The impact of chain length and GAC characteristics on PFAS thermal degradation
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Authors
Edwards, Lauren
Issue Date
2025
Type
Thesis
Language
en_US
Keywords
byproducts , FTIR , Oxygen , PFCA , Pyrolysis
Alternative Title
Abstract
PFAS are anthropogenic “forever chemicals” that are ubiquitous in the environment that have been linked to negative health outcomes. Due to widespread pollution, it is necessary to have an analytical technique that is more affordable, easy, and quick than the standard options. Therefore, the first objective of this thesis was to demonstrate a novel field technique for detection of organofluorine compounds. To meet this objective, a combustion-FTIR system developed in previous work was mobilized to a known PFAS contaminated site to screen nearby soils for organofluorine. This demonstration was effective, and organofluorine was detected in soils in northern Nevada. To remove PFAS from contaminated water, one effective treatment is the use of granular activated carbon (GAC). Spent GAC can then be regenerated through thermal treatment to near-virgin state for reuse in treatment. The thermalregeneration of PFAS laden GAC represents a potential sustainable route to end the cycle of the “forever chemical”. PFAS sorbed to GAC has been shown to thermally degrade at lower temperatures and have increased mineralization,
although the mechanisms behind these catalytic effects is unclear. Therefore, the second objective of this thesis research was to qualitatively understand the changes in thermal decomposition of perfluorocarboxylic acids (PFCAs) caused by GAC surface. To investigate this mechanism, a bench study on thermal degradation of PFAS-laden GAC was conducted. Three well-characterized GAC were spiked with industrially relevant concentrations of four total types of PFAS. The key findings from this thesis are that the presence of GAC, GAC characteristics, and PFAS size have an effect on PFAS thermal decomposition. There were changes in organofluorine products of incomplete destruction, and statistical differences in the amounts of hydrogen fluoride and silicon tetrafluoride generated by sample.