Efficient sol-gel synthesis of zwitterion functionalized titania for nanofiltration membrane with enhanced selectivity and antifouling performance

The construction of a compact separation layer with selective channel and hydrophilic surface is a promising way to fabricate the composite nanofiltration membranes with both high selectivity and antifouling performance. In this study, a strategy that incorporating zwitterion functionalized titania (ZTi) into membrane surface through facile in-situ sol-gel process is proposed. The titania sol is firstly prepared using tetrabutyl titanate as the precursor and then functionalized by abundant zwitterions based on the chelation reaction. Finally, the ZTi is introduced into polyamide (PA) on the surface of porous polyethersulfone (PES) by in-situ sol-gel method during interfacial polymerization. The physical and chemical structure of the membrane surface is tuned by varying the loading level of titania. Due to the good interfacial compatibility between inorganic ZTi and PA polymer, the optimized PA-ZTi/PES membrane shows a high water flux of 283.5 L m −2 h −1 MPa −1 and a high Na 2 SO 4 rejection ratio of 92.7%, which overcomes the trade-off effect between permeability and selectivity. Moreover, the PA-ZTi/PES series membranes also show superior antifouling performance with flux recovery ratios of 92.9% (against bovine serum albumin) and 95.6% (against humic acid).