Effects of Fe(II) on As(III) oxidation in Fe(II)-As(III) co-oxidation: Limiting and driving roles

Xin Zhang; Qingling Fu; Hongqing Hu; Jun Zhu; Yonghong Liu

doi:10.1016/j.jhazmat.2023.130790

Effects of Fe(II) on As(III) oxidation in Fe(II)-As(III) co-oxidation: Limiting and driving roles

J Hazard Mater. 2023 Apr 5:447:130790. doi: 10.1016/j.jhazmat.2023.130790. Epub 2023 Jan 14.

Authors

Xin Zhang¹, Qingling Fu², Hongqing Hu¹, Jun Zhu¹, Yonghong Liu³

Affiliations

¹ Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtse River), Ministry of Agriculture and Rural Affairs, College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, Hubei Province, China.
² Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtse River), Ministry of Agriculture and Rural Affairs, College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, Hubei Province, China. Electronic address: fuqingling@mail.hzau.edu.cn.
³ College of Science, Huazhong Agricultural University, Wuhan 430070, Hubei Province, China.

PMID: 36669406
DOI: 10.1016/j.jhazmat.2023.130790

Abstract

The co-oxidation of Fe(II) and As(III) occurs under aerobic conditions, and Fe(II) may largely determine the fate of As(III), but the effect of Fe(II) on the As(III) oxidation is barely explored. In this research, the limiting and driving roles of Fe(II) in As(III) oxidation were systematically studied through batch kinetic studies in combination with X-ray photoelectron spectroscopy (XPS) depth profiling, scanning electron microscopy and energy dispersive X-ray spectrometry (SEM-EDS), and quenching experiments. The results showed that As(III) oxidation efficiency increased with the increase of Fe/As molar ratio (from 63.1% to 98.3%), but decreased with the increase of pH (from 96.0% to 44.2%) and the increase of air flow rate (from 88.1% to 75.1%). The Fe(II) oxidation rate increased with the increase of pH and air flow rate. When Fe(II) was oxidized rapidly, As(III) was more likely to be immobilized in the "inner sphere" of formed Fe (hydr)oxides, limiting As(III) oxidation. On the other hand, Fe(II) was oxidized to produce Fe (hydr)oxides to adsorb or fix As(III); meanwhile, the ROS generated by Fenton-like reaction of Fe(II) promoted As(III) oxidation, especially, •O₂^- and H₂O₂ were important ROS that drove the As(III) oxidation. These findings might provide a new insight for Fe(II) and As(III) geochemistry cycling in naturally occurring environment.

Keywords: As(III) oxidation efficiency; Fe (hydr)oxides; Fe(II) and As(III) co-oxidation; Fe(II) oxidation rate; Reactive oxygen species.