Improving permeability and antifouling performance of polyethersulfone ultrafiltration membrane by incorporation of ZnO-DMF dispersion containing nano-ZnO and polyvinylpyrrolidone

Abstract

A new approach for fabricating polyethersulfone (PES)/ZnO ultrafiltration membrane is demonstrated. Nano-ZnO coated with polyvinylpyrrolidone (PVP) was prepared using dimethylformamide (DMF) as the solvent. The obtained ZnO-DMF dispersion was blended as an additive to fabricate PES/ZnO membranes with wet phase separation. The structure and performance of PES/ZnO membranes were characterized by the evaluation of surface pore size, porosity, water contact angle, pure water flux, BSA rejection and filtration resistance. The overall effect of ZnO-DMF dispersion addition on the structure and performance of the membrane was investigated by contrast with pure PES membrane. Compared with a pure PES membrane, PES/ZnO membranes have higher surface pore size, pore density and porosity, as well as improved surface hydrophilicity. The water fluxes of PES/ZnO membranes increased by approximately 210% compared with the pure PES membrane, with little change in BSA rejection. Besides, PES/ZnO membranes were also fabricated with different ZnO-DMF dispersions comprising a fixed content of PVP and different contents of nano-ZnO. The concrete contribution of nano-ZnO in ZnO-DMF dispersion on improving membrane performance was investigated by comparison with PES/PVP membrane. The results indicated that the incorporated nano-ZnO was favorable to the improvement of compaction resistance and antifouling property. The thermal stability of the PES/ZnO membranes was also improved compared to that of PES membrane.