Performance and mechanism of bicarbonate-assisted heterogeneous peroxymonosulfate activation with CoMn2O4 catalyst toward contaminant remediation

Co/Mn-based heterogeneous peroxymonosulfate (PMS) activation is promising for refractory organic contaminant removal, whereas reaction-pH variation and metal leaching may compromise process stability. In this study, bicarbonate (HCO 3 − ) was incorporated into a CoMn 2 O 4 /PMS system to regulate the aqueous reaction environment while maintaining effective catalytic oxidation. The addition of 5 mmol/L HCO 3 − effectively maintained the reaction pH at 7.5 ± 0.2, minimized Co/Mn leaching and preserved the catalytic performance. Hydroxyl radical ( OH) and sulfate radical (SO 4 − ) were formed and served as the primary reactive species mediated AO7 oxidation based on the electron paramagnetic resonance (EPR) and quenching experiments in the CoMn 2 O 4 /PMS/HCO 3 − process. The plausible degradation pathway of AO7 was proposed, based on the intermediates identified and density functional theory (DFT) calculations. Seed germination tests showed substantially reduced phytotoxicity of the treated effluent, with an SGI above 80%. The CoMn 2 O 4 catalyst showed stable performance during repeated cycles and 48 h continuous operation with low metal leaching. It also maintained >97% removal efficiency in real water matrices with good tolerance to coexisting ions. Overall, the results demonstrate that bicarbonate-mediated regulation of the reaction environment can enhance the stability and adaptability of heterogeneous PMS-based water treatment.