UV-Assisted Graft Polymerization of N-vinyl-2-pyrrolidinone onto Poly(ether sulfone) Ultrafiltration Membranes: Comparison of Dip versus Immersion Modification Techniques

Two different techniques were used to photochemically modify 50 kDa poly(ether sulfone) (PES) membranes with the monomer N-vinyl-2-pyrrolidinone (NVP) to increase surface wettability and decrease adsorptive fouling during the constant volume diafiltration of 0.1 wt % bovine serum albumin (BSA). The filtration performance of the modified membranes was compared to that of a commercially available PES membrane and a regenerated cellulose membrane. Both the dip and immersion modification techniques produced membranes with essentially the same wettability as regenerated cellulose, a wettability increase of 30% over the base PES membrane. There was a substantial decrease in the irreversible adsorptive fouling of the base membrane as measured by the permanent flux drop after water cleaning with respect to the initial buffer flux using either modification (from 0.42 to 0−0.09). The immersion-modified membrane with the best performance exhibited no adsorptive fouling, similar permeability, and higher rejection tha...