Heterogeneous photo-Fenton degradation of acid orange 7 activated by red mud biochar under visible light irradiation

Kun Lin; Shahzad Afzal; Liheng Xu; Tao Ding; Feng Li; Ming Zhang

doi:10.1016/j.envpol.2023.121454

Heterogeneous photo-Fenton degradation of acid orange 7 activated by red mud biochar under visible light irradiation

Environ Pollut. 2023 Jun 15:327:121454. doi: 10.1016/j.envpol.2023.121454. Epub 2023 Mar 28.

Authors

Kun Lin¹, Shahzad Afzal¹, Liheng Xu¹, Tao Ding¹, Feng Li², Ming Zhang³

Affiliations

¹ Department of Environmental Engineering, China Jiliang University, Hangzhou, 310018, Zhejiang, China.
² College of Environment Science and Resources, Xiangtan University, Xiangtan, 411105, China.
³ Department of Environmental Engineering, China Jiliang University, Hangzhou, 310018, Zhejiang, China. Electronic address: zhangming@cjlu.edu.cn.

PMID: 36997142
DOI: 10.1016/j.envpol.2023.121454

Abstract

The heterogeneous photo-Fenton process is an effective technology for degrading organic contaminants in wastewater, and Fe-based catalysts are recently preferred due to their low biotoxicity and geological abundance. Herein, we synthesized a Fe-containing red mud biochar (RMBC) via one-step co-pyrolysis of red mud and shaddock peel as a photo-Fenton catalyst to activate H₂O₂ and degrade an azo dye (acid orange 7, AO7). RMBC showed excellent AO7 removal capability with a decolorization efficiency of nearly 100% and a mineralization efficiency of 87% in the heterogeneous photo-Fenton process with visible light irradiation, which were kept stable in five successive reuses. RMBC provided Fe²⁺ for H₂O₂ activation, and the light irradiation facilitated the redox cycle of Fe²⁺/Fe³⁺ in the system to produce more reactive oxygen species (ROS, i.e., •OH) for AO7 degradation. Further investigation revealed that •OH was the predominant ROS responsible for AO7 degradation in the light-free condition, while more ROS were produced in the system with light irradiation, and ¹O₂ was the primary ROS in the photo-Fenton process for AO7 removal, followed by •OH and O₂^•-. This study provides insight into the interfacial mechanisms of RMBC as a photo-Fenton catalyst for treating non-degradable organic contaminants in water through advanced oxidation processes under visible light irradiation.

Keywords: Advanced oxidation process; Fe-based biochar; Photo-fenton; Reactive oxygen species; Red mud biochar.

MeSH terms

Azo Compounds
Catalysis
Hydrogen Peroxide*
Iron*
Light
Oxidation-Reduction
Reactive Oxygen Species

Substances

biochar
Iron
2-naphthol orange
Hydrogen Peroxide
Reactive Oxygen Species
Azo Compounds