investigated and optimized. The optimal moisture content and air flow rate were detd. at 5% and 1.0 L min-1, resp. Ciprofloxacin degrdn. increased with pulse voltage and pulse repetition rate and decreased with higher initial concns. in the soil. At optimal conditions (pulse voltage 17.4 kV, pulse frequency 200 Hz), ciprofloxacin was completely degraded (∼99%) in soil, at very short nsp-DBD treatment time (∼3 min), with the corresponding energy efficiency being 4.6 mg/kJ. The relative distribution and identity of major ciprofloxacin degradants generated was detd. by UPLC-MS anal. This led to the generation of a degrdn. map that is consistent with hydroxyl radical-driven successive hydrogen atom abstractions and hydroxyl radical recombination events at the onset of the process followed by singlet oxygen mediated degrdn. Interestingly, the degrdn. pattern obsd. under nsp-DBD conditions shares several aspects with the in-vivo metabolic profile of ciprofloxacin.
- 103Ghaedi, H.; Ayoub, M.; Sufian, S.; Lal, B.; Uemura, Y. Thermal stability and FT-IR analysis of Phosphonium-based deep eutectic solvents with different hydrogen bond donors. J. Mol. Liq. 2017, 242, 395– 403, DOI: 10.1016/j.molliq.2017.07.016103Thermal stability and FT-IR analysis of Phosphonium-based deep eutectic solvents with different hydrogen bond donorsGhaedi, Hosein; Ayoub, Muhammad; Sufian, Suriati; Lal, Bhajan; Uemura, YoshimitsuJournal of Molecular Liquids (2017), 242 (), 395-403CODEN: JMLIDT; ISSN:0167-7322. (Elsevier B.V.)Recently, deep eutectic solvent (DES), a relatively new type of solvent, has received a considerable amt. of attention from researchers in different fields of research. DESs have a high potential to be an alternative to ionic liqs. (ILs) and traditional solvents. It is important the knowledge of thermal stability and interaction of functional groups on both salt as a hydrogen bond acceptor (HBA) and hydrogen bond donor (HBD) in order to use of DESs as alternative solvents for numerous industrial applications. In this work, four DESs have been selected with the same salt but four different HBDs. Salt was allyltriphenyl phosphonium bromide (ATPPB) and HBDs were glycerol (GL), ethylene glycol (EG), diethylene glycol (DEG) and triethylene glycol (TEG). DESs were prepd. easily into the same molar ratio of 1:4 salt to HBDs. Fourier transform IR spectroscopy (FT-IR) as an effective technique was conducted to gain information about hydrogen-bonding and vibration modes as well as investigate the functional groups of DESs. Finally, the thermal stability of DESs was studied under nitrogen at a temp. range of 30 to 800°C.
- 104Pootawang, P.; Saito, N.; Takai, O. Solution plasma for template removal in mesoporous silica: pH and discharge time varying characteristics. Thin Solid Films 2011, 519 (20), 7030– 7035, DOI: 10.1016/j.tsf.2011.01.213104Solution plasma for template removal in mesoporous silica: pH and discharge time varying characteristicsPootawang, Panuphong; Saito, Nagahiro; Takai, OsamuThin Solid Films (2011), 519 (20), 7030-7035CODEN: THSFAP; ISSN:0040-6090. (Elsevier B.V.)The evaluation of the ability of soln. plasma process, SPP, depending on the pH of the discharge soln. and discharge time for template removal in mesoporous silica was described. In the synthesis of mesoporous silica, ternary surfactant system contg. tri-block copolymer EO20PO69EO20 (P123), sodium dodecylbenzene sulfonate (SDBS), and 1,1,2,2,3,3,4,4,4-nonafluoro-1-Bu sulfonate (NFBS) was chem. used for synthesis under acid condition via sol-gel method then SPP was employed for template removal. The ordered 2D hexagonal arrangement was obsd. by the evidence of high resoln. TEM and the diffraction mode of X-ray. The efficiency of SPP depending on the pH of the discharge soln. and discharge time was scientifically demonstrated as a function of BET surface area. In the case of pH dependence, it was achieved that the ability of template removal in acid and base solns. was clearly higher than those of such results in neutral soln. In the term of discharge time, moreover, the percentage of template removal comparing in the result of BET surface area increased as the increase in discharge time.
- 105Pootawang, P.; Saito, N.; Takai, O. Solution Plasma Process for Template Removal in Mesoporous Silica Synthesis. Jpn. J. Appl. Phys. 2010, 49 (12), 126202, DOI: 10.1143/JJAP.49.126202105Solution plasma process for template removal in mesoporous silica synthesisPootawang, Panuphong; Saito, Nagahiro; Takai, OsamuJapanese Journal of Applied Physics (2010), 49 (12), 126202/1-126202/7CODEN: JJAPB6 ISSN:. (Japan Society of Applied Physics)The plasma discharge in aq. soln. was scientifically studied and applied to template removal in mesoporous silica synthesis. Highly dispersed spherical mesoporous silica particles were synthesized by the ternary surfactant system contg. the Pluronic P123 copolymer (EO20PO69EO20), sodium dodecylbenzene sulfonate, and 1,1,2,2,3,3,4,4,4-nonafluoro-1-butane sulfonate, via the sol-gel method in acid solns. The soln. plasma process (SPP), instead of conventional thermal calcinations, was used to remove the template. The mechanism of the removal of the org. template occurred via oxidn. by the hydroxyl radicals generated during discharge. The transformation of a mesopore structure from a disordered wormlike structure to a hexagonally arranged structure was obsd. by X-ray diffraction anal. and was confirmed by transmission electron microscopy. The results of the thermal anal. and functional group identification of mesoporous silica after SPP showed evidence of org. template removal. The surface area calcd. using the Brunauer-Emmett-Teller (BET) theory and the mean pore diam. results could be used to evaluate the plasma efficiency, demonstrating that this method does not affect the pore size in the case of discharge in a soln. of pH 3 compared with the results of thermal calcination. Hence, SPP was proved to be highly efficient for org. template removal, exhibiting short consumption time and less contamination.
- 106Lu, B.; Kawamoto, K. A novel approach for synthesizing ordered mesoporous silica SBA-15. Mater. Res. Bull. 2012, 47 (6), 1301– 1305, DOI: 10.1016/j.materresbull.2012.03.020106A novel approach for synthesizing ordered mesoporous silica SBA-15Lu, Baowang; Kawamoto, KatsuyaMaterials Research Bulletin (2012), 47 (6), 1301-1305CODEN: MRBUAC; ISSN:0025-5408. (Elsevier Ltd.)Ordered SBA-15 with a high sp. surface area, large pore size and pore vol. could be synthesized at a short time (overnight) without further calcination. During the SBA-15 synthesis process, TEOS hydrolysis, the condensation of the silica species and the decompn. of the Pluronic P123 template were completed by using sulfuric acid. The decompd. Pluronic P123 could be completely exacted by solvent after synthesis. SBA-15 had high hydrothermal stability.
- 107de Ávila, S. G.; Silva, L. C. C.; Matos, J. R. Optimisation of SBA-15 properties using Soxhlet solvent extraction for template removal. Microporous Mesoporous Mater. 2016, 234, 277– 286, DOI: 10.1016/j.micromeso.2016.07.027107Optimisation of SBA-15 properties using Soxhlet solvent extraction for template removalde Avila, Simone G.; Silva, Luis Carlos C.; Matos, Jivaldo R.Microporous and Mesoporous Materials (2016), 234 (), 277-286CODEN: MIMMFJ; ISSN:1387-1811. (Elsevier B.V.)Surfactants are utilized as templates in the synthesis of mesoporous materials. Normally, they are removed using a calcination process, however, careful removal is necessary to conserve the properties of the material. This work proposed surfactant removal from SBA-15 mesoporous silica using a Soxhlet extractor and different solvents. The thermal decompn. of the template was studied in order to understand the process of calcination of SBA-15. The results show that the calcination process influences the properties of the material. All of the utilized solvents enabled the removal of template. Some solvents such as water, acetonitrile and dichloromethane promoted template removal primarily from the surface of the material and others such as ethanol, acetone and methanol promoted the removal of template from within the porous silica. All samples were calcined after the extn. process, however the properties of the resulting materials were different. The greater the template removal, the greater was the surface area and pore size of the materials. Increased pore size caused decreased wall thickness. Methanol was the best of the studied solvents in terms of template removal. The extn. time required was studied and 6 h was necessary to complete the process. Soxhlet extn. is not efficient for the complete removal of template from mesoporous materials. However, the reduced quantity of template in the matrix means that less aggressive calcination is required, and therefore the properties of the mesoporous material can be preserved.
- 108Barczak, M. Template removal from mesoporous silicas using different methods as a tool for adjusting their properties. New J. Chem. 2018, 42 (6), 4182– 4191, DOI: 10.1039/C7NJ04642A108Template removal from mesoporous silicas using different methods as a tool for adjusting their propertiesBarczak, MariuszNew Journal of Chemistry (2018), 42 (6), 4182-4191CODEN: NJCHE5; ISSN:1144-0546. (Royal Society of Chemistry)Removal of the surfactant template is the final step in the synthesis of silica-based mesoporous materials. This step influences the properties of the final sample, including porosity, surface chem., and ordering. Three methods: (1) calcination, (2) extn., and (3) treatment with hydrogen peroxide are applied to remove the polymeric template from 2 types of mesoporous materials: ordered SBA-15 and silica nanorings. The 3 above-mentioned methods lead to materials with different properties as indicated by nitrogen sorption measurements, elemental anal., FTIR, NMR, and electron microscopy. The content of carbon in the final samples also differs testifying to variations in the efficiency of template removal. The detemplating scheme influences not only the structural and chem. properties but also the adsorption performance of the materials. The adsorption uptakes of L-histidine vary largely depending on the no. of silanol groups remaining on the surface after detemplation. Thus, template removal should be considered not only as the last necessary step in the synthesis of mesoporous silicas but also as a tool for tailoring the properties of the final structures.
- 109Gao, F.; Lu, Q.; Liu, X.; Yan, Y.; Zhao, D. Controlled Synthesis of Semiconductor PbS Nanocrystals and Nanowires Inside Mesoporous Silica SBA-15 Phase. Nano Lett. 2001, 1 (12), 743– 748, DOI: 10.1021/nl0156383109Controlled Synthesis of Semiconductor PbS Nanocrystals and Nanowires Inside Mesoporous Silica SBA-15 PhaseGao, Feng; Lu, Qingyi; Liu, Xiaoying; Yan, Yushan; Zhao, DongyuanNano Letters (2001), 1 (12), 743-748CODEN: NALEFD; ISSN:1530-6984. (American Chemical Society)A new flexible approach is developed to fabricate uniform nanocrystals and nanowires of binary compd. semiconductor PbS inside the channels of mesoporous silica SBA-15. The approach combines functionalization of the channel surface with thiol groups, absorption of Pb2+, and heating in N2 atmosphere at high temp. The sep. introduction of thiol groups and Pb2+ makes the loading of a binary compd. efficient and as easy as the loading of a single element. The nanocrystals are uniform and their sizes (5 nm) are consistent with the diam. of mesoporous SBA-15. The diam. of the PbS nanowires is about 6 nm and the length is several hundred nanometers. TEM images first intuitively confirm the formation of binary sulfide nanocrystals and nanowires dispersing uniformly inside the channels of mesoporous SBA-15. The key for transition from nanocrystals to nanowires is to increase the amt. of the Si-OH group on the channel surface of SBA-15, and ethanol extn. proves to be effective to keep large amt. of Si-OH groups during removing of the block copolymer. A massive blue shift is obsd. in photoluminescence spectra, and this clearly shows the quantum size effects of the PbS nanocrystals and nanowires.
