The first quantitative investigation of compounds generated from PFAS, PFAS-containing aqueous film-forming foams and commercial fluorosurfactants in pyrolytic processes

Bin Yao, Runze Sun, Ali Alinezhad, Alena Kubátová, Matt F. Simcik, Xiaohong Guan, Feng Xiao

Research output: Contribution to journalArticlepeer-review

1 Scopus citations

Abstract

Pyrolysis as a thermochemical technology is commonly used in waste management and remediation of organic-contaminated soil. This study, for the first time, investigated fluorinated and non-fluorinated compounds emitted from per- and polyfluoroalkyl substances (PFAS) and relevant products upon pyrolysis (200–890 °C) and their formation mechanisms. Approximately 30 non-fluorinated compounds were detected from PFAS-containing aqueous film-forming foams (AFFFs) and commercial surfactant concentrates (SCs) after heating, including glycols and glycol ethers that were predominant at 200 °C. Oxygen (e.g., 1,4-dioxane) and nitrogen heterocycles and benzene were unexpectedly observed at higher temperatures (300–890 °C), which were likely formed as a consequence of the thermal dehydration, dehydrogenation, and intermolecular cyclization of glycols and glycol ethers. Fluorinated volatiles in six major classes were detected at low and moderate temperatures (200–500 °C), including perfluoroalkenes, perfluoroalkyl aldehydes, fluorotelomer alcohols, and polyfluorinated alkanes/alkenes. Several features of the pyrolyses of PFAS suggest that the underlying decomposition mechanism is radical-mediated. Perfluoroheptene thermally decomposed at 200 °C to shorter-chain homologues following a radical chain-scission mechanism. Most of these volatiles observed at low/moderate temperatures were not detected at 890 °C. Ultra-short-chain fluorinated greenhouse gases (e.g., perfluoromethane) were not found.

Original languageEnglish (US)
Article number129313
JournalJournal of Hazardous Materials
Volume436
DOIs
StatePublished - Aug 15 2022

Bibliographical note

Funding Information:
This work was mainly supported by the U.S. National Science Foundation CAREER Program ( 2047062; F.X. ). B.S. was supported by the University of North Dakota Pilot Postdoctoral Program from the Office of Vice President for Research & Economic Development. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the NSF.

Publisher Copyright:
© 2022 Elsevier B.V.

Keywords

  • Aromatics and heteroaromatics
  • Cationic and zwitterionic PFAS
  • Perfluoroalkenes
  • Radical-chain reactions
  • Thermal transformation

PubMed: MeSH publication types

  • Journal Article
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, Non-U.S. Gov't

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