Stikstofoksiedvorming in huishoudelike osoongenerators
Rademeyer, Renée Maria
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Ozone (03) is used as a steriliser of air and water, but the nitrogen oxides (NOx) are harmful to man and the environment. Ozone generators excite electrons to higher energy levels so that O3 and NOx can be manufactured from oxygen and nitrogen in the air feed. The factors that influence the NOx production in domestic ozone generators, in particular Sterizone ozone generators were investigated, so that their design, operation and marketability could be improved. Sterizone ozone generators are designed with an exceptionally fast change in electrical field of 3 x 10xy8V mm-1 s-1 with the aim of optimalising ozone production and decreasing NOx production. In this study it was found that Sterizone does produce NOx. After optimalising the analytical methods, the influence of the following reaction conditions on the production of O3 and NOx by Sterizone was investigated: 1) Feed of synthetic air 2) Water vapour pressure of the feed gas 3) N2/02 ratio of the feed gas 4) Contaminants in the air feed 5) C02 in the air feed 6) Change in the frequency of the pulses 7) Temperature of the feed gas It was found that the Sterizone unit showed comparable properties with other ozone generators. High temperatures lower the ozone production so that the air feed must remain sufficiently high to prevent overheating which leads to high N0,/03 ratios. The ozone production of Sterizone is dependent on the quality of the environmental air. Air humidity and contaminants like diesel fuel, ethanol, paraffin and xylene vapours lead to a drastic decrease in O3 production. Carbon dioxide on the other hand causes a much smaller decrease in ozone production. No reaction conditions were found that led to a significant lowering of NO, production. The determination of nitrogen oxides was problematic and better analytical methods should be developed. It is recommended that an investigation is done into the possibility of removing the nitrogen oxides by means of an external filter or decreasing the product by means of ultraviolet radiation. The development of a more comprehensive theoretical model for the ozone formation processes will be beneficial to the optimalisation of ozone generators.