- 110Aguado, J.; Arsuaga, J. M.; Arencibia, A.; Lindo, M.; Gascón, V. Aqueous heavy metals removal by adsorption on amine-functionalized mesoporous silica. J. Hazard. Mater. 2009, 163 (1), 213– 221, DOI: 10.1016/j.jhazmat.2008.06.080110Aqueous heavy metals removal by adsorption on amine-functionalized mesoporous silicaAguado, Jose; Arsuaga, Jesus M.; Arencibia, Amaya; Lindo, Montana; Gascon, VictoriaJournal of Hazardous Materials (2009), 163 (1), 213-221CODEN: JHMAD9; ISSN:0304-3894. (Elsevier B.V.)Amino functional mesoporous silica SBA-15 materials have been prepd. to develop efficient adsorbents of heavy metals in wastewater. Functionalization with amino groups has been carried out by using two independent methods, grafting and co-condensation. Three org. moieties have been selected to incorporate the active amino sites: aminopropyl (H2N-(CH2)3-), [2-aminoethylamino]-Pr (H2N-(CH2)2-NH-(CH2)3-), and [(2-aminoethylamino)-ethylamino]-Pr (H2N-(CH2)2-NH-(CH2)2-NH-(CH2)3-). Materials have been characterized by XRD, nitrogen sorption measurements and chem. anal. We have found that all materials preserve the mesoscopic order and exhibit suitable textural properties and nitrogen contents to act as potential adsorbents. Metal removal from aq. soln. has been examd. for Cu(II), Ni(II), Pb(II), Cd(II), and Zn(II); adsorption performances of materials prepd. by the two functionalization methods have been compared. In addn., copper adsorption process has been thoroughly studied from both kinetic and equil. points of view for some selected materials. Aq. Cu(II) adsorption rates show that the overall process is fast and the time evolution can be successfully reproduced with a pseudo-second-order kinetic model. Whole copper adsorption isotherms have been obtained at 25°. Significant max. adsorption capacities have been found with excellent behavior at low concn.
- 111Lu, F.; Wu, S.-H.; Hung, Y.; Mou, C.-Y. Size Effect on Cell Uptake in Well-Suspended, Uniform Mesoporous Silica Nanoparticles. Small 2009, 5 (12), 1408– 1413, DOI: 10.1002/smll.200900005111Size effect on cell uptake in well-suspended, uniform mesoporous silica nanoparticlesLu, Fang; Wu, Si-Han; Hung, Yann; Mou, Chung-YuanSmall (2009), 5 (12), 1408-1413CODEN: SMALBC; ISSN:1613-6810. (Wiley-VCH Verlag GmbH & Co. KGaA)The size of it: Mesoporous silica nanoparticles (MSNs) of controlled size in the range 30 to 280 nm are obtained by adjusting the pH of the reaction soln. The uptake of fluorescein-labeled MSNs (green, see image) by HeLa cells is size dependent, with max. uptake at a nanoparticle size of 50 nm.
- 112Laghaei, M.; Sadeghi, M.; Ghalei, B.; Dinari, M. The effect of various types of post-synthetic modifications on the structure and properties of MCM-41 mesoporous silica. Prog. Org. Coat. 2016, 90, 163– 170, DOI: 10.1016/j.porgcoat.2015.10.007112The effect of various types of post-synthetic modifications on the structure and properties of MCM-41 mesoporous silicaLaghaei, Milad; Sadeghi, Morteza; Ghalei, Behnam; Dinari, MohammadProgress in Organic Coatings (2016), 90 (), 163-170CODEN: POGCAT; ISSN:0300-9440. (Elsevier B.V.)MCM-41 mesoporous silicas synthesized by hydrothermal method were subsequently modified by 3-aminopropyltrimethoxysilane (APTMS) and trimethylchlorosilane (TMCS) via two different grafting methods, i.e. attaching functional groups with or without solvent. The post-synthetic modification, grafting, was applied due to its flexibility for the introduction of functional moieties into the favorite locations of the particles. The primary purpose of this study was to evaluate the effects of grafting methods as well as organosilanes on the modified MCM-41 particles. To achieve this aim, the obtained materials were investigated by various techniques including Fourier transform IR spectroscopy (FTIR), X-ray diffraction (XRD), N2 adsorption-desorption, transmission electron microscope (TEM), dynamic light scattering (DLS) and thermogravimetric anal. (TGA) to examine the functional groups, crystallinity, surface area, morphol., particle size distribution and amts. of functional groups, resp. The results confirmed that the spherical MCM-41 particles were successfully functionalized by APTMS and TMCS. Moreover, the surface area and av. pore diams. of the particles were affected by the inherent properties of organosilanes such as their side chains and catalytic behaviors. In addn. to the type of organosilanes, the grafting methods due to the various interactions between different components such as the surfactant, organosilane and acid had a tremendous impact on the modification process.
- 113Cheng, S.; Wang, X.; Chen, S.-Y. Applications of Amine-functionalized Mesoporous Silica in Fine Chemical Synthesis. Top. Catal. 2009, 52 (6), 681– 687, DOI: 10.1007/s11244-009-9216-2113Applications of Amine-functionalized Mesoporous Silica in Fine Chemical SynthesisCheng, Soofin; Wang, Xueguang; Chen, Shih-YuanTopics in Catalysis (2009), 52 (6-7), 681-687CODEN: TOCAFI; ISSN:1022-5528. (Springer)SBA-15 silica contg. homogeneously distributed amine-functional groups and of fiber or platelet morphol. was prepd. through a modified co-condensation method using P123 copolymer as template under acidic condition. Synthetic factors which led to well-ordered mesoporous materials with high loadings of various amine groups were discussed. The resultant mesoporous materials were efficient base catalysts in Knoevenagel and Claisen-Schmidt addn. reactions. The activities over SBA-15 materials with different amino-functional groups are compared. Moreover, the advantage of ordered large mesopores of SBA-15 in catalyzing liq. phase reactions was demonstrated, and the reaction rate could be further increased when SBA-15 was with platelet morphol. and short mesochannels.
- 114Gokulakrishnan, N.; Karbowiak, T.; Bellat, J. P.; Vonna, L.; Saada, M.-A.; Paillaud, J. L.; Soulard, M.; Patarin, J.; Parmentier, J. Improved hydrophobicity of inorganic–organic hybrid mesoporous silica with cage-like pores. Colloids Surf., A 2013, 421, 34– 43, DOI: 10.1016/j.colsurfa.2012.11.066114Improved hydrophobicity of inorganic-organic hybrid mesoporous silica with cage-like poresGokulakrishnan, Narasimhan; Karbowiak, Thomas; Bellat, Jean Pierre; Vonna, Laurent; Saada, Mohamed-Ali; Paillaud, Jean Louis; Soulard, Michel; Patarin, Joel; Parmentier, JulienColloids and Surfaces, A: Physicochemical and Engineering Aspects (2013), 421 (), 34-43CODEN: CPEAEH; ISSN:0927-7757. (Elsevier B.V.)Hydrophobic ordered mesoporous silica particles with cage-like pores (SBA-1 type) were prepd. through co-condensation of phenyltriethoxysilane (PhTES) and tetraethylorthosilicate (TEOS) at different TEOS/PhTES molar ratios. It is shown that the hydrophobic character of the particles is enhanced by increasing the Ph loading (decreasing the TEOS/PhTES molar ratio) and that it could be further enhanced by subsequent trimethylsilyl (TMS) grafting on remaining silanol groups (TMS-PhSBA-1 sample). This increase of hydrophobicity has been evidenced on the internal surface (mesoporosity) of the particles using water adsorption and, on the external surface of the particles (in the form of a pellet) using contact angle measurements. Interestingly, a high hysteresis was measured on the most hydrophobic sample (TMS-PhSBA-1), both on its internal surface during high pressure intrusion/extrusion of liq. water and on its external surface using advancing/receding contact angle measurements. This hydrophobic/hydrophilic behavior is explained by surface silanol sites, first shielded by hydrophobic org. moieties and, which subsequently trap water mols. within the porosity or on the external surface after a forced contact with liq. water. The absence of water extrusion (bumper behavior) of this material is then related both to the presence of silanol sites and to the restricted aperture of the cage-like pore morphol.
- 115Gao, J.; Wu, S.; Tan, F.; Tian, H.; Liu, J.; Lu, G. Q. M. Nanoengineering of amino - functionalized mesoporous silica nanospheres as nanoreactors. Progress in Natural Science: Materials International 2018, 28 (2), 242– 245, DOI: 10.1016/j.pnsc.2018.01.015115Nanoengineering of amino - functionalized mesoporous silica nanospheres as nanoreactorsGao, Jinsuo; Wu, Shouchun; Tan, Feng; Tian, Hao; Liu, Jian; Lu, G. Q. MaxProgress in Natural Science: Materials International (2018), 28 (2), 242-245CODEN: PNSMBB ISSN:. (Elsevier B.V.)Selective functionalization of mesoporous silica nanospheres (MSNs) is crucial for nanoengineering of MSNs. Herein, we have combined "surface-protected etching strategy" and "cationic surfactant assisted etching strategy" to prep. functionalized MSNs with externally attached amino groups. The externally attached NH2 groups endow the catalysts with excellent catalytic performance for nitroaldol reaction between nitromethane and benzaldehyde. In addn., those NH2-MSNs can also be used to support gold nanoparticles, which display very good catalytic performance for redn. of 4-nitrophenol. It can be envisioned that the synthesis protocol developed in this work could also be extended to nanoengineered MSNs, which provides opportunities for nanoreactors design.
- 116Wang, J.; Zheng, S.; Liu, J.; Xu, Z. Tannic acid adsorption on amino-functionalized magnetic mesoporous silica. Chem. Eng. J. 2010, 165 (1), 10– 16, DOI: 10.1016/j.cej.2010.08.066116Tannic acid adsorption on amino-functionalized magnetic mesoporous silicaWang, Jiahong; Zheng, Shourong; Liu, Jingliang; Xu, ZhaoyiChemical Engineering Journal (Amsterdam, Netherlands) (2010), 165 (1), 10-16CODEN: CMEJAJ; ISSN:1385-8947. (Elsevier B.V.)Amino-functionalized magnetic mesoporous silica (magMCM-41-NH2) was prepd. and adsorption of org. pollutant tannic acid (TA) from aq. soln. on the resulting material was studied. The adsorbent was characterized by elemental anal., XRD, TEM, N2 adsorption-desorption, IR spectroscopy, Zeta potential measurements and vibration sample magnetometer (VSM). Characterization results showed that magMCM-41-NH2 had ordered mesoporous structure with amino group content of 4.57%, BET surface area of 668 m2/g and the pore vol. of 0.525 cm3/g. Batch adsorption tests indicated that magMCM-41-NH2 adsorbent exhibited high adsorption affinity towards aq. TA with a max. adsorption capacity of 510.2 mg/g. The Freundlich model could fit the adsorption isotherm of TA over magMCM-41-NH2 very well, implying that adsorption process is heterogeneous. TA adsorption on magMCM-41-NH2 could be well described by the pseudo-second-order kinetics. Adsorption of TA on the adsorbent is strongly dependent on pH and ionic strength, suggesting that electrostatic interaction played a crucial role in TA adsorption. XPS anal. confirmed the formation of complex compd. between TA and surface amino groups of magMCM-41-NH2 upon adsorption.
