Prediction of the Indirect Advanced Oxidation of Acid Orange 7 using a 3D RVC Cathode for H2O2 Production in a Divided Electrochemical Reactor

Abstract

A three dimensional reticulate vitreous carbon piece is used to design an electrode for the cathodic O2 reduction reaction in a divided (by a Nafion 117 membrane) parallel plate reactor. The anode is a commercial stainless steel mesh. This approach allows producing H2O2 at low energy (6.85 kWKg-1 H2O2) in a low ionic acidic medium (0.05M Na2SO4, pH 2). Under these conditions the H2O2 can be activated, in the presence of 1 mM Fe 2+ , as soon as it is produced to develop the Fenton Reagent. It is found that Acid Orange 7 indirect oxidation (in the concentration range of 0.07 to 0.19 mM) by Fenton process follows a first order kinetic equation. From each experimental AO7 oxidation the main parameters (a,mM and k,min 1) of the first order kinetic equation are obtained. These parameters can be correlated with AO7 concentration in the concentration range studied. A semi-empirical chemical model to predict AO7 degradation, in the electrochemical reactor, can be developed taking into account the main equations derived from experimental data. The prediction of the main parameters (H2O2 electro-produced, oxidation rate, energy required, electrolysis time) shows good agreement with the experimental data. Therefore, it was found that 1.83 kWhm-3 are needed to oxidize 0.191 mM AO7 in 3h. The chemical model can be used to predict both time and the energy required to treat a textile effluent with a variable pollutant organic load.