Technoeconomic Analysis for Biodegradable and Recyclable Paper Coated with Synthetic Ionic PBAT for Packaging Application

This study presents a technoeconomic analysis (TEA) for a novel ionic polybutylene adipate-co-terephthalate (PBAT), CPBAT, as a paper coating material, showcasing excellent water and oil resistance. This TEA determined total capital investment, operating costs, and minimum selling prices for a production capacity of 1,000 kg of CPBAT per day. The minimum selling prices of CPBAT coated on Kraft paper (CPBAT-K) and CPABT coated on starch-coated Kraft paper (CPBAT-S) are estimated to be $1.327/m2 and $1.864/m2, respectively. Additionally, the results of a sensitivity analysis show that the production of CPBAT-K and CPBAT-S is highly sensitive to the production capacity, raw material costs, energy efficiency of the coating process, reaction energy, and reaction yield. Recovery of the ionization solvent only marginally increases the selling prices of CPBAT-K and CPBAT-S, and hence, it is highly favorable. By increasing production capacity, lowering raw material costs, using energy-efficient coating machines, and partially recovering energy from reactions, the prices of CPBAT-K and CPBAT-S can be reduced to $0.588/m2 and $0.914/m2, respectively. Given that commercial polyethylene-coated paper prices range from $0.94/m2 to $1.850/m2, CPBAT-based coated papers with comparable mechanical and barrier properties along with biodegradability and recyclability are positioned as highly competitive and sustainable alternatives in the market.

This section details the calculation methods used to perform the technoeconomic analysis (TEA).

Overview of the Process
A Process flow diagram is in Figure S1 that shows the production starts with drying PBAT in a rotary dryer, then the dried PBAT is reacted with 1,4-butanediol in the presence of zinc acetate as a catalyst in a continuous stirred tank reactor (CSTR), PBAT-diol production reactor, to yield smaller polymer chains of PBAT-diol within 6 hours at 200 °C.PBAT-diol is then allowed to react with meso-butane-1,2,3,4tetracarboxylic dianhydride (MBTCA) in another CSTR, CPBAT production reactor, at 170 °C for 30 min to produce CPBAT.To emulsify CPBAT in water, it is mixed with aqueous ammonium hydroxide solution in a CSTR, CPBAT emulsification reactor, for 45 min at 77 °C and transferred into tank I for storage.The energy for reactions is generated by the combustion of natural gas in a furnace.The cost and minimum selling price (MSP) of production of CPBAT include drying PBAT and the first two reaction steps.For finding the cost and minimum selling price of kraft paper coated with CPBAT, the coating step along with drying is included.The coating machine on the left side is used to coat CPBAT on kraft paper or starch coated kraft paper and is a press coating machine with the drying unit that is integrated into it.To analyze the impact of the coating step alone, the drying step is designed separately.Evaporated ionization/emulsification solvent is condensed, in an ionization solvent condenser, and recycled back into the CPBAT emulsification reactor.

Coating CPBAT emulsion
Second dryer/boiler (built in coating machine)

Condenser
Condensation of water-ammonium mixture

Starch solution storage
Coating machine with built-in dryer Drying starch coated paper Below is the stream table according to Error! Reference source not found..

Drying wet PBAT
Commercial PBAT usually has 1-2% water.Herein, it is assumed that the commercial PBAT has 2% water.The energy for drying PBAT goes both for evaporating water and preheating PBAT to the reaction temperature in reactor I. Ideally, moisture content was reduced to 0%.
The feedstock data have been summarized in Table S3.S3.
Additionally, for designing the dryer using hot air, the data in Table S4 was used.C. Higher Heating Values: The higher heating values (HHV) required for calculating the heat of reactions, were calculated using the Gaur and Reed formula [1].
Eq S1.Gaur and Reed Expression for calculation of HHV (X i = mass percentage and HHV is in MJ/kg)

Supporting Information
S-10 While this reaction is exothermic, some energy input is required to move the reaction forward.This energy is estimated based on the energy requirement for the bench-top experiments, scaled up to industrial production capacity.
The energy from a hot plate goes partly to the reaction and partly to the environment through convection.Several studies have shown that the power was almost linearly related to the temperature below 600 K [3], [4].Hence energy requirement for the samples at 200 °C with the maximum temperature of the instrument (200 °C) power demand is (200/200x100)% of the maximum power of the instrument.Specifications of the hot plate is listed in Table S6 and the schematic of the hot plate is shown in Figure S3.This energy is much higher than the energy requirement for an industrial setting due to the large heat requirement for glassware with no insulation while an adiabatic reaction in an insulated reactor can be used.Herein, in our base case scenario, we have considered the energy from the exothermic is not used

