Environmental Applications of Pulsed Electrical Discharges in Bubbled Water

Abstract

Summary form only given. Pulsed electrical discharges in water find environmental applications in water sterilization and decoloration due to the production of active species, such as ozone, hydrogen peroxide, O, H, and OH radicals. We investigated the production of active species and the decomposition of organic compounds using electrical discharges between horizontal mesh-to-mesh electrodes in water with Ar or Oxygen bubbles passing vertically through the electrodes. The production of active species was investigated using optical emission spectroscopy and a variety of chemical analytical methods. These methods have been used to investigate Rhodamine decoloration and the production of hydrogen peroxide under varying experimental conditions, such as gas flow rate, solution flow rate, mesh size, distance between the electrodes, and electrical power delivered to the system. The ratio of bubble size to mesh size and the distance between the electrodes affect the type of the discharge. The discharge changes from a streamer-discharge to a spark discharge with streamers propagating along the bubble surface. The spark mode with Ar bubbles was shown to be the most effective in the production of active species and Rhodamine WT decoloration. The following observations are noteworthy: The electrical characteristics of the discharge in DI water resemble those of a barrier discharge. Experiments with SiO2 coated electrodes confirm these similarities.