Ceria-Catalyzed Hydrolytic Cleavage of Sulfonamides

Nanoceria is a promising nanomaterial for the catalytic hydrolysis of a wide variety of substances. In this study, it was experimentally demonstrated for the first time that CeO2 nanostructures show extraordinary reactivity toward sulfonamide drugs (sulfadimethoxine, sulfamerazine, and sulfapyridine) in aqueous solution without any illumination, activation, or pH adjustment. Hydrolytic cleavage of various bonds, including S–N, C–N, and C–S, was proposed as the main reaction mechanism and was indicated by the formation of various reaction products, namely, sulfanilic acid, sulfanilamide, and aniline, which were identified by HPLC-DAD, LC-MS/MS, and NMR spectroscopy. The kinetics and efficiency of the ceria-catalyzed hydrolytic cleavage were dependent on the structure of the sulfonamide molecule and physicochemical properties of Nanoceria prepared by three different precipitation methods. However, in general, all three ceria samples were able to cleave SA drugs tested, proving the robust and unique surface reactivity toward these compounds inherent to cerium dioxide. The demonstrated reactivity of CeO2 to molecules containing sulfonamide or even sulfonyl (and similar) functional groups may be significant for both heterogeneous catalysis and environmentally important degradation reactions.

aging for two hours and then refluxed at 100 °C for 24 hours.The yellowish precipitate was rinsed with water by decantation and using dialysis membrane, then filtered and air-dried.
The CeUREA sample: 1L of Ce(NO 3 ) 3 × 6H 2 O aqueous solution (0.02 M) was mixed with 200 g of urea and the solution was heated at 92 °C for 5 hour.The evaporated water was regularly replenished during the entire process.After cooling down, the precipitate was rinsed with water by decantation and using dialysis membrane, then filtered and air-dried.
Subsequently, the powder was then calcined in a furnace for 2 hours at 500 °C with a temperature increase of 5 °C/min.

