Kinetic modelling of Fe(III)/H 2O 2 oxidation reactions in dilute aqueous solution using atrazine as a model organic compound

Abstract

In this paper, experimental data are presented to test and to validate a kinetic model for the oxidation of organic compound in dilute aqueous solution by the Fe(III)/H 2O 2 process in a batch reactor (NaClO 4/HClO 4 solutions, Ionic strength: I=0.1 M, pH≤3.0, 25.0°C). Atrazine was used as a model compound. Under the conditions employed in this study ([Atrazine] o<1 μM), the OH radical was the unique species responsible for the oxidation of atrazine. Propagation and termination reactions involving organic radicals were assumed to be of little importance and were not incorporated in the model. The data showed that the effects of pH (pH range: 1–3) and of the concentrations of reactants ([H 2O 2] o and [Fe(III)] o) on the rates of oxidation of atrazine and of decomposition of hydrogen peroxide were in good agreement with model predictions. The concentration-time profiles for transient species (Fe(II), HO 2/O − 2 and OH radicals) obtained by computer calculations were also useful to explain the lag period and the pseudo-first order decay which were observed on the experimental kinetic curves of degradation of atrazine