Electrochemical production of perchlorates using conductive diamond electrolyses

In this work, the electrochemical production of perchlorates with conductive-diamond electrodes is studied. The use of different chlorine raw materials, and the effect of several operation parameters (current density and pH) are studied in order to increase knowledge about production of chlorine oxoanions. Results show that the conductive-diamond electrolysis of different raw chlorine solutions leads to the production of a chlorine oxospecies mixture with significant concentrations of hypochlorite, chlorite, chlorate and also of perchlorate, and that complete conversion to perchlorate can be achieved if large current charges are passed through the cell. Alkaline pH and high current density seems to favor the production of perchlorate. The very significant increase in the perchlorate production with the current density may be related to the fact that in conductive-diamond electrolysis high current densities favor hydroxyl radicals formation. The counter ion of the chloride salts used as raw materials does not seem to influence the efficiency of the electrochemical process but on the stability of the perchlorate electrogenerated. On the contrary, the type of chlorine raw matter does not affect to the efficiency, but just on the stoichiometric current charge needed to complete the process. (C) 2010 Elsevier B.V. All rights reserved.