High-permeability reverse osmosis membranes with a sequentially constructed antifouling and bactericidal interface for surface water treatment

Membrane fouling, particularly that induced by microbial and organic contaminants, severely limits the efficiency and lifespan of reverse osmosis (RO) membranes in surface water treatment. Herein, a sequential covalent post-modification strategy is developed by exploiting the native carboxyl groups of a commercial RO membrane to fabricate a novel dual-defense RO membrane. Specifically, sulfaguanidine (SG) and poly(glycidyl methacrylate- co -sulfobetaine methacrylate) (PGS) are sequentially immobilized on the polyamide layer via amidation and epoxy ring-opening reactions, with SG and PGS serving as the bactericidal and antifouling components, respectively. Benefiting from this interfacial structure, the resulting membrane (ROSP) achieves a 2.4-fold higher water flux of 34.04 L·m −2 ·h −1 than that of the pristine membrane while maintaining a high NaCl rejection of 98.47%. Furthermore, the ROSP membrane exhibits low irreversible fouling ratios (< 8.27%) during 11 h cyclic fouling filtration tests, displays over 99% bactericidal efficiency against both E. coli and S. aureus , and enhances the tolerated chlorine exposure by 42.9% to 10,000 ppm·h. More importantly, during 144 h of continuous filtration using real surface water, the ROSP membrane maintains stable separation performance and a bactericidal efficiency of 92.63% against native microorganisms. This work offers an effective covalent surface-modification strategy for developing durable RO membranes for surface water treatment.