Development of fouling-resistant polyethersulfone ultrafiltration membranes via surface UV photografting with polyethylene glycol/aluminum oxide nanoparticles

Abstract

Polyethersulfone ultrafiltration membranes prepared via immersion precipitation with similar pore size were modified using UV irradiation with two nano-sized hydrophilic compounds of a different nature (an organic compound and a metal oxide). Effects of PEG/Al2O3 nanoparticles on membrane structure and the resulting performance were compared to determine the material with the best antifouling properties. Membranes were characterized by hydrophilicity (water contact angle, porosity, equilibrium water content and average pore radius), surface microscopic techniques (ATR-FTIR, SEM, EDX and AFM) and cross-flow ultrafiltration experiments (hydraulic permeability, membrane resistance and antifouling measurements). Membrane antifouling properties were analyzed by several fouling/rinsing cycles using feed solutions of PEG of 35,000 g mol 1 with a concentration of 5 g L 1.Water contact angle measurements, ATR-FTIR spectra, SEM images and EDX analysis indicated the presence of PEG/Al2O3 nanoparticles on the membrane surface. All UV-grafted membranes had higher hydraulic permeability than the unmodified membrane. Furthermore, polyethersulfone membranes photografted with 2.0 wt% PEG and 0.5 wt% Al2O3 displayed superior antifouling properties and desirable performance compared to all membranes tested. Therefore, this study proved that UV photografting of PEG/Al2O3 onto membrane surfaces is an appropriate technique for modifying polyethersulfone membranes to minimize membrane fouling.