Investigation of the Influence of Plasma Parameters on PFAS Decomposition Using Gas-Liquid Interface Plasma

Per- and polyfluoroalkyl substances (PFAS) are persistent environmental pollutants known for their resistance to conventional degradation methods due to their strong carbon-fluorine bonds. Advanced oxidation processes, particularly plasma-based treatments, have recently attracted attention for PFAS decomposition. Among these, gas-liquid interface plasma combined with bubble generation offers enhanced mass transfer and reactive species generation, potentially improving PFAS degradation efficiency. However, the influence of solution properties, especially electrical parameters, on this combined plasma-bubble system remains unclear. In the previous study, the observed enhancement in PFOA degradation is attributed to the occurrence of surface discharge, which increases the contact area between the plasma and the treated water, facilitating more effective degradation. However, further increasing the conductivity may suppress the occurrence of surface discharge, suggesting the existence of an optimal conductivity range for PFOA degradation. Additionally, experiments incorporating bubble injection revealed that 90% of PFAS was decomposed within 15 minutes. This result indicates that scaling up the reactor improves the decomposition efficiency of PFAS. In addition to optimal conductivity, it was further hypothesized that by optimizing the plasma parameters while introducing bubbles, an unprecedentedly high efficiency of PFAS decomposition could be achieved. This hypothesis was experimentally tested, and the results were promising, demonstrating the potential of the combined approach for enhanced treatment performance. These findings provide valuable insights into the interplay between plasma parameters and bubble-assisted gas-liquid plasma in PFAS decomposition, contributing to the development of more effective plasma-based water treatment technologies.