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Oxidative Degradation of Organic Contaminants by FeS in the Presence of O2

Lookup NU author(s): Dr Anke Neumann

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This is the authors' accepted manuscript of an article that has been published in its final definitive form by American Chemical Society, 2020.

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Abstract

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.


Publication metadata

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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