Performance evaluation of a synthesized and characterized Pebax1657/PEG1000/γ-Al2O3 membrane for CO2/CH4 separation using response surface methodology

In this work, the response surface methodology (RSM) based on the central composite design (CCD) was used to examine effects of different gamma alumina (.-Al2O3) loadings (0 to 8 wt.%) and various polyethylene glycol 1000 (PEG1000) contents (0 to 40 wt.%) as parameters on membrane preparation. Accordingly, pure carbon dioxide (CO2) and methane (CH4) gasses permeability and ideal CO2/CH4 selectivity values were considered as responses. Poly (ether block amide) 1657 (Pebax1657) was used as the base polymer matrix for the membranes fabrication. The neat Pebax1657 membrane was prepared via solution casting-solvent evaporation method and the other membranes were prepared via solution blending technique. Analysis of variance (ANOVA) was used to analyze the experiments statistically and the results indicated that the optimized amounts of gamma-Al2O3 nanoparticles and PEG1000 in order to enhance both CO2 permeability and ideal CO2/CH4 selectivity were 8 wt.% and 10 wt.%, respectively. Additionally, a comparison between the separation performance of the neat membrane, the nanocomposite membrane with the optimum amount of gamma-Al2O3 nanoparticles, the blended membrane with optimum amounts of PEG1000, and the blended nanocomposite membrane with optimum amounts of gamma-Al2O3 nanoparticles and PEG1000 was presented. The obtained gas permeation results showed that the blended nanocomposite membrane exhibits the highest CO2/CH4 separation performance compared to the neat Pebax membrane.