Trace Cu(II), which inherently exists in soil and some water/wastewater, can trigger persulfate oxidation of some pollutants, but the oxidation capability and mechanism are not well understood, especially toward refractory pollutants. We report in this research that benzothiazole (BTH), a universal refractory pollutant typically originating from tire leachates and various industrial wastewater, can be facilely and selectively removed by peroxydisulfate (PDS) with an equimolar BTH/PDS stoichiometry in the presence of environmental-relevant contents of Cu(II) (below several micromoles). Comprehensive scavenging tests, electron spin resonance analysis, spectroscopy characterization, and electrochemical analysis, revealed that PDS first reduces the BTH-coordinated Cu(II) to Cu(I) and then oxidizes Cu(I) to high-valent Cu(III), which accounts for the BTH degradation. Moreover, once the reaction is initiated, the superoxide radical is probably produced in the presence of dissolved oxygen, which subsequently dominates the reduction of Cu(II) to Cu(I). This facile oxidation process is also effective in removing a series of BTH derivatives (BTHs) that are of environmental concern, thus can be used for their source control. The results highlight the sequential Cu(II)-Cu(I)-Cu(III) transition during PDS activation and the crucial role of contaminant coordination with Cu(II) in oxidative transformation.
Bibliographical noteKAUST Repository Item: Exported on 2023-09-06
Acknowledgements: The authors want to thank the funding support from the Natural Science Foundation of China (#52070188 and #52200078) and China Postdoctoral Science Foundation (#2022M713305). The authors would like to thank Yifan Song (China University of Mining and Technology) for helping with the EasySpin simulation. Part of this work was conducted at the King Abdullah University of Science and Technology (KAUST), Saudi Arabia. Professor Jean-Philippe Croué at the University of Poitiers, France, is gratefully acknowledged for his advice to improve the quality of this work.
This publication acknowledges KAUST support, but has no KAUST affiliated authors.
ASJC Scopus subject areas
- Environmental Chemistry