The influence of liquid conductivity on electrical breakdown and hydrogen peroxide production in a nanosecond pulsed plasma discharge generated in a water-film plasma reactor

The influence of liquid conductivity on electrical breakdown and hydrogen peroxide (H2O2) production in a nanosecond pulsed filamentary discharge generated in a water film plasma reactor was investigated over the liquid conductivity range from 0.01 mS cm(-1) to 36 mS cm(-1) by adding KCl to deionized (DI) water and using helium and argon as carrier gases. The plasma properties, including electron density, gas temperature, and plasma volume, the H2O2 production rate and energy yield, and the energy dissipation into the liquid were determined at different liquid conductivity. The energy dissipation into the bulk liquid increased as the liquid conductivity increased causing the total input energy to increase and resulting in a small decrease in H2O2 energy yield. In addition, the production rate of H2O2 did not change significantly with conductivity for the helium plasma but decreased about 13 percent in the argon plasma. The energy deposited in the helium plasma did not change with conductivity, thereby causing the H2O2 energy yield based upon energy in the plasma to be constant with conductivity. A model based upon the electrical circuit was used to predict the breakdown voltage for a range of liquid conductivity up to 36 mS cm(-1). This model also showed that decreasing the rise time of the applied voltage (i.e. faster rising rate) significantly increased the breakdown voltage, and therefore improved the liquid conductivity tolerance of the plasma system allowing it to function at near sea-water conductivity.