Behavior of N2 and nitrogen oxides in nonthermal plasma chemical processing of hazardous air pollutants

Nonthermal plasma chemical behavior of N-2-O-2 mixed gases and nitrogen oxides such as N2O, NO, and NO2 was investigated to obtain baseline information on the generation of active oxygen species and the formation of inorganic byproducts in the nonthermal plasma chemical processing of hazardous air pollutants (HAPs) with a ferroelectric packed-bed reactor. Ozone concentrations were too low, even in air, to oxidatively decompose 300-1000 ppm of BAPs, The O-2 concentration in N-2-O-2 was the determining factor in the formation of all the nitrogen oxides. N2O formation was enhanced with increases in O-2 concentration and in specific energy density, while a threshold value was observed around at 5% of O-2 concentration in the formation of NO and NO2 Rate-suppressing effect by O-2, detailed byproduct analyses, and thermochemical data suggest that NOx decomposes in its reactions with nitrogen atoms derived from N-2 dissociation, and that the unimolecular N-O cleavage predominantly occurs for N2O, The behavior of nitrogen oxides and their precursors was not affected by hydrogen atoms evolved from hydrogen-rich HAPs such as ethylene and benzene. Halogenated HAPs enhanced NOx formation and NO2 selectivity Different additive effects of chlorinated and brominated HAPs were observed in the formation of NOx and N2O, indicating the involvement of different active oxygen species.