International Journal of Hydrogen Energy, Vol.32, No.15, 3163-3169, 2007
Indirect electrochemical oxidation of cyanide by hydrogen peroxide generated at a carbon cathode
The oxidation of cyanide was performed in aqueous sodium hydroxide solutions. Cyanide was oxidized over 90% to cyanate by hydrogen peroxide electrochemically generated at a 60 ppi reticulated vitreous carbon electrode from oxygen reduction. Cyanide depletion was recorded as a function of time from the analysis of cyanide based on the titration procedure using silver nitrate with p-dimethylamino-benzal-rhodanine indicator. Cyanate was further oxidized to mineralization by decreasing the pH of the solution obtaining a recovery of carbon dioxide over 90%. The employment of copper together with hydrogen peroxide to increase the destruction of cyanide was also studied. Different molar ratios of hydrogen peroxide/cyanide and copper/cyanide were tested achieving over 98% of cyanide destruction in a time period of 40 min by increasing either the concentration of hydrogen peroxide or copper ion. (C) 2007 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.
Keywords:hydrogen peroxide generation;oxygen reduction;reticulated vitreous carbon electrode;cyanide destruction;carbon dioxide