DC glow discharge in atmospheric air as a source for volatile organic compounds abatement

In this article, a direct current (DC) discharge in atmospheric pressure air as a source for pollution control is presented. The investigated continuous discharge occurring between two metal electrodes was of the glow type. The discharge generated a highly ionized, non-equilibrium air plasma with gas temperatures of 1500-2500 K. Single and multiple discharges of this type were successfully tested in glass and copper tube reactors for the abatement of selected VOCs (cyclohexanone and toluene). Depending on the reactor type, discharge parameters and the energy density, abatement efficiencies of 30-95% were obtained, with energy costs of 200-1000 eV/molecule. The thermal VOC decomposition in the discharge was coupled with radical-induced volume reactions. It was found that extending the radical-dominated decomposition phase yielded a better performance. The VOCs tested were converted to some gaseous and some condensed products. Copper electrode surfaces influenced the character of the condensed products and seemed to have a certain catalytic effect on the process.