Enhancing the antifouling properties and permeability of polyamide TFC RO membranes via Ag₃PO₄ nanoparticle incorporation

Freshwater scarcity remains a critical global challenge, driving the advancement of efficient and sustainable desalination technologies like reverse osmosis (RO). Here, thin-film composite (TFC) RO membranes were modified by embedding silver orthophosphate (Ag₃PO₄) nanoparticles into the polyamide active layer to enhance antifouling performance, water permeability, and resistance to chlorine-induced degradation. Ag₃PO₄, known for its strong antibacterial activity, was incorporated via interfacial polymerization. The resulting membranes were systematically characterized in terms of surface morphology, hydrophilicity, surface charge, and chemical functionality. The optimal membrane containing 0.01 g Ag₃PO₄ exhibited a reduced contact angle of 48.8° (by 20 %), confirming enhanced surface hydrophilicity, and a slightly more negative zeta potential compared to the bare membrane. It achieved a water flux of 66 L/m².h at an operating pressure of 1.5 MPa, high salt rejection (98.4 %), and excellent antifouling behavior, with a flux recovery ratio of 94 % after protein fouling and physical cleaning. Chlorine resistance was significantly enhanced, with only ∼1 % decline in salt rejection after chlorination, compared to >10 % loss in the unmodified membrane. Long-term operational stability under saline conditions was confirmed, with ∼99 % salt rejection maintained over 96 h. These results demonstrate the potential of Ag₃PO₄ as an effective additive for developing robust, high-performance TFC RO membranes for practical water purification applications.