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Lookup NU author(s): Dr Anke Neumann
This is the authors' accepted manuscript of an article that has been published in its final definitive form by American Chemical Society, 2020.
For re-use rights please refer to the publisher's terms and conditions.
Reductive transformation of organic contaminants by FeS in anoxic environments has been documented previously, whereas the transformation in oxic environments remains poorly understood. Here we show that phenol can be efficiently oxidized in oxic FeS suspension at circumneutral pH value. We found that hydroxyl radicals (•OH) were the predominant reactive oxidant and that a higher O2 content accelerated phenol degradation. Phenol oxidation depended on •OH production and utilization efficiency, i.e., phenol degraded per •OH produced. Low FeS contents (≤1 g/L) produced less •OH but higher utilization efficiency, while high contents produced more •OH but lower utilization efficiency. Consequently, the most favorable conditions for phenol oxidation occurred during the long-term interaction between dissolved O2 and low levels of FeS (i.e., ≤1 g/L). Mössbauer spectroscopy suggests that FeS oxidation to lepidocrocite initially produced an intermediate Fe(II) phase that could be explained by the apparent preferential oxidation of structural S(-II) relative to Fe(II), rendering a higher initial •OH yield upon unit of Fe(II) oxidation. Trichloroethylene can be also oxidized under similar conditions. Our results demonstrate that oxidative degradation of organic contaminants during the oxygenation of FeS can be a significant but currently underestimated pathway in both natural and engineered systems.
Author(s): Cheng D, Neumann A, Yuan S, Liao W, Qian A
Publication type: Article
Publication status: Published
Journal: Environmental science & technology
Year: 2020
Volume: 54
Issue: 7
Pages: 4091-4101
Print publication date: 07/04/2020
Online publication date: 06/03/2020
Acceptance date: 06/03/2020
Date deposited: 02/06/2020
ISSN (print): 0013-936X
ISSN (electronic): 1520-5851
Publisher: American Chemical Society
URL: https://doi.org/10.1021/acs.est.9b07012
DOI: 10.1021/acs.est.9b07012
PubMed id: 32142604
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