S-13
elsewhere and in our sensitivity analysis, we assumed the maximum energy requirement is the scale up from the bench-top experiment is demanded.
All other energy input to the reactors is calculated in the same way.The energy requirement for PBAT-diol production is the highest as the energy loss correlates with the temperature and duration of the reaction in bench-top experiments.Similarly, the energy requirement for the reaction with lower temperature, e.g.CPBAT emulsification at 77 °C is much lower.
To compare how much this method of energy calculation can be higher than the industrial scale, a study was found for calculating the breaking of the ester bonds in PETG.In this investigation, the energy for 1,000 kg PETG cards containing 920 kg PETG reaction with EG is estimated to be 800 MJ.Considering 18.57 wt% of PETG is the CHDM molecule, the rest has a similar structure to PET and the number of ester bonds should be the same.Hence, the mass of PET is 749.16 kg which equals 3,824.5 mol PET.In each repeating unit of PET, there are two ester bonds, therefore, there are 7,648 mol ester bonds present.It is assumed that 49.16/1,000 of the total energy for the reaction goes to breaking the ester bond and the energy for breaking one ester bond is as follows: Energy for rection comes from burning natural gas in a furnace.Composition of natural gas is up to 97% methane [5], hence it is assumed that it is only composed of methane.The furnace was designed in HYSYS Aspen software with the following information.
When the total amount of energy from scale up of the bench-top experiment is found, for the furnace designed in HYSYS Aspen, the natural gas enters the furnace at 200 °C with a flow rate of 12.5 kg/h while air has flowed to the furnace at the rate of 225.3 kg/h at 25 °C.The flare gas leaves the furnace at 505.5 °C.
In this situation, the shell's overall volume is 9.7 m 3 .

Reactor Design
For designing the reactor, 1 st order reaction is assumed for all reactions.The graph below shows the reaction rate for PBAT-diol production that is 1 st order with respect to PBAT concentration.For converting mol of PABT to concentration, melt density of PBAT and density of butanediol were used from Perry's handbook [6].

Figure S4.
The reaction rate for PBAT-diol production from PABT and butanediol 0.0E+00 Assuming that only 2-3 rd of the reactor is filled, the actual volume would be: The cost of the reactor is found in Figure 13-15 of the book Plant Design and Economics for Chemical Engineers [7].

Coating
CPBAT and/or starch are applied using a press coating machine.The oven is integrated into the coating machine.However, the evaporation of solvent is designed separately to give some insights about the impact of coating alone as well as drying.S9 and Table S10.S11 is the summary of specifications of each paper as well as the price per area.

Drying coated paper
As mentioned earlier, while the drying step is integrated into the coating machine, energy for heating and evaporation of solvents were estimated separately and deducted from the coating process to have a clearer idea of how much energy is allocated to coating versus drying.Energy for evaporating waterammonia mixture was calculated by modeling the process in HYSYS Aspen software with the inputs and outputs derived from the model summarized in Table S12.

Figure S5 .
Figure S5.Xiamen Simy Customizable Coating Line Solvent Coater Machine with OvenSince the maximum capacity of coating machine is limited to 7,200 meter per day, 5 coating machines can work with lower coating speed than 5 m/min to coat 1,000 kg/day of CPBAT.Coating starch is analogous, and 5 coating machines should work with lower speed to deliver the required starch coated papers.Data required for energy calculation and price of the coating machine is summarized in TableS9

Table S1 .
Label Definitions for the Process Flow Diagram

Table S4 .
Parameters for designing the dryer.

Table S6 .
Hot plate specifications Schematics of the hot plate and energy inputs and output.The maximum energy output of the hot plat working at 200 °C is as follows: = 15,076.8Energyloss to the surroundings from a 20 cm by 20 cm square hot plate and a 5 cm tall oil bath with a 15 cm diameter is as follows: ,1 = 2.5   2 × (182 -25)  × (3.14 × 0.15 × 0.05)  2 × 6 × 3,600  ×

Table S8 .
Specifications of the coating machine

Table S10 .
[5]a for starch coated on unbleached Kraft paper from ULINE (75 lb)Data for ULINE 50 lb and 75 lb Kraft paper as well 50 lb ULINE Poly coated paper (polyethylene coated paper) was available in their website[5].Since in our experiments, 50 lb Kraft paper was used, data for 75 lb Poly coated paper was estimated based on 75 lb Kraft paper and 50 lb Poly coated paper.Table

Table S11 .
Specification and price of Kraft paper and Poly coated paper (50 lb and 75 lb) from Uline.

Table S13 .
Summary of equipment costs and sizing for CPBAT, CPABT-K and CPBAT-S production.