Efficient Daunorubicin Degradation and Detoxification via UV-LED/ZVI/Oxone: LC-MS-Based Transformation Pathways

Pharmaceutical residues, particularly anticancer compounds, are persistent aquatic contaminants that require efficient treatment strategies. This study developed a UV-LED-assisted peroxymonosulfate (PMS)/zero-valent iron (ZVI) advanced oxidation system for the degradation and toxicity reduction of daunorubicin in aqueous solution. The effects of key operational parameters were optimized using response surface methodology. Under optimal conditions (pH 3, PMS 1.5 mM, ZVI 0.3 g/L, and daunorubicin 10 mg/L), nearly complete degradation was achieved within 15 min, following pseudo-first-order kinetics (R2 > 0.95). LC–MS analysis revealed the formation of transformation products and suggested oxidative fragmentation pathways of daunorubicin. The process achieved 65% total organic carbon removal after 6 h, indicating substantial but incomplete mineralization. Fe2+ evolution and ESR analysis demonstrated that ZVI-mediated PMS activation generated reactive species, with sulfate radicals playing a major role and hydroxyl radicals contributing to oxidation. Toxicity and mutagenicity assays confirmed significant reductions in biological effects after treatment. These findings demonstrate that the UV-LED/PMS/ZVI system is a promising approach for the treatment of daunorubicin-containing wastewater.