Semi-empirical chemical model for indirect advanced oxidation of Acid Orange 7 using an unmodified carbon fabric cathode for H2O2 production in an electrochemical reactor

•Unidirectional Carbon Fabric can be used in environmental applications.•Unidirectional Carbon Fabric is a feasible cathode for O2 reduction in acidic media.•H2O2 can be electro-produced at low energy, 2.08 kWh kg−1 H2O2.•The energy required for 0.24 mM AO7 degradation is 1.04 kWh m−3.•A semi-empirical chemical model was developed to predict the AO7 abatement.

A commercial Unidirectional Carbon Fabric piece was used to design an electrode for the cathodic O2 reduction reaction in a divided (by a Nafion® 117 membrane) parallel plate reactor. The anode was a commercial stainless steel mesh. Under this approach it is feasible to produce H2O2 at low energy (2.08 kWh kg−1 H2O2) in low ionic acidic medium. In the catholyte side the H2O2 can be activated with Fe2+ to develop the Fenton reagent. It was found that Acid Orange 7 (AO7) indirect oxidation (in the concentration range of 0.12–0.24 mM) by Fenton chemistry follows a first order kinetic equation. The energy required for 0.24 mM AO7 degradation is 1.04 kWhm−3. 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. Based on this method a semi-empirical chemical model was developed to predict the AO7 abatement, by means of Fenton chemistry. Good AO7 oxidation predictions can be made in the concentration range studied. A detailed discussion of the energy required for oxidizing AO7 and the accuracy of the chemical model to predict its oxidation is included in this paper.

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