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Photoreductive defluorination of trifluoroacetic acid (TFA) in the aqueous phase by hydrated electrons

Jiao, Hanwei and Zhang, Chaojie and Yang, Mo and Wu, Yanhui and Zhou, Qi and Hoffmann, Michael R. (2022) Photoreductive defluorination of trifluoroacetic acid (TFA) in the aqueous phase by hydrated electrons. Chemical Engineering Journal, 430 . Art. No. 132724. ISSN 1385-8947. doi:10.1016/j.cej.2021.132724.

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Due to its extremely high stability and continuous accumulation in the environment, which lead to a widespread environmental distribution, trifluoroacetic acid (TFA) is a global concern in ecosystems. In this study, TFA was decomposed through photoreduction by hydrated electrons (e_(aq)⁻) with potassium iodide (KI) as a mediator in the aqueous phase. The reaction proceeded under irradiation at 254 nm in a solution with the following parameters: pH 11.0, anoxic conditions and room temperature (25℃). In 48 h, 91.4% ± 1.1% of the fluoride ions (F⁻) on all the TFA molecules in the UV/KI system were released, indicating the effective defluorination of TFA. Kinetic analysis indicated that TFA decomposition fit the first-order model with a rate constant of 0.147 ± 0.014 h⁻¹. The optimal reaction conditions were 0.2 mM KI, 0.05 mM TFA and pH 11.0. In addition to fluoride ions (F⁻) and CO₂, other intermediates, including formic acid (HCOO⁻) and acetic acid (CH₃COO⁻), were identified and quantified in the aqueous phase by Ion chromatography (IC), and small amounts of gas-phase CF₃H and CF₄ were detected by gas chromatography-mass spectrometry (GC/MS). Finally, possible TFA degradation pathways were proposed. This method may be effective for the treatment of TFA in aquatic environments.

Item Type:Article
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URLURL TypeDescription
Zhang, Chaojie0000-0003-3108-8271
Hoffmann, Michael R.0000-0001-6495-1946
Additional Information:© 2021 Elsevier. Received 8 May 2021, Revised 26 September 2021, Accepted 27 September 2021, Available online 30 September 2021. This study was supported by the National Natural Science Foundation of China (Project No. 21976135, No.22078249). The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Funding AgencyGrant Number
National Natural Science Foundation of China21976135
National Natural Science Foundation of China22078249
Subject Keywords:Trifluoroacetic acid; Hydrated electron; Photoreductive degradation; Potassium iodide
Record Number:CaltechAUTHORS:20211008-224633542
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Official Citation:Hanwei Jiao, Chaojie Zhang, Mo Yang, Yanhui Wu, Qi Zhou, Michael R. Hoffmann, Photoreductive defluorination of trifluoroacetic acid (TFA) in the aqueous phase by hydrated electrons, Chemical Engineering Journal, Volume 430, Part 1, 2022, 132724, ISSN 1385-8947,
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:111338
Deposited By: George Porter
Deposited On:11 Oct 2021 14:55
Last Modified:12 Oct 2021 19:07

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