© by PSP Volume 17 – No 9a. 2008 Fresenius Environmental Bulletin 1294 SIMULTANEOUS ELECTROCHEMICAL OXIDATION AND REDUCTION OF REPRESENTATIVE ORGANIC POLLUTANTS Rodrigo Mayen-Mondragon, Jorge G. Ibanez * and Ruben Vasquez-Medrano Depto. de Ing. y Ciencias Quimicas, Universidad Iberoamericana. Prol. Paseo de la Reforma # 880, 01219 Mexico, D.F. Mexico. ABSTRACT In the present work we present a proof-of-concept for the simultaneous treatment of representative organic pol- lutants at the anode and cathode of an electrolytic cell. The experimental procedure entails the separate study of the anodic and cathodic processes, followed by that of the si- multaneous process. Analysis of the products on both sides of the cell proves the validity of the proposed concept. KEYWORDS: simultaneous electrochemical processes, electro- chemical treatment of pollutants, hazardous materials treatment, phenol, dichlorophenol. INTRODUCTION Typical methods for the treatment/removal of organic pollutants from industrial aqueous effluents include incin- eration, biological treatment, adsorption, chemical treatment, and electrochemical oxidation. Incineration is an expensive process because it implies physical transportation, fuel con- sumption, secondary pollutant generation, as well as direct and indirect losses due to the corrosivity of some chemi- cal compounds [1]. Biological treatments are more com- monly used; nonetheless, the degree of biodegradability of a given substance strongly depends on its chemical nature and there are many substances not amenable to undergo these treatments [1, 2]. According to the list of priority pollutants of the Euro- pean Community, halogenated organic compounds (of which chlorinated aromatics are on the top of the list) are considered among the most abundant and dangerous to the environment [3]. An increase in toxicity and decrease in biodegradability are directly related to the number of chlo- rine substituents in the molecule [3]. Non-halogenated or- ganics like phenols and other organics are important pollut- ants as well. The electrochemical route has gained importance as an alternative final treatment method or else as an intermedi- ate stage, depending on the specific problem. There are nu- merous studies involving for example halogenated and non- halogenated organics [1-13]. Advantages include the utili- zation of ambient pressures and temperatures, environ- mental compatibility, versatility, cost efficiency, and ame- nability to automation and control [14, 15]. Previous works have typically focused either on the reduction or the oxi- dation reactions, allowing the concomitant decomposition of the solvent at the counter electrode. We hereby propose that the energy used at the counter electrode can also be used for the treatment of pollutants in a simultaneous fash- ion at both electrodes [16]. This increases the energetic yield, and decreases operation times and costs. The present work is intended to demonstrate as a proof- of-concept the possibility of performing the simultaneous electrochemical treatment of dichlorophenol and phenol as representative, non biocompatible pollutants in aqueous media. Analogous processes have been proposed for the simultaneous removal of a metal ion (e.g., Cd(II) or Cu(II)) and the destruction of CN - [17, 18], and for the combined electroprecipitation and Fenton oxidation of organics [19]. However - to the best of our knowledge - this is the first time that a direct electrolytic approach is proposed for the simultaneous treatment of organic compounds. MATERIALS AND METHODS All the experiments were performed in a small-scale glass cell divided in two compartments (each one with an approximate volume of 10 mL), and equipped with a cati- onic exchange membrane, CEM sandwiched between them (membrane R1010, The Electrosynthesis Co.). The two cell compartments and the membrane were kept together by several layers of parafilm that also prevented liquid leakage (see Figure 1). Magnetic stirring bars were inserted in the anodic and cathodic compartments, and constant stirring was provided during the experiments. The poten- tial source was an AMEL Instruments potentiostat (Model 2051), and an Ag/AgCl electrode (Bioanalytical Systems) was the reference electrode. The working and counter elec- trodes are described in each experiment below. The chemicals used were nitric acid (Baker Analyzed Reagent, 65.3%), dichlorophenol (Baker Analyzed Reagent,