Plasma decoloration of dye using dielectric barrier discharges with earthed spraying water electrodes

The plasma decoloration process of indigo carmine aqueous solution is investigated in this paper using a dielectric barrier discharge with earthed spraying water electrodes (spraying DBD). The influence of high voltage and air gaps on decoloration and the power consumption in the process are discussed. The indigo carmine aqueous solution was employed as a grounded spraying water electrode. The plate electrode was covered by a layer of glass dielectric on its inter-electrode surface and supplied with AC 50 Hz high voltage. The spraying DBD non-thermal plasma was formed in the air gap between the water electrodes and the glass dielectric plate. The experimental results have shown that the decoloration rate increases with rising high voltages and decreasing air gaps. When the air gaps were 30 mm and the voltage was 30 kV, the decoloration rate went up to 95% in 18 min. Using a lesser amount of power the higher decoloration rate could be reached when the air gaps were 30 mm and the voltage was 25 kV. (C) 2008 Elsevier B.V. All rights reserved.