Interfacial electron transfer and surface dual-sites on Fe-Mn bimetallic catalyst for synergistic peroxymonosulfate activation and reactive oxygen species generation.

Abstract

The remediation of persistent chlorophenolic contaminants in aquatic environments remains a formidable challenge, necessitating the development of highly efficient and sustainable advanced oxidation technologies. Peroxymonosulfate-based advanced oxidation processes (PMS-AOPs) have been recognized as a significant approach, yet their catalytic performance is often limited by insufficient active sites, sluggish electron transfer kinetics, and poor catalyst stability. To overcome these limitations, a novel biochar-supported Fe-Mn bimetallic catalyst (Fe-Mn@BC) was rationally designed and synthesized as an efficient peroxymonosulfate (PMS) activator for the removal of 2,4,6-trichlorophenol (TCP). Under optimal parameters, the Fe-Mn@BC/PMS system realized complete TCP degradation within 150 min. Mechanism studies revealed that reactive oxygen species (ROSs), including , , , and , were the dominant active species responsible for TCP degradation. Characterization results and electrochemical analysis demonstrated that the synergistic Fe(II)/Fe(III) and Mn(II)/Mn(III)/Mn(IV) redox cycles not only facilitated electron transfer but also promoted O-O bond cleavage within the PMS molecule, thereby sustaining continuous ROSs generation. Furthermore, surface functional groups (e.g., C=O) on the catalyst contributed to ROSs formation via a non-radical pathway, further enhancing the oxidative capacity. This work provided a robust bimetallic catalyst system with enhanced PMS activation capability, offering an sustainable and effective solution for the treatment of chlorophenolic contaminants.