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

Abstract In this study, the production and destruction pathways of the most important biomedically active species (H 2 O 2aq , O 3aq , ONOOH aq , OH aq and NO x aq ) 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 NO x fed into the air Dielectric Barrier Discharge (DBD) plasma. The model is experimentally verified by measuring the concentrations of NO 3aq − and NO 2aq − , along with the pH value in the liquid phase. The results indicate that the addition of NO increases the density of HNO 2aq in the water film, which facilitates the formation of ONOOH aq . The addition of NO 2 promotes an increase in the density of HNO 3aq in the water film, thereby enhancing the acidity of the solution. In addition, the NO/NO 2 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 HNO x and N x O y 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.