Decomposition of Dye in Water Solution by Pulsed Power Discharge in a Water Droplets Spray

A method for decomposing dye by spraying water solution of dye into non-equilibrium plasma in gas phase was investigated using pulsed-corona discharge reactor. A corona reactor used consists of a discharge wire and a cylindrical electrode. Water solution of indigo carmine with a concentration of 20 mg/L was sprayed into the reactor from a showerhead. The sprayed water solution was circulated into the reactor. The dependence of the discharging power injected into the reactor on the decomposition rates of chromogenic bond and unsaturated bond in indigo carmine was investigated. Indigo blue was decolored by 1.5 minutes circulation for the discharging power of 2 W. The result of NMR spectrometry showed that indigo carmine was decomposed completely by 60- minutes treatment. The chromogenic bond and the unsaturated bond were almost decomposed at 9 J/mg and 360 J/mg, respectively. As the discharging power increased, decomposition rates of both bonds in indigo carmine increased. Regardless of the set value of discharge repetition rate and charging voltage to the capacitor, the decomposition rate of the chromogenic bond was constant in the same discharging power. However, the higher repetitive pulses were more effective for the decomposition of the unsaturated bond rather than the magnitude of charging voltage in the constant discharge power.