Peroxymonosulfate activation by SrCoO₃@g-C₃N₅ composite catalyst for efficient diclofenac degradation via radical and non-radical pathways

Diclofenac (DCF) is a broadly prescribed nonsteroidal anti-inflammatory drug used worldwide. DCF is often excreted in a biologically active form and resistant to conventional wastewater treatment, posing ecological risks when released into aquatic systems. In this study, a composite consisting of SrCoO₃ and nitrogen-rich graphitic carbon nitride (g-C₃N₅) was fabricated for the oxidative degradation of DCF by peroxymonosulfate (PMS). Different loadings of the composite were then incorporated into a cellulose acetate based mixed-matrix membrane, denoted as SCN- x ( x = 0.5, 1, 3, and 5 wt% SrCoO₃@g-C₃N₅). The samples were characterized to investigate their physicochemical properties, with the SCN-5 being the most effective for PMS activation and thus DCF degradation in aqueous solutions. Specifically, the SCN-5 achieved a 96.5 % removal efficiency for DCF and retained a high efficiency of 68.9 % even after five consecutive reuses. The degradation mechanism is driven by the activation of PMS via Co²⁺/Co³⁺ redox cycle within SCN-5, wherein the g-C₃N₅ matrix facilitates electron transfer and enhances the formation of reactive radical and non-radical species. The major intermediates of DCF were identified, and acute/chronic toxicity assessments were conducted. These findings suggest that SCN-5 shows strong potential as a sustainable polymer-based membrane for removing organic contaminants from water.