Preparation of antifouling TFC RO membranes by facile grafting zwitterionic polymer PEI-CA

In this work, we synthesized a zwitterionic polymer PEI-CA for the first time and then grafted it onto the surface of polyamide RO membrane via layer-by-layer interfacial polymerization (LbL-IP). XPS and ATR-FTIR techniques were used to verify the successful modification with PEI-CA. The zwitterionic hyperbranched polymer PEI-CA endowed the modified membrane with much improved surface hydrophilicity and decreased surface negative charge. The tailored M-PEICA exhibited a high water permeance up to 3.92 L m(-2) h(-1) bar(-1) (increased by 62 %) while holding a good NaCl rejection (98.93 %). The dynamic fouling experiments proved that grafting of PEI-CA can help to effectively elevate its antifouling performance against most organic foulants except small molecular negatively charged surfactant SDS. Therefore, we further employed the mixed reagents modification strategy with arginine and PEI-CA, the resulting RO membrane M-mixed presented obviously improved antifouling performance towards SDS, the overall antifouling performances are even better than the well-known RO membrane CR100 of DOW FILMTEC (TM), that well illustrated multiple reagents modification strategy could be an efficient way that can meet all critical standards. Overall, the novel polymer PEI-CA and as-fabricated RO membranes with outstanding antifouling performances in this study have vast application potential in field of water treatment.

Automated summary

In this study, a zwitterionic polymer PEI-CA was synthesized and grafted onto a polyamide RO membrane, resulting in improved hydrophilicity, decreased negative charge, and enhanced water permeance and NaCl rejection. The modification strategy of mixing reagents with arginine and PEI-CA further improved the antifouling performance against SDS. The novel polymer and modified RO membranes demonstrated excellent potential for water treatment.