Atmospheric pressure glow discharge for ozone generation

Abstract

Ozone is now attracting much attention worldwide as a pollutionfree oxidant for a wide range of applications, including deodorisation, decolourisation, disinfection, various bleaching processes, gas treatment and chemical synthesis. In each of these, ozone requires less energy than the alternative chlorination process [1]. The consequent surge in the use of ozone has brought about the requirement for its generation at the rate of grams per kilowatt hour (g/kWh), at the same time as producing a high part per million (ppm) concentration. To fulfil these demands, extensive research has been undertaken recently on a number of different experimental configurations and discharge techniques. Ozone is generated by means of an electric discharge, when a high-energy electric field exists between two conductors that are separated by a dielectric and a discharge gap and have a gas containing oxygen or air flowing between them. The high electric field in the resulting low current discharge causes an electron flow across the discharge gap, and by providing sufficient energy to dissociate the oxygen molecules leads to the formation of ozone. For many years silent electric discharge have been commonly used to generate ozone and for other chemical processes [2-7]. The use of dielectric material on one or both side of the electrodes is necessary for the silent technique, as the dielectric barrier serves to distribute the micro-discharges evenly over the entire electrode area and thereby limits the amount of charge and energy that is fed into any individual micro-discharge [2,3,6,7]. Other techniques that are used for ozone generation include corona discharge [8,9], surface discharge [10,11,12], pulsed streamer discharge [13-18] and atmospheric pressure glow discharge [20-24]. This study focuses on the production of ozone using atmospheric pressure glow discharge (APGD). A study of the relevant literature has confirmed that this technique has the potential to generate ozone more efficiently and effectively than the silent discharge. Results from initial experimental work and an outline of future work are presented.