Trichloroethylene oxidation performance in sodium percarbonate (SPC)/Fe2+ system.

In this study, in-situ chemical oxidation technique employing Fe(II) catalytic sodium percarbonate (SPC) to stimulate the oxidation of trichloroethylene (TCE) in contaminated groundwater remediation was investigated. The effects of various factors including the SPC/TCE/Fe2+ molar ratio, the initial solution pH and the widely found constituents in groundwater matrix such as Cl(-), HCO3(-), SO4(2-) and NO3(-) anions and natural organic matters were evaluated. The experimental results showed that TCE could be completely oxidized in 5 min at 20 degrees C with a SPC/TCE/Fe2+ molar ratio of 5:1:10, indicating the significant effectiveness of the SPC/Fe2+ system for TCE removal. The initial solution pH value (from 3 to 11) has less influence on TCE oxidation rate. In contrast, Cl(-) and HCO3(-) anions had a negative effect on TCE removal in which HCO3(-) possesses a stronger influence than Cl(-), whereas the effects of both SO4(2-) and NO3(-) anions appeared to be negligible. With the 1.0-10 mg/L concentrations of humic acid in solution, slightly inhibitive effect was observed, suggesting that dissolved organic matters consumed less SPC and had a negligible effect on the oxidation of TCE in SPC/Fe2+ system. From the intermediate products' analyses and the released Cl(-) contents from TCE parent contaminant in solution, all the decomposed TCE had completely dechlorinated and led to carbon dioxide and hydrocarbon. In conclusion, Fe(II) catalytic SPC oxidation is a highly promising technique for TCE-contaminated groundwater remediation, but some complex constituents such as HCO3(-), in in-situ groundwater matrix should be carefully considered for its practical application.