XPS measurement details.
The samples were loaded into the XPS apparatus in dry powder form.Drying was completed in the load-lock chamber of the XPS instrument, where a pressure of about 4x10 -7 mbar was reached before introducing the samples into the analytical chamber of the XPS instrument.An Al anode at pass energy 40 eV and 10 eV was used to obtain a survey spectrum and a high-resolution spectrum, respectively.The spectra were collected in the normal direction and the sample charge was not compensated during the measurement.The analyzer was set to operate in Fixed Analyzer Transmission mode and Medium Area setting (Magnification M = 5) with an entrance slit of 7 × 20 mm 2 and an aperture diameter of 35 mm, so the measured area was about 1.4 × 4 mm 2 .During the measurement, the pressure was kept below 7 x 10 -7 Pa.
The acquired data were processed in CasaXPS software with a Shirley background profile and the built-in RSF was used to calculate the elemental composition.Samples were placed for carbon double-sided tape in sufficient quantities to completely cover the tape so that no carbon from the tape is detectable in the spectra.The pump down time was the minimum necessary and the load lock time was about 90 minutes.
The atomic concentration of oxygen was calculated from the high-resolution spectra of O1s and Ce3d (with using RSF factors in CasaXPS software), then the chemical bonding in the O1s high resolution spectra were analyzed and -OH groups identified.The oxygen peak was deconvoluted to bulk oxygen and -OH groups and the relative percentage of -OH in O1s spectra was multiplied by the atomic concentration of oxygen in the samples to obtain at.%. HPLC-DAD measurement details.HPLC system was equipped with a high-pressure pump, column thermostat, autosampler and DAD detector.A Gemini® column, grain size 3 μm, stac.
was used for the separation of SA drugs and their reaction products.phase C18, 110 Å (manufactured by Phenomenex®, USA) with dimensions of 100 x 4.6 mm.The measurement was realized in the gradient elution mode, the mobile phase: acetonitrile (compartment C) with acetate buffer -sodium acetate solution (c = 0.02 M) with the addition of acetic acid adjusted to pH ~ 4.5 (compartment A).The flow rate of the mobile phase was 0.7 mL/min.The separation was realized at a temperature of 30 °C and the injection volume was 10 μl.The gradient elution settings for individual drugs and their degradation products are presented below (Table S1) together with the specific optimized conditions for the detection of drugs and their degradation products (Table S2).Table S3.Crystallite sizes calculated using the Scherrer equation.In more details, the highest binding energy peaks, u``` and v``` located at about 916.9 eV and 898.5 eV, respectively, are results of the Ce 3d 9 4f 0 O 2p 6 final state.The satellite peak u``` associated with the Ce 3d3/2 is characteristic of the presence of Ce 4+ .The lowest binding energy states u, v, u``, and v``, respectively located at 901.1 eV, 882.7 eV, 907.3 eV, and 888.8 eV, are the results of the Ce 3d 9 4f 2 O 2p 4 and Ce 3d 9 4f 1 O 2p 5 final states.Ce 3+ oxides have Ce 3d3/2 and Ce 3d5/2 spectra composed of two multiplets.The highest binding energy peaks, u` and v` located at about 903.4 eV and 885.0 eV, respectively, are the results of the Ce 3d 9 4f 1 O 2p 6 final state.The lower binding energy states, u 0 and v 0 respectively located at 899.6 eV and 881.1 eV, are the result of the Ce 3d 9 4f 2 O 2p 5 final state.
Chromatographic separation was achieved using a binary mobile phase (water (A) with 0.5 mM NH 4 F + 5 mM CH 3 COONH 4 /acetonitrile (B)) delivered in the gradient mode at a flow rate of 0.3 -0.4 mL/min.Gradient elution started at 10% of B (0 -6 min) and linearly increased to 100% of B 0.1 min; then maintained at 100% of B for 60 sec (6 -7 min); then decreased to 10% of B (7.1 -11 min) for re-equilibration of the column.The injection volume of the samples was 100 μl.Mass spectrometric detection was performed using an MRM and SIM scan with an electrospray ionization source in positive mode (ESI+).The measurement conditions: gas temperature 150 °C; gas flow 15 L/min; ion spray voltage 3000 V; sheat gas temperature 400°C; sheat gas flow 11 L/min; nebulizer 30 psi; nozzle voltage 500 V.NMR spectroscopy measurements details.The reaction mixtures of CeAMM, CePER and CeUREA samples with SDM were concentrated by vacuum manifold before the measurement.0.5 ml of each sample was collected in an NMR cuvette containing a capillary sealed with deuterated solvent. 1 H and 1 H-1 H COSY experiments were used to determine the individual signals in samples.The chemical shifts, integration, coupling constant, distances and appearance of signals were compared with the signals of the expected compounds SDM and the decomposition products, i.e. aniline, sulfanilamide and sulfanilic acid.

Figure S3 .
Figure S3.XPS (left) survey spectrum and (right) high-resolution Ce 3d spectrum of prepared

Figure S4 .
Figure S4.In situ DRIFT spectra of the ceria samples recorded at RT (dotted lines) and 200 °C

Figure S5 .
Figure S5.Hydrodynamic particle size as a function of pH measured by DLS.

Figure S6 .
Figure S6.The pH measurement of the solution of SDM (10 mg/L) in RO water.

Figure S7 .
Figure S7.The kinetics of SDM degradation at pH 3.38 and 4.79 without ceria catalyst.

Figure S8 .
Figure S8.The kinetics of adsorption and degradation of SDM on nanoceria samples in

Figure S10 .
Figure S10.(a) LC-MS extracted ion chromatograms of reference standards of the expected

Figure S11 .
Figure S11.LC-MS analysis of samples obtained by extraction of different ceria samples after

Figure S12 .
Figure S12.LC-MS analysis of samples obtained by extraction of different ceria samples after

Table S2 .
Optimized conditions for the analysis of individual drugs and their degradation products.