Highly selective and chlorine-resistant polyamide reverse osmosis membranes for advanced water treatment via...

Polyamide (PA) reverse osmosis (RO) membranes face persistent challenges including the trade-off between permeance and selectivity, limited chlorine resistance, and insufficient long-term stability. In this work, these challenges were addressed by developing a synergistic modification strategy in which Fenton oxidation facilitates the grafting of aromatic amine monomers, with p-aminobenzenesulfonamide (SAs), p-aminobenzoic acid (PABA), and p-aminobenzenesulfonic acid (SFA) as functional modifiers, marking the first application of this approach in membrane modification. This approach introduces phenazine-based quinone imine structures and additional functional groups onto the membrane surface, facilitating rearrangement of aromatic ring stacking from "π-π" to "T-π" configurations within the PA molecular backbone, while simultaneously modulating surface hydrophilicity and charge. As a result, water permeance increases from 4.91 to 6.01 L·m^-2·h^-1·bar^-1, NaCl permeance decreases from 0.373 to 0.201 L·m^-2·h^-1, and perm-selectivity (A/B) rises from 14.8 to 24.4 bar^-1 for PA-PABA membranes. Notably, modified membranes maintain NaCl rejection above 98.50% even after 50,000 ppm·h of active chlorine, with PA-SAs showing particularly robust chlorine resistance, far superior to conventional PA membranes. These results highlight that Fenton-assisted aromatic amine grafting, based on aqueous-phase reactions, low energy consumption, and scalable grafting monomers, provides a new approach for the scalable fabrication of high-performance RO membranes, holding significant industrial potential and offering a promising solution to extend membrane operational lifetimes in advanced water treatment applications.