A rigid-flexible interpenetrating polyamide reverse osmosis membrane with improved antifouling property fabricated via two step modifications

Polyamide thin-film composite reverse osmosis (RO) membranes usually suffer from fouling problem, which greatly limits the wide application of RO technology. In this study, a novel rigid-flexible interpenetrating polyamide RO membrane was fabricated via two step modifications to alleviate the membrane fouling during the RO process. The first step modification was carried out by incorporation a new aliphatic diamine of 1,3-diamino-2-propanol (DAPL) into the aromatic m-phenylenediamine (MPD) aqueous solution to react with trimesoyl chloride (TMC) to form a rigid-flexible interpenetration polyamide (PA) separation layer for enhancing its permeability. Then, the second modification was performed by grafting PVA on the top surface of the DAPL-based PA layer to tailor more hydrophilic, smoother and less negatively charged surface and endowed the modified membrane favorable antifouling property. Under the optimized condition, the permeability flux of the modified RO membrane reached 58.6 L/m2h with an about 58.8% increase than the pristine RO membrane (about 36.9 L/m2h), and the salt rejection was also maintained about 99.6% without any loss. At the same time, the modified RO membrane presented a favorable resistance to the dye foulants of methylene blue (MB) and crystal violet (CV) with flux recovery rate of 76.8% and 84.2% respectively. This study provides a facile and effective way to fabricate a novel antifouling reverse osmosis composite membrane with favorable comprehensive separation performance.