In Situ-Formed Phenoxyl Radical on the CuO Surface Triggers Efficient Persulfate Activation for Phenol Degradation

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Indexed by:Journal paper

First Author:Mingjie Huang, Yi Han, Wei Xiang, Delai Zhong, Chen Wang, Tao Zhou,* Xiaohui Wu, and Juan Mao

Journal:Environmental Science & Technology

Included Journals:SCI

Discipline:Engineering

First-Level Discipline:Environmental Science and Engineering

Document Type:J

Volume:55

Page Number:15361-15370

ISSN No.:0013-936X

Key Words:persulfate activation, CuO, phenol degradation, phenoxyl radical, selectively, organic wastewater treatment, persulfate utilization efficiency

DOI number:10.1021/acs.est.1c03758

Date of Publication:2021-10-26

Impact Factor:11.357

Abstract:Transition-metal oxide (MxOy)-based persulfate (PDS) activation processes have demonstrated enormous potential for pollutant degradation in water purification. However, the mechanistic insight of PDS activation by a MxOy catalyst concerning the mediate role of the organic substrate remains obscure. Here, we demonstrated that the in situ-formed phenoxyl radical on the CuO surface can trigger efficient persulfate activation for phenol degradation. The formation of the phenoxyl radical was an innersphere process, which involved the successive steps of chemisorption through surface hydroxyl group substitution and the subsequent spontaneous electron transfer reaction from adsorbed phenol to CuO. The organic substrate phenol can be oxidized by the PDS molecule and surface-bound SO4·- through the nonradical and free-radical pathways, respectively. Such a unique “half-radical” mechanism resulted in an extraordinarily high PDS utilization efficiency of 188.9%. More importantly, a general rule for phenoxyl radical formation was concluded; it can be formed in the cases of organic substrates with a Hammett constant σ+ lower than -0.02 and metal ion of a 3d subshell between half-filled and fully filled. This study clarifies the mediate role of the organic substrate for interfacial PDS activation on MxOy and also gives new insights into the rational design of a highly efficient MxOy catalyst for selective phenolic/aniline pollutant degradation in wastewater.

Links to published journals:https://pubs.acs.org/doi/10.1021/acs.est.1c03758?cookieSet=1