Influence of solvent exchange time on mixed matrix membrane separation performance for CO2/N2and a kinetic sorption study

Carbon dioxide (CO 2 ) is the largest contributor of greenhouse gas emissions. Mixed matrix membranes (MMMs) have recently received attention as an attractive candidate for membrane-based separation, for which MMMs can serve as an alternative to conventional polymeric and inorganic membranes. In this work, MMMs were developed using a cellulose acetate polymer with multi-walled carbon nanotubes. Vacuum drying and solvent-exchange drying methods were compared with different solvent exchange times (ethanol and hexane) based on the MMM morphologies and separation performances. The sorption of CO 2 and the diffusion and solubility coefficients of the MMMs that were synthesized using the two drying methods mentioned above were determined kinetically. The separation results supported the effectiveness of the newly proposed solvent-exchange technique, where the MMMs that were treated with ethanol for 4h followed by n-hexane for 1h (M6) had greater mechanical strength and a better CO 2 /nitrogen (N 2 ) separation performance at 40.17. Additionally, the kinetic results indicated that the solubility coefficient directly influenced the CO 2 permeance, with the highest value of 198.352×10 11 cm 3 (STP)/cm 4 cmHg observed for the M6 membrane sample (4h ethanol followed by 1h n-hexane)