N-Doped Co–Mn/C Dual Metal Oxide as an Activator of Peroxymonosulfate Considering Radical and Nonradical Pathways

Abstract

The Mn–Co dual-metal oxide is recognized as an effective activator for peroxymonosulfate (PMS), but its activation mechanism remains controversial. In this study, a Co/Mn–C–N (CMCN) nanocatalyst was synthesized using a simple pyrolysis method, and its catalytic activity along with the PMS activation mechanism was comprehensively explored. The findings indicated that the synergistic effect of Mn and Co within the bimetallic composition significantly enhanced the catalytic efficiency of CMCN compared to those of individual metal oxides (Mn–C–N and Co–C–N). Bisphenol A underwent successful degradation within 3 min in a neutral environment, with a degradation kinetic rate of 1.59 min–1 and a total organic carbon removal efficiency of 63.8%. Moreover, CMCN nanoparticles demonstrated remarkable stability and reusability, maintaining their efficacy over four cycles. Employing a series of experiments and analytical characterizations, a novel activation mechanism for PMS was proposed, involving both radical and nonradical pathways. This mechanism involves the oxidation of organic pollutants through a direct electron transfer process from metastable intermediate complexes. Notably, the CMCN/PMS system exhibited a robust resistance to interference factors. This research provides novel insights into the development of bimetallic oxide composites for the effective removal of recalcitrant water pollutants.