An experimental and modeling study of the chain initiation reaction in heterogeneous Fenton systems with zero valent iron

The main aim of this manuscript was to investigate the kinetics of zero valent iron (ZVI) oxidation to produce Fe2+ in hydrogen peroxide-water solutions. The experiments were performed in a batch reactor by submerging an iron plate in agitated aqueous H2O2 at 25 degrees C and pH similar to 2-4. A shrinking core model described properly the kinetics of iron oxidation. The overall rate of this reaction was governed by the rate of transport of protons through an iron (hydr)oxide film formed over the iron plate. To validate the model, additional kinetic experiments were carried out at different surface area of ZVI, initial concentration of H2O2, and pH. The determined concentrations of total iron, Fe2+, Fe3+ and H2O2 were reproduced by a detailed kinetic model for the Fenton-like process with ZVI that comprised 14 species and 22 reactions. Tests of oxidation of chlorpyrifos confirmed the reliability of the model to describe the Fenton-like process with ZVI.