Cited by 339Advanced oxidation water treatmentEnvironmental remediation with nanomaterialsAdsorption and biosorption for pollutant removal

Persistent free radicals in carbon-based materials on transformation of refractory organic contaminants (ROCs) in water: A critical review

Qin, Yaxin, Li, Guiying, Gao, Yanpeng, Zhang, Lizhi, Ok, Yong Sik, An, Taicheng·2018·Water Research

Abstract

With the increased concentrations and kinds of refractory organic contaminants (ROCs) in aquatic environments, many previous reviews systematically summarized the applications of carbon-based materials in the adsorption and catalytic degradation of ROCs for their economically viable and environmentally friendly behavior. Interestingly, recent studies indicated that carbon-based materials in natural environment can also mediate the transformation of ROCs directly or indirectly due to their abundant persistent free radicals (PFRs). Understanding the formation mechanisms of PFRs in carbo-based materials and their interactions with ROCs is essential to develop their further applications in environment remediation. However, there is no comprehensive review so far about the direct and indirect removal of ROCs mediated by PFRs in amorphous, porous and crystalline carbon-based materials. The review aims to evaluate the formation mechanisms of PFRs in carbon-based materials synthesized through pyrolysis and hydrothermal carbonization processes. The influence of synthesis conditions (temperature and time) and carbon sources on the types as well as the concentrations of PFRs in carbon-based materials are also discussed. In particular, the effects of metals on the concentrations and types of PFRs in carbon-based materials are highlighted because they are considered as the catalysts for the formation of PFRs. The formation mechanisms of reactive species and the further transformation mechanisms of ROCs are briefly summarized, and the surface properties of carbon-based materials including surface area, types and number of functional groups, etc. are found to be the key parameters controlling their activities. However, due to diversity and complexity of carbon-based materials, the exact relationships between the activities of carbon-based materials and PFRs are still uncertain. Finally, the existing problems and current challenges for the ROCs transformation with carbon-based materials are also pointed out.

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Crossref · 10.1016/j.watres.2018.03.012

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  • Formation of EPFRs usually originates from initial physisorption, elimination of water or hydrogen chloride, and subsequent electron transfer from substituted aromatic units to adsorbed transition metals.

    “In comparison, the formation of EPFRs usually originates from a series of reactions including initial physisorption, elimination of water or hydrogen chloride, and subsequent electron transfer from substituted aromatic units to adsorbed transitions metals.”

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Authors
Qin, Y., Li, G., Gao, Y., Zhang, L., Ok, Y. S., & An, T.
Affiliations
  • Guangdong University of Technology (CN)
  • Central China Normal University (CN)
  • Korea University (KR)
Corresponding author
An, Taicheng
Venue
Water Research
Publisher
Elsevier BV
Published
2018-06
Volume
137
Pages
130-143
ISSN
0043-1354 (ISSN-L)
OpenAlex
W2790153550
Cited by
339
References
194
Citations by year
2026: 20 · 2025: 40 · 2024: 45 · 2023: 54 · 2022: 43 · 2021: 41 · 2020: 46 · 2019: 40 · 2018: 9
FWCI
2.09
Type
journal article
Language
en
Open access
closed
Locations
  • Water Research (publishedVersion)
  • PubMed (publishedVersion)
Funders
National Natural Science Foundation of China (41425015, 41573086, 41373102)
Topics
  • Physical Sciences › Environmental Science › Water Science and Technology › Advanced oxidation water treatment
  • Physical Sciences › Engineering › Biomedical Engineering › Environmental remediation with nanomaterials
  • Physical Sciences › Environmental Science › Water Science and Technology › Adsorption and biosorption for pollutant removal
Keywords
persistent free radicals, carbon materials, refractory organic pollutants, water treatment, pyrolysis, hydrothermal carbonization, metal catalysis, reactive species, surface functional groups, environmental remediation
MeSH terms
Carbon, Free Radicals, Water Pollutants, Water Purification, Environmental Restoration and Remediation

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