Potassium Ferrate(VI)를 이용한 Trichloroethylene 분해특성 연구

Abstract

Trichloroethylene(TCE) which has been widely used as industrial solvents for decreasing metals and for dry cleaning is a major concern and a serious threat to human health . Many soils and ground water have been contaminated as a result of leaks from underground storage tanks and improper disposing practices. This contamination is one of the recent major issues because this chemical is toxic, non-biodegradable and extremely persist in the environment. There have been many recent works on oxidation processes even though the half life of oxidative degradation for chlorinated organic compounds is of the order of several minutes in Fenton's reagent, ozone, and O3/H2O2 systems. An apparent limitation with these reactions are that the key reactive intermediate, hydroxyl radical generated in these advanced oxidation processes(AOPs) strongly reacts with common inorganic species in ground water. Ferrate(Fe(VI)) is a powerful oxidant over wide pH range and can be used as an environmentally friendly chemical in treated and natural water. The redox potential of ferrate(VI) are 2.20V and 0.72V under acidic and alkaline conditions, respectively. During the oxidation reaction, ferrate(VI) is reduced to Fe(III) ions or ferrihydrite(Fe(OH)3), resulting in the simultaneous coagulation in a single unit process. In addition, ferrate(VI) is an efficient coagulant for removing toxic contaminants after oxidation. Therefore, ferrate(VI) can serve as a dual-function chemical reagent in water treatment. In this study, the degradation characteristics of TCE by Ferrate(VI) oxidation have been studied. The degradation efficiency of TCE in aqueous solution was investigated at various pH values, Ferrate(VI) doses, initial concentrations of TCE and aqueous solution temperature values. GC-ECD was used to analyze TCE. The optimum conditions of TCE degradation were obtained pH 7.0 and 25℃in aqueous solution. Also, the experimental results showed that TCE removal efficiency increased with the decrease of initial concentration of TCE. And intermediate products were identified by GC-MS techniques. Ethyl Chloride, Chloroform, Ethylene, 1,2-dichloroethane and 1,1,2-trichloroethane were identified as a reaction intermediate, and Cl- was identified as an end product.