Oxygen vacancies-dominated reactive species generation from peroxymonosulfate activated by MoO3-x for pollutant degradation

Xiaolei Wang; Xiantang Liu; Yunping Tong; Cun Liu; Yingzhi Ding; Juan Gao; Guodong Fang; Xianghao Zha; Yujun Wang; Dongmei Zhou

doi:10.1016/j.jhazmat.2023.131798

Oxygen vacancies-dominated reactive species generation from peroxymonosulfate activated by MoO_3-x for pollutant degradation

J Hazard Mater. 2023 Sep 15:458:131798. doi: 10.1016/j.jhazmat.2023.131798. Epub 2023 Jun 9.

Authors

Xiaolei Wang¹, Xiantang Liu², Yunping Tong³, Cun Liu⁴, Yingzhi Ding³, Juan Gao⁴, Guodong Fang⁵, Xianghao Zha⁶, Yujun Wang⁴, Dongmei Zhou²

Affiliations

¹ College of Chemistry and Environmental Science, Kashi University, Kashi 844000, PR China; Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, PR China; State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210023, PR China.
² State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210023, PR China.
³ Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, PR China; University of Chinese Academy of Sciences, Beijing 100049, PR China.
⁴ Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, PR China.
⁵ Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, PR China. Electronic address: gdfang@issas.ac.cn.
⁶ College of Chemistry and Environmental Science, Kashi University, Kashi 844000, PR China. Electronic address: zhaxianghao@163.com.

PMID: 37336112
DOI: 10.1016/j.jhazmat.2023.131798

Abstract

Interface oxygen vacancies (OVs) are commonly used to improve the catalytic performance of activators in persulfate-based advanced oxidation processes, but the underlying mechanism was not fully explored. This work reports a facile heat treatment method to regulate OVs in MoO_3-x to elucidate the mechanism of peroxymonosulfate (PMS) activated by OVs to degrade 2,4,4-Trichlorobiphenyl (PCB28). Electron spin resonance, free radical quenching, X-ray photoelectron spectroscopy, and Raman spectroscopy confirmed that both reducing Mo species and OVs of MoO_3-x surface were responsible for PMS activation. Further experiments and Density Function Theory (DFT) calculation suggest that OVs in MoO_3-x induced the formation of superoxide radical (O₂^•-), and then O₂^•- was transformed into singlet oxygen (¹O₂) or mediated PMS activation to generate radicals, which contritbued to 70.2% of PCB28 degradation. The steady-state concentrations of free radical calculated with the kinetics model show that OVs were more favorable to mediate PMS to generate hydroxyl radicals (^•OH) under oxic conditions, while reducing Mo species would like to induce PMS to produce sulfate radicals (SO₄^•-). Overall, this study is dedicated to a new insight into the in-depth mechanism of PMS activation by OVs-rich catalysts and provides a novel strategy for reactive species regulation in PMS based oxidation process.

Keywords: Activation; MoO(3−x); Oxygen vacancy; PMS.