Degradation of naproxen and diclofenac from aqueous solutions via catalytic activation of peroxymonosulfate using MMT@CuFe2O4

The presence of naproxen (NPX) and diclofenac (DCF) in aquatic environments poses a serious threat to ecosystems and human health due to their persistence and biological activity. Conventional treatment methods often fail to completely remove these pollutants, highlighting the need for efficient and environmentally friendly alternatives. In this study, a novel copper ferrite-loaded montmorillonite (MMT@CuFe₂O₄) composite was synthesized and applied in peroxymonosulfate (PMS) activation to degrade NPX and DCF. Structural analyses confirmed the successful fabrication of the catalyst, featuring a surface area of 43.55 m²/g, an average pore diameter of 11.89 nm, and a particle size of 12.50 nm. Response surface methodology (RSM) with ANOVA results (R² > 0.89, p < 0.0001) effectively described the influence and interaction of operational parameters. Optimal conditions (pH 9, PMS dosage 1.497 mM, reaction time 21.95 min, pollutant concentration 5 mg/L, and catalyst dosage 151.64 mg/L) yielded removal efficiencies of 99.91 % for DCF and 95.41 % for NPX. The inhibitory effect of anions on pollutant removal followed the order: phosphate > sulfate > nitrate > bicarbonate > chloride. More than 80 % mineralization and a BOD₅/COD ratio > 0.4 confirmed conversion to biodegradable products, with m-xylene, 2-oxopropanoic acid, and indolin-2-one identified as the final degradation intermediates. Toxicity assessment using plant growth indicated a relative growth rate of 95.19 %. Radical quenching experiments revealed that ¹O₂, O₂^•-, ^•OH, and SO₄^•- were the main reactive species. The reaction stoichiometric efficiency (RSE⁾ of PMS was evaluated for various activation methods, with the MMT@CuFe₂O₄ catalyst showing the highest efficiency.