Ultrahigh Molecular Weight PEI-GO Membranes Overcome the Separation Performance-Swelling Trade-Off for High-Performance MeOH/DMC Separation

Dimethyl carbonate (DMC) is an eco-friendly organic compound, but its production process generates a methanol (MeOH)/DMC azeotrope, resulting in high energy consumption for separation. With its low energy consumption and environmental benefits, pervaporation membrane separation technology presents a promising solution for separating azeotropic organic mixtures. In this study, polyethyleneimine (PEI) is employed as the membrane material for the separation of MeOH/DMC, owing to its strong affinity for MeOH. However, the poor organic solvent swelling resistance is a significant challenge for the PEI matrix. Therefore, ultrahigh molecular weight PEI (Mn = 750,000) is utilized, and graphene oxide (GO) is incorporated to improve the organic solvent resistance of the PEI-based membrane. The results indicate that the optimized membrane demonstrates a total flux of 0.67 kg·m -2 ·h -1 and a separation factor of 89 for a 10 wt% MeOH/DMC mixture at 60°C. Notably, enhancing the molecular weight of PEI and introducing GO contribute to a significant improvement in the membrane's resistance to solvent swelling, breaking the trade-off between separation performance and swelling resistance. This work demonstrates the strong potential of PEI membrane materials for effective application in the separation of MeOH/DMC.