Nanoporous polyethersulfone membranes prepared by mixed solvent phase separation method for protein separation

Nanoporous polyethersulfone (PES) membranes with high surface porosity and uniform pore size distribution were prepared by combining the phase separation in NMP/nonane mixed solvent system with the traditional nonsolvent induced phase inversion process. The effects of PES concentration, nonane concentration, evaporation time, casting solution temperature, and varied mixed solvent systems on the porous PES membrane surface morphology were thoroughly investigated and optimized. The optimized nanoporous PES membrane showed a high surface porosity with a uniform pore size of 20 nm, rendering an exceptional molecular weight cut-off of as low as 100 k Dalton. In addition, the membrane exhibited a significant molecular size exclusion with water permeance of 121 LMH bar−1, bovine serum albumin (BSA) protein rejection of 60.1%, and γ-globulin protein rejection of 99.5% at 0.5 bar, respectively, demonstrating the potential of the as-prepared nanoporous PES membrane for application in protein separation.