Zwitterion grafted forward osmosis membranes with superwetting property via atom transfer radical polymerization

A superwetting forward osmosis membrane was prepared by grafting a zwitterion (2-methacryloyloxyethyl phosphorylcholine, MPC) onto the polyamide membrane layer via atom transfer radical polymerization (ATRP) to enhance antifouling property. The modification of the hydrophilic layer was confirmed by the characterization including Fourier-transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and contact angle goniometer. Moreover, membrane antifouling performance was evaluated by dynamic membrane fouling test using bovine-serum-albumin (BSA) and sodium alginate (SA). The grafted membranes not only showed high fouling resistance after being exposed to up to 500 ppm SA for 10 h, but also demonstrated excellent water flux recovery with the presence of up to 1000 ppm BSA, which was significantly improved as compared to the unmodified membrane. Robust hydration layer formed by the grafted zwitterion polymer could act as a physical and energy barrier preventing attachment of organic foulants on the membrane surface, thus significantly improving membrane fouling resistance.