- 117Ghorbani, M.; Nowee, S. M.; Ramezanian, N.; Raji, F. A new nanostructured material amino functionalized mesoporous silica synthesized via co-condensation method for Pb(II) and Ni(II) ion sorption from aqueous solution. Hydrometallurgy 2016, 161, 117– 126, DOI: 10.1016/j.hydromet.2016.02.002117A new nanostructured material amino functionalized mesoporous silica synthesized via co-condensation method for Pb(II) and Ni(II) ion sorption from aqueous solutionGhorbani, Masoomeh; Nowee, Seyyed Mostafa; Ramezanian, Navid; Raji, FoadHydrometallurgy (2016), 161 (), 117-126CODEN: HYDRDA; ISSN:0304-386X. (Elsevier B.V.)In this investigation, MCM-41/N-(3-trimethoxysilyl)-propyl)diethylenetriamine (MCM-41/TMSPDETA) adsorbent was prepd. via co-condensation method and characterized by FTIR, BET, XRD, TEM, SEM and DLS anal. techniques. Expts. were carried out to investigate the influence of different sorption parameters, such as pH, adsorbent dosage, contact time, initial concn. of heavy metal ions and soln. temp. in a batch system. Optimum conditions of sorption expts. were obtained at 20 °C with the pH of 6.0 and contact time of 60 min for Pb(II) and 120 min for Ni(II). The pseudo-first-order, the pseudo-second-order and intraparticle diffusion models have been used to analyze the sorption kinetic results. The sorption process was found to be well described by the pseudo-second-order rate model. The Langmuir and Freundlich isotherms have been used to describe the equil. sorption; the adsorption data obeyed the Langmuir isotherm. The max. capacity of the nanosorbent was 77.52 and 58.47 mg g-1 for Pb (II) and Ni (II) ions, resp. In order to verify the nature of sorption processes as phys. or chem., the equil. data were also fitted to the Dubinin-Radushkevitch (D-R) model. Based on D-R isotherm results, the values of mean free energy were 13.36 and 9.13 kJ mol-1 for Pb(II) and Ni(II) sorption, resp. These values of E (kJ mol-1) indicating chem. sorption for both metal ions. The selectivity order of lead and nickel sorption onto the adsorbent was Pb(II) > Ni(II).
- 118Wu, H.-C.; Chen, T.-C.; Budi, C. S.; Huang, P.-H.; Chen, C.-S.; Kao, H.-M. Confinement of Pt nanoparticles in cage-type mesoporous silica SBA-16 as efficient catalysts for toluene oxidation: the effect of carboxylic groups on the mesopore surface. Catalysis Science & Technology 2019, 9 (24), 6852– 6862, DOI: 10.1039/C9CY01787A118Confinement of Pt nanoparticles in cage-type mesoporous silica SBA-16 as efficient catalysts for toluene oxidation: the effect of carboxylic groups on the mesopore surfaceWu, Hung-Chi; Chen, Tse-Ching; Budi, Canggih Setya; Huang, Pin-Hsuan; Chen, Ching-Shiun; Kao, Hsien-MingCatalysis Science & Technology (2019), 9 (24), 6852-6862CODEN: CSTAGD; ISSN:2044-4753. (Royal Society of Chemistry)In this work, 3D cage-type mesoporous silica SBA-16, which is functionalized either with or without -COOH groups, is used to support Pt nanoparticles (NPs) and then applied for toluene oxidn. The -COOH functionalized SBA-16 exhibits higher affinity towards Pt4+ species, and as a result highly dispersed and nanosized Pt nanoparticles are formed in comparison to the case of its counterpart pure silica SBA-16 without -COOH groups. When pure SBA-16 without -COOH is used as the support, Pt NPs are formed outside the mesopores of SBA-16, resulting in larger Pt NPs. The catalytic activity for toluene oxidn. over Pt nanoparticles deposited on SBA-16 with -COOH is significantly higher than that on pure SBA-16. The intermediate species, reaction mechanisms and active sites in the course of toluene oxidn. are probed by in situ IR spectroscopy of CO and toluene adsorption. The Pt nanoparticles confined in the cage-type mesopores of SBA-16 with -COOH can induce the breakage of the strong C-C bonding between Ph and Me groups to form CO and carbonyl intermediates, and thus enhance the catalytic activity for toluene oxidn. The defect sites of Pt particles on SBA-16 with -COOH may play a role in the adsorption and decompn. of toluene. The low reducibility of Pt on SBA-16 results in a poor ability to degrade toluene, thus leading to a low catalytic rate for toluene oxidn.
- 119Suteewong, T.; Sai, H.; Lee, J.; Bradbury, M.; Hyeon, T.; Gruner, S. M.; Wiesner, U. Ordered mesoporous silica nanoparticles with and without embedded iron oxide nanoparticles: structure evolution during synthesis. J. Mater. Chem. 2010, 20 (36), 7807– 7814, DOI: 10.1039/c0jm01002b119Ordered mesoporous silica nanoparticles with and without embedded iron oxide nanoparticles: structure evolution during synthesisSuteewong, Teeraporn; Sai, Hiroaki; Lee, Jinwoo; Bradbury, Michelle; Hyeon, Taeghwan; Gruner, Sol M.; Wiesner, UlrichJournal of Materials Chemistry (2010), 20 (36), 7807-7814CODEN: JMACEP; ISSN:0959-9428. (Royal Society of Chemistry)This work reports on the structural evolution during room temp. synthesis of hexagonally ordered mesoporous silica nanoparticles with and without embedded iron oxide particles. Oleic acid-capped iron oxide nanoparticles are synthesized and transferred to an aq. phase using the cationic surfactant, hexadecyltrimethylammonium bromide (CTAB). MCM-41 type silica and composite nanoparticles are fabricated via sol-gel synthesis. Aliquots are taken from the soln. during synthesis to capture the particle formation process. TEM and Small Angle x-ray Scattering (SAXS) reveal a transition from a disordered to an ordered structure in both synthesis systems. Along with the evolution of structure, iron oxide nanoparticles acting as seeds at the early stages are relocated from the particle centers to the edges. Nitrogen sorption measurements for iron oxide-embedded mesoporous nanoparticles indicate surface areas as high as for the mesoporous silica nanoparticles without iron oxide.
- 120Karimi, S.; Heydari, M. Voltammetric mixture analysis of tyrosine and tryptophan using carbon paste electrode modified by newly synthesized mesoporous silica nanoparticles and clustering of variable-partial least square: Efficient strategy for template extraction in mesoporous silica nanoparticle synthesis. Sens. Actuators, B 2018, 257, 1134– 1142, DOI: 10.1016/j.snb.2017.11.014120Voltammetric mixture analysis of tyrosine and tryptophan using carbon paste electrode modified by newly synthesized mesoporous silica nanoparticles and clustering of variable-partial least squareKarimi, Sadegh; Heydari, MaryamSensors and Actuators, B: Chemical (2018), 257 (), 1134-1142CODEN: SABCEB; ISSN:0925-4005. (Elsevier B.V.)A sensitive, selective and efficient sensor based on carbon paste electrode modified by newly synthesized mesoporous silica nanoparticles (MSNs/CPE) is proposed for electrochem. detn. of tyrosine (Tyr) and tryptophan (Trp). In the proposed synthesis procedure of MSN, a weak acid such as NH4NO3 has been used in the washing stage, instead of strong acid, HCl. Brunauer-Emmett-Teller, BET, and Barrett-Joyner-Halenda (BJH) analyses confirms that the creation of cavities in MSN was happen more efficiently when NH4NO3 was applied respect to HCl procedure. Moreover, the obtained result shows the superiority of proposed approach compared with the unmodified carbon paste electrode, CPE; reported result for com. SiO2 modified electrode, SiO2/CPE, and also MSN/CPE by HCl procedure, such that the oxidn. peak current improved significantly for both amino acids. After optimization of exptl. parameters, the oxidn. peak current of Trp was linear over a concn. range of 0.05-600μM with a detection limit of 1.13 × 10-8 M. Similarly, the concn. range for Tyr, based on oxidn. peak current, was in the range from 0.3-600μM with limit of detection 4.97 × 10-8 M. Finally, since the differential pulse voltammetric peaks of Trp and Tyr has severe overlapping degree, the clustering of variables concept based PLS has been used as an efficient variable selection algorithm for simultaneous detn. of Tyr and Trp. The results demonstrated that the variable clustering combined with PLS can split the voltammogram spectra into useful and redundant ones and then based on informative cluster, stable model can be reached. Anal. of artificial urine as a real sample, confirms the potential ability of the proposed method for simultaneous detn. of these amino acids.
- 121Zhang, J.; Li, X.; Rosenholm, J. M.; Gu, H.-c. Synthesis and characterization of pore size-tunable magnetic mesoporous silica nanoparticles. J. Colloid Interface Sci. 2011, 361 (1), 16– 24, DOI: 10.1016/j.jcis.2011.05.038121Synthesis and characterization of pore size-tunable magnetic mesoporous silica nanoparticlesZhang, Jixi; Li, Xu; Rosenholm, Jessica M.; Gu, Hong-chenJournal of Colloid and Interface Science (2011), 361 (1), 16-24CODEN: JCISA5; ISSN:0021-9797. (Elsevier B.V.)Magnetic mesoporous silica nanoparticles (M-MSNs) are emerging as one of the most appealing candidates for theranostic carriers. Herein, a simple synthesis method of M-MSNs with a single Fe3O4 nanocrystal core and a mesoporous shell with radially aligned pores was elaborated using tetra-Et orthosilicate (TEOS) as silica source, cationic surfactant CTAB as template, and 1,3,5-triisopropylbenzene (TMB)/decane as pore swelling agents. Due to the special localization of TMB during the synthesis process, the pore size was increased with added TMB amt. within a limited range, while further employment of TMB lead to severe particle coalescence and not well-developed pore structure. On the other hand, when a proper amt. of decane was jointly incorporated with limited amts. of TMB, effective pore expansion of M-MSNs similar to that of analogous mesoporous silica nanoparticles was realized. The resultant M-MSN materials possessed smaller particle size (about 40-70 nm in diam.), tunable pore sizes (3.8-6.1 nm), high surface areas (700-1100 m2/g), and large pore vols. (0.44-1.54 cm3/g). We also demonstrate their high potential in conventional DNA loading. Maximum loading capacity of salmon sperm DNA (375 mg/g) was obtained by the use of the M-MSN sample with the largest pore size of 6.1 nm.
- 122Chun, B.-S.; Pendleton, P.; Badalyan, A.; Park, S.-Y. Mesoporous silica synthesis in sub- and supercritical carbon dioxide. Korean J. Chem. Eng. 2010, 27 (3), 983– 990, DOI: 10.1007/s11814-010-0130-x122Mesoporous silica synthesis in sub- and supercritical carbon dioxideChun, Byung-Soo; Pendleton, Phillip; Badalyan, Alexander; Park, Sun-YoungKorean Journal of Chemical Engineering (2010), 27 (3), 983-990CODEN: KJCHE6; ISSN:0256-1115. (Korean Institute of Chemical Engineers)Mesoporous silicas were synthesized from sodium silicate (Na2Si3O7) and tetraethylorthosilicate (TEOS) with Pluronic F127 (polyethylene oxide-polypropylene oxide-polyethylene oxide, EO106PO70EO106) triblock copolymer using sub- and supercrit. carbon dioxide (SubCO2 and SCO2) resp., as solvents. Templates were removed using liq. carbon dioxide (LCO2) and SCO2. The most efficient template removal was achieved by LCO2 - 92.7% (wt./wt.), followed by LCO2 with ethanol entrainer - 85.6% (wt./wt.), and by methanol - 78.8% (wt./wt.). The best efficiency of template removal by SCO2 was 50.7%. Values of sp. surface areas, ABET, were increased by 10% with the increase of an aging time from 6 to 24 h for Na2Si3O7-based silicas at aq. prepn. conditions, whereas the use of SCO2 reduced this value by 19.4%. Tor TEOS-based silicas synthesized using SCO2, ABET values increased by 3.8 times. Application of SCO2 for synthesis of TEOS-based silicas resulted in higher mesopore vols. of 0.719 and 1.241 mL/g with an av. mesopore width varying from 3.4 to 3.9 nm. Although Na2Si3O7-based silicas have almost similar mesopore width range, their mesopore vols. were 7 times less than those for TEOS-based silicas. Formation of mesopores in Na2Si3O7- and TEOS-based silicas was at the expense of micropores when prepd. in SCO2.
