Per - and polyfluoroalkyl substances (PFAS) are a group of environmental contaminants, that are dispersed throughout the world. A number of areas have been affected by their persistence and biomagnification. PFAS remediation of contaminated material requires extensive knowledge of the species involved. A method to simplify the study of the thermal degradation of PFAS is presented in this paper, providing a solution to experimental and analytical challenges. A three-zone furnace allowed manipulation of both reaction temperature and gas flowrate (and consequently residence time). The PFAS compound could be charged and vaporised in a separate zone. Adopting this experimental methodology, a kinetic model describing the decomposition of the PFAS can be devised. When reacting under an inert nitrogen atmosphere, perfluorooctanoic acid (PFOA) degraded at temperatures above 450 °C. The products observed were found to be hydrofluoric acid (HF) and carbon dioxide (CO2), along with a perfluoro-1-heptene species. Additional products of 1H-perfluorohexane or 1H-perfluoroheptane were also observed when residence times were increased. The effect of water vapour was also investigated, with similar behaviour to pyrolysis being observed, where a significantly higher concentration of HF was detected under otherwise similar reaction conditions. These preliminary results suggest water vapour accelerates the rate of PFAS decomposition.
CITATION STYLE
Stockenhuber, S., Weber, N., Dixon, L., Lucas, J., Grimison, C., Bennett, M., … Kennedy, E. (2022). Thermal degradation of perfluorooctanoic acid (PFOA). In Proceedings of the 16th International Conference on Environmental Science and Technology (Vol. 16). Cosmos S.A. https://doi.org/10.30955/gnc2019.00155
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