Oxidative removal of hexane from the gas stream by dielectric barrier discharge reactor and effect of gas environment

The removal of hexane from a gas stream using a dielectric barrier discharge (DBD) reactor was conducted at ambient temperature and atmospheric pressure. The role of N2, dry and humidified air carrier gases were investigated in terms of removal efficiency and product selectivity. The oxygen concentration was also varied over the range of 0 - 21% at constant power and residence time in an N2-O2 mixture for further insight into oxygen's role. A semi-empirical model of NTP-decomposition in the presence of O2, N2 and H2O is proposed. It was observed that hexane removal efficiency and product selectivity increased with increasing plasma power, regardless of the carrier gas used. The maximum removal efficiency (hexane) was 94.4% in the humidified air carrier gas. The introduction of water vapour with a relative humidity of 25% at 20 degrees C in the plasma DBD system significantly increased the hexane removal efficiency and CO2 selectivity (84.7%) while eliminating the production of solid residue and O3. This was probably due to the action of OH radicals. Increasing O2 concentration from 0 to 21% increased the removal efficiency and CO2 selectivity due to the generation of oxygen radicals. The results imply that the decomposition of hexane by non-thermal plasma DBDs is dominated by the effect of OH and O radicals. A semi-empirical model shows that the non-thermal plasma decomposition of hexane is first order. The DBD reactor has been demonstrated to be an effective and promising technology for removing hexane emissions from air streams. The effects of N2, O2 and H2O have been quantified, and mechanisms for their action proposed.