Assessment of a new carbon tetrachloride destruction system based on a microwave plasma torch operating at atmospheric pressure

A new system for destroying volatile organic waste based on a microwave plasma torch that operates at atmospheric pressure and is coupled to a reactor affording isolation of output gases and adjustment of the plasma discharge atmosphere is proposed. The system was assessed by using carbon tetrachloride as the target volatile organic compound (VOC) and argon as the main gas in a helium atmosphere. Under optimal conditions, a microwave power of less than 1000 W was found to reduce the CCl4 concentration at the reactor outlet to the parts-per-billion level and hence to virtually completely destroy the VOC. With high argon flow-rates and CCl4 concentrations, the energy efficiency can reach levels in excess of 3000 g/kW h. Output gases and species in the plasma, which were identified by gas chromatography and light emission spectroscopy, respectively, were found to include no halogen-containing derivatives resulting from the potential cleavage of CCl4. In fact, the main gaseous byproducts obtained were CO2, NO and N2O, in addition to small traces of Cl2, and the solid byproducts Cl2Cu and various derivatives depending on the particular reactor zone.