Evaluation of the effectiveness of poly (phenyl sulfone) / nanoclay mixed matrix membranes for carbon dioxide/methane separation

Abstract

Poly (phenyl sulfone) (PPSU) is a recently introduced poly (aryl sulfone) polymer that has attracted much attention for membrane fabrication. PPSU could fabricate both porous and non-porous membranes. Intrinsic gas permeability of pure PPSU is low, but it has good selectivity for CO2/CH4 separation. Therefore, this study aimed to investigate the effect of adding a layered nanoclay material to PPSU on CO2 permeability and CO2/CH4 selectivity. The fabricated membranes were characterized by FTIR, FESEM, XRD, DSC, EDS, Contact angle, gas solubility, and gas permeability. The permeability of each gas was measured by the constant volume-variable pressure method, and ideal selectivity was determined. The effect of nanoclay loading (1-3 wt.%) and feed pressure (2-8 bar) on the gases' permeability and CO2/CH4 selectivity was investigated at a constant temperature of 27 ± 2°C. The results showed that the addition of the nanoclay to PPSU has a considerable effect on CO2 permeability (up to 52% increase) while CO2/CH4 selectivity remains nearly unchanged or slightly decreases (down to 6%). Solubility measurement results revealed that adding the nanoclay to the PPSU polymer increases the solubility selectivity by 22%, while the diffusivity selectivity is decreased by 23%, revealing the formation of an intercalated morphology, confirmed by XRD analysis.