Synthesis of novel oxidants by electrochemical technology

Abstract

In this work it has been studied the electrochemical production of different oxidants with conductive-diamond anodes. This technology was found to allow the production of stable oxidants that can not be easily synthesized using other electrodes or by other more usual techniques. Thus, it has been found that monoperoxophosphoric acid, and peroxodiphosphate, peroxodisulphate and ferrate salts can be easily produced by this technology, when the right operation conditions are used. In contrast, the production of pure hypochlorite is not favoured, because this technology leads to the formation of a mixture of hypochlorite with other oxoanions of chlorine in a higher oxidation state, particularly chlorates and perchlorates, which seems to be the final product in these electrolyses. The production of perbromates salts has also been pointed, although in this case only preliminary results are shown. In every case, it has been observed two marked trends in the process efficiency as function of the current density applied. This fact can be explained in terms of the contribution of hydroxyl radicals in the oxidation mechanisms that occur on diamond surfaces. Results obtained in this work also allow explaining the influence of the electrolyte salt on the efficiency of the electrochemical oxidation of wastewaters.