Abstract

Reverse osmosis (RO) membranes that have been widely used in desalination degrade over time require frequent replacement and produce significant waste. This study examines an innovative approach for recycling end-of-life (EoL) RO membranes by combining sodium hypochlorite oxidation with ultrasonication to degrade the polyamide layer and repurpose the membranes. The methodology consists in subjecting EoL RO membranes to controlled NaOCl oxidation, with and without ultrasonication, to assess their effects on permeability, rejection, and membrane characteristics. Results indicate that NaOCl combined with ultrasonication significantly enhances membrane permeability, increasing water flux, as compared to NaOCl oxidation. Porometry analysis confirms a substantial increase in pore size, while FTIR and SEM analyses reveal structural alterations, including polyamide layer thinning and enhanced surface porosity. The NaOCl treatment accelerates polyamide degradation, leading to a transition from RO membrane behavior to nanofiltration membrane characteristics, while ultrasonication significantly increases pore size, further shifting membrane performance towards ultrafiltration characteristics. This study reveals that NaOCl+ultrasonication is a promising method for RO membrane recycling, enabling their transformation into UF-like membranes.