Hydrogen Peroxide Production of Individual Nanosecond Pulsed Discharges Submerged in Water of Elevated Conductivity.

The production of hydrogen peroxide (H2O2) is a key parameter for the performance of pulsed discharges submerged in water utilized as advanced oxidation process. So far, any related assessment of the underlying mechanism was conducted for the application of several hundred discharges, which did not allow for a correlation with physical processes. Moreover, the production was rarely  investigated depending on water conductivity as one of the most important parameters for the development of submerged discharges. Accordingly, H2O2 generation was investigated here for individual single discharge events instigated with 100ns high-voltage pulses in water with three different conductivities and was associated with the discharge development, i.e. spatial expansion and dissipated electrical energy. The approach necessitated the improvement of an electrochemical flow injection analysis based on the reaction of Prussian-blue with H2O2. H2O2 concentrations were quadratically increasing with propagation time and stable for different water conductivities. H2O2 production per unit volume of a discharge was constant over time with an estimated rate constant of 3.2mol·m-1·s-1, averaged over the cross-sectional area of all discharge filaments. However, the individually dissipated energy increased with conductivity, hence, the production efficiency decreased from 6.1g·kWh-1 to 1.4g·kWh-1, which was explained by increased resistive losses within the bulk liquid.