Kinetic Modelling of Phenol Oxidation in a Bioremediation Medium Using Fenton's Reagent

Abstract

The present study is aimed at kinetic modeling of phenol oxidation using Fenton’s reagent in a medium suitable for bioremediation of organic pollutants. Batch experiments were conducted to study the effects of H2O2 concentration (29.26 to 146.31 mM), temperature (5 to 35°C), and to compare the oxidation of phenol in a bioremediation medium to that in pure water. The reaction mechanism used for kinetic modeling is based on the intermediate oxidation products identified in this study using LC-MS and ion chromatography. Progress of the chemical oxidation by Fenton’s reagent was monitored by determining the residual phenol concentration and concentrations of evolved intermediate compounds (catechol and hydroquinone) at regular time intervals. The rate of phenol oxidation and ultimate conversion of phenol were found to increase with increase in hydrogen peroxide concentration. The increase in temperatures has a positive effect on phenol oxidation and the rate of phenol oxidation was found to increase with temperature in the range of 5-35°C. Kinetic parameters, namely rate constants and activation energies for reactions involved, were determined by best-fitting the experimental data to the proposed reaction model. The values of the rate constants for oxidation of phenol and intermediate compounds, k1 (phenol to catechol), k2 (phenol to hydroquinone), k3 (catechol to maleic acid), k4 (hydroquinone to maleic acid) at 25°C were found to be 7.02x10-5±4.63x10-5, 7.22x10-4±6.09x10-4, 1.82x10-4±1.08x10-4, 1.68x10-3±1.29x10-3 L/mM min, respectively.