Enhancing the Chlorine Stability and Antifouling Properties\nof Thin-Film Composite Reverse Osmosis Membranes via Surface Grafting <i>L</i>‑Arginine-Functionalized Polyvinyl Alcohol

Polyamide thin-film composite reverse\nosmosis (RO) membranes face\npoor chlorine resistance and antifouling properties, which greatly\nlimit the wide application of RO technology. To evidently enhance\nchlorine stability, antifouling properties, and the permeability of\nthe RO membrane, in this research, <i>L</i>-arginine (Arg)\nhad been grafted on polyvinyl alcohol (PVA) first, and the functionalized\nPVA (denoted as PVA–Arg) had been grafted on the RO membrane\nsurface subsequently. Results of X-ray photoelectron spectroscopy\nand Fourier transform infrared spectroscopy indicated the successful\nsynthesis of PVA–Arg as well as the successful grafting of\nPVA or PVA–Arg on the RO membrane surface. The permeability,\nchlorine resistance property, and antifouling properties of all RO\nmembranes were tested. The PVA- or PVA–Arg-grafted RO membranes\nshowed obvious enhancements in permeability, chlorine resistance property,\nand antifouling properties. For PVA-modified RO membranes, the bonus\nPVA layer deteriorated its water flux while filtrating. However surprisingly,\nthe PVA–Arg-grafted RO membranes exhibited excellent enhancement\nin water flux and antifouling properties. For the optimized sample,\nthe pure water flux of the PVA–Arg-grafted RO membrane is 8.3%\nhigher than the nascent RO membrane (57.2 L/m² h compared\nwith 52.8 L/m² h); the salt rejection of membranes is promoted\nto around 99.50% from the original 95.58%. Meanwhile, the antifouling\nproperties of PVA–Arg-grafted RO membranes are further enhanced\nthan that of PVA-grafted RO membranes.