Thermal Transformation of Perfluorooctanesulfonic Acid (PFOS) and Perfluorooctanoic Acid (PFOA) in Spiked Sand: Identification of Novel Products of Incomplete Degradation
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Authors
AL-Dirani, Samer
Date
Type
thesis
Language
eng
Keyword
PFAS , Thermal Remediation , Novel Products , PFAS destruction Mechanism , fluorinated compounds , PFOA , PFOS , PFAS destruction , short chain PFAS , Long chain PFAS , PFAS spiked Sand , Unknown fluorinated compounds
Alternative Title
Abstract
This study explored thermal conductive heating (250 °C to 550 °C) in the presence of air for remediating silica sand spiked with perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) at 50 and 200 mg PFAS/kg sand. The fate of PFAS and fluorine was quantified with sand and emission analysis, including targeted PFAS, transformation products, and soluble fluorine. Post-treatment PFAS sand concentrations at temperatures above 400 °C were below detection limits (0.0004 mg/kg), with >99% removal efficiency. However, at 300 °C and 250 °C, PFOA and PFOS remained above regulatory guidelines. TFA and PFPA were the most detected PFAS in emissions at temperatures >400 °C, whereas PFHpA, PFHxA, and PFPeA were the main emissions at 300 °C and 250°C. Long-chain PFAS (>C9) were identified in the emission system at all temperatures indicating that PFAS radicals can combine to form long-chain PFAS. Several novel PFAS transformation products, including 4,5,6,6,7,7,8,8,8-nonafluorooct-2,4-enoic acid and 2,3,4,5,6,6,7,7,8,8,8-undecafluorooct-2,4-enoic acid, and homologous series of perfluoroalkyl amides (C8HONF15) were detected during high-resolution analysis of the emissions. The finding from this study proves the wide presence of PFAS in emissions during thermal treatment processes and that some of these compounds are not fully understood in terms of their physiochemical or toxicological characteristics.
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ProQuest PhD and Master's Theses International Dissemination Agreement
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Copying and Preserving Your Thesis
This publication is made available by the authority of the copyright owner solely for the purpose of private study and research and may not be copied or reproduced except as permitted by the copyright laws without written authority from the copyright owner.