Electrochemical incineration of glucose as a model organic substrate - II.Role of active chlorine mediation

The electrochemical incineration of glucose mediated by active chlorine in alkaline media has been studied under different electrolysis conditions. Fo r the sake of comparison, the electrolysis has been carried out in the pres ence of 1 M Na2SO4 + 0.01 M NaOH at Pt, SnO2-Pt composite electrodes and Pb O2 electrodes in the absence of sodium chloride. At the first two electrode materials, only partial oxidation could be achieved and complete mineraliz ation was observed only at PbO7 electrode. While the other parameters remai n constant, addition of NaCl to the solution causes a sharp increase of the reactivity of glucose and its oxidation intermediates, toward the electroc hemical incineration. At a NaCl concentration as low as 1 g dm(-3), the med iation of the incineration process by active chlorine is already significan t. A maximum is achieved at [NaCl] = 5 g dm(-3) (in 0.01 M NaOH). At this s odium chloride concentration, the chemical oxygen demand of glucose solutio ns has been found to decrease faster, the lower the solution temperature an d the higher the current density. This acceleration of the mineralization i s accompanied by an increase of faradaic efficiency. (C) 2000 The Electroch emical Society. S0013-3651(99)06-107-8. All rights reserved.