Study On The Removal Of Chlorinated Hydrocarbons In Groundwater By Chemical Oxidation

The control of chlorinated hydrocarbons contamination in groundwater has become one of the popular research fields in modern world along with the economic development. Based on the chemical oxidation mechanism, the widely existent pollutants （1, 1-DCE, TCE and PCE） were chosen as the aim pollutants, the self-made potassium permanganate solution and novel oxidant solution were chosen as oxidants. The removal efficiency, reaction kinetics, main influence factors and dechlorination mechanism of aim pollutants were investigated by batch experiment method and conclusions are as follows:（1） The oxidations of 1, 1-DCE, TCE and PCE by potassium permanganate and 1,1-DCE,TCE by novel oxidant followed the pseudo-first order kinetics equations. The reaction rate constant under best experimental conditions were respectively 0.3824 min^-1, 0.1718 min^-1, 0.0090 min^-1 and0.4003 h-1,1.3364 h-1, the half-life t1/2 were respectively 1.81 min, 4.03 min ,77.02 min and 1.73 h, 0.51 h. The oxidation of PCE by novel oxidant followed the pseudo-second order kinetics equation. The reaction rate constant under best experimental conditions was 0.0570 h-1 and half-life t1/2 was12.16 h.（2） Various pH values had no obvious impact on potassium permanganate.The degradation rate of TCE by novel oxidant was highest at neutral pH and decreased with either an increase or a decrease in pH within the range of pHs evaluated in this study. The impact was more pronounced at higher system temperature. The oxidations rate constants of 1,1-DCE,TCE and PCE by potassium permanganate or novel oxidant increased with increased system temperature,and activation energy Ea were respectively 44.37 kJ/mol,52.96 kJ/mol,57.12 kJ/mol and 59.45 kJ/mol,119.64 kJ/mol,55.37 kJ/mol. Under the range of 0⁰.2mol/L, the oxidation of 1,1-DCE,TCE and PCE by potassium permanganate were almost not affected by iron strength, and the oxidation rate constants of TCE by novel oxidant decreased with the increased iron strength. The oxidations rate constants of 1, 1-DCE, TCE and PCE by potassium permanganate increased with the potassium permanganate concentration increasing. The reaction was first order in potassium permanganate.（3） Under conditions of excess potassium permanganate, there was no organic compound in end products. In other words, there would not be secondary pollution at the end of the reaction.