Uncertainty and misinterpretation over identification, quantification and transformation of reactive species generated in catalytic oxidation processes: A review

Lingli Wang; Xu Lan; Wenya Peng; Zhaohui Wang

doi:10.1016/j.jhazmat.2020.124436

Uncertainty and misinterpretation over identification, quantification and transformation of reactive species generated in catalytic oxidation processes: A review

J Hazard Mater. 2021 Apr 15:408:124436. doi: 10.1016/j.jhazmat.2020.124436. Epub 2020 Nov 2.

Authors

Lingli Wang¹, Xu Lan², Wenya Peng¹, Zhaohui Wang³

Affiliations

¹ Shanghai Key Lab for Urban Ecological Processes and Eco-Restoration, School of Ecological and Environmental Sciences, East China Normal University, Shanghai 200241, China.
² Shanghai Institute of Quality Inspection and Technical Research, 900 Jiangyue Road, Minhang District, Shanghai 201114, China.
³ Shanghai Key Lab for Urban Ecological Processes and Eco-Restoration, School of Ecological and Environmental Sciences, East China Normal University, Shanghai 200241, China; Technology Innovation Center for Land Spatial Eco-Restoration in Metropolitan Area, Ministry of Natural Resources, 3663 N. Zhongshan Road, Shanghai 200062, China; Shanghai Engineering Research Center of Biotransformation of Organic Solid Waste, Shanghai 200241, China. Electronic address: zhwang@des.ecnu.edu.cn.

PMID: 33191023
DOI: 10.1016/j.jhazmat.2020.124436

Abstract

The identification of reactive radical species using quenching and electron paramagnetic resonance (EPR) tests has attracted extensive attention, but some mistakes or misinterpretations are often present in recent literature. This review aims to clarify the corresponding issues through surveying literature, including the uncertainty about the identity of radicals in the bulk solution or adsorbed on the catalyst surface in quenching tests, selection of proper scavengers, data explanation for incomplete inhibition, the inconsistent results between quenching and EPR tests (e.g., SO₄^•- is predominant in quenching test while the signal of ^•OH predominates in EPR test), and the incorrect identification of EPR signals (e.g., SO₄^•- is identified by indiscernible or incorrect signals). In addition, this review outlines the transformation of radicals for better tracing the origin of radicals. It is anticipated that this review can help in avoiding mistakes while investigating catalytic oxidative mechanism with quenching and EPR tests.

Keywords: EPR; Probe; Quenching test; Radicals; Transformation.

Publication types

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