The role of water and oxygen impurities on ozone production in a negative corona discharge of CO2

Abstract

The production of ozone in a negative corona discharge fed by carbon dioxide with embedded traces of oxygen and water has been studied. The presence of traces of oxygen in both pure and dry CO2 leads to an increase in nascent ozone concentrations. In contrast, traces of water vapour (0–800 ppm) are shown to rapidly suppress ozone concentrations with the largest decreases being observed at lowest gas pressures in the discharge (300 Torr). The presence of water vapour did not considerably affect the electrical properties of negative dc corona suggesting that a chemical process is responsible for the ozone loss. We have shown that the addition of water up to a concentration of 1500 ppm has only a marginal effect on the processes of ozone formation but the catalytic cycle of ozone destruction involving OH radicals can be the reason for observed decrease in the total ozone concentration with increasing water concentration.