Application of DBD plasma packed with glass and ceramic pellets for SO2 removal at ambient temperature: optimization and modeling using response surface methodology

Air pollution is a major health problem in developing countries which has adverse effects on human health and environment. Non-thermal plasma (NTP) is an effective air pollution treatment technology. In this research, the performance of dielectric barrier discharge (DBD) plasma reactor packed with glass and ceramic pellets were evaluated in removal of SO2 as a major air pollutant, from air in ambient temperature. Response surface methodology (RSM) was used to evaluate the effect of three key parameters (gas concentration, flow rate, and voltage) as well as their simultaneous effects and interactions on SO2 removal process. Reduced cubic models were derived to predict the SO2 removal efficiency (R. E.) and energy yielding (E. Y.). Analysis of variance (ANOVA) results showed that the studied packed-bed reactors (PBRs) were more energy efficient and had high SO2 R. E. which was at least four times more than that of non-packed reactor one. Moreover, the results showed that the performance of ceramic pellets was better than that of glass pellets in PBRs. It may be due to porous surface of ceramic pellets which allows formation of micro-discharges in fine-cavities of porous surface when placed in plasma discharge zone. The maximum SO2 R. E. and E.Y. were obtained 94% and 0.81 gr/kWh, respectively under the optimal conditions of a gas concentration of 750 ppm, flow rate of 2 l/min, and voltage of 18 kV, which are achieved by the DBD plasma packed with ceramic pellets. Finally, the results of model's predictions and the experiments showed good agreement.