Development of Air Treatment Technology Using Plasma Method

Due to the physicochemical properties of nitrogen oxides as active molecules, the removal of this group of pollutants has always been considered as a matter of concern for specialists. The present study seeks to develop the removal technique of nitrogen oxides "as a major type of air pollutant" by means of nonthermal plasma process under atmospheric conditions. Besides having the potential to reduce energy consumption in the pollutant removal process, non-thermal plasma technology also provides particular flexibility for the simultaneous removal and mitigation of the secondary pollutants. In this research we have used the Dielectric Barrier Discharge (DBD) plasma process to achieve an effective conversion of Nitrogen Oxides (NOx). As a result of the collisions between the electrons and the airflow containing NOx, active radicals and molecules are generated in a limited and controlled volume (plasma reactor) and the conversion and removal process is then carried out in the presence of hydrocarbon as reducer gas. The key factors for NOx conversion especially in the non-thermal plasma condition are the geometric structure and design of the reactor, type of discharge, type of power supply, temperature, space velocity, propane/NOx mole ratio, and voltage. In the present study, the factors of temperature, mole ratio of the reducer and input voltage were examined. The results showed that the optimal conditions for conversion of NOx into N2 and O2 are temperature of 180°C, propane/NOx mole ratio of 0.5, and voltage of 5 KV. Under the optimal conditions acquired, NOx conversion was 0.79 in the 100 PPM concentration. Under the conditions of the present study, 1-5 PPM Ozone, Formaldehyde, and CO was generated as the undesirable pollutants.