Cross-linked copolyimide-P84/CAU-10-H/branched polyethyleneimine membranes for organic solvent nanofiltration

The advancement of organic solvent nanofiltration (OSN) is often hindered by the inherent trade-off between permeance and rejection. In this study, we present a novel nanocomposite mixed matrix membrane (MMM) fabricated by integrating a compatible metal–organic framework (CAU-10-H) into a co-polyimide (P84) matrix. The resulting P84/CAU-10-H membrane was cross-linked using branched polyethyleneimine (PEI) to produce a P84/CAU-10-H/PEI MMM with robust resistance to harsh organic solvents, making it suitable for OSN applications. The integration of CAU-10-H, PEI, and P84 significantly enhanced the OSN performance, improving sieving efficiency and reducing fouling tendencies. The fabricated membrane exhibited outstanding permeance across various solvents, with values of 42.4, 45.4, 24.5, and 27.1 LMH/bar for methanol, acetone, N-methyl-2-pyrrolidone (NMP), and dimethyl sulfoxide (DMSO), respectively. Besides, the P84/CAU-10-H/PEI MMM demonstrated excellent rejection (Brilliant yellow (BY) > 90 %, Congo red (CR), Methyl blue (MB), Evans blue (EB), and Alcian blue (AB) > 99 %, respectively). In a 96-hour long-term test, the membrane demonstrated excellent stability and anti-fouling properties. This study presents a facile and viable approach for designing and constructing novel OSN MMMs.