- 123Gunathilake, C.; Jaroniec, M. Mesoporous Organosilica with Amidoxime Groups for CO2 Sorption. ACS Appl. Mater. Interfaces 2014, 6 (15), 13069– 13078, DOI: 10.1021/am5028742123Mesoporous Organosilica with Amidoxime Groups for CO2 SorptionGunathilake, Chamila; Jaroniec, MietekACS Applied Materials & Interfaces (2014), 6 (15), 13069-13078CODEN: AAMICK; ISSN:1944-8244. (American Chemical Society)Incorporation of basic species such as amine-contg. groups into porous materials is a well-established strategy for achieving high uptake of acidic mols. such as CO2. This work reports a successful use of the aforementioned strategy for the development of ordered mesoporous organosilica (OMO) with amidoxime groups for CO2 sorption. These materials were prepd. by two-step process involving: (1) synthesis of OMO with cyanopropyl groups by co-condensation of (3-cyanopropyl)triethoxysilane and tetraethylorthosilicate in the presence of Pluronic P123 triblock copolymer under acidic conditions, and (2) conversion of cyanopropyl groups into amidoxime upon treatment with hydroxylamine hydrochloride under suitable conditions. The resulting series of amidoxime-contg. OMO was prepd. and used for CO2 sorption at low (25 °C) and elevated (60, 120 °C) temps. These sorbents exhibited relatively high adsorption capacity at ambient conditions (25 °C, 1 atm) and remarkable high sorption uptake (∼3 mmol/g) at 60 and 120 °C. This high CO2 uptake at elevated temps. by amidoxime-contg. OMO sorbent makes it a noticeable material for CO2 capture.
- 124Tsoncheva, T.; Rosenholm, J.; Linden, M.; Ivanova, L.; Minchev, C. Iron and copper oxide modified SBA-15 materials as catalysts in methanol decomposition: Effect of copolymer template removal. Applied Catalysis A: General 2007, 318, 234– 243, DOI: 10.1016/j.apcata.2006.11.008124Iron and copper oxide modified SBA-15 materials as catalysts in methanol decomposition: Effect of copolymer template removalTsoncheva, Tanya; Rosenholm, Jessica; Linden, Mika; Ivanova, Lyubomira; Minchev, ChristoApplied Catalysis, A: General (2007), 318 (), 234-243CODEN: ACAGE4; ISSN:0926-860X. (Elsevier B.V.)Several SBA-15 type mesoporous silicas, where different means of surfactant removal were used, were modified by copper and iron oxide, and tested as catalyst for methanol decompn. The materials were thoroughly characterized by nitrogen physisorption, x-ray diffraction, Moessbauer spectroscopy and temp. programmed redn. with hydrogen. The different means of template removal results in SBA-15 materials different in mesopore size and degree of microporosity. These parameters have a strong influence on the reductive and catalytic properties of the obtained composite materials.
- 125Ji, H.; Fan, Y.; Jin, W.; Chen, C.; Xu, N. Synthesis of Si-MCM-48 membrane by solvent extraction of the surfactant template. J. Non-Cryst. Solids 2008, 354 (18), 2010– 2016, DOI: 10.1016/j.jnoncrysol.2007.11.011125Synthesis of Si-MCM-48 membrane by solvent extraction of the surfactant templateJi, Hua; Fan, Yiqun; Jin, Wanqin; Chen, Changlin; Xu, NanpingJournal of Non-Crystalline Solids (2008), 354 (18), 2010-2016CODEN: JNCSBJ; ISSN:0022-3093. (Elsevier B.V.)Mesoporous MCM-48 SiO2 membranes were synthesized on porous supports under hydrothermal conditions, using tetra-Et orthosilicate (TEOS) as SiO2 source, cetyltrimethylammonium bromide (CTAB) as template surfactant. Then the templates were removed by solvent extn. instead of calcination. The results of the TG and FTIR showed that the solvent of 1 M HCl/EtOH soln. was feasible to ext. the templates in the MCM-48 materials and over 90% of the templates were extd. at room temp. for 24 h. The results of XRD, SEM indicated that the MCM-48 membranes were prepd. on the porous supports and extn. did not destroy the mesostructure of the MCM-48. The compactness of the extd. MCM-48 membrane was evaluated by the permeation of single gas (N2 and H2) with transmembrane pressure of 60-220 kPa. The permeance of N2 was independent of the transmembrane pressure and the ideal sepn. factor was ∼3.45. All the method, solvent extn. to remove surfactant template, is more effective to synthesize high quality MCM-48 membranes than calcination.
- 126Zhuang, X.; Qian, X.; Lv, J.; Wan, Y. An alternative method to remove PEO–PPO–PEO template in organic–inorganic mesoporous nanocomposites by sulfuric acid extraction. Appl. Surf. Sci. 2010, 256 (17), 5343– 5348, DOI: 10.1016/j.apsusc.2009.12.074126An alternative method to remove PEO-PPO-PEO template in organic-inorganic mesoporous nanocomposites by sulfuric acid extractionZhuang, Xin; Qian, Xufang; Lv, Jiahui; Wan, YingApplied Surface Science (2010), 256 (17), 5343-5348CODEN: ASUSEE; ISSN:0169-4332. (Elsevier B.V.)Sulfuric acid is used as an extn. agent to remove PEO-PPO-PEO templates in the org.-inorg. mesoporous nanocomposites from the triconstituent co-assembly which includes the low-polymd. phenolic resins, TEOS and triblock copolymer F127. The XRD and TEM results show well ordered mesostructure after extn. with sulfuric acid. As followed from the N2 sorption isotherms the extd. composites possess high surface areas (332-367 m2/g), large pore vols. (0.66-0.78 cm3/g), and large pore sizes (about 10.7 nm). The FT-IR anal. reveals almost complete elimination of triblock copolymer F127, and the maintenance of org. groups. This method shows potentials in removing templates from nanocomposites contg. functional moieties.
- 127Yang, C.-M.; Zibrowius, B.; Schmidt, W.; Schüth, F. Consecutive Generation of Mesopores and Micropores in SBA-15. Chem. Mater. 2003, 15 (20), 3739– 3741, DOI: 10.1021/cm031109j127Consecutive Generation of Mesopores and Micropores in SBA 15Yang, Chia-Min; Zibrowius, Bodo; Schmidt, Wolfgang; Schueth, FerdiChemistry of Materials (2003), 15 (20), 3739-3741CODEN: CMATEX; ISSN:0897-4756. (American Chemical Society)The authors provide a method for the consecutive generation of mesopores and micropores in SBA 15 through ether cleavage and subsequent thermal treatment at 200 °C. The mesopores are 1st vacated by partial decompn. of the template via ether cleavage by H2SO4. The occluded poly(ethylene oxide) chains in the SiO2 matrix, which are less accessible to the acid, can be decompd. subsequently by thermal treatment in air to create micropores. In addn., because the entire process is based on reactions at low temps., the resulting SBA 15 has larger mesopores and a greater micropore vol., which is also beneficial for certain applications.
- 128Grudzien, R. M.; Grabicka, B. E.; Jaroniec, M. Effective method for removal of polymeric template from SBA-16 silica combining extraction and temperature-controlled calcination. J. Mater. Chem. 2006, 16 (9), 819– 823, DOI: 10.1039/B515975J128Effective method for removal of polymeric template from SBA-16 silica combining extraction and temperature-controlled calcinationGrudzien, Rafal M.; Grabicka, Bogna E.; Jaroniec, MietekJournal of Materials Chemistry (2006), 16 (9), 819-823CODEN: JMACEP; ISSN:0959-9428. (Royal Society of Chemistry)An effective method for the removal of polymeric template, which combines extn. and temp.-controlled calcination, is proposed to obtain high pore vol. and large pore size ordered mesoporous silicas, SBA-16 (Im3m symmetry group), synthesized in the presence of sodium chloride at low acid concns. using poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (Pluronic F127) as a structure directing agent and tetraethylorthosilicate as a silica source. The aforementioned materials were characterized by small angle X-ray powder diffraction, nitrogen adsorption, high resoln. thermogravimetry and elemental anal.
- 129Gai, F.; Zhou, T.; Chu, G.; Li, Y.; Liu, Y.; Huo, Q.; Akhtar, F. Mixed anionic surfactant-templated mesoporous silica nanoparticles for fluorescence detection of Fe3+. Dalton Transactions 2016, 45 (2), 508– 514, DOI: 10.1039/C5DT03052H129Mixed anionic surfactant-templated mesoporous silica nanoparticles for fluorescence detection of Fe3+Gai, Fangyuan; Zhou, Tianlei; Chu, Guang; Li, Ye; Liu, Yunling; Huo, Qisheng; Akhtar, FaridDalton Transactions (2016), 45 (2), 508-514CODEN: DTARAF; ISSN:1477-9226. (Royal Society of Chemistry)This work demonstrates a method for the synthesis of large pore mesoporous silica nanoparticles (MSNs) with a pore diam. of 10.3 nm and a particle diam. of ∼50 nm based on the incorporation of mixed anionic surfactants sodium dodecyl benzenesulfonate (SDBS) and sodium dodecyl sulfate (SDS) as the template in the synthesis process. The dispersity, morphol., pore structure and size of mesoporous nanoparticles were adjusted by changing the molar ratio of two anionic surfactants, the concn. of the co-structure-directing agent (3-aminopropyltrimethoxysilane) and the reaction temp. The results of synthesis expts. suggested that the formation of large pore MSNs involved a nucleation and growth process. MSNs were post-grafted with a Schiff base moiety for fluorescence sensing of Fe3+ in water. The applicability of functionalized MSNs was demonstrated by selective fluorescence detection of Fe3+ in aq. media.
- 130Zheng, J.; Tian, X.; Sun, Y.; Lu, D.; Yang, W. pH-sensitive poly(glutamic acid) grafted mesoporous silica nanoparticles for drug delivery. Int. J. Pharm. 2013, 450 (1), 296– 303, DOI: 10.1016/j.ijpharm.2013.04.014130pH-sensitive poly(glutamic acid) grafted mesoporous silica nanoparticles for drug deliveryZheng, Jin; Tian, Xuejiao; Sun, Yangfei; Lu, Daru; Yang, WuliInternational Journal of Pharmaceutics (Amsterdam, Netherlands) (2013), 450 (1-2), 296-303CODEN: IJPHDE; ISSN:0378-5173. (Elsevier B.V.)PH-sensitive poly(l-glutamic acid) grafted mesoporous silica nanoparticles (MSN-PLGA) were prepd. by the surface-initiated N-carboxyanhydride polymn. method. The resultant MSN-PLGA was well dispersed in aq. medium and showed high drug loading efficiency, superior stability, and significantly higher drug release rates. The cumulative release of doxorubicin hydrochloride (DOX) from DOX-loaded MSN-PLGA (DOX@MSN-PLGA) was pH-dependent and the release rate was much higher at pH 5.5 than that at pH 7.4. The cytotoxicity results indicated that the blank MSN-PLGA was biocompatible and the DOX@MSN-PLGA had potent in vitro cytotoxicity effect similar to free DOX. Overall, these results demonstrate that MSN-PLGA is a promising platform to build pH controlled drug delivery systems for cancer therapy.
