An investigation of blended polymeric membranes and their gas separation performance

Abstract

This research work was carried out to investigate the influence of blending polymer membranes on the performance of CO₂/CH₄ separation. This was obtained via blending glassy and rubbery polymers at different concentrations, using solution casting and a solvent evaporation method. All fabricated membranes were characterized by field emission scanning electron microscopy (FESEM), thermo gravimetric analysis (TGA) and Differential Scanning Calorimetry (DSC). The membranes were observed to have a dense structure as depicted by FESEM, low residue solvent by TGA and a miscible homogeneous blend structure by DSC. The performance of CO₂/CH₄ separation of the new blend membranes was compared against that of pure PES membrane at pressures varying from 2 to 10 bar. The experimental results showed that the incorporation of rubbery polymer, polyvinyl acetate (PVA_c), into pure polyethersulfone (PES), which is a glassy polymer, resulted in membranes having more efficient CO₂ separation. However, by increasing the pressure, the permeability dropped because of the glassy behavior of the membranes. The significant improvement of CO₂/CH₄ selectivity by adding PVA_c in comparison to pure PES membrane indicates that the rubbery polymer (PVA_c) can be used to enhance CO₂ separation from CO₂/CH₄ mixtures.