Reaction mechanisms of biomedically active species in water film activated by nitrogen oxides synergized with air DBD plasma

In this study, the production and destruction pathways of the most important biomedically active species (H2O2aq, O3aq, ONOOHaq, OHaq and NOxaq) in a water film exposed to a cold atmospheric pressure plasma (CAP) were investigated using a comprehensive kinetic model. The primary focus is on the regulatory mechanism of aqueous phase RONS density with a small amount of NOx fed into the air DBD plasma. The model is experimentally verified by measuring the concentrations of NO3aq- and NO2aq-, along with the pH value in the liquid phase. The results indicate that the addition of NO increases the density of HNO2aq in the water film, which facilitates the formation of ONOOHaq. The addition of NO2 promotes an increase in the density of HNO3aq in the water film, thereby enhancing the acidity of the solution. In addition, the NO/NO2 inlet ratio and the distance between the discharge outlet and the sample have been studied as parameters for optimizing the discharge source. The results show that these two factors can be adjusted to regulate the gas-phase HNOx and NxOy densities, thereby influencing the density of RONS in the water film. Such distinct control mechanisms provide valuable insights for the design of atmospheric pressure plasma sources for sterilization applications.