Degradation of Perfluorooctanoic Acid (PFOA) in a Nanosecond Pulse Plasma Discharge Gas-Liquid Reactor

Interaction of water with plasma results in dissociation of water molecules (H 2 O), which leads to the formation of oxidative species i.e. hydroxyl radicals (OH), hydrogen peroxide (H 2 O 2 ), atomic oxygen (O), and reductive species like atomic hydrogen (H), molecular hydrogen (H2), and aqueous electrons. Literature suggests that perfluorooctanoic acid (PFOA) can be degraded by either oxidative species or reductive species. The main objective of this work is to utilize an Ar carrier gas combined with a H 2 O/PFOA mixture (50 ppm) as the liquid phase to study the reaction pathway direction, i.e. oxidative or reductive, in a gas-liquid plasma discharge reactor. The gas phase was analyzed for by-products using gas chromatography mass spectrometry (GC-MS) and Fourier-transform infrared spectroscopy (FTIR). The liquid phase was analyzed using ion chromatography for F ⁻ and liquid chromatography with tandem mass spectrometry (LC/MS-MS) for final concentration of PFOA and shorter chain intermediate products. In this work, the role of OH and e ⁻ aq on the degradation pathway of PFOA in gas-liquid plasma reactors will be investigated. A variable nanosecond power supply is utilized to determine the effects of pulse width, frequency and input voltage on the efficiency of OH, H, e ⁻ aq generation, and in turn on PFOA degradation. (This work was supported by the National Science Foundation, CBET 1702166 and Florida State University)