Study On Influencing Factors And The Degradation Mechanism Of Aqueous 2, 4, 6-trinitrotoluene By Pulsed Gas Phase Discharge

Water treatment by high-voltage discharge is one of the new advanced oxidation technologies in recent years.Degradation of 2,4,6-trinitrotoluene(TNT)in water was investigated by a pulsed high voltage gas phase discharge above the water surface.Different experimental conditions,including peak pulsed voltage, pulsed frequency and the initial value of pH,on the TNT degradation rate were studied.The following results obtained.a)The removal efficiency of TNT increased with the increase of peak pulsed voltage and pulsed frequency.b)The initial value of pH also raked place an influence on the TNT degradation rate.c)In the case of 9.8k V peak pulsed voltage,120Hz pulsed frequency,the degradation rate of 30mg/L TNT solution with pH value of 6.8 reached 66.1%after 60min treatment.d)The experimental data showed that Fe²⁺had a remarkable catalytic effect on degradation.When the concentration of Fe²⁺was 0.15mmol/L,it could accelerate the degradation rate reach 84.0%.But added H₂O₂ into TNT solution could restrain the speed of reaction.e)After 2h treatment,the degradation rate of 100mg/L TNT was 87%,COD reduced 80%.The results showed that the degradation efficiency of TNT by plasma system was high.f)TNT conversion and the production of major oxidation products in the solution had been determined, using ion chromatography with conductivity detector and gas chromatography with MS detector.It was found that hydroxyl radical played an important role on TNT degradation.The degradation of 2,4,6-trinitrotoluene was attacked by hydroxyl radical to form 2,4,6-trinitrotobenzoic acid.The later was oxidize d tol,3,5- trinitrobenzene.Therefore,the ring was opened to simple organic acids such as formate acid,NO₂^-and NO₃^-,etc.