Atmospheric Oxidation of Per- And Polyfluoroalkyl Substances (PFAS) Thermal Decomposition Products and Its Potential for Secondary Organic Aerosol Formation

LILLIAN TRAN, Linhui Tian, Ying-Hsuan Lin, University of California, Riverside

     Abstract Number: 68
     Working Group: Chemicals of Emerging Concern in Aerosol: Sources, Transformations, and Impacts

Abstract
Due to decades of widespread manufacturing and use of per- and polyfluoroalkyl substances (PFAS) to produce water, fire, and oil resistant products, the environment has become contaminated with such substances. During the thermal destruction of PFAS-related substances (e.g., firefighting, thermal treatment, urban fires, etc.), products of incomplete destruction (PIDs) in the form of volatile organofluorines (VOFs) can be emitted into the atmosphere. There is little known about the potential atmospheric transformation of PFAS thermal products. In this research, many unsaturated VOFs were identified from the pyrolysis of PFAS, including those in constrained ring formations. Previous studies have demonstrated the ozonolysis of similar perfluoroalkenes. Hydrogenated VOFs were also identified, which could also be oxidized via OH radicals. We hypothesize that the unsaturated and hydrogenated nature of these compounds creates potential for these VOFs to react with oxidants like ozone and OH to produce more oxygenated organofluorines that can partition in the particle phase and contribute to particle formation. Thermal products of PFAS were generated by pyrolysis of PFOA in its pure chemical form as a model compound to compare to the pyrolysis of PFAS-containing household items. The thermal products were then subject to atmospheric oxidation under a variety of conditions relevant to urban fires. The thermal products and thermal oxidation products were analyzed by a variety of mass spectrometry techniques. This research explores the novel atmospheric implications of PFAS thermal degradation.