Single sheet iron oxide: An efficient heterogeneous electro-Fenton catalyst at neutral pH

Li-Zhi Huang; Mingtao Zhu; Zizheng Liu; Zongping Wang; Hans Christian B Hansen

doi:10.1016/j.jhazmat.2018.10.026

Single sheet iron oxide: An efficient heterogeneous electro-Fenton catalyst at neutral pH

J Hazard Mater. 2019 Feb 15:364:39-47. doi: 10.1016/j.jhazmat.2018.10.026. Epub 2018 Oct 11.

Authors

Li-Zhi Huang¹, Mingtao Zhu², Zizheng Liu³, Zongping Wang⁴, Hans Christian B Hansen⁵

Affiliations

¹ School of Civil Engineering, Wuhan University, No. 8, East Lake South Road, Wuhan, China; Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Gustav Wieds Vej 14, DK8000 Aarhus C, Denmark; Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, DK-1871 Frederiksberg C, Denmark.
² School of Environmental Science and Engineering, Huazhong University of Science and Technology (HUST), Wuhan 430074, China.
³ School of Civil Engineering, Wuhan University, No. 8, East Lake South Road, Wuhan, China. Electronic address: lzz2015@whu.edu.cn.
⁴ School of Environmental Science and Engineering, Huazhong University of Science and Technology (HUST), Wuhan 430074, China. Electronic address: zongpingw@hust.edu.cn.
⁵ Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, DK-1871 Frederiksberg C, Denmark.

PMID: 30336334
DOI: 10.1016/j.jhazmat.2018.10.026

Abstract

In order to overcome the inefficiency of heterogeneous electro-Fenton process for water treatment at neutral pH, single sheet iron oxide (SSI) derived from layered Fe(II)-Fe(III) double hydroxides (green rusts) was fabricated on an indium tin oxide electrode via layer by layer assembly and used in an undivided electrolysis cell. Use of radical scavengers demonstrated the formation of oxygen radicals by electrochemical reduction of oxygen at the SSI electrode, and the key role of hydroxyl radicals (OH) and superoxide anion (O₂^-) radicals in degradation of the azo dye orange II. Analysis of degradation products by UV-vis, LC-MS and GC-MS further demonstrated that direct reduction toke place in addition to indirect oxidation. The reactivity of SSI as a heterogeneous electro-Fenton catalyst is two order of magnitude higher than its homogenous counterparts. The SSI electrode was highly stable as the dye degradation did not decrease after use for 19 h with no Fe leaching. The high dye removal efficiency was maintained in a wide pH range from 7 to 10 and in different supporting electrolytes, demonstrating the application of this process under various conditions mimicking natural waters.

Keywords: Advanced oxidation processes; Electro-Fenton; Green rust; Heterogeneous electro catalyst; Single sheet iron oxide.

Publication types

Research Support, Non-U.S. Gov't