The generation pathways of OH and H2O2 by plasma-liquid interactions

Abstract

Plasma-liquid interactions (PLIs) are a rich source providing many reactive oxygen species (ROS). These ROS species, such as OH and H2O2, feature powerful oxidative properties, which are excellent utilization for bacterial killing, water treatment, and other applications. Lifetime and reaction pathways of ROS species from plasma into the bulk liquid are complex. Understanding these behaviors is essential for the applications of the ROS species. In this work, we presented two pathways for generation of OH radicals and H2O2 from the plasma into the bulk liquid. Firstly, OH radicals are mainly produced via the dissociation of water molecules by free electrons in the plasma. Generated radicals then quickly recombine into H2O2. These species with a high Henry constant easily absorb and disperse into the bulk liquid. In a second way, OH radicals and H2O2 are also generated by the reaction of O3 with H2O molecules. At first, O3 is absorbed into the bulk liquid and reacts with H2O2 molecules to generate H2O2. Next, O3 continues reacting with this generated H2O2 to produce OH radicals.