Effects of the O2 concentration on the removal efficiency of volatile organic compounds with dielectric barrier discharges in Ar and N2

This article presents experimental results on the effects of the O-2 concentration on the removal efficiency of two exemplaric volatile organic compounds (VOCs): toluene (TOL) and trichloroethylene (TCE), with dielectric barrier discharges in dry Ar and N-2. For both carrier gases, there is an optimal oxygen concentration of 0.3% for the removal efficiency, suggesting optimal utilization of oxygen radicals for VOC attack, rather than ozone production which has slow reaction rates with TOL and TCE. This is manifested by measurements of ozone concentrations in mixtures of Ar/O-2/TCE as a function of the oxygen concentration, showing a minimum at maximal removal efficiencies. All results are discussed in terms of changes in the discharge behavior, radical formation, and chemical reaction pathways with changing O-2 concentration in the carrier gas. (C) 1999 American Institute of Physics. [S0021-8979(99)09001-5].