Enhancing the Chlorine Stability and Antifouling Properties of Thin-Film Composite Reverse Osmosis Membranes via Surface Grafting L-Arginine-Functionalized Polyvinyl Alcohol

Polyamide thin-film composite reverse osmosis (RO) membranes face poor chlorine resistance and antifouling properties, which greatly limit the wide application of RO technology. To evidently enhance chlorine stability, antifouling properties, and the permeability of the RO membrane, in this research, L-arginine (Arg) had been grafted on polyvinyl alcohol (PVA) first, and the functionalized PVA (denoted as PVA-Arg) had been grafted on the RO membrane surface subsequently. Results of X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy indicated the successful synthesis of PVAArg as well as the successful grafting of PVA or PVA-Arg on the RO membrane surface. The permeability, chlorine resistance property, and antifouling properties of all RO membranes were tested. The PVA- or PVA-Arg-grafted RO membranes showed obvious enhancements in permeability, chlorine resistance property, and antifouling properties. For PVA-modified RO membranes, the bonus PVA layer deteriorated its water flux while filtrating. However surprisingly, the PVA-Arg-grafted RO membranes exhibited excellent enhancement in water flux and antifouling properties. For the optimized sample, the pure water flux of the PVA-Arg-grafted RO membrane is 8.3% higher than the nascent RO membrane (57.2 L/m(2) h compared with 52.8 L/m(2) h); the salt rejection of membranes is promoted to around 99.50% from the original 95.58%. Meanwhile, the antifouling properties of PVA-Arg-grafted RO membranes are further enhanced than that of PVA-grafted RO membranes.