- 131Yokoi, T.; Yoshitake, H.; Tatsumi, T. Synthesis of Anionic-Surfactant-Templated Mesoporous Silica Using Organoalkoxysilane-Containing Amino Groups. Chem. Mater. 2003, 15 (24), 4536– 4538, DOI: 10.1021/cm034499i131Synthesis of anionic-surfactant-templated mesoporous silica using organoalkoxysilane-containing amino groupsYokoi, Toshiyuki; Yoshitake, Hideaki; Tatsumi, TakashiChemistry of Materials (2003), 15 (24), 4536-4538CODEN: CMATEX; ISSN:0897-4756. (American Chemical Society)Mesoporous silica was prepd. by dissolving sodium dodecyl sulfate in a water-ethanol mixt. (molar ratio 9:1), adding 3-aminopropyltriethoxysilane and tetra-Et orthosilicate, stirring for 1 h and ambient temp., and keeping statically at 373 K for 2 days. The resulting white ppt. was filtered, washed in deionized water and dried in air at 373 K. The anionic templating route suggests a structural control by functional groups in inorg. precursors for the formation of mesoporous metal oxides.
- 132Yokoi, T.; Yoshitake, H.; Tatsumi, T. Synthesis of mesoporous silica by using anionic surfactant. In Studies in Surface Science and Catalysis; van Steen, E., Claeys, I. M., Callanan, L. H., Eds.; Elsevier: 2004; Vol. 154, pp 519– 527.There is no corresponding record for this reference.
- 133Rahman, N. A.; Widhiana, I.; Juliastuti, S. R.; Setyawan, H. Synthesis of mesoporous silica with controlled pore structure from bagasse ash as a silica source. Colloids Surf., A 2015, 476, 1– 7, DOI: 10.1016/j.colsurfa.2015.03.018133Synthesis of mesoporous silica with controlled pore structure from bagasse ash as a silica sourceRahman, Nanik Astuti; Widhiana, Ika; Juliastuti, Sri Rachmania; Setyawan, HeruColloids and Surfaces, A: Physicochemical and Engineering Aspects (2015), 476 (), 1-7CODEN: CPEAEH; ISSN:0927-7757. (Elsevier B.V.)Mesoporous silica with controlled pore structure was prepd. from bagasse ash as a silica source. The silica in the bagasse ash was dissolved by NaOH soln. to produce sodium silicate precursor for the mesoporous silica, with or without polyethylene glycol (PEG) template. Without the PEG template, the pore structure was greatly influenced by the pH and the presence of Na+ ions. The porous silica produced in the presence of Na+ possessed higher surface area and pore diam. than those produced in the absence of Na+. The surface area and pore diam. reached approx. 525 m2 g-1 and 18 nm, resp., when the gelation pH was 3. When the gelation pH was increased, the surface area decreased while the pore diam. increased. The use of PEG template increased significantly the surface area, which reached approx. 656 m2 g-1 when the template was removed by solvothermal extn. Calcination at high temp. caused a densification of pore structure resulting a smaller surface area, pore diam. and pore vol. The pore diam. for all cases was greater than 4 nm, indicating that the silicas were mesoporous.
- 134Zhou, Y.; Schattka, J. H.; Antonietti, M. Room-Temperature Ionic Liquids as Template to Monolithic Mesoporous Silica with Wormlike Pores via a Sol–Gel Nanocasting Technique. Nano Lett. 2004, 4 (3), 477– 481, DOI: 10.1021/nl025861f134Room-Temperature Ionic Liquids as Template to Monolithic Mesoporous Silica with Wormlike Pores via a Sol-Gel Nanocasting TechniqueZhou, Yong; Schattka, Jan H.; Antonietti, MarkusNano Letters (2004), 4 (3), 477-481CODEN: NALEFD; ISSN:1530-6984. (American Chemical Society)This paper reports a novel room-temp. ionic liq. (RTIL), 1-Butyl-3-methyl-imidazolium-tetrafluoroborate ([C4mim]+BF4-), as template to monolithic mesoporous silica with wormhole framework via a convenient nanocasting technique. In contrast with the applied liq. crystal self-assembly of long-chain surfactants on the prepn. of mesoporous nanostructures, a new so-called hydrogen bond-co-π-π stack mechanism was proposed to be responsible for the present self-assembly of the RTIL in the reaction system for the formation of the wormlike mesopore, in which both the hydrogen bonds formed between the [BF4]- and silano group of silica gel and the π-π stack interaction of the neighboring imidazolium rings play crucial roles in the formation of the wormhole framework of mesporous silica. The proposed hydrogen bond-co-π-π stack mechanism with the RTIL as template may open a new pathway to prep. mesoporous materials.
- 135Pérez, L. L.; Ortiz-Iniesta, M. J.; Zhang, Z.; Agirrezabal-Telleria, I.; Santes, M.; Heeres, H. J.; Melián-Cabrera, I. Detemplation of soft mesoporous silica nanoparticles with structural preservation. Journal of Materials Chemistry A 2013, 1 (15), 4747– 4753, DOI: 10.1039/c3ta01240a135Detemplation of soft mesoporous silica nanoparticles with structural preservationPerez, Lidia Lopez; Ortiz-Iniesta, Maria J.; Zhang, Zheng; Agirrezabal-Telleria, Iker; Santes, Martijn; Heeres, Hero Jan; Melian-Cabrera, IgnacioJournal of Materials Chemistry A: Materials for Energy and Sustainability (2013), 1 (15), 4747-4753CODEN: JMCAET; ISSN:2050-7496. (Royal Society of Chemistry)A mild protocol that allows the template removal of soft un-aged silica nanoparticles was investigated. After oxidizing the org. template by Fenton chem., a good structural preservation is only achieved when the material is equilibrated and dried in a low-surface tension solvent. This avoids excessive capillary stress induced by the high surface tension of water, a major component in the Fenton reaction medium. The Fenton reaction should be carried out under mild conditions as well; otherwise the sample deteriorates by extensive hydrolysis, and capillary stress, and the structural ordering diminishes severely. The authors propose employing 10 ppm Fe concn. at 70°C for 24 h for the cetyltrimethylammonium bromide template. The proposed protocol involves two steps resulting in an overall significantly higher pore vol. attributed to the wider pores and limited particle agglomeration, while the calcined counterpart evidences aggregation and loss of the hexagonal ordering. N-BuOH exchange is unnecessary when the mesophase is stabilized by ageing, as the structure resists the water capillary stress.
- 136Melián-Cabrera, I.; Kapteijn, F.; Moulijn, J. A. Room temperature detemplation of zeolites through H2O2-mediated oxidation. Chem. Commun. 2005, 21, 2744– 2746, DOI: 10.1039/b502167gThere is no corresponding record for this reference.
- 137Melián-Cabrera, I.; Kapteijn, F.; Moulijn, J. A. One-pot catalyst preparation: combined detemplating and Fe ion-exchange of BEA through Fenton’s chemistry. Chem. Commun. 2005, (16), 2178– 2180, DOI: 10.1039/B500291E137One-pot catalyst preparation: combined detemplating and Fe ion-exchange of BEA through Fenton's chemistryMelian-Cabrera, I.; Kapteijn, F.; Moulijn, J. A.Chemical Communications (Cambridge, United Kingdom) (2005), (16), 2178-2180CODEN: CHCOFS; ISSN:1359-7345. (Royal Society of Chemistry)BEA zeolite has been simultaneously detemplated and Fe-exchanged by treating the parent zeolite with a Fenton's-type reagent (Fe3+-H2O2) at low temp. This one-pot process simplifies and speeds up considerably the prepn. route. The catalyst shows excellent performance on N2O decompn. compared to conventionally prepd. Fe-BEA.
- 138Zhang, Z.; Santangelo, D. L.; ten Brink, G.; Kooi, B. J.; Moulijn, J. A.; Melián-Cabrera, I. On the drug adsorption capacity of SBA-15 obtained from various detemplation protocols. Mater. Lett. 2014, 131, 186– 189, DOI: 10.1016/j.matlet.2014.05.173138On the drug adsorption capacity of SBA-15 obtained from various detemplation protocolsZhang, Zheng; Santangelo, Diana L.; ten Brink, Gert; Kooi, Bart J.; Moulijn, Jacob A.; Melian-Cabrera, IgnacioMaterials Letters (2014), 131 (), 186-189CODEN: MLETDJ; ISSN:0167-577X. (Elsevier B.V.)The effect of the mild detemplation method, based on Fenton chem. (with and without previous solvent extn.), and calcination was evaluated by the drug uptake capacity of SBA-15 materials. A no. of characterization techniques were applied for evaluation and comparison of the materials properties such as TGA, CNH, N2 physisorption and 29Si NMR. The mild Fenton detemplation method rendered a nearly pristine SBA-15 without structural shrinkage, low residual template, improved surface area, pore vol. and silanol concn. The drug (ibuprofen) adsorption expts. were carried out by soln. immersion in powdery form. The mild detemplated samples experienced an enhanced uptake that could be explained by the enhanced d. of silanols (mmol/g), originated from the absence of calcination in the Fenton approaches.
- 139Zhang, Z.; Melián-Cabrera, I. Modifying the Hierarchical Porosity of SBA-15 via Mild-Detemplation Followed by Secondary Treatments. The. J. Phys. Chem. C 2014, 118 (49), 28689– 28698, DOI: 10.1021/jp5096213139Modifying the Hierarchical Porosity of SBA-15 via Mild-Detemplation Followed by Secondary TreatmentsZhang, Zheng; Melian-Cabrera, IgnacioJournal of Physical Chemistry C (2014), 118 (49), 28689-28698CODEN: JPCCCK; ISSN:1932-7447. (American Chemical Society)Fenton-chem.-based detemplation combined with secondary treatments offers options to tune the hierarchical porosity of SBA-15. This approach has been studied on a series of SBA-15 mesophases and has been compared to the conventional calcination. The as-synthesized and detemplated materials were studied with regard to their template content (TGA, CHN), structure (SAXS, TEM), surface hydroxylation (Blin-Carteret's approach), and texture (high-resoln. argon physisorption). Fenton detemplation achieves 99% of template removal, leading to highly hydroxylated materials. The structure is better preserved when a secondary treatment is applied after the Fenton oxidn., due to the intense capillary forces during drying in water. Two successful approaches are presented: drying in a low-surface-tension solvent (such as n-BuOH) and a hydrothermal stabilization to further condense the structure and make it structurally more robust. Both approaches give rise to remarkably low structural shrinkage, lower than calcination and the direct water-dried Fenton. Interestingly, the derived textural features are remarkably different. The n-BuOH exchange route gives rise to highly hierarchical structures with enhanced interconnecting pores and the highest surface areas. The hydrothermal stabilization produces large-pore SBA-15 structures with high pore vol., intermediate interconnectivity, and minimal micropores. Therefore, the hierarchical texture can be fine-tuned in these two fashions while the template is removed under mild conditions.
