Degradation of Trichloroethylene from Groundwater by Sodium Percarbonate and Sodium Persulfate Double Oxidation System
To solve the problem of low efficiency in the degradation of trichloroethylene in groundwater by a single oxida-tion system,citric acid chelated Fe2+was used to catalyze the synergistic degradation of trichlorethylene in groundwater by sodium percarbonate and sodium persulfate.The effects of the ratio of sodium percarbonate and sodium persulfate,water quality conditions(pH,typical anions)and the initial concentration of trichlorethylene on the degradation effect of tri-chlorethylene were investigated.The results show that when the initial concentration of trichlorethylene is 0.16 mmol/L,citric acid chelated Fe2+catalyzing sodium percarbonate and sodium persulfate double oxidation system can significantly increase the degradation rate of trichlorethylene in groundwater under neutral conditions.The degradation of trichloroethy-lene is influenced by the ratio of sodium percarbonate to sodium persulfate.When the molar ratio of sodium percarbonate,sodium persulfate,citric acid,Fe2+,and trichloroethylene is 10:8:5:10:1,the degradation rate of trichlorethylene after 180 min of reaction is 98.5％.The pH has a certain influence on the degradation of trichlorethylene,and the degradation rate of trichlorethylene decreases gradually with the increasing of pH.The common anions SO42-,and NO3-in ground-water have a relatively small impact on the removal of trichloroethylene from groundwater by this double oxidation system,but higher concentrations of HCO3-and Cl-significantly inhibit the degradation of trichloroethylene.The free radical scavenging experiments determine the presence of free radicals such as hydroxyl radical HO·,sulfate radical SO4-·,superoxide radical O2-·in the double oxidation system,and HO·plays a leading role in the degradation of trichlorethylene.
groundwater remediationtrichloroethylenein situ chemical oxidation technologydouble oxidation system
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