Abstract Atmospheric pressure plasmas (APPs) can efficiently activate liquids by simultaneous delivery of electrons, ions, photons, and excited neutral species to the liquid surface. With the goal of controlling APP-liquid interactions, the impact of operational parameters on the formation and development of surface ionization waves (SIWs) was investigated with a two-dimensional numerical model, including the effects of the: (i) applied voltage pulse; (ii) liquid thickness (capacitance); (iii) liquid conductivity; and (iv) Ar/He gas mixture ratio. These parameters can be used to control the type and flux of reactive species arriving at the liquid surface, providing a means to tune the plasma-initiated chemistry. Higher voltages, thinner liquids, higher liquid conductivities, and helium-rich mixtures shift the system towards charge-dominated interfacial reactivity, whereas lower voltages, thicker liquids, lower conductivities, and argon-rich mixtures enhance photon-driven pathways. The ability to control reactivity delivered to the surface was applied to an investigation of APP destruction of per- and polyfluoroalkyl substances (PFAS) in water. Since long-chain PFAS preferentially accumulate at the gas–liquid interface, APPs that generate SIWs provide a targeted means of delivering reactive fluxes directly to these contaminants.
Dias et al. (Sat,) studied this question.