Tetrachloroethylene and hexachloroethane degradation in Fe(III) and Fe(III)-citrate catalyzed Fenton systems

Abstract

Background: Tetrachloroethylene (PCE) and hexachloroethane (HCA) degradation, individually and in mixture, is investigated by Fe(III) or Fe(III)-citrate initiated Fenton reaction under a range of hydrogen peroxide (H 2O 2) concentrations to illustrate the applicability and constraints of Fenton chemistry in degrading contaminants in polluted groundwater. Results: In individual solutions Fe(III) rapidly degraded PCE for all H 2O 2 concentrations, but HCA at ≥ 0.2 mol L -1 H 2O 2; the apparent PCE degradation rate initially increased but then decreased with increasing H 2O 2, while the HCA degradation rate was either unaffected or increased. With Fe(III)-citrate PCE degradation was lower and no HCA degradation occurred. PCE degradation was lower in PCE-HCA mixture, but the trend with H 2O 2 concentration was similar to the individual chemical; for HCA the residual was smaller for higher H 2O 2 concentration, but the apparent degradation rate constant was unaffected. Conclusion: Fe(III) catalyzed reactions can potentially degrade chemicals through reductive as well as oxidative transformations. Degradation of chemicals in mixtures occurs at a slower rate due to competition for radical moieties. The Fe(III)-citrate complex further slowed chemical transformation. This study expands on the use of different forms of iron to catalyze the Fenton reaction to degrade chemicals. © 2012 Society of Chemical Industry.