Persulfate Activation on Crystallographic Manganese Oxides: Mechanism of Singlet Oxygen Evolution for Nonradical Selective Degradation of Aqueous Contaminants

Minerals and transitional metal oxides of earth-abundant elements are desirable catalysts for in situ chemical oxidation in environmental remediation. However, catalytic activation of peroxydisulfate (PDS) by manganese oxides was barely investigated. In this study, one-dimension manganese dioxides (...

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Bibliographic Details
Published in:Environmental science & technology 2019-01, Vol.53 (1), p.307-315
Main Authors: Zhu, Shishu, Li, Xiaojie, Kang, Jian, Duan, Xiaoguang, Wang, Shaobin
Format: Article
Language:English
Subjects:
Activation
Biodegradation
Catalysis
Catalysts
Chemical evolution
Chemical pollution
Contaminants
Crystal structure
Crystallography
Degradation
Electron paramagnetic resonance
Environmental science
Ion recombination
Manganese
Manganese dioxide
Manganese oxides
Minerals
Nanorods
Organic chemistry
Organic contaminants
Oxidation
Oxides
Oxygen
Phenols
Pollutant removal
Reactive oxygen species
Recombination
Singlet oxygen
Superoxide
Wastewater
Wastewater pollution
Wastewater treatment
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Summary:Minerals and transitional metal oxides of earth-abundant elements are desirable catalysts for in situ chemical oxidation in environmental remediation. However, catalytic activation of peroxydisulfate (PDS) by manganese oxides was barely investigated. In this study, one-dimension manganese dioxides (α- and β-MnO2) were discovered as effective PDS activators among the diverse manganese oxides for selective degradation of organic contaminants. Compared with other chemical states and crystallographic structures of manganese oxide, β-MnO2 nanorods exhibited the highest phenol degradation rate (0.044 min–1, 180 min) by activating PDS. A comprehensive study was conducted utilizing electron paramagnetic resonance, chemical probes, radical scavengers, and different solvents to identity the reactive oxygen species (ROS). Singlet oxygen (1O2) was unveiled to be the primary ROS, which was generated by direct oxidation or recombination of superoxide ions and radicals from a metastable manganese intermediate at neutral pH. The study dedicates to the first mechanistic study into PDS activation over manganese oxides and provides a novel catalytic system for selective removal of organic contaminants in wastewater.
ISSN:0013-936X
1520-5851
DOI:10.1021/acs.est.8b04669