Peroxymonosulfate Activation with Manganese-Cobalt Sulfide for Antibiotic Degradation: Coupling Electron Flow Modulation and Dual Reaction Pathways

Abstract

Persistent antibiotic pollutants pose significant risks to ecological safety and human health. Developing high-performance catalysts for peroxymonosulfate (PMS) activation is an essential way for efficient antibiotic wastewater remediation. Herein, a three-dimensional nickel foam-supported manganese-cobalt sulfide (MnCo2S4/NF) catalyst was synthesized and employed to activate PMS for sulfamethoxazole (SMX) degradation. The MnCo2S4/NF/PMS system achieved 87.7% SMX removal within 20 minutes and maintained over 82% efficiency after seven consecutive cycles, demonstrating excellent catalytic activity and stability. Density functional theory (DFT) studies revealed that the metallic nature of MnCo2S4 facilitates strong PMS adsorption, which facilitates electron transfer from the catalyst to PMS and promotes O-O bond cleavage. Specifically, Mn sites act as the primary electron-donating centers, while Co sites synergistically reduce charge-transfer resistance. Quenching experiments and electron paramagnetic resonance (EPR) analysis confirmed that superoxide radical (•O2‒) and non-radical singlet oxygen (1O2) synergistically contributed to SMX degradation. Fukui function analysis further identified a pronounced susceptibility of the nitrogen atom (N7) of SMX to electrophilic radical attack, as well as the critical involvement of specific carbon atoms (e.g., C1, C5) in nucleophilic interactions. Moreover, this system demonstrates excellent performance across various water matrices, showing its strong potential for practical water treatment.