Anodic mineralization of organic substrates in chloride-containing aqueous media

The electrochemical incineration of glucose in alkaline media, in the presence of sodium chloride, has been investigated. The process has been followed through the dependence of chemical oxygen demand (COD) and total organic carbon content, on electrolysis duration, t. The influence of current density, sodium chloride concentration, temperature, sodium hydroxide concentration on the rate of COD abatement has been followed. The rate of the incineration was found to increase with increasing the current density and pH and decreasing the solution temperature. With increasing the chloride concentration up to a given critical value, the mineralization rate increases. Further increase causes a decrease of efficiency of the process of interest. The critical value of the mediator concentration has been found to be lower at higher pH. On the basis of this preliminary screening, an attempt of optimization of the mediated electrochemical incineration as a function of current density and chloride concentration has been carried out, basing the analysis on the Simplex algorithm. Two different response functions have been chosen: the glucose oxidation rate and a weighed combination of electrolysis time and energy consumption. On the basis of the obtained results, an explanation of the mediating role of chloride ions has been proposed. (C) 2000 Elsevier Science Ltd. All rights reserved.