Protective Alumina Nanolayers Enhance Ozone Resistance of Polyamide Reverse Osmosis Membranes

Water scarcity is an escalating global challenge, leaving billions without consistent access to clean water. Desalination, particularly through reverse osmosis (RO), has become a critical method of producing fresh water from saline sources. However, thin-film composite (TFC) polyamide (PA) RO membranes, which are the standard for industrial desalination, are susceptible to biofouling and chemical degradation by disinfectants, which limits their performance and longevity. Biofouling reduces the efficiency of desalination by increasing the energy demand, while ozone, a commonly used disinfectant, degrades the PA active layer, reducing salt rejection and structural integrity. This work presents a novel approach to enhancing the durability of TFC-PA membranes exposed to ozone disinfection. The atomic layer deposition (ALD) of ultrathin alumina coatings on the membrane surface created a protective layer that provided active and passive defense against oxidative damage. Alumina-coated membranes demonstrated substantially higher tolerance to ozone exposure than uncoated membranes. They also maintained stable water permeability and salt rejection after prolonged filtration and effectively prevented biofilm formation. These findings offer a promising pathway to improving the reliability and sustainability of RO membranes by addressing critical barriers to their long-term desalination performance, thereby contributing to addressing the problem of global water scarcity.