CO2-selective poly (ether-block-amide)/polyethylene glycol composite blend membrane for CO2 separation from gas mixtures

This work focuses on the preparation of composite blend membranes based on poly (ether-block-amide) (Pebax-1657) by incorporating polyethylene glycol (PEG) for gas separation applications. The influence of PEG with different molecular weights (PEG600, PEG1500, and PEG4000) at loading content in the range of 10%wt. to 40%wt. was investigated on the microstructure and gas separation performance of the prepared blend membranes. The fabricated membranes were characterized using SEM, XRD, and water contact angle analyses. Based on the experimental results, the blending of low molecular weight PEG (PEG600) into the Pebax-1657 matrix increased the chain mobility of the membrane, led to a smooth microstructure, and improved the hydrophilicity of the blend membranes, as well as enhanced the gas permeability of N-2, O-2, CH4, and CO2, but only slightly affected the ideal selectivity of O-2/N-2, CH4/N-2, CO2/N-2, and CO2/CH4. In contrast, the incorporation of PEG1500 and PEG4000 meaningfully increased the membrane crystallinity, decreased chain mobility, resulted in a rough microstructure, and reduced the blend membranes' hydrophilicity. For CO2/N-2 mixture, the Pebax/40%PEG600 membrane had CO2 permeability of 62.9 Barrer and selectivity of 83.8, while the Pebax/20%PEG600 showed the CO2 permeability of 63.12 Barrer and selectivity of 23.6 for CO2/CH4 separation.

Automated summary

This study focused on preparing composite blend membranes for gas separation by incorporating polyethylene glycol (PEG) with different molecular weights into a poly (ether-block-amide) matrix, finding that low molecular weight PEG increased membrane chain mobility and gas permeability, while high molecular weight PEG increased membrane crystallinity and decreased hydrophilicity.