The Role of Pulse Voltage Amplitude on Chemical Processes Induced by Streamer Discharge at Water Surface

Ruma Ruma,Hamid Hosano,Hidenori Akiyama,Takashi Sakugawa

doi:10.3390/catal8050213

Abstract

The paper reports the effects of pulse voltage amplitude on streamer discharge propagation at water surface. The subsequent chemical processes in a reactor following the surface discharges with different voltages are presented. A pulsed power modulator (PPM) system equipped with a control unit was employed to generate 0–25 kV pulses at 500 Hz. A point-plane electrode configuration was used for experiments, with the point electrode placed with 1 mm gap from the water surface in atmospheric air, and plane ground submerged with 30 mm gap in water. The streamer length at water surface was significantly influenced by the pulse voltage amplitude. Colorimetric measurement of hydrogen peroxide (H2O2) and treatment of indigo carmine organic dye solution were carried out to elucidate the chemical processes produced at various pulse voltages. The experimental results reveal that the applied voltage is a factor that greatly affects water surface discharges and their chemical processes.

Highlights

The application of high voltage pulses can generate corona or streamer discharge directly in water, or at the water’s surface
The main purpose of the present study is to investigate the effects of pulse voltage amplitude on the chemical process of streamer discharge at the water’s surface
The dye color changed to almost transparent after 6.0 min of surface discharge treatment at 21.6 kV, which color changed to almost transparent after 6.0 min of surface discharge treatment at 21.6 kV, which was significantly different from the treatment at 9.1 kV. These results indicate that the strong was significantly different from the treatment at 9.1 kV. These results indicate that the strong chromogenic C=C double bond, which is mainly responsible for the blue color of dye solution, is chromogenic C=C double bond, which is mainly responsible for the blue color of dye solution, is broken rapidly due to contact of discharge plasma at water surface

Summary

Introduction

The application of high voltage pulses can generate corona or streamer discharge directly in water, or at the water’s surface. Atmospheric water surface discharge reactors combine the facilities of gas phase discharge formed above the water surface with those of liquid phase discharge in water, without using supplementary gases [3,4]. These reactors enhance the liquid phase reactions through absorption of reactive species formed in the gas phase, and improve the overall efficiency of plasma chemical processes for the treatment of water [5,6]. After initiation at the high voltage (H.V.) electrode tip, discharges directly propagate through the gas phase, and spread radially over the water surface within a very short period (several nanoseconds)

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