A novel reverse osmosis membrane with regenerable anti-biofouling and chlorine resistant properties

Currently, biofouling and the chlorine degradation of membrane during the control of biofouling are still the major obstacles to the development of reverse osmosis (RO) membranes technology. In this work, both the anti-biofouling and the chlorine resistant properties of a commercial aromatic polyamide RO membrane (RE4021-TL, Woongjin Chemical Co., Ltd.) are improved by carbodiimide-induced grafting with imidazolidinyl urea (IU). The grafted IU not only endows the membrane with high anti-biofouling property by acting as an anti-microbial agent but also endows the membrane with the other durable and regenerable anti-biofouling and chlorine resistant properties by acting as the precursor of N-halamine. The grafting of IU and the grafting amount are analyzed by ATR-FTIR and XPS, respectively. The hydrophilicity of the membrane surface is improved obviously and the isoelectric point of the membrane surface shifts toward higher value. A cycling experiment indicates the high regeneration abilities of both the anti-biofouling and the chlorine resistant properties. Moreover, the long-term investigation (100 days) results show that the IU modification accompanied with the periodical free chlorine pretreatment in the RO systems is a potential strategy to increase the lifetime of the commercial RO membranes in practical application.