Fixed-bed catalytic antibiotics detoxification through singlet oxygen-mediated nonradical oxidation: Mechanisms and...

This study presents an immobilized ZIF-67-derived catalyst, Co-N/C@EP-600, designed for efficient antibiotic detoxification via singlet oxygen (¹O₂)-mediated nonradical oxidation. The catalyst features a unique Co-N₃ combined with Co nanocluster (Co-N_3-NCs) structure, as confirmed by X-ray absorption fine structure (XAFS) and density functional theory (DFT) analyses. This structure enhances peroxymonosulfate (PMS) activation by reducing the energy barrier and promoting electron transfer, achieving ultrafast and near-complete degradation of ofloxacin (OFC, initial concentration of 10 mg L^-1) and other refractory organic pollutants within 20 min. Mechanistic studies revealed that ¹O₂ dominates the oxidation process, affirmed by quenching tests, electron spin resonance (ESR), and isotopic experiments. The catalyst exhibited exceptional stability, maintaining > 90 % efficiency over 30 cycles with minimal cobalt leaching (< 1.0 mg L⁻¹). Practical application in a continuous-flow fixed-bed reactor demonstrated long-term performance, degrading fluoroquinolone antibiotics (OFC and enrofloxacin (ENR)) at high (10.0 mg L⁻¹) and low (1.0 mg L⁻¹) concentrations up to 30 and 20 days, respectively. Comprehensive toxicity assessments, encompassing microbial viability, activated sludge activity, and phytotoxicity assays, confirmed substantial detoxification toward fluoroquinolone antibiotics. This work provides a strategic blueprint for developing immobilized, eco-friendly catalysts that unite high performance, durability, and environmental compatibility in advanced wastewater treatment.