Degradation of Perchloroethylene by Fenton's Reagent: Speciation and Pathway

Silica sand contaminated with perchloroethylene (PCE) was effectively treated by Fenton's reagent. Silica sand contaminated with PCE at 1000 mg/kg was totally mineralized in 3 h by Fenton's reagent with initial concentration of about 2.1 M of H₂O₂ and 5 mM of FeSO₄. Results from gas chromatography‐mass spectroscopy (GC‐MS) revealed that dichloroacetic acid was the sole significant intermediate species generated, and was believed to be the limiting species leading to mineralization. Experimental measurements of chloride and total organic C suggested that total dechlorination was achieved before decarboxylation in the process of mineralization. A degradation pathway of PCE with Fenton's reagent is proposed based on experimental observations and reactions reported in literature. Formic acid is proposed to be the final intermediate species before it is mineralized to CO₂. Perchloroethylene and H₂O₂ followed pseudo first‐order decomposition kinetics and the rate constants were determined to be 1.65/h ± 0.475/h and 0.206/h ± 0.036/h, respectively.