Highly stable epoxy-crosslinked polybenzimidazole membranes for organic solvent nanofiltration under strongly basic conditions

Organic solvent nanofiltration (OSN) often needs to be conducted under extreme conditions in the chemical and food industries. In this work, we fabricated polybenzimidazole (PBI)-based OSN membranes that possess excellent stability under strongly basic conditions at pH 13. Two crosslinked PBI membranes were prepared by treating pristine PBI membranes with two epoxy-containing crosslinkers. Various permeation and characterization tests were performed to investigate the resistance of the membranes to solvents and basic environments. Both crosslinked membranes displayed reasonable permeance in pure solvents at room temperature under 10 bar operating pressure, along with a sharp molecular discrimination performance in ethanol environments. The crosslinked PBI membranes were found to be stable and did not completely lose their separation properties at high pH, although the effective pore size of the membranes increased presumably due to swelling. The separation performance of the membranes was found to be reversible between filtrations of neutral and basic aqueous solutions. Therefore, our crosslinked PBI membranes, which display exceptional stability, hold great potential for applications in OSN under basic conditions. • Polybenzimidazole (PBI) OSN membranes were fabricated using crosslinkers containing epoxy groups at both ends. • The OSN performance of PBI membrane was found to be controlled by the structures of the crosslinkers. • The crosslinked PBI membranes exhibited a sharp molecular separation performance in organic solvents. • The crosslinked PBI membranes showed an outstanding chemical resistance under strongly basic conditions.