Accurate identification of radicals by in-situ electron paramagnetic resonance in ultraviolet-based homogenous advanced oxidation processes
Accurate identification of radicals in advanced oxidation processes (AOPs) is important to study the mechanisms on radical production and subsequent oxidation-reduction reaction. The commonly applied radical quenching experiments cannot provide direct evidences on generation and evolution of radicals in AOPs, while electron paramagnetic resonance (EPR) is a cutting-edge technology to identify radicals based on spectral characteristics. However, the complexity of EPR spectrum brings uncertainty and inconsistency to radical identification and mechanism clarification. This work presented a comprehensive study on identification of radicals by in-situ EPR analysis in four typical UV-based homogenous AOPs, including UV/HO, UV/peroxodisulfate (and peroxymonosulfate), UV/peracetic acid and UV/IO systems. Radical formation mechanism was also clarified based on EPR results. A reliable EPR method using organic solvents was proposed to identify alkoxy and alkyl radicals (CHC(=O)OO·, CHC(=O)O· and ·CH) in UV/PAA system. Two activation pathways for radical production were proposed in UV/IO system, in which the produced IO·, IO·, ·OH and hydrated electron were precisely detected. It is interesting that addition of specific organic solvents can effectively identify oxygen-center and carbon-center radicals. A key parameter in EPR spectrum for 5,5-dimethyl-1-pyrroline N-oxide (DMPO) spin adduct, A, is ranked as: ·CH (23 G) >·OH (15 G) >IO· (12.9 G) >O· (11 G) ≥·OOH (9–11 G) ≥IO· (9–10 G) ≥SO· (9–10 G) >CHC(=O)OO· (8.5 G) > CHC(=O)O· (7.5 G). This study will give a systematic method on identification of radicals in AOPs, and shed light on the insightful understanding of radical production mechanism.
NI Journal Papers ; ESI Hot Papers ; ESI Highly Cited Papers
China Postdoctoral Science Foundation[2021M690208];China Postdoctoral Science Foundation[2021M700213];National Key Research and Development Program of China Stem Cell and Translational Research[2021YFA1202500];National Natural Science Foundation of China;National Natural Science Foundation of China;Beijing Nova Program[Z191100001119054];
|WOS Research Area|
Engineering ; Environmental Sciences & Ecology ; Water Resources
Engineering, Environmental ; Environmental Sciences ; Water Resources
|WOS Accession No|
|EI Accession Number|
Electron resonance ; Electron spin resonance spectroscopy ; Electrons ; Organic solvents ; Oxidation ; Paramagnetism ; Redox reactions
|ESI Classification Code|
Magnetism: Basic Concepts and Phenomena:701.2 ; Chemistry:801 ; Chemical Reactions:802.2 ; Chemical Agents and Basic Industrial Chemicals:803 ; Organic Compounds:804.1
|ESI Research Field|
Cited Times [WOS]:76
|Document Type||Journal Article|
|Department||School of Environmental Science and Engineering|
1.The Key Laboratory of Water and Sediment Sciences,Ministry of Education,College of Environmental Sciences and Engineering,Peking University,Beijing,100871,China
2.State Environmental Protection Key Laboratory of Integrated Surface Water-Groundwater Pollution Control,School of Environmental Science and Engineering,Southern University of Science and Technology,Shenzhen,518055,China
3.Department of Civil and Environmental Engineering,Louisiana State University,Baton Rouge,70803,United States
4.State Key Laboratory of Hydraulics and Mountain River Engineering,College of Architecture and Environment,Sichuan University,Chengdu,610065,China
Chen，Long,Duan，Jun,Du，Penghui,et al. Accurate identification of radicals by in-situ electron paramagnetic resonance in ultraviolet-based homogenous advanced oxidation processes[J]. WATER RESEARCH,2022,221.
Chen，Long,Duan，Jun,Du，Penghui,Sun，Weiliang,Lai，Bo,&Liu，Wen.(2022).Accurate identification of radicals by in-situ electron paramagnetic resonance in ultraviolet-based homogenous advanced oxidation processes.WATER RESEARCH,221.
Chen，Long,et al."Accurate identification of radicals by in-situ electron paramagnetic resonance in ultraviolet-based homogenous advanced oxidation processes".WATER RESEARCH 221(2022).
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