A study on advanced oxidation mechanism of MnCo2O4/g-C3N4 degradation of nitrobenzene: Sacrificial oxidation and radical oxidation

Abstract

In this study, the MnCo2O4/g-C3N4 (CMCN2) is used to activate peroxymonosulfate (PMS), for treating nitrobenzene (NB) and industrial wastewater containing nitrobenzene homologue. Different from traditional sulfate radical-based advanced oxidation processes (SR-AOPs), high-valent metal-oxo species (MIV(O)/MV(O)) is a major reactive component via dimethyl sulfoxide (DMSO) as a verify compound. The mechanism is speculated that the bond of nitrogen–metal = oxygen (N–M = O) activates PMS to form MIV(O)/MV(O) during sacrificial oxidation. The quenching experiments and electron spin resonance (ESR) confirm that CMCN2 activated PMS to form OH and SO4–. The Langmuir-Hinshelwood model conforms to the NB degradation curve, and the best removal efficiency is 96.7% in 240 min. The CMCN2/PMS system has excellent stability between pH 3–10. Also, the CMCN2/PMS system exhibited satisfactory removal of NB in the presence of inorganic anions and natural organic matters. The treatment effect of industrial wastewater containing phenyl homologues shows that CMCN2/PMS has a high mineralization capacity. This study details the electron transfer during the formation of active components and provides new ideas for selecting active ingredients that degrade phenyl pollutants in the field of advanced oxidation.