Remediation of dichloromethane (CH2Cl2) using non-thermal, atmospheric pressure plasma generated in a packed-bed reactor.

This work describes the application of a non-thermal plasma generated in a dielectric barrier packed-bed plasma reactor for the remediation of dichloromethane (CH2Cl2, DCM). The overall aim of this investigation is to identify the role of key process parameters and chemical mechanisms on the removal efficiency of DCM in plasma. The influence of process parameters, such as oxygen concentration, concentration of initial volatile organic compounds (VOCs), energy density, plasma residence time, and background gas, on the removal efficiency of 500 ppm DCM was investigated. Results showed a maximum removal efficiency with the addition of 2-4% oxygen into a nitrogen plasma. It is thought that oxygen concentrations in excess of 4% decreased the decomposition of chlorinated VOCs as a result of ozone and nitrogen oxide formation. Increasing the residence time and the energy density resulted in increasing the removal efficiency of chlorinated VOCs in plasma. A chemical kinetic model has been developed on the basis of the proposed reaction scheme, and the calculation of end product concentrations are in general good agreement with the observed values. With the understanding of the effect of the key parameters, it has been possible to optimize the remediation process.