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5080314 
Journal Article 
Breakdown Products from Perfluorinated Alkyl Substances (PFAS) Degradation in a Plasma-Based Water Treatment Process 
Singh, RK; Fernando, S; Baygi, SF; Multari, N; Thagard, SM; Holsen, TM 
2019 
Environmental Science & Technology
ISSN: 0013-936X
EISSN: 1520-5851 
American Chemical Society 
53 
2731-2738 
English 
Byproducts produced when treating perfluorooctanoic acid (PFOA) and perfluorooctanesulfonate (PFOS) in water using a plasma treatment process intentionally operated to treat these compounds slowly to allow for byproduct accumulation were quantified. Several linear chain perfluoroalkyl carboxylic acids (PFCAs) (C4 to C7) were identified as byproducts of both PFOA and PFOS treatment. PFOA, perfluorohexanesulfonate (PFHxS), and perfluorobutanesulfonate (PFBS) were also found to be byproducts from PFOS degradation. Significant concentrations of fluoride ions, inorganic carbon, and smaller organic acids (trifluoroacetic acid, acetic acid, and formic acid) were also identified. In addition to PFCAs, PFHxS, and PFBS, trace amounts of 43 PFOA-related and 35 PFOS-related byproducts were also identified using a screening and search-based algorithm. Minor concentrations of gas-phase byproducts were also identified (<2.5% of the F originally associated with the parent molecules) some of which are reported for the first time in perfluoroalkyl substance degradation experiments including cyclic perfluoroalkanes (C4F8, C5F10, C6F12, C7F14, and C8F16). The short chain PFCAs detected suggest the occurrence of a stepwise reduction of the parent perfluoroalkyl substances (PFAS) molecule, followed by oxidation of intermediates, perfluoroalkyl radicals, and perfluoro alcohols/ketones. Using a fluorine mass balance, 77% of the fluorine associated with the parent PFOA and 58% of the fluorine associated with the parent PFOS were identified. The bulk of the remaining fluorine was determined to be sorbed to reactor walls and tubing using sorption experiments in which plasma was not generated. 
Environmental Studies; Carboxylic acids; Formic acid; Ketones; Degradation; Fluoride; Fluorine; Alcohols; Water treatment; Acetic acid; Oxidation; Byproducts; Perfluoro compounds; Trifluoroacetic acid; Inorganic carbon; Mass balance; Intermediates; Organic acids; Perfluoroalkyls; Perfluorooctanoic acid; Algorithms 
PFAS
• Additional PFAS (formerly XAgency)
• Expanded PFAS SEM (formerly PFAS 430)
     Perfluorooctane
• PFAS 150
     Literature Search Update December 2020
          PubMed
     Literature Search August 2019
          PubMed
     Ammonium perfluorooctanoate
     Perfluorobutanesulfonate
     Perfluorobutanesulfonic acid
     Perfluorobutanesulfonyl fluoride
     Perfluorohexanesulfonic acid
     Perfluorooctanesulfonate
     Perfluorooctanesulfonic acid
     Perfluorooctanoic acid
     Trifluoroacetic acid
• PFAS Universe
     Data Source
          Web of Science
          Pubmed
     2,​2,​2-​trifluoro-Acetic acid-​d
     Perfluorobutanesulfonate
     Perfluorobutanesulfonic acid
     Perfluorohexanesulfonate
     Perfluorohexanesulfonic acid
     Perfluorooctane
     Perfluorooctanesulfonate
     Perfluorooctanesulfonic acid
     Perfluorooctanoate
     Sodium perfluorohexanesulfonate
     Perfluorooctanoic acid
• PFBS
     Search
          PubMed
          WOS
     Lit Search Update: May 2019
          PubMed
          WOS
     Scopus: April 2021
• PFHxS
     Database searches
          Pubmed
          WOS
          Scopus
     Supplemental
          TiAb
          Environmental fate or occurrence (including food)
          Manufacture, engineering, use, treatment, remediation, or laboratory methods
     Literature Search Update April 2023
          Supplemental
               Environmental fate or occurrence (including food)
OW - HHRAB
• PFOA (335-67-1) and PFOS (1763-23-1)
     Literature Search Update (2013-2019)
          PubMed
          WOS