Enhancing chlorine resistances and anti-biofouling properties of commercial aromatic polyamide reverse osmosis membranes by grafting 3-allyl-5,5-dimethylhydantoin and N,N′-Methylenebis(acrylamide)

Abstract

To enhance membrane chlorine resistance and anti-biofouling property, a commercial aromatic polyamide reverse osmosis (RO) membrane was modified by free-radical graft polymerization of 3-allyl-5,5-dimethylhydantoin (ADMH) and then crosslinked by N,N′-Methylenebis(acrylamide) (MBA). Attenuated total reflective Fourier transform infrared spectra (ATR-FTIR) verified the successful modification of ADMH and MBA on membrane surface. It was shown that a new FTIR adsorption band at 1716cm−1 corresponding to carbonyl groups in hydantoin ring and MBA appeared after graft polymerization. Based on X-ray photoelectron spectroscopy (XPS) and contact angle measurements, graft polymerization increased the nitrogen atom content and surface hydrophilicity of the raw membrane. The salt rejections of the modified membranes were higher than those of the raw membranes, but the water fluxes decreased. After chlorination and sterilization cycles, slighter changes were observed in water fluxes, salt rejections and sterilization effects on Escherchia coli compared with the raw membranes. The repeatable chlorine resistances and anti-biofouling properties of the membranes modified by ADMH and MBA were significantly enhanced.