The anodic oxidation of p-benzoquinone and maleic acid

The oxidation of organics, in particular of p-benzoquinone and maleic acid, at high anodic potentials has been studied using a range of anode materials such as noble-metal-based oxides and antimony-doped tin oxides. The influence of the current density was also investigated showing that the oxidation rate of p-benzoquinone increased only slightly with increasing current density. The efficiency of the p-benzoquinone oxidation was found to depend on several properties of the anode material, not just its chemical nature. Furthermore, efficiencies for the partial oxidation of p-benzoquinone using specially prepared noble-metal-oxide-based anodes were found to be only somewhat smaller or even as high as those observed for PbO2 or antimony-doped tin oxide anodes, respectively. The anodic electrolysis of maleic acid solutions was found to decrease the activity of IrO2 for the oxidation of organic compounds. This was not observed when PbO2 was employed for the oxidation of maleic acid. (C) 1999 The Electrochemical Society. S0013-4651(98)12-099-2. All rights reserved.