Modification of PES/PU membrane by supercritical CO2 to enhance CO2/CH4 selectivity: Fabrication and correlation approach using RSM

Integrally skinned asymmetric gas separation membranes of polyethersulfone (PES)/polyurethane (PU) blend were prepared using supercritical CO2 (SC-O-2) as a nonsolvent for the polymer solution. The membrane consisted of a dense and a porous layer, which were conjoined to separate CO2 from CH4. The FTIR, DSC, tensile and SEM tests were performed to study and characterize the membranes. The results revealed that an increase in SC-CO2 temperature causes an increment in permeance and a decrease in membrane selectivity. Furthermore, by raising the pressure, both permeance and selectivity increased. The modified membrane with SC-CO2 had much higher selectivity, about 5.5 times superior to the non-modified membrane. This higher selectivity performance compared to previous works was obtained by taking the advantages of both using partial miscible blend polymer due to the strong polar-polar interaction between PU PES and SC-CO2 to fabricate the membrane. The response surface methodology (RSM) was applied to find the relationships between several explanatory variables and CO2 and CH4 permeance and CO2/CH4 selectivity as responses. Finally, the results were validated with the experimental data, which the model results were in good agreement with the available experimental data. (C) 2018 The Chemical Industry and Engineering Society of China, and Chemical Industry Press. All rights reserved.