Optimizing process parameters of dielectric barrier discharge-based plasma source for efficient generation of plasma-activated water

Plasma-activated water (PAW) has remarkable biochemical activity owing to the synergistic action of reactive oxygen and nitrogen species [1]. However, optimization of the plasma source is required to facilitate seamless translation of PAW into practical applications [2, 3]. In this paper, a study of PAW generation was conducted to understand the effect of changes in treatment distance, voltage, and time on the resulting water chemistry while maintaining a consistent plasma discharge in a pin-to-plate gas phase dielectric barrier discharge configuration. The liquid conductivity, in particular, was examined experimentally to influence plasma discharge significantly. Accordingly, physicochemical characteristics of DI, tap, and seawater in consonance with the plasma discharge were analyzed. Strong oxidizing agents, like hydroxyl radicals, were produced significantly and found to be 108.5 µM at a voltage of 5 kV and frequency of 20 kHz during the bipolar-pulse discharge operation. This can be attributed to the erosion of the high-voltage electrodes in PAW. Nevertheless, the generation of such reactive oxidants was beneficial in the PAW for the fast elimination of bio-contaminants. This has been confirmed by treating E. coli bacteria, which has demonstrated antibacterial characteristics and exhibited around 3 log reduction in the optimal operation of the source.