Heterogeneous electro-Fenton oxidation of catechol catalyzed by nano-Fe3O4: kinetics with the Fermi's equation

Abstract

The degradation of catechol in a heterogeneous electro-Fenton system catalyzed by nano-Fe3O4 was studied. The effects of the main parameters such as temperature, pH, current density, catalyst load and initial catechol concentration on the degradation rate were investigated by carrying out batch experiments. Catechol was nearly completely degraded within 120 min when the current density was kept at 10 mA/cm2, with the addition of 1.0 g/L catalyst at an initial pH 3.0. Stability and reuse of the catalyst were also tested, which put evidence for its potential application. The catechol concentration evolutions were described with a simple semi-empirical kinetic model based on the Fermi's equation. A few adjustable parameters were involved to simultaneously describe the two-part degradation processes. The correlation between the model and the experimental data was remarkable. The apparent rate constant and transition time could be simultaneously obtained by model fitting. The heterogeneous electro-Fenton reaction was interface determined process according to the analysis of the apparent rate constant and surface rate constant.