Effect of reactor configuration of surface dielectric barrier discharge in contact with liquids on the production of reactive species

Surface dielectric barrier discharge (SDBD), ignited directly from liquid electrodes at the three-phase plasma/liquid/solid interface, represents a novel approach to liquid and polymer surface treatment. This study examines the formation of reactive oxygen and nitrogen species (RONS) in both gas and liquid phases, focusing on the effects of reactor geometry and electrode liquid type—oxalic acid solution and tap water were tested. Ozone dominated the gas phase in the open-air reactor, whereas restricting the air volume above the discharge increased the relative humidity and the concentration of nitrogen-containing species. The spatial limitations of the discharge region also affected the pH of the treated liquid. In the liquid phase, key RONS (H₂O₂, NO₂ − , NO₃ − , O₃) were identified. The liquid type had the most pronounced effect on NO₂ − and NO₃ − formation dynamics. The concentrations of all detected species increased with the plasma energy density input. Additionally, electrical measurements of the SDBD with liquid electrodes were performed, and its operational characteristics are discussed. While various reactor configurations may be used in practice, our results demonstrate that the choice of setup significantly influences the underlying plasma chemistry and must be carefully considered in real-world applications. • Surface DBD plasma at the gas/liquid/solid interface is investigated. • Three configurations of the plasma reactor are studied. • Reactive oxygen and nitrogen species generated in gas and liquid phases are studied. • Varied RONS concentration trends were observed depending on the reactor configuration and the treated liquid.