Degradation of perfluorosurfactant in aqueous solution using non-thermal plasma generated by nano-second pulse corona discharge reactor

Abstract

Perfluorosurfactants (PFS) are global environmental pollutants and are considered as a new anthropogenic type of carcinogenic contaminant that remains untreated by conventional wastewater treatment plants. These organic surfactants are typically refractory, non-biodegradable, and pose great threats to environmental safety and human health. The gradual increase in PFS product consumption by various industries resulted in their abundant occurrence in the ecosystem. Non-thermal plasma-based advanced oxidation processes with powerful oxidation ability appeared to be applicable for the degradation of refractory organic pollutants and enhancing biodegradability. In this work, the decomposition of Perfluorooctanesulfonic acid (PFOS) in water by the application of nano-second pulse corona discharge under oxygen was examined. Working corona discharge under oxygen, argon, and helium has no effects on the decomposition rate. The energy yields at 50% conversion (G50) of about 1 mg L−1 initial PFOS concentration was estimated as 22 mg/kWh under argon or oxygen and 27 mg/kWh under helium. The energy yield G50 for initial concentrations of 7.5 and 18.5 µg L−1 in helium and oxygen was estimated as 0.20 and 0.33 mg/kWh, respectively. A considerable difference in the generation of short perfluoroalkyl acids by-products and fluoride ions was observed when corona discharge was conducted under oxygen and much more of these by-products are formed. A synergistic effect was observed in the presence of other surface-active compounds. Degradation efficiency was enhanced by 10% after the addition of surface-active sulfobetaine into the medium following the same experimental procedure.

Keywords

• Non-thermal plasma
• Perfluorooctanesulfonic acid
• Sulfobetaine
• Nano-pulse corona discharge