Enhanced Antifouling and Antibacterial Properties of Reverse Osmosis Membranes via Surface Modification Using Zwitterionic Polymer-Grafted Chitosan

Since the long-term stability of polyamide thin-film composite (PA-TFC) reverse osmosis (RO) membranes is crucial for water treatment processes under different operating conditions susceptible to fouling, various strategies have been employed to maintain the separation performance and address the fouling challenges. Herein, water-soluble poly(2-methacryloxyethyl phosphorylcholine)-grafted chitosan (PMPC-CS) was utilized as a surface modifier for fabricating high-performance PA membranes with enhanced water permeance, antifouling, and antibacterial properties. PMPC-CS was prepared via a one-step in situ radical polymerization using MPC as a monomer and then covalently bonded to the polyamide (PA) layer through amide bond formation. The resulting PMPC-CS modified PA membrane achieved a 22% increase in water permeance (from 1.23 Lm –2 h –1 bar –1 to 1.49 Lm –2 h –1 bar –1 ) while maintaining high salt rejection. Furthermore, it exhibited enhanced antifouling performance, with a flux recovery ratio of ∼93.4% against BSA, and strong antibacterial activity, achieving ∼87.7% inhibition against E. coli . These enhancements are attributed to the synergistic effects of the zwitterionic PMPC’s antifouling behavior and chitosan’s antibacterial functionality. This study presents a facile method for preparing a bio-based grafting material from chitosan and applying it in a simple surface modification process, resulting in high-performance PA membranes with excellent antifouling and antibacterial properties for sustainable water purification.