- 140Kecht, J.; Bein, T. Oxidative removal of template molecules and organic functionalities in mesoporous silica nanoparticles by H2O2 treatment. Microporous Mesoporous Mater. 2008, 116 (1), 123– 130, DOI: 10.1016/j.micromeso.2008.03.027140Oxidative removal of template molecules and organic functionalities in mesoporous silica nanoparticles by H2O2 treatmentKecht, Johann; Bein, ThomasMicroporous and Mesoporous Materials (2008), 116 (1-3), 123-130CODEN: MIMMFJ; ISSN:1387-1811. (Elsevier)The H2O2-mediated oxidn. of cetyltrimethylammonium (CTA) template inside the channels of mesoporous silica is investigated. Furthermore, the influence of H2O2 on the decompn. of various functional groups inserted by co-condensation is examd. The resulting oxidized products are compared to materials obtained by extn. in acidic ethanolic media. The concept of oxidative template removal is then transferred to colloidal suspensions contg. mesoporous silica nanoparticles. By using phenyltriethoxysilane as a co-condensation agent, it is possible to control the size and shape of such nanosized porous hosts. The optimized H2O2 treatment is applied in order to produce suspensions of unfunctionalized mesoporous silica nanoparticles with accessible pores and controlled morphologies by a quick and efficient one-pot reaction.
- 141Yang, L. M.; Wang, Y. J.; Luo, G. S.; Dai, Y. Y. Simultaneous removal of copolymer template from SBA-15 in the crystallization process. Microporous Mesoporous Mater. 2005, 81 (1), 107– 114, DOI: 10.1016/j.micromeso.2005.01.023141Simultaneous removal of copolymer template from SBA-15 in the crystallization processYang, L. M.; Wang, Y. J.; Luo, G. S.; Dai, Y. Y.Microporous and Mesoporous Materials (2005), 81 (1-3), 107-114CODEN: MIMMFJ; ISSN:1387-1811. (Elsevier B.V.)The triblock copolymer templates were successfully removed from as-synthesized mesoporous mol. sieve SBA-15 by a new treatment process with H2O2 as oxidizing agent, and the process couples the crystn. process into one step to make the synthesis process compact. The effect of operation conditions on removal efficiency was studied, including treating time and temp., H2O2 concn., and the quantity ratio of H2O2 to org. templates. The prepd. mesoporous SBA-15 materials by the new process, characterized by XRD, N adsorption and desorption, TEM, SEM, IR spectroscopy (FTIR), and hydrothermal stability expts., exhibited higher surface areas, larger micropore vols., more uniform particle sizes and higher d. of silanol groups on the pore wall than those obtained by conventional methods. Also, the removal of templates in the crystn. process facilitates a further condensation and mild shrinkage of the SiO2 framework, and rearrangement of the materials, which prevents the hydrothermally treated SBA-15 materials from shrinking significantly during subsequent calcination and makes them show higher hydrothermal stabilities.
- 142Lu, A.-H.; Li, W.-C.; Schmidt, W.; Schüth, F. Low temperature oxidative template removal from SBA-15 using MnO4– solution and carbon replication of the mesoporous silica product. J. Mater. Chem. 2006, 16 (33), 3396– 3401, DOI: 10.1039/B607542H142Low temperature oxidative template removal from SBA-15 using MnO4- solution and carbon replication of the mesoporous silica productLu, An-Hui; Li, Wen-Cui; Schmidt, Wolfgang; Schueth, FerdiJournal of Materials Chemistry (2006), 16 (33), 3396-3401CODEN: JMACEP; ISSN:0959-9428. (Royal Society of Chemistry)We report a new method of low temp. removal of template from SBA-15 by KMnO4 chem. oxidn. Using this silica as template, mesoporous carbon with thick pore walls and relatively small mesopores can be cast. The results from XRD and nitrogen sorption show that the silica obtained after surfactant removal has high surface area, high pore vol. and good structural ordering. The obtained carbon replica also shows good structural ordering as reflected from XRD and TEM characterizations. EDX anal. shows that no residue of potassium and manganese in the carbon sample can be detected, indicating the complete removal of such species during the washing step. Interestingly, the anal. of the micropore vol. based on the DFT method shows that these carbon replicas have a large fraction of micropores with respect to the total pore vol. These micropore rich carbon materials could be candidates as mol. sieve type adsorbents and catalyst supports.
- 143Hiura, H.; Ebbesen, T. W.; Tanigaki, K. Opening and purification of carbon nanotubes in high yields. Adv. Mater. 1995, 7 (3), 275– 276, DOI: 10.1002/adma.19950070304143Opening and purification of carbon nanotubes in high yieldsHiura, Hidefumi; Ebbesen, Thomas W.; Tanigaki, KatsumiAdvanced Materials (Weinheim, Germany) (1995), 7 (3), 275-6CODEN: ADVMEW; ISSN:0935-9648. (VCH)C nanotubes, produced by the C arc discharge synthesis method, were opened and purified by treating them with a mixt. of H2SO4 and KMnO4. The method, useful for gram quantities of purified product, gave yields of 40%. The obtained nanotubes were examd. with XPS.
- 144Ding, Z.; Chen, J.; Guo, Yu; Xuzhong, G. Study on Removing Organic Template from SBA-15 by HNO3 Oxidation Treatment. Bulletin of the Chinese Ceramic Society 2009, 28, 80– 84There is no corresponding record for this reference.
- 145Wang, Y.; Yang, R. T. Template Removal from SBA-15 by Ionic Liquid for Amine Grafting: Applications to CO2 Capture and Natural Gas Desulfurization. ACS Sustainable Chem. Eng. 2020, 8 (22), 8295– 8304, DOI: 10.1021/acssuschemeng.0c01941145Template Removal from SBA-15 by Ionic Liquid for Amine Grafting: Applications to CO2 Capture and Natural Gas DesulfurizationWang, Yiren; Yang, Ralph T.ACS Sustainable Chemistry & Engineering (2020), 8 (22), 8295-8304CODEN: ASCECG; ISSN:2168-0485. (American Chemical Society)A new ionic liq. treatment method has been developed for removing the org. template from mesoporous silica SBA-15. Compared with conventional template removal by air calcination, the novel ionic liq. treatment method efficiently removed the org. template at a low temp. and preserved the surface silanol groups. The significantly increased silanol d. led to higher amine loadings on amine grafted SBA-15. Consequently, the ionic liq. treated sample showed 63% more CO2 capacity at conditions relevant to CO2 capture from flue gas. Moreover, the ionic liq. treated sample exhibited significantly higher capacities for H2S capture from natural gas as well as CO2 adsorption capacities for direct air capture which were nearly 3 times higher than the conventionally treated sample. The adsorbent stability, the isosteric heats of adsorption, and the effect of moisture were also investigated for the ionic liq. treated sample. The mechanism of template removal by ionic liq. is discussed, and the feasibility of recovery/reuse of the ionic liq. and the template is shown. A novel template removal method using ionic liq. is developed to enhance selective adsorption capacities of CO2 and H2S by amine grafted SBA-15.
- 146Ghaedi, H.; Akbari, S.; Zhou, H.; Wang, W.; Zhao, M. Excess Properties of and Simultaneous Effects of Important Parameters on CO2 Solubility in Binary Mixture of Water-Phosphonium Based-Deep Eutectic Solvents: Taguchi Method. Energy Fuels 2022, na, DOI: 10.1021/acs.energyfuels.1c03623There is no corresponding record for this reference.
- 147Ghaedi, H.; Kalhor, P.; Zhao, M.; Clough, P. T.; Anthony, E. J.; Fennell, P. S. Potassium carbonate-based ternary transition temperature mixture (deep eutectic analogues) for CO2 absorption: Characterizations and DFT analysis. Frontiers of Environmental Science & Engineering 2022, 16 (7), 92, DOI: 10.1007/s11783-021-1500-9147Potassium carbonate-based ternary transition temperature mixture (deep eutectic analogues) for CO2 absorption: Characterizations and DFT analysisGhaedi, Hosein; Kalhor, Payam; Zhao, Ming; Clough, Peter T.; Anthony, Edward J.; Fennell, Paul S.Frontiers of Environmental Science & Engineering (2022), 16 (7), 92CODEN: FESECJ; ISSN:2095-221X. (Higher Education Press)Abstr.: Is it possible to improve CO2 soly. in potassium carbonate (K2CO3)-based transition temp. mixts. (TTMs). To assess this possibility, a ternary transition-temp. mixt. (TTTM) was prepd. by using a hindered amine, 2-amino-2-methyl-1,3-propanediol (AMPD). Fourier transform IR spectroscopy (FT-IR) was employed to detect the functional groups including hydroxyl, amine, carbonate ion, and aliph. functional groups in the prepd. solvents. From thermogravimetric anal. (TGA), it was found that the addn. of AMPD to the binary mixt. can increase the thermal stability of TTTM. The viscosity findings showed that TTTM has a higher viscosity than TTM while their difference was decreased by increasing temp. In addn., Eyring's abs. rate theory was used to compute the activation parameters (ΔG*, ΔH*, and ΔS*). The CO2 soly. in liqs. was measured at a temp. of 303.15 K and pressures up to 1.8 MPa. The results disclosed that the CO2 soly. of TTTM was improved by the addn. of AMPD. At the pressure of about 1.8 MPa, the CO2 mole fractions of TTM and TTTM were 0.1697 and 0.2022, resp. To confirm the exptl. data, d. functional theory (DFT) was employed. From the DFT anal., it was found that the TTTM + CO2 system has higher interaction energy (|ΔE|) than the TTM + CO2 system indicating the higher CO2 affinity of the former system. This study might help scientists to better understand and to improve CO2 soly. in these types of solvents by choosing a suitable amine as HBD and finding the best combination of HBA and HBD. [graphic not available: see fulltext].
- 148Ghaedi, H.; Zhao, M.; Clough, P. T.; Anthony, E. J.; Fennell, P. S. High CO2 absorption in new amine based-transition-temperature mixtures (deep eutectic analogues) and reporting thermal stability, viscosity and surface tension: Response surface methodology (RSM). J. Mol. Liq. 2020, 316, 113863, DOI: 10.1016/j.molliq.2020.113863148High CO2 absorption in new amine based-transition-temperature mixtures (deep eutectic analogues) and reporting thermal stability, viscosity and surface tension: Response surface methodology (RSM)Ghaedi, Hosein; Zhao, Ming; Clough, Peter T.; Anthony, Edward J.; Fennell, Paul S.Journal of Molecular Liquids (2020), 316 (), 113863CODEN: JMLIDT; ISSN:0167-7322. (Elsevier B.V.)To study CO2 capture potential, three types of transition-temp. mixts. (TTMs) were prepd. by mixing ethyltriphenylphosphonium bromide (MTPPB) as a hydrogen bond acceptor (HBA) and n-Me diethanolamine (MDEA) as a hydrogen bond donor (HBD) in different molar ratios (1:7, 1:10 and 1:16). Fourier transform IR spectroscopy (FT-IR) results showed that TTMs have almost similar spectra to their HBD (MDEA) with different levels of transmittance and exhibit similar behavior. From the exptl. results, it was found that the thermal stability, viscosity and surface tension of TTMs decreased as the concn. of MDEA in the mixt. increased. According to response surface methodol. (RSM) models and anal. of variance (ANOVA), temp. and molar ratio had a great effect on the viscosity and surface tension of TTMs. Finally, it was found that CO2 soly. in TTMs (at 303.15 K at pressure up to 1.35 MPa) was enhanced as the MDEA quantity increased in the mixt. up to 1:10 mol ratio. However, by increasing MDEA concn. to 16:1 mol ratio, there was a decreasing trend in the CO2 soly. data. Also, all TTMs, particularly TTM contg. 10:1 mol MDEA (MTPPB-MDEA 1:10) exhibited an equil. loading capacity approaching 1 mol CO2 per mol solvent at high pressure, revealing their high potential for CO2 capture. A comparison showed that the CO2 soly. in the studied solvents was higher than that of existing deep eutectic solvents (DESs) and other TTMs as well as several ionic liqs. (ILs) to date. To the best of our knowledge, this is the first study to report the CO2 soly. in phosphonium-base TTMs contg. MDEA.
