Degradation of DDTs in thermal desorption off-gas by pulsed corona discharge plasma.

Thermal desorption has been widely employed to treat soils contaminated with chlorinated organics. The off-gas of thermal desorption must be treated to avoid secondary pollution. In this study, the treatment of DDTs in thermal desorption off-gas by pulsed corona discharge plasma was investigated. The effects of important operation parameters, including energy density, gas temperature, humidity, and O content, on DDTs degradation were investigated. The main degradation products were also studied. The DDTs degradation efficiency increased with the increase in energy density, gas temperature, and O content. The degradation efficiency of DDTs was achieved to 84.6% when the initial concentration, energy density, and gas flow rate were 2.0 mg/m, 17.8 J/L, and 3.0 L/min, respectively. Maximum DDTs degradation efficiency was observed when the gas was at 5% relative humidity. The main degradation products identified were DM, phenol, benzene, acetic acid, and formic acid. It was calculated that 87% of chlorine in the degraded DDTs was converted into chloride ion.