Reduction of generation of by-products by homogeneous barrier discharge type air fed ozoinzer

Abstract

Summary form only given. Ozone is mainly synthesized by Dielectric Barrier Discharge (DBD) and it can be applied to air and water treatment etc. In case of air fed ozonizer, O radical is generated by electron impact, and three-body reaction between O radical, O2 and/or N2 leads to the ozone generation. However, N2O and N2O5 exist within ozone gas and they are well known as by-products. Here, N2O is selected as one of the greenhouse gases and it is desirable to suppress N2O generation. In 2009, we succeeded in generating a homogeneous DBD in air using alumina barrier (Kyocera, A473). This homogeneous DBD was recognized as an Atmospheric Pressure Townsend Discharge (APTD). The reduced electrical field of the APTD was around 1.5 eV. On the other hand, in the conventional filamentary DBD, the reduced electrical field at the streamer head is around 10 e V. Generally, the threshold dissociation energy of nitrogen molecule is 9.76 eV. Therefore, if we apply the APTD to air fed ozonizers, considerable reduction of the amount of N2O and N2O5 are expected. In this study, comparative study of by-products generation from air fed ozonizer by APTD and conventional filamentary DBD was carried out using an FTIR with a long path gas cell (1 m). The results showed that in both types of air fed ozonizers, N2O5, HNO3, N2O were detected in the ozone gas. In case of FD type air fed ozonizer, the intensities of absorption lines of N2O5, HNO3, and N2O in the ozone gas of 2197 ppm were 5.40×10-2, 1.09×10-1 and 3.60×10-2 respectively. On the other hand, in case of APTD type air fed ozonizer, the intensities of absorption lines of N2O5, HNO3 and N2O of the same ozone concentration were 9.17×10-3, 3.32×10-2 and 1.61×10-2 respectively. Therefore, our conclusion is that APTD can suppress by-products generation of the air fed ozonizer.