Temperature Dependence of the Oxidation of 2-Chlorophenol by Hydrogen Peroxide in the Presence of Goethite

The oxidation of 2-chlorophenol by hydrogen peroxide in the presence of goethite has been investigated over the 299-323 K temperature range. Kinetic studies suggest that two different reaction stages exist, and that under the experimental conditions used in this work, each may be modeled as a pseudo-first-order reaction. The first stage involves the dissolution of goethite, based on experiments conducted on the effect of prior stirring time. However, comparison of the apparent activation energy for the first stage with those found in the literature indicates the concomitant oxidation of 2-chlorophenol likely takes places from hydroxyl radicals produced from reaction at the goethite surface, rather than those from a Fenton-based mechanism. The apparent activation energy for the second stage is closer to that for a Fenton-based reaction, suggesting that the second stage mainly involves oxidation of 2-chlorophenol by hydroxyl radicals formed from hydrogen peroxide reacting with the dissolved iron species. Taken together, these results provide further insight towards a molecular-level understanding of the reactivity of chlorinated phenols in the presence of minerals during remediation processes.