Surface modification on thin-film composite reverse osmosis membrane by cation complexation for antifouling

Abstract

A facile surface modification method has been developed for improving the antifouling property of TFC membranes by immobilizing poly(ethylene glycol) (PEG) onto polyamide (PA) surface. PEG has been chelated and immobilized onto PA surface by ion-dipole interaction between ether oxygen atoms in PEG backbone and –COONa in PA layer. The resulting TFC membranes were characterized by ATR-FTIR, XPS, SEM, AFM, WLI, zeta potential as well as static contact angle. The changes in chemical composition and morphology of the membrane surface indicate the successful modification process. The permeation property of the PEG modified TFC membranes dependence on PEG concentration, treatment temperature and time has been investigated thoroughly. The optimized PEG modified membrane shows a NaCl rejection of 99.04%, higher than that (97.79%) of the virgin membrane. More importantly, PEG modified membrane exhibits much more improved organic fouling-resistance ability than control sample. Typically, after BSA fouling for 12 h, PEG modified membrane loses about 19% of the initial flux, much lower than that of the virgin PA membrane (40%). Furthermore, the flux recovery of the PEG modified membrane reaches about 95% after cleaning, much higher than that of the virgin PA membrane (79%). Therefore, this simple, rapid, environment-friendly and cost-effective modification approach will provide a method for mitigating the long-term fouling of reverse osmosis membrane.