Electrical Characteristics of Pulsed-Discharge Plasma for Decoloration of Dyes in Water

The electrical characteristics of pulsed-discharge plasma for decoloration of dyes in water were systematically investigated with a view toward getting insight into discharge process. Methylene blue (MB) dye water was selected as the target object. The discharge behavior was found to depend on the power supply voltage, conductivity of MB solution, and pulse-forming capacity. A strong positive linear relationship existed between power supply voltage and initial capacitor voltage. The injection energy per pulse increased when increasing the power supply voltage and a maximal energy efficiency of injection of approximately 85% was obtained at power supply voltage of 50 V. The conductivity of MB solution had appreciable impact on the voltage-current characteristics and discharge time of pulse-forming capacitor. Remarkable increase of pulse current was observed as the pulse-forming capacity increasing, while it had slight effect on the pulse voltage. The pulsed corona discharge in MB solution could change into spark discharge by way of increasing the air flow rate and reducing the electrode distance. Increasing pulse-forming capacity and pulse frequency significantly accelerated the decoloration rate of MB in solution. This paper is expected to provide reference for improving the application of pulsed-discharge plasma in treating dye solution.