Performance and potential mechanism of transformation of polycyclic aromatic hydrocarbons (PAHs) on various iron oxides

Zheng Ni; Chi Zhang; Zhiqiang Wang; Song Zhao; Xiaoyun Fan; Hanzhong Jia

doi:10.1016/j.jhazmat.2020.123993

Performance and potential mechanism of transformation of polycyclic aromatic hydrocarbons (PAHs) on various iron oxides

J Hazard Mater. 2021 Feb 5:403:123993. doi: 10.1016/j.jhazmat.2020.123993. Epub 2020 Sep 17.

Authors

Zheng Ni¹, Chi Zhang², Zhiqiang Wang¹, Song Zhao¹, Xiaoyun Fan³, Hanzhong Jia⁴

Affiliations

¹ College of Resources and Environment, Northwest A & F University, Yangling 712100, China.
² College of Resources and Environment, Northwest A & F University, Yangling 712100, China; Key Laboratory of Plant Nutrition and the Agri-environment in Northwest China, Ministry of Agriculture, Yangling, Shaanxi 712100, China.
³ Jinan University, School of Environment, Guangdong Province Key Lab Environment Pollution & Health, Guangzhou 510632, China. Electronic address: xyfan@jnu.edu.cn.
⁴ College of Resources and Environment, Northwest A & F University, Yangling 712100, China; Key Laboratory of Plant Nutrition and the Agri-environment in Northwest China, Ministry of Agriculture, Yangling, Shaanxi 712100, China. Electronic address: jiahz@nwafu.edu.cn.

PMID: 33265030
DOI: 10.1016/j.jhazmat.2020.123993

Abstract

The abiotic transformation of polycyclic aromatic hydrocarbons (PAHs) is significantly impacted by soil components, especially inorganic redox species like iron oxides. In this study, the catalytic activities of three types of iron oxides in PAHs degradation without light irradiation were evaluated using a combination of experimental techniques. The results showed that α-Fe₂O₃ possessed the highest transformation rate for anthracene (ANT), with a reaction rate constant (K_obs) up to 0.28 d^-¹, followed by Fe₃O₄ (K_obs = 0.06 d^-¹) and α-FeOOH (K_obs = 0.06 d^-¹). X-ray photoelectron spectroscopy (XPS) characterization suggested that α-Fe₂O₃ had the highest oxygen vacancy concentration, which was conducive to the adsorption of O₂ by α-Fe₂O₃, providing sufficient adsorbed oxygen species. Oxygen vacancy contributed to the exposure of Fe(III), and accordingly, more active sites were created that were responsible for ANT degradation. According to these results, two possible pathways for the degradation of PAHs on iron oxides can be concluded: (1) direct oxidation by Fe(III) and (2) oxidation by the O₂^•- generated onto oxygen vacancies. This study provides significant insights into the environmental fate of PAHs on iron oxides, and raises the possibility that iron oxides may be used as catalytic materials in the remediation PAHs-contaminated soil.

Keywords: Iron oxides; Oxygen vacancy; Polycyclic aromatic hydrocarbons; Reactive oxygen species.

Publication types

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