Investigation Of Gas-liquid Hybrid Pulsed Discharges Reactor Characteristics And Dye Decolorization

The pulsed high-voltage discharge is a new advanced oxidation water treatment technology. It gathers high energy electron radiation, chemical oxidation, photochemical oxidation in one process. The whole system has no needs of external oxidant and the technology has a broad application prospect. In this paper, methyl orange(MO) dye wastewater was chosen as the objective, some investigations were conducted in the following factors: the discharge characteristics of reactor, parameter optimization, the impact of electrical changes on MO dye wastewater decolorization, as well as the effects of additives H₂O₂, Na₂CO₃ on active species and the degradation mechanism of organic pollutant. The results were as follows:The color group of azo dyes MO could be effectively destroyed by pulsed high-voltage discharge and a high decolorization rate was obtained. The decolorization rate was increased with the growth of the treatment time for discharge, the improvement of peak voltage, and frequency. Under the condition of 30kV peak voltage the decolorization rate of MO was 86% after discharge treatment for 15min.The liquid conductivity has an increasing trend during the discharge treatment process. As the initial conductivity was 1700μS/cm, the decoloration of MO was up to 85.34%. The largest energy was injected into the reactor. After addition of H₂O₂, a large amount of hydroxyl radicals were produced so that the decolorization rate of MO was increased.The optimum distance between needle electrode and water surface was 1mm and the optimum immersion depth of ground plate electrode was 28mm, as well as the optimum numbers of needle electrode was 24 and the distance between the needle electrode was 7.5mm.When bubbling different gas into the reactor system, the degradation mechanisms were different. The different impacts of the decolorization rate were ordered as follows: oxygen> air> argon> nitrogen. pH values of solutions after discharge have been shown by a downward trend. If the gas source contained N₂, pH values decrease faster than oxygen and air condition.By addition of Na₂CO₃, the product of·OH did not react with MO so that the decoloration of MO was decreased. Hydroxyl radical was the main active species that promote organic compound degradation. On the other hand, both the roles of ozone and hydroxyl radicals were subjected to be suppressed.