Effect of Polydimethylsiloxane (PDMS) Coating Concentration on the Physicochemical Properties and CO₂/CH₄ Separation Performance of Cellulose Acetate Hollow Fiber Membranes

In this research, Polydimethylsiloxane (PDMS) -layered hollow fiber membranes (HFMs) of cellulose acetate (CA) have been studied for CO₂/CH₄ separation. PDMS coatings at three different loading, i.e., 1, 3, and 5 wt.%, have been introduced to improve gas transport performance and membrane stability. The CA membrane coated with 3 wt.% PDMS performed the best, having permeance of CO₂ 32.65 GPU and CO₂/CH₄ selectivity of 18.6, with approximately 19% and 63% increases in permeance and selectivity over the pristine CA membrane, respectively. Fourier Transform Infrared Spectroscopy (FTIR) analysis showed the corresponding peaks PDMS in the membranes, while thermogravimetric analysis (TGA) confirmed their stability. Robeson plot analysis revealed that the optimized membrane is close to the upper bound for CO₂/CH₄. This study shows that optimized spinning conditions, post treatment coating enhanced the CO2/CH4 selectivity.