Applicability of pulsed corona discharge treatment for the degradation of chloroform

Abstract

Degradation of chloroform was investigated using plasma corona discharge by a needle-plate reactor. Chloroform concentration of 200 mg/L was completely degraded in 10 min of treatment. Almost complete dechlorination happened in 10 min and 91% total organic carbon (TOC) removal occurred in 12 min of treatment. Several important parameters such as input voltage, initial concentration, pH, conductivity, alkalinity, presence of OH radical and aqueous electron scavengers were evaluated to understand their effect on rate of chloroform degradation. The degradation rate of chloroform increased with increase in pH, conductivity and alkalinity of the solution. The maximum concentrations of OH radical, H2O2 and superoxide produced after 10 min of corona discharge were estimated to be 0.260 mM, 0.353 mM and 0.046 mM respectively. Various intermediates such as dichloromethane, dichloroethane, trichloroethane, trichloroethylene (TCE), tetrachloroethylene (PCE), trichloronitromethane and acetaldehyde were identified using GC-MS purge and trap technique. Based on the identified intermediates, reductive and oxidative degradation pathway of chloroform is proposed.