# Mn–Fe3O4 heterogeneous Fenton catalytic oxidation: mechanism and performance in sauce-flavored liquor wastewater degradation

## TL;DR

This study explores how Mn–Fe3O4 catalysts improve wastewater treatment by efficiently breaking down organic pollutants using a Fenton oxidation process.

## Contribution

The study introduces a novel Mn–Fe3O4 catalyst that enhances COD removal and provides insights into its catalytic mechanism.

## Key findings

- The Mn–Fe3O4 system improved COD removal by 26% compared to conventional Fenton methods.
- The catalyst showed stability and magnetic recoverability, making it suitable for reuse.
- The system followed second-order kinetics and produced more hydroxyl radicals for efficient pollutant degradation.

## Abstract

This study aims to investigate the mechanism of synthesized Mn–Fe3O4 catalysts in the deep degradation of COD in sauce-flavored liquor wastewater by heterogeneous Fenton oxidation. Additionally, the study evaluates the impact of operational factors, including pH, catalyst composition, and dosage on the COD removal rate. The physicochemical characteristics of Mn–Fe3O4 catalysts were comprehensively analyzed using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The oxidation mechanism of the Mn–Fe3O4 heterogeneous Fenton system was elucidated through gas chromatography–mass spectrometry (GC-MS) analysis, kinetic modeling, and radical quenching experiments involving tert-butanol (TBA) and benzoquinone (BQ). The results demonstrated that the Mn–Fe3O4-based system enhanced COD removal by 26% compared to the conventional Fenton process, exhibiting remarkable stability and magnetic recoverability. The catalyst system followed second-order kinetics, with the dual Mn–Fe active centers on the catalyst surface facilitating electron transfer via charge redistribution, promoting redox cycling of Fe2+/Fe3+ and Mn2+/Mn3+, and significantly increasing hydroxyl radical (·OH) production, thereby enabling the efficient degradation of refractory organic pollutants. This study provides valuable insights for the development of innovative catalytic materials for the effective treatment of industrial wastewater containing phenolic quinones, which are challenging to degrade, and sets the stage for further industrial applications.

This study aims to investigate the mechanism and performance of synthesized Mn–Fe3O4 catalysts in the deep degradation of COD in sauce-flavored liquor wastewater by heterogeneous Fenton oxidation.