Oxidation of Chlorinated Phenols Using Fenton's Reagent

Abstract

Oxidation of chlorinated phenols using Fenton's reagent (hydrogen peroxide and ferrous iron catalyst) both oxidize and dechlorinate phenol species. The kinetics of the Fenton's oxidation of the three monochlorophenol isomers and five of the six dichlorophenol isomers were examined under batch and semibatch conditions. Concentrations of the organic species, oxidant utilization and caustic demand required to maintain a pH of 3.5 were monitored. The in-situ chloride concentration were monitored in selected tests as well. Ultimate oxidation to CO₂, H₂O, and HCl was not obtained under the test conditions, but the extent of oxidation to final products can be estimated from the measured parameters. A mechanism is hypothesized to explain the observed behavior of the oxidation processes. Test results show that the monochlorinated phenols oxidize about as rapidly as phenol itself. The dechlorinated phenols demonstrate a wide range of oxidation rates under the same test conditions. Mineralization was slightly affected by the mode of oxidation, and usually lagged behind the oxidation rate of the substrate, suggesting that dechlorination occurs primarily to daughter species.