ELECTROCATALYSIS OF ANODIC OXYGEN-TRANSFER REACTIONS - THE ELECTROCHEMICAL INCINERATION OF BENZOQUINONE

The electrochemical performance of several anode materials is compared for the electrochemical incineration of p-benzoquinone in acetate buffer media (pH 5). The chemical oxygen demand (GOD) estimated for benzoquinone by titration with standard permanganate solution can be decreased to virtually zero by electrolysis at electrodes comprised of Fe(III)-doped beta-PbO2 films on Ti substrates. Carbon dioxide is a product of the electrochemical process; however, the possibility of other volatile products cannot be dismissed. Addition of solid benzoyuinone to acetate media is followed by slow formation of a brownish black color that is concluded to result from one or more humic compounds produced by condensation of benzoquinone; however, it cannot be concluded whether the condensation reaction is a necessary prerequisite to successful electrochemical incineration of benzoquinone. Optimal operating conditions suggested for electrochemical incineration of benzoquinone in acetate buffer include heating of the anode (e.g., 60 degrees C) to increase the rate of anodic discharge of H2O and, thereby, decrease the anodic overpotential. Evidence also is presented that the rate of electrochemical incineration is enhanced slightly by the addition of a traces of Fe(III) with reduction of dioxggen (O-2) to hydrogen peroxide (H2O2) at a cooled stainless steel cathode (e.g., 15 degrees C) in an undivided cell.