- 149Ghaedi, H.; Zhao, M.; Ayoub, M.; Zahraa, D.; Shariff, A. M.; Inayat, A. Preparation and characterization of amine (N-methyl diethanolamine)-based transition temperature mixtures (deep eutectic analogues solvents). J. Chem. Thermodyn. 2019, 137, 108– 118, DOI: 10.1016/j.jct.2018.12.014149Preparation and characterization of amine (N-methyl diethanolamine)-based transition temperature mixtures (deep eutectic analogues solvents)Ghaedi, Hosein; Zhao, Ming; Ayoub, Muhammad; Zahraa, Diana; Shariff, Azmi Mohd; Inayat, AbrarJournal of Chemical Thermodynamics (2019), 137 (), 108-118CODEN: JCTDAF; ISSN:0021-9614. (Elsevier Ltd.)In this study, three mixts.of methylyltriphenylphosphonium bromide (MTPPB) as hydrogen bond acceptor (HBA) and N-Me diethanolamine (MDEA) as hydrogen bond donor (HBD) component was used to prep.transition temp.mixts.(TTMs) into different mole ratios of 1:7, 1:10 and 1:16 HBA/HBD. Two important physicochem. properties of TTMs such as d.and refractive index were investigated at the atm. pressure and temp. ranges of (293.15-353.15) K and (293.15-343.15) K, resp. The exptl.d.data were used to derive the molar volume, mol.vol., lattice energy and isobaric thermal expansion coeffs. With the help of exptl.refractive index data, the electronic polarization, molar refraction, and free vol.were calcd.at the whole temps. Several empirical equations were used to correlate refractive indexes such as an empirical equation and one-parameter equations (Dale-Gladstone, Eykman, Lorentz-Lorenz, Newton, Arago-Biot, and Oster). Finally, the response surface methodol.(RSM) was applied to evaluate the effects of two main factors such as temp. and mole ratio on the d.and refractive index of TTMs. The results revealed that the molar ratio has almost a higher effect on the studied properties than temp.
- 150Ghaedi, H.; Ayoub, M.; Sufian, S.; Shariff, A. M.; Lal, B.; Wilfred, C. D. Density and refractive index measurements of transition-temperature mixture (deep eutectic analogues) based on potassium carbonate with dual hydrogen bond donors for CO2 capture. The. J. Chem. Thermodyn. 2018, 118, 147– 158, DOI: 10.1016/j.jct.2017.11.008150Density and refractive index measurements of transition-temperature mixture (deep eutectic analogues) based on potassium carbonate with dual hydrogen bond donors for CO2 captureGhaedi, Hosein; Ayoub, Muhammad; Sufian, Suriati; Shariff, Azmi Mohd.; Lal, Bhajan; Wilfred, Cecilia DeviJournal of Chemical Thermodynamics (2018), 118 (), 147-158CODEN: JCTDAF; ISSN:0021-9614. (Elsevier Ltd.)The transition-temp. mixt. (TTM) is a new type of solvent and is known as a tuneable solvent similar to deep eutectic solvent (DES). The new type of solvent called ternary transition-temp. mixt. (TTTM) was prepd. to use for CO2 capture purposes. In this work, TTMs and TTTMs were prepd. with potassium carbonate (PC) as a hydrogen bond acceptor (HBA) and three hydrogen bond donors (HBDs) such as glycerol (GL), ethylene glycol (EG) and 2-amino-2-methyl-1-3-propanediol (AMPD) known as a hindered amine (HA). Binary TTMs were PC-GL with mole ratios 1:10 and 1:16 and PC-EG with the same mole ratios. TTTMs were prepd. by adding AMPD in binary TTMs such as PC-GL-AMPD 1:16:1 and PC-EG-AMPD 1:10:1. The exptl. d. and refractive index of all mixts. were measured at temps. from 293.15 K to 343.15 K with an interval of 5 K. The effect of temp., mole ratio, molar mass and alkyl chain length on the properties was investigated. The molar volumes and isobaric thermal expansion were calcd. using exptl. d. data. The exptl. refractive index values were used to derive the specific refraction, molar refraction, free molar volume, electronic polarization and polarizability at several temps.
- 151Ghaedi, H.; Ayoub, M.; Sufian, S.; Hailegiorgis, S. M.; Murshid, G.; Khan, S. N. Thermal stability analysis, experimental conductivity and pH of phosphonium-based deep eutectic solvents and their prediction by a new empirical equation. J. Chem. Thermodyn. 2018, 116, 50– 60, DOI: 10.1016/j.jct.2017.08.029151Thermal stability analysis, experimental conductivity and pH of phosphonium-based deep eutectic solvents and their prediction by a new empirical equationGhaedi, Hosein; Ayoub, Muhammad; Sufian, Suriati; Hailegiorgis, Sintayehu Mekuria; Murshid, Ghulam; Khan, Saleem NawazJournal of Chemical Thermodynamics (2018), 116 (), 50-60CODEN: JCTDAF; ISSN:0021-9614. (Elsevier Ltd.)Deep eutectic solvents (DESs) are derived from two or more salts as the hydrogen bond acceptors (HBAs) and hydrogen bond donors (HBDs). Because of many unique features, DESs can be a versatile alternative to ionic liqs. and traditional solvents. In this work, DESs were prepd. namely allyltriphenylphosphonium bromide-diethylene glycol (ATPPB-DEG) and allyltriphenylphosphonium bromide-triethylene glycol (ATPPB-TEG) into three mole ratios 1:4, 1:10, and 1:16 salt to HBDs. The thermal stability was comprehensively analyzed under the temp. range of (30-800) °C. The cond. and pH values were detd. within the temp. range of 293.15 K-343.15 K. The results revealed that the amt. and type of HBDs have an effect on these properties. Moreover, the effect of temp. was studied on these properties. As the temp. increases, the cond. values increase while the pH values decrease. Finally, a new empirical equation was applied to correlate the exptl. cond. and pH data. It was found that this equation is powerful and reliable to correlate these properties of DESs.
- 152Ghaedi, H.; Ayoub, M.; Sufian, S.; Hailegiorgis, S. M.; Murshid, G.; Farrukh, S.; Khan, S. N. Experimental and prediction of volumetric properties of aqueous solution of (allyltriphenylPhosphonium bromide─Triethylene glycol) deep eutectic solvents. Thermochim. Acta 2017, 657, 123– 133, DOI: 10.1016/j.tca.2017.09.025152Experimental and prediction of volumetric properties of aqueous solution of (allyltriphenylPhosphonium bromide-Triethylene glycol) deep eutectic solventsGhaedi, Hosein; Ayoub, Muhammad; Sufian, Suriati; Hailegiorgis, Sintayehu Mekuria; Murshid, Ghulam; Farrukh, Sarah; Khan, Saleem NawazThermochimica Acta (2017), 657 (), 123-133CODEN: THACAS; ISSN:0040-6031. (Elsevier B.V.)Deep eutectic solvents (DESs) are derived from two or more salts as the hydrogen bond acceptors (HBAs) and hydrogen bond donors (HBDs). In this work, DES namely allyltriphenylphosphonium bromide- triethylene glycol (ATPPB-TEG) was prepd. by using three molar ratios; i.e.,1:4, 1:10, and 1:16 of salt to HBDs. The volumetric properties of aq. mixt. of DESs, such as d., molar volume, isobaric thermal expansion, apparent molar volume and apparent molar expansibility were reported at several temps. from 293.15 to 343.15 K. A math. equation, namely Jouyban-Acree model (JAM), was used to correlate the exptl. d. and molar volume data. Furthermore, in order to calc. the limiting apparent molar volume values, the apparent molar volume values were fitted into a Redlich-Mayer equation. By applying Hepler equation, it was found that DESs 1:4 and 1:10 are as structure-maker solutes, while DES 1:16 is a structure-breaking solute in aq. solns.
- 153Ghaedi, H.; Ayoub, M.; Sufian, S.; Shariff, A. M.; Murshid, G.; Hailegiorgis, S. M.; Khan, S. N. Density, excess and limiting properties of (water and deep eutectic solvent) systems at temperatures from 293.15K to 343.15K. J. Mol. Liq. 2017, 248, 378– 390, DOI: 10.1016/j.molliq.2017.10.074153Density, excess and limiting properties of (water and deep eutectic solvent) systems at temperatures from 293.15-343.15 KGhaedi, Hosein; Ayoub, Muhammad; Sufian, Suriati; Shariff, Azmi Mohd.; Murshid, Gulam; Hailegiorgis, Sintayehu Mekuria; Khan, Saleem NawazJournal of Molecular Liquids (2017), 248 (), 378-390CODEN: JMLIDT; ISSN:0167-7322. (Elsevier B.V.)Deep eutectic solvents (DESs) are derived from two or more salts as the hydrogen bond acceptors (HBAs) and hydrogen bond donors (HBDs). In this work, DES namely allyltriphenyl phosphonium bromide-diethylene glycol (ATPPB-DEG) was prepd. by using three molar ratios of 1:4, 1:10 and 1:16 salt to HBD. The volumetric properties of aq. DESs, such as d., molar volume, isobaric thermal expansion, apparent molar volume and apparent molar expansibility were reported at several temps. from 293.15 to 343.15 K. A math. equation, so-called Jouyban-Acree model (JAM), was used to correlate the exptl. d. and molar volume data of aq. soln. of DESs with respect to the concn. and temp. The results disclosed that this model is an accurate and reliable model for the prediction of aq. DES properties. The excess properties, such as excess molar volume and excess isobaric thermal expansion were reported and fitted to two different equations. In order to calc. the limiting apparent molar volume values, the apparent molar volume values were fitted into a Redlich-Mayer equation. By applying the Hepler equation, it was found that DESs with molar ratios of 1:4 and 1:10 are as structure-maker solutes, while the DES 1:16 is a structure-breaking solute in aq. solns. at different temps.
- 154Ghaedi, H.; Ayoub, M.; Sufian, S.; Murshid, G.; Farrukh, S.; Shariff, A. M. Investigation of various process parameters on the solubility of carbon dioxide in phosphonium-based deep eutectic solvents and their aqueous mixtures: Experimental and modeling. International Journal of Greenhouse Gas Control 2017, 66, 147– 158, DOI: 10.1016/j.ijggc.2017.09.020154Investigation of various process parameters on the solubility of carbon dioxide in phosphonium-based deep eutectic solvents and their aqueous mixtures: Experimental and modelingGhaedi, Hosein; Ayoub, Muhammad; Sufian, Suriati; Murshid, Ghulam; Farrukh, Sarah; Shariff, Azmi Mohd.International Journal of Greenhouse Gas Control (2017), 66 (), 147-158CODEN: IJGGBW; ISSN:1750-5836. (Elsevier B.V.)This research presents the application of predictive regression model such as quadratic regression for estn. of CO2 soly. in deep eutectic solvents namely allyltriphenylphosphonium bromide-triethylene glycol (ATPPB-TEG) into different molar ratios and their aq. solns. A quadratic regression model was developed after validation and confirmation through several strong approaches. The results disclose that the prediction of developed quadratic regression model is in acceptable agreement with exptl. soly. data. The overall R-squared (R2) and abs. relative error (ARE) values of proposed quadratic regression model were 0.9966 and 0.0725, resp. Moreover, anal. of variance (ANOVA) indicates that pressure is the most significant factor influencing the XCO2. Finally, the signal to noise (S/N) ratio shows that the highest levels for pressure, concn. of DES in mixt., and molar ratio, and lowest level for temp. are the optimal levels of input parameters to obtain the highest CO2 soly. in this system. The developed quadratic regression model and correlation are effective and provide quick, reliable and accurate predictions of CO2 soly. in DESs without carrying out any time consuming, difficult and expensive exptl. measurements. To the best of our knowledge, this is the first time a regression model was developed for prediction of CO2 soly. in DESs and their aq. solns.
