Application of a Microwave Helium Plasma Torch Operating at Atmospheric Pressure to Destroy Trichloroethylene

We examined the influence of the gas flow-rate, microwave power and trichloroethylene concentration on the destruction of trichloroethylene with a system based on a microwave helium plasma operating at atmospheric pressure. Based on the experimental results obtained, the proposed system allows input concentrations of C₂HCl₃ in the ppmv range to be reduced to output concentrations in the ppbv range (i.e. virtually quantitative destruction) by using a microwave plasma power below 1000 W. High helium flow-rates and C₂HCl₃ concentrations allow energy efficiency values above 600 g/kW h to be obtained. Analyses of the output gases by gas chromatography and species present in the plasma by optical emission spectroscopy confirmed the negligible presence of halogen compounds resulting from the destruction of C₂HCl₃, and that of CCl₄ and C₂Cl₄ as the sole chlorine species exceeding levels of 30 ppbv. Gaseous by-products consisted mainly of CO₂, NO and N₂O in addition to Cl₂ traces.