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Vitamin B12 (Co^(II)) initiates the reductive defluorination of branched perfluorooctane sulfonate (br-PFOS) in the presence of sulfide

Sun, Zhuyu and Geng, Dan and Zhang, Chaojie and Chen, Jiabin and Zhou, Xuefei and Zhang, Yalei and Zhou, Qi and Hoffmann, Michael R. (2021) Vitamin B12 (Co^(II)) initiates the reductive defluorination of branched perfluorooctane sulfonate (br-PFOS) in the presence of sulfide. Chemical Engineering Journal, 423 . Art. No. 130149. ISSN 1385-8947. doi:10.1016/j.cej.2021.130149. https://resolver.caltech.edu/CaltechAUTHORS:20210512-085620776

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Abstract

Due to the extremely high stability of perfluorooctane sulfonate (PFOS), effective defluorination is difficult. Previous studies indicated that PFOS can be decomposed under the catalysis of vitamin B12 (VB12) with strong artificial reductants such as Ti(III)-citrate and nZn0. In this study, we explored if naturally occurring reductant like sulfide (S²⁻) could initiate the reaction. In S²⁻/VB12 system, branched PFOS (br-PFOS) can undergo effective decomposition and defluorination at the temperature of 70 °C and pH greater than 12. The degradation of br-PFOS fits pseudo-first-order kinetic with a rate constant of 0.0984 ± 0.0034 d⁻¹ in the presence of 30 mM Na₂S and 300 μM VB12, while linear PFOS (L-PFOS) remained stable during 30 d reaction process. UV–Vis spectral characterization indicates that S²⁻ reduces VB12(Co^(III)) to Co^(II), which is able to initiate the reductive defluorination. Based on the product analysis, HF/2F elimination followed by C–C scission is the dominant degradation pathway of br-PFOS instead of stepwise H/F exchange. The primary products include F− and polyfluorinated sulfonates and carboxylates. The degradation of br-PFOS is strongly dependent on temperature due to a relatively high apparent activation energy of 62.86 kJ/mol. Strong alkaline condition can greatly enhance the decomposition efficiency since S²⁻ is the primary reactive form. This study provides new insights into the VB12-catalyzed defluorination of PFOS and a feasible approach for future natural or engineered remediations of br-PFOS.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1016/j.cej.2021.130149DOIArticle
ORCID:
AuthorORCID
Hoffmann, Michael R.0000-0001-6495-1946
Alternate Title:Vitamin B12 (CoII) initiates the reductive defluorination of branched perfluorooctane sulfonate (br-PFOS) in the presence of sulfide
Additional Information:© 2021 Elsevier B.V. Received 21 January 2021, Revised 24 April 2021, Accepted 27 April 2021, Available online 4 May 2021. This study has been supported by the National Natural Science Foundation of China (Project No. 21906016, 21976135, 21677109), the Fundamental Research Funds for the Central Universities (No. 2232020D-25) and the State Key Laboratory of Pollution Control and Resource Reuse Foundation (No. PCRRF19007). 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. We declare that we have no actual or potential conflict including financial, personal or other relationships with other people or organizations within three years of beginning the submitted work that could inappropriately influence, or be perceived to influence, their work.
Funders:
Funding AgencyGrant Number
National Natural Science Foundation of China21906016
National Natural Science Foundation of China21976135
National Natural Science Foundation of China21677109
Fundamental Research Funds for the Central Universities2232020D-25
State Key Laboratory of Pollution Control and Resource Reuse FoundationPCRRF19007
Subject Keywords:Perfluorooctane sulfonate (PFOS); Reductive defluorination; Vitamin B12 (VB12); CoII oxidation state; Degradation pathway
DOI:10.1016/j.cej.2021.130149
Record Number:CaltechAUTHORS:20210512-085620776
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20210512-085620776
Official Citation:Zhuyu Sun, Dan Geng, Chaojie Zhang, Jiabin Chen, Xuefei Zhou, Yalei Zhang, Qi Zhou, Michael R. Hoffmann, Vitamin B12 (CoII) initiates the reductive defluorination of branched perfluorooctane sulfonate (br-PFOS) in the presence of sulfide, Chemical Engineering Journal, Volume 423, 2021, 130149, ISSN 1385-8947, https://doi.org/10.1016/j.cej.2021.130149. (https://www.sciencedirect.com/science/article/pii/S1385894721017344)
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:109090
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:12 May 2021 16:23
Last Modified:12 May 2021 16:23

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