Initiation of Oxidation in Aqueous Solutions by Cold Plasma from a Corona Electric Discharge

A possible new method for the generation of ozone–hydroxyl mixtures is considered: the use of cold plasma from a corona electric discharge between a point electrode and a plane, with negative voltage at the point electrode. Discharges in air and in water vapor are considered. The lifetime of hydroxyl radicals in these conditions is ~0.12 s; ozone is consumed in sustaining the hydroxyl radicals. The parameters of the power supply circuit for the point electrodes is considered. As an example, the functional configurations of a closed generator (volume of liquid to be treated 50 mL; total discharge current 0.5 mA), a flow-type reactor (discharge current 5 mA; productivity 250 L/h), and a circulatory reactor productivity 25–250 L/h) are presented. The circulatory system permits increase in the dose created in the liquid by decrease in productivity of the water. The energy consumption in generating a single hydroxyl radical in the corona discharge is around 500 eV. It is not economically expedient to process extremely polluted water. To remove impurities that are hard to break down, treatment with ozone–hydroxyl mixture is preceded by regular water treatment. For each reactor, the doses created in the liquid are determined. The advantages and disadvantages of each system are compared.