| AVS 55th International Symposium & Exhibition | |
| Plasma Science and Technology | Thursday Sessions |
| Session PS1-ThM |
| Session: | Atmospheric Plasma Processing and Micro Plasmas |
| Presenter: | Š. Potocký, Nagoya University, Japan |
| Authors: | Š. Potocký, Nagoya University, Japan N. Saito, Nagoya University, Japan O. Takai, Nagoya University, Japan |
| Correspondent: | Click to Email |
During recent years plasma systems in liquid have become a topical interest. They open new possibilities in wastewater treatment. Those systems are able to produce highly active species which finally results in conversion of the organic to innocuous materials. Nevertheless, the drawback of such system meets with the requirement of very high voltage for sustaining the plasma discharge and relatively low energy efficiency. Another important process is the erosion of the electrodes that limits the operating lifetime or leads to the pollution of treated water with metal particles released from the electrodes. We demonstrate operation of solution plasma process under relatively low discharge voltage (below 4 kV) and two different plasma regimes with pulse energies in mJ range using a high frequency bipolar pulsed DC power supply. It can be operated up to the repetition frequency of 30 kHz with a pulse width range from 2 µs to 10 µs and a maximum voltage and current of ±6 kV and 7 A, respectively. The oxidative decoloration of organic dyes by the bipolar pulsed discharge plasma between needle-to-needle electrodes in water solution has been investigated in two discharge modes: (i) corona, (ii) spark/streamer mode. Ratio between H-alpha and hydroxyl radical emission line intensity differ by two orders of magnitude in those two modes even for high value of solution conductivity (1 mS/cm) which is close to typical value of a wastewater. The current-voltage characteristics of the system together with an optical emission spectroscopy of plasma discharge were used to characterize regimes of plasma discharge operation. Analysis of generated hydrogen peroxide concentration by colorimetric method using titanium reagent and the absorption spectroscopy was performed. Measurement of electrodes erosion and metal concentration (by inductively coupled plasma mass spectroscopy) due to solution plasma process was also carried out indicating obvious difference in two modes of plasma discharge operation.