Fe-Co synergistic CoFe2O4 activates peroxymonosulfate for singlet oxygen-dominated 2,2′,4,4′,6,6′-hexanitrostilbene oxidation in energetic wastewater

The treatment of wastewater laden with energetic compounds, particularly 2,2′,4,4′,6,6′-hexanitrostilbene (HNS), remains highly challenging owing to the environmental persistence and inherent toxicity of nitroaromatic derivatives. Herein, we reported a CoFe 2 O 4 /PMS system for the first-time efficient degradation of HNS. The CoFe 2 O 4 /PMS process afforded 96.3% removal of HNS within 150 min, together with 89.3% chemical oxygen demand (COD) removal and 49.5% total organic carbon (TOC) removal, indicating substantial deep oxidation and partial mineralization. Mechanistic studies combining quenching experiments, EPR spectroscopy, electrochemical analysis, and DFT calculations disclosed a synergistic radical/non-radical pathway dominated by 1 O 2 , with Fe incorporation enhancing PMS adsorption, charge transfer, and catalytic activation. HPLC-MS revealed degradation intermediates and supported three plausible degradation pathways, whereas QSAR analysis indicated progressive detoxification during oxidation. The catalyst further exhibited excellent stability, negligible metal leaching, and broad applicability toward actual HNS production wastewater and other energetic organic pollutants. These findings identify CoFe 2 O 4 /PMS as a promising platform for the efficient remediation of hazardous energetic compound wastewater.