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

作者：Shishu Zhu, Xiaojie Li, Jian Kang, Xiaoguang Duan, Shaobin Wang · 发表于：Environmental Science & Technology · 年份：2018 · DOI：10.1021/acs.est.8b04669 · 被引用次数：1242 · 研究领域：Advanced oxidation water treatment、Advanced Photocatalysis Techniques、Catalytic Processes in Materials Science

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-MnO 2 ) 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-MnO 2 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 ( 1 O 2 ) 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.