Plasma-Based Water Treatment: An Effective Method to Degrade Perfluorooctanoic Acid and Other Emerging Contaminants

Electrical discharge plasma is an effective and versatile advanced oxidation process due to the formation of reactive species such as hydroxyl radicals, hydroperoxyl radicals, and hydrogen peroxide. Plasma treatment also includes a broad range of other treatment mechanisms, including electron-based reduction, UV radiation, cavitation, and thermal degradation.

This study employed a plasma reactor that featured a point-to-ring electrode configuration with discharges in the gas contacting the water surface and the grounded ring electrode in the water with foam generated by bubbling argon. This reactor was tested on a mixture of 23 emerging environmental contaminants including perfluorinated compounds, nitrosamines, pharmaceuticals, personal care products, and haloacetic acids at environmentally relevant concentrations.

The reactor was effective in degrading the majority of contaminants. Perfluorooctanoic acid and perfluorooctanesulfonic acid were completely degraded in less than 5 minutes, with a solution volume of 1400 mL and an input power of 9.7 W.