Analysis of Electrical Discharge Plasma in a Gas-Liquid Flow Reactor Using Optical Emission Spectroscopy and the Formation of Hydrogen Peroxide

Optical emission spectroscopy was used to characterize an electrical discharge plasma reactor with a liquid H2O film contacting different carrier gases. The plasma gas temperatures for Ar, He, and 1% N2 in Ar were 1000–1200 K and did not vary significantly with liquid flow rate. Increasing solution conductivity by adding KCl to deionized water in the Ar case lowered the temperature by 13%, increased the discharge power and lowered the H2O2 formation rates. The temperature was highest in the case of air (2400 K), and in the case of Ar the temperature increased with the addition of O2. The temperatures for this reactor are comparable to previous studies with discharges in humid gases, while the effects of liquid conductivity were similar to those reported with direct discharge in the liquid phase. Gas‐liquid discharge propagating along a liquid water film exhibits plasma temperatures similar to gas discharges, but the effect of liquid conductivity is similar to discharges directly inside a liquid. In the photograph pure Ar carrier gas contacts a liquid stream of pure water.