Electrochimica Acta 46 (2000) 305 – 314
Anodic mineralization of organic substrates in
chloride-containing aqueous media
F. Bonfatti, A. De Battisti, S. Ferro *, G. Lodi, S. Osti
Dipartimento di Chimica dell’Uniersita ` , ia L. Borsari 46, I -44100 Ferrara, Italy
Received 27 October 1999; received in revised form 31 January 2000
Abstract
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. © 2000
Elsevier Science Ltd. All rights reserved.
Keywords: Glucose; Mediated electrochemical incineration; Simplex; Chemometric approach; Sodium chloride
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1. Introduction
In previous works, the electrochemical incineration
of glucose as a model organic substrate has been stud-
ied, at different anode materials [1] and in presence of
chloride as incineration mediator [2]. In both papers,
the role of different process variables like solution pH,
electric current density, temperature and chloride con-
centration, has been shown. The influence of the anode
material was found to be decisive in the case of non-
mediated incineration.
The case of the mediated incineration shows, in
particular, the complexity of the choice of optimal
electrolysis conditions, once a general feasibility of the
process has been proved. A one-factor-at-a-time ‘se-
quential-wise’ approach consisting of a systematic study
of the incineration rate at different current densities,
different temperatures, different chloride concentration,
would require a cumbersome experimental work of
discouraging size.
A more effective approach would require a definition
of the variables playing a major role in the process, i.e.
the main process variables. In a second step, the true
optimization can be carried out with a dedicated soft-
* Corresponding author.
E-mail address: fre@dns.unife.it (S. Ferro).
0013-4686/00/$ - see front matter © 2000 Elsevier Science Ltd. All rights reserved.
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