- 155Ghaedi, H.; Ayoub, M.; Sufian, S.; Hailegiorgis, S. M.; Krishnan, S. Toxicity of Several Potassium Carbonate and Phosphonium-Based Deep Eutectic Solvents towards Escherichia coli and Listeria monocytogenes Bacteria. J. Environ. Anal Toxicol 2017, 7 (485), 2161– 0525, DOI: 10.4172/2161-0525There is no corresponding record for this reference.
- 156Ghaedi, H.; Ayoub, M.; Sufian, S.; Shariff, A. M.; Lal, B. The study on temperature dependence of viscosity and surface tension of several Phosphonium-based deep eutectic solvents. J. Mol. Liq. 2017, 241, 500– 510, DOI: 10.1016/j.molliq.2017.06.024156The study on temperature dependence of viscosity and surface tension of several Phosphonium-based deep eutectic solventsGhaedi, Hosein; Ayoub, Muhammad; Sufian, Suriati; Shariff, Azmi Mohd.; Lal, BhajanJournal of Molecular Liquids (2017), 241 (), 500-510CODEN: JMLIDT; ISSN:0167-7322. (Elsevier B.V.)Deep eutectic solvents (DESs) are derived from two or more salts as the hydrogen bond acceptors (HBAs) and hydrogen bond donors (HBDs). In this work, six deep eutectic solvents (DESs) were prepd. namely allyltriphenyl phosphonium bromide- diethylene glycol (ATPPB-DEG) and allyltriphenyl phosphonium bromide - triethylene glycol (ATPPB-TEG) using three molar ratios of 1:4, 1:10 and 1:16 salt to HBDs. The temp. range for exptl. viscosity was from 293.15 to 343.15 K and that of the exptl. surface tension was between 298.15 and 343.15 K. The results disclosed that hydrogen bonding in DESs has a great effect on the properties. Among all DESs with the same components, the DESs with the strong hydrogen bonding in their structures had the higher viscosity and surface tension. Besides, by increasing the temp. and quantity of HBDs in DESs, both of these properties experienced a decreasing trend in the amt. It was found that the mol. wt. of DESs with the same component has an effect on the properties. The higher mol. wt. caused the higher viscosity and surface tension. Further, ATPPB-TEG DESs had the higher viscosity and lower surface tension than ATPPB-DEG DESs because of the higher alkyl chain in their structures. Several models and a new empirical equation were used to correlate the exptl. viscosity data. It was found that there is a well agreement between theor. and exptl. values esp. when the new empirical equation is used. In addn., the activation parameters for all DESs were calcd. using the exptl. viscosity data and application of Eyring's abs. rate theory. The exptl. surface tension was employed to predict the crit. temp., surface entropy and internal surface energy of DESs. Finally, two empirical equations were used for relating the exptl. surface tension to the exptl. viscosity of DESs.
- 157Ghaedi, H.; Ayoub, M.; Sufian, S.; Lal, B.; Shariff, A. M. Measurement and correlation of physicochemical properties of phosphonium-based deep eutectic solvents at several temperatures (293.15K–343.15K) for CO2 capture. J. Chem. Thermodyn. 2017, 113, 41– 51, DOI: 10.1016/j.jct.2017.05.020157Measurement and correlation of physicochemical properties of phosphonium-based deep eutectic solvents at several temperatures (293.15 K-343.15 K) for CO2 captureGhaedi, Hosein; Ayoub, Muhammad; Sufian, Suriati; Lal, Bhajan; Shariff, Azmi Mohd.Journal of Chemical Thermodynamics (2017), 113 (), 41-51CODEN: JCTDAF; ISSN:0021-9614. (Elsevier Ltd.)Recently, deep eutectic solvents (DESs) as the new solvents have received considerable amt. of attention between researchers in different research fields and are under investigation so find out their potential to become a versatile alternative to ionic liqs. (ILs) and traditional solvents. DESs are derived from two or more salts as the hydrogen bond acceptors (HBAs) and hydrogen bond donors (HBDs). Six DESs were synthesized namely allyltriphenylphosphonium bromide- diethylene glycol (ATPPB-DEG) and allyltriphenylphosphonium bromide- triethylene glycol (ATPPB-TEG) using three mole ratios of 1:4, 1:10 and 1:16 salt to HBDs. In this work, we report physicochem. properties of these DESs, which include d., molar volume, isobaric thermal expansion, refractive index, specific refraction, molar refraction, free molar volume, electronic polarization and internal pressure at several temps. from 293.15 K to 343.15 K. Most of these properties are fitted to a linear equation by the method of least-squares using the Levenberg-Marquardt algorithm to derive the corresponding parameters and est. the root mean square error (RMSE) and least squared correlation coeff. (R2).
- 158Ghaedi, H.; Ayoub, M.; Sufian, S.; Shariff, A. M.; Hailegiorgis, S. M.; Khan, S. N. CO2 capture with the help of Phosphonium-based deep eutectic solvents. J. Mol. Liq. 2017, 243, 564– 571, DOI: 10.1016/j.molliq.2017.08.046158CO2 capture with the help of Phosphonium-based deep eutectic solventsGhaedi, Hosein; Ayoub, Muhammad; Sufian, Suriati; Shariff, Azmi Mohd.; Hailegiorgis, Sintayehu Mekuria; Khan, Saleem NawazJournal of Molecular Liquids (2017), 243 (), 564-571CODEN: JMLIDT; ISSN:0167-7322. (Elsevier B.V.)Deep eutectic solvents (DESs) are derived from the concomitant reaction of two or more salts i.e. between hydrogen bond acceptor (HBA) and hydrogen bond donors (HBD) components. In this work, DESs were prepd. namely allyltriphenyl phosphonium bromide-diethylene glycol (ATPPB-DEG) and allyltriphenyl phosphonium bromide-triethylene glycol (ATPPB-TEG) into three molar ratios 1:4, 1:10, and 1:16 salt to HBDs. The carbon dioxide soly. in DESs at temp. of 303.15 K and pressure up to 2 MPa were detd. and reported in terms of mole fraction, CO2 loading and Henry's law consts. Krichevsky-Kasarnovsky equation was used to correlate the soly. data and obtain Henry's law consts. at 303.15 K. Finally, the effects of hydrogen bonding within DESs, molar ratio, molar volume, free vol., ether group and alkyl chain length were investigated based on CO2 soly. in DESs. To the best of our knowledge, this is the first time CO2 soly. in these DESs was studied.
- 159Satlewal, A.; Agrawal, R.; Bhagia, S.; Sangoro, J.; Ragauskas, A. J. Natural deep eutectic solvents for lignocellulosic biomass pretreatment: Recent developments, challenges and novel opportunities. Biotechnol. Adv. 2018, 36, 2032, DOI: 10.1016/j.biotechadv.2018.08.009159Natural deep eutectic solvents for lignocellulosic biomass pretreatment: Recent developments, challenges and novel opportunitiesSatlewal, Alok; Agrawal, Ruchi; Bhagia, Samarthya; Sangoro, Joshua; Ragauskas, Arthur J.Biotechnology Advances (2018), 36 (8), 2032-2050CODEN: BIADDD; ISSN:0734-9750. (Elsevier)Conversion of lignocellulosic biomass to fuels and chems. has attracted immense research and development around the world. Lowering recalcitrance of biomass in a cost-effective manner is a challenge to commercialize biomass-based technologies. Deep eutectic solvents (DESs) are new 'green' solvents that have a high potential for biomass processing because of their low cost, low toxicity, biodegradability, easy recycling and reuse. This article discusses the properties of DESs and recent advances in their application for lignocellulosic biomass processing. The effectiveness of DESs in hydrolyzing lignin-carbohydrate complexes, removing lignin/hemicellulose from biomass as well as their effect on biomass deconstruction, crystallinity and enzymic digestibility have been discussed. Moreover, this review presents recent findings on the compatibility of natural DESs with enzymes and microorganisms.
- 160Tan, Y. T.; Chua, A. S. M.; Ngoh, G. C. Deep eutectic solvent for lignocellulosic biomass fractionation and the subsequent conversion to bio-based products – A review. Bioresour. Technol. 2020, 297, 122522, DOI: 10.1016/j.biortech.2019.122522160Deep eutectic solvent for lignocellulosic biomass fractionation and the subsequent conversion to bio-based products - A reviewTan, Yee Tong; Chua, Adeline Seak May; Ngoh, Gek ChengBioresource Technology (2020), 297 (), 122522CODEN: BIRTEB; ISSN:0960-8524. (Elsevier Ltd.)A review. Since the introduction of deep eutectic solvent (DES) in biomass processing field, the efficiency of DES in lignocellulosic biopolymer model compds.' (cellulose, hemicellulose and lignin) solubilization and conversion was widely recognized. Nevertheless, DES's potential for biorefinery application can be reflected more accurately through their performance in raw lignocellulosic biomass processing rather than model compd. conversion. Therefore, this review examines the studies on raw lignocellulosic biomass fractionation using DES and the subsequent conversion of DES-fractionated products into bio-based products. The review stresses on three key parts: performance of varying types of DESs and pretreatment schemes for biopolymer fractionation, properties and conversion of fractionated saccharides as well as DES-extd. lignin. The prospects and challenges of DES implementation in biomass processing will also be discussed. This review provides a front-to-end view on the DES's performance, starting from pretreatment to DES-fractionated products conversion, which would be helpful in devising a comprehensive biomass utilization process.
- 161Zhang, C.-W.; Xia, S.-Q.; Ma, P.-S. Facile pretreatment of lignocellulosic biomass using deep eutectic solvents. Bioresour. Technol. 2016, 219, 1– 5, DOI: 10.1016/j.biortech.2016.07.026161Facile pretreatment of lignocellulosic biomass using deep eutectic solventsZhang, Cheng-Wu; Xia, Shu-Qian; Ma, Pei-ShengBioresource Technology (2016), 219 (), 1-5CODEN: BIRTEB; ISSN:0960-8524. (Elsevier Ltd.)In this work, three kinds of deep eutectic solvents (DESs) were facilely prepd. and used in the pretreatment of corncob, including monocarboxylic acid/choline chloride, dicarboxylic acid/choline chloride and polyalc./choline chloride. The enhanced delignification and subsequent enzymic hydrolysis efficiency were found to be related to the acid amt., acid strength and the nature of hydrogen bond acceptors. The XRD, SEM and FT-IR results consistently indicated that the structures of corncob were disrupted by the removal of lignin and hemicellulose in the pretreatment process. In addn., the optimal pretreatment temp. and time were 90 °C and 24 h, resp. This study explored the roles of various DESs combinations, pretreatment temp. and time to better utilize the DESs in the pretreatment of lignocellulosic biomass.