A facile crosslinking method for polybenzimidazole membranes toward enhanced organic solvent nanofiltration performance

• A facile method of crosslinking polybenzimidazole membranes using KMnO 4. • Crosslinking is quick and performed under relatively green and mild conditions. • Membrane shows superior separation performance and solvent stability. • No significant change in the membrane with either polar or nonpolar solvents. • Applications in petrochemical and pharmaceutical industries. Herein, a facile method for crosslinking polybenzimidazole membranes applied in organic solvent nanofiltration (OSN) using an aqueous potassium permanganate (KMnO 4 ) solution is presented. The membranes were crosslinked under mild water-based conditions at room temperature for less than 4 h. The crosslinked polybenzimidazole OSN membrane exhibited superior separation performance and enhanced stability in various solvents, including dimethylformamide and N -methyl-2-pyrrolidone. The crosslinked membranes exhibited greater than 90% rejection rate for dyes with molecular weights in the range of 327 to 1017 Da, and they were compatible with various common organic solvents such as ethanol, isopropyl alcohol, acetone, and dimethylformamide. Furthermore, no significant change in the membrane performance was observed when polar and nonpolar solvents were used in filtration experiments.