Extreme decrease of ozone product using high pure oxygen

The ozone-zero phenomenon named by the authors of this paper is investigated by emission spectroscopy and temporal variations of ozone concentrations. The measurements of ozone concentrations are performed by ozone monitors placed at the outlets of two ozone generators. The two generators are operated independently; however a gas flow system is connected in series through the gas flow direction. Ozone-zero means that the ozone concentration at the outlet of the generator during the ozone-zero phenomenon, is almost zero when using dielectric barrier discharge (DBD) in pure oxygen as the feed gas. It is considered that the main causes of the phenomenon are certain reactions in the gas phase or on the surface of the electrode in the generator. To distinguish between reactions, step responses of the ozone concentration at the outlets of both ozone generators are observed using the combined operation of the two generators. A clear difference in the response time of the ozone concentration is observed between the two grenerators. Thus, we succeeded in distinguishing the main cause of the ozone-zero phenomenon by analyzing both reactions in the generator. From the results of our investigation, we concluded that the ozone-zero phenomenon caused by ozone decomposition on the electrode surface is accompanied by some changes in the surface of the ozone generator. The recovery from the phenomenon is accomplished by covering the changed surface with NO2, which is considered to compose in the generator with the addition of a small amount of air or N-2 to pure oxygen as the feed gas.