Insight into the generation network of reactive oxygen species in H2O under nonthermal atmospheric-pressure plasma irradiation using a kinetic modeling approach

A kinetic model incorporating the dominant generation networks of reactive oxygen species (ROS) in H2O under nonthermal atmospheric-pressure plasma irradiation was developed in this study. In the proposed model, the minimum necessary elementary reactions involving ROS were considered based on the behaviors of the dissolved O2 and H2O2 observed in plasma-irradiated H2O. The ROS included not only OH radicals but also other ROSs such as OOH, O, and these anionic radicals. The model agrees well with the experimental results for various initial dissolved O2 concentrations, pH values, and input power conditions. Further, the model could predict specific behavior under extrapolated conditions, which are in the presence of H2O2 at the initial conditions. In addition, the reaction rates of elementary reactions involving dissolved O2, which are difficult to measure in the experiments, were simulated by the model. It was found that the reaction rates between the consumption and production reactions of dissolved O2 were balanced at later stages of nonthermal atmospheric-pressure plasma irradiation. The model is expected to provide fundamental guidelines for the effective utilization of nonthermal atmospheric-pressure plasma irradiation.