High energy radiation - Induced cooperative reductive/oxidative mechanism of perfluorooctanoate anion (PFOA) decomposition in aqueous solution
Copyright © 2022 Elsevier Ltd. All rights reserved..
The mechanism of high-energy radiation induced degradation of perfluorooctanoate anion (PFOA, C7F15COO-) was investigated in aqueous solutions. Identification and quantification of transient species was performed by pulse radiolysis and of final products by gas and ion chromatography, electrochemical method using fluoride ion-selective electrode and ESI-MS after γ-radiolysis. Experimental data were further supported by kinetic simulations and quantum mechanical calculations. Radiation induced degradation of PFOA includes as a primary step one-electron reduction of PFOA by hydrated electrons (e-aq) resulting in formation of [C7F15COO-]●-. The rate constants of this reaction were found to be in the range 7.7 × 107-1.3 × 108 M-1s-1 for ionic strength of the solutions in the range 0.01-0.1 M and were independent of pH of the solutions. At pH > 11 [C7F15COO-]●- tends to defluorination whereas at lower pH undergoes protonation forming [C7F15COOH]•-. A sequence of consecutive reactions involving [C7F15COOH]•- leads to PFOA regeneration what explains a high radiation resistance of PFOA at moderately acidic solutions. A simultaneous presence of oxidizing transient species (●OH) in the irradiated system enhanced decomposition of (C7F14)·COO- as well as [C7F15COOH]•-. The key steps in this complex radical mechanism are the reactions of both these radical anions with ●OH leading to semi-stable products which further undergo consecutive thermal reactions. On the other hand, direct reactions of PFOA with ●OH and ●H were found to be relatively slow (7 × 103 and <4 × 107 M-1s-1, respectively) and do not play relevant role in PFOA degradation. Collected for the first time results, such as dependence of selected reaction rate constants and selected products radiation chemical yields on pH as well as finding of several semi-stable products, missing in previous studies, indicate incompleteness of published earlier reaction pathways of PFOA degradation. The presented overall mechanism explains experimental results and verifies previously suggested mechanisms found in the literature.
| Medienart: |
E-Artikel |
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| Erscheinungsjahr: |
2022 |
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| Erschienen: |
2022 |
| Enthalten in: |
Zur Gesamtaufnahme - volume:295 |
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| Enthalten in: |
Chemosphere - 295(2022) vom: 01. Mai, Seite 133920 |
| Sprache: |
Englisch |
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| Beteiligte Personen: |
Szreder, Tomasz [VerfasserIn] |
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| Links: |
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| Anmerkungen: |
Date Completed 15.03.2022 Date Revised 15.03.2022 published: Print-Electronic Citation Status MEDLINE |
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| doi: |
10.1016/j.chemosphere.2022.133920 |
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| funding: |
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| Förderinstitution / Projekttitel: |
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| PPN (Katalog-ID): |
NLM336760620 |
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| 100 | 1 | |a Szreder, Tomasz |e verfasserin |4 aut | |
| 245 | 1 | 0 | |a High energy radiation - Induced cooperative reductive/oxidative mechanism of perfluorooctanoate anion (PFOA) decomposition in aqueous solution |
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| 500 | |a Date Revised 15.03.2022 | ||
| 500 | |a published: Print-Electronic | ||
| 500 | |a Citation Status MEDLINE | ||
| 520 | |a Copyright © 2022 Elsevier Ltd. All rights reserved. | ||
| 520 | |a The mechanism of high-energy radiation induced degradation of perfluorooctanoate anion (PFOA, C7F15COO-) was investigated in aqueous solutions. Identification and quantification of transient species was performed by pulse radiolysis and of final products by gas and ion chromatography, electrochemical method using fluoride ion-selective electrode and ESI-MS after γ-radiolysis. Experimental data were further supported by kinetic simulations and quantum mechanical calculations. Radiation induced degradation of PFOA includes as a primary step one-electron reduction of PFOA by hydrated electrons (e-aq) resulting in formation of [C7F15COO-]●-. The rate constants of this reaction were found to be in the range 7.7 × 107-1.3 × 108 M-1s-1 for ionic strength of the solutions in the range 0.01-0.1 M and were independent of pH of the solutions. At pH > 11 [C7F15COO-]●- tends to defluorination whereas at lower pH undergoes protonation forming [C7F15COOH]•-. A sequence of consecutive reactions involving [C7F15COOH]•- leads to PFOA regeneration what explains a high radiation resistance of PFOA at moderately acidic solutions. A simultaneous presence of oxidizing transient species (●OH) in the irradiated system enhanced decomposition of (C7F14)·COO- as well as [C7F15COOH]•-. The key steps in this complex radical mechanism are the reactions of both these radical anions with ●OH leading to semi-stable products which further undergo consecutive thermal reactions. On the other hand, direct reactions of PFOA with ●OH and ●H were found to be relatively slow (7 × 103 and <4 × 107 M-1s-1, respectively) and do not play relevant role in PFOA degradation. Collected for the first time results, such as dependence of selected reaction rate constants and selected products radiation chemical yields on pH as well as finding of several semi-stable products, missing in previous studies, indicate incompleteness of published earlier reaction pathways of PFOA degradation. The presented overall mechanism explains experimental results and verifies previously suggested mechanisms found in the literature | ||
| 650 | 4 | |a Journal Article | |
| 650 | 4 | |a Advanced oxidation/reduction processes | |
| 650 | 4 | |a Gamma-radiolysis | |
| 650 | 4 | |a Mechanism of radiation degradation | |
| 650 | 4 | |a PFOA | |
| 650 | 4 | |a Perfluorooctanoate anion | |
| 650 | 4 | |a Pulse radiolysis | |
| 650 | 7 | |a Anions |2 NLM | |
| 650 | 7 | |a Caprylates |2 NLM | |
| 650 | 7 | |a Fluorocarbons |2 NLM | |
| 650 | 7 | |a perfluorooctanoic acid |2 NLM | |
| 650 | 7 | |a 947VD76D3L |2 NLM | |
| 700 | 1 | |a Kisała, Joanna |e verfasserin |4 aut | |
| 700 | 1 | |a Bojanowska-Czajka, Anna |e verfasserin |4 aut | |
| 700 | 1 | |a Kasperkowiak, Małgorzata |e verfasserin |4 aut | |
| 700 | 1 | |a Pogocki, Dariusz |e verfasserin |4 aut | |
| 700 | 1 | |a Bobrowski, Krzysztof |e verfasserin |4 aut | |
| 700 | 1 | |a Trojanowicz, Marek |e verfasserin |4 aut | |
| 773 | 0 | 8 | |i Enthalten in |t Chemosphere |d 1994 |g 295(2022) vom: 01. Mai, Seite 133920 |w (DE-627)NLM074698028 |x 1879-1298 |7 nnns |
| 773 | 1 | 8 | |g volume:295 |g year:2022 |g day:01 |g month:05 |g pages:133920 |
| 856 | 4 | 0 | |u http://dx.doi.org/10.1016/j.chemosphere.2022.133920 |3 Volltext |
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