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Persulfate Oxidation of Sulfamethoxazole by Magnetic Iron-Char Composites via Nonradical Pathways: Fe(IV) Versus Surface-Mediated Electron Transfer

  • Jun Liang
    Jun Liang
    School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
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  • Xiaoguang Duan
    Xiaoguang Duan
    School of Chemical Engineering and Advanced Materials, The University of Adelaide, Adelaide SA5005, Australia
  • Xiaoyun Xu*
    Xiaoyun Xu
    School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
    *Email: [email protected]. Phone: +86 21 54743926.
    More by Xiaoyun Xu
  • Kexin Chen
    Kexin Chen
    School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
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  • Yue Zhang
    Yue Zhang
    Eco-environmental Protection Institute of Shanghai Academy of Agricultural Science, Shanghai 201403, China
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  • Ling Zhao
    Ling Zhao
    School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
    More by Ling Zhao
  • Hao Qiu
    Hao Qiu
    School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
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  • Shaobin Wang
    Shaobin Wang
    School of Chemical Engineering and Advanced Materials, The University of Adelaide, Adelaide SA5005, Australia
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  • , and 
  • Xinde Cao
    Xinde Cao
    School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
    Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, China
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Cite this: Environ. Sci. Technol. 2021, 55, 14, 10077–10086
Publication Date (Web):July 2, 2021
https://doi.org/10.1021/acs.est.1c01618
Copyright © 2021 American Chemical Society
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Abstract

Despite the vital roles of reactive radical species in the coupled iron–carbon composite/persulfate (PS) system for eliminating pollutants, nonradical contributions are typically overlooked. Herein, we developed two efficient magnetic iron–char composites via low-temperature (BCFe-400) and high-temperature (BCFe-700) pyrolysis. The two composites activated PS through nonradical pathways for sulfamethoxazole (SMX) degradation. In the BCFe-400/PS system, high-valent iron Fe(IV) was the dominant active species for the oxidation, evidenced by methyl phenyl sulfoxide-based probe tests, Mössbauer spectroscopy, and in situ Raman analyses with kinetic evaluation. In the BCFe-700/PS system, surface-mediated electron transfer dominated the oxidation, and the nonradical regime was probed by the electrochemical test and in situ Raman analysis. Furthermore, the BCFe-400/PS system maintained high efficiency in continuous degradation of SMX due to the feasible Fe2+generation toward Fe(IV) formation. In the BCFe-700/PS system, the stability of the system was limited due to the hindered electron transfer between the surface reactive complex (i.e., BCFe-700–PS*) and SMX, and thermal treatment would help recover the reactivity. Both BCFe-400/PS and BCFe-700/PS systems exhibited high performances for SMX removal in the presence of chloride and humic acid and in real water matrixes (e.g., seawater, piggery wastewater, and landfill leachate), exhibiting the great merits of the nonradical system. Overall, the study would provide new insights into PS activation by iron-loaded catalysts to efficiently degrade pollutants via nonradical pathways.

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The Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/acs.est.1c01618.

  • Materials and experimental reagents; characterization of biochars; Mössbauer experiment, electrochemical tests and in situ Raman analysis; UHPLC–MS; summary of the iron–char composites/PS system; properties of the iron–char composite; Mössbauer parameters for fitted spectra; second-order rate constants of radicals toward probe compounds; molecular formula, m/z, and molecular structure of SMX and degradation intermediates; characteristics of the real water samples; SEM images and elemental mapping; HAADF images and elemental mapping; SMX removal by the iron–char composite; kobs of SMX removal in different systems; EPR spectra; chronoamperometry test; molar yield of PMSO2; Fe2+ concentration; degradation removal of SMX, NB, and BA in different systems; MS spectrum and MS2 spectrum of products in the BCFe-400/PS system; MS spectrum and MS2 spectrum of products in the BCFe-700/PS system; proposed degradation pathway; and magnetic performance (PDF)

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Cited By


This article is cited by 1 publications.

  1. Hongyu Dong, Qinghua Xu, Lushi Lian, Yang Li, Shuchang Wang, Cong Li, Xiaohong Guan. Degradation of Organic Contaminants in the Fe(II)/Peroxymonosulfate Process under Acidic Conditions: The Overlooked Rapid Oxidation Stage. Environmental Science & Technology 2021, 55 (22) , 15390-15399. https://doi.org/10.1021/acs.est.1c04563