Identifying the Persistent Free Radicals (PFRs) Formed as Crucial Metastable Intermediates during Peroxymonosulfate (PMS) Activation by N-Doped Carbonaceous Materials

• DOI: 10.1021/acs.est.1c01974
• Publication Date: 2021-06-18T05:31:09Z
• Authors: Yufei Zhen; Shishu Zhu; Zhiqiang Sun; Yu Tian; Zeng Li; Chen Yang; Jun Ma
• Keywords: Metastability; Reaction intermediate

A nonradical mechanism involved in peroxymonosulfate (PMS) activation carbonaceous materials (CMs) is still controversial. In this study, we prepared N-doped CMs, including hollow carbon spheres (NHCSs) and nanotubes (N-CNTs), to probe the crucial intermediates during PMS activation. The results suggested that higher efficiency lower energy (13.72 kJ mol-1) toward phenol (PN) degradation an NHCS/PMS system than alone (∼24.07 depended on a typical reaction. Persistent free radicals (PFRs) with g factor of 2.0033-2.0045, formed as metastable NHCS or N-CNT presence PMS, contribute largely organic (∼73.4%). Solid evidence formation PFRs relied attack surface-bonded •OH SO4•- peroxides among which was most thermodynamically favorable based theoretical calculations. Electron holes within NHCSs shifted Fermi level positive valance band increasing from 1.18 1.98 eV, promoting reactivity nucleophilic substances. aromatic compounds (e.g., PN) electron rearrangement triggered evolution oxygen-centered carbon-centered radicals. Moreover, due specific configuration, graphitic N critical for stabilizing PFRs. This study provides insightful understanding fate contaminants structure-activity relationship CMs