Electrochemical decontamination of waters by advanced oxidation processes (aops): case of the mineralization of 2,4,5-t on bdd electrode

  • Birame Boye University of Barcelona, Department of Physical Chemistry, LCTEM, c. Marti i Franques, 1-11, 08028, Barcelona, Spain
  • Enric Brillas University of Barcelona, Department of Physical Chemistry, LCTEM, c. Marti i Franques, 1-11, 08028, Barcelona, Spain
  • Beatrice Marselli Swiss Federal Institute of Technology, School of Basic Sciences, Section of Chemistry and Chemical Engineering, ISP-CO, CH-1015 Lausanne, Switzerland
  • Pierre-Alain Michaud Swiss Federal Institute of Technology, School of Basic Sciences, Section of Chemistry and Chemical Engineering, ISP-CO, CH-1015 Lausanne, Switzerland
  • Christos Comninellis Swiss Federal Institute of Technology, School of Basic Sciences, Section of Chemistry and Chemical Engineering, ISP-CO, CH-1015 Lausanne, Switzerland
  • Mor Marième Dieng University C.A. DIOP of Dakar (UCAD), School of Sciences and Techniques, Department of Chemistry, LCPOAI, BP 5055, Dakar – Fann, Senegal
Keywords: Electrochemical decontamination, Cyclic voltammetry, 2, 4, 5-T herbicide, Mineralization, BDD electrodes

Abstract

In the present work, herbicide 2,4,5-trichlorophenoxyacetic acid, more commonly known as 2,4,5-T herbicide, has been completely mineralized (i.e. transformed into CO2 and H2O) in saturated aqueous solutions using a semi-industrial electrochemical cell that contains a boron doped diamond anode and a zirconium cathode. We have performed cyclic voltammetry, chronoamperometry and bulk electrolysis to give the optimization characteristics of the degradation of such a compound and its by-products. Bulk electrolysis in the potential region of electrolyte decomposition leads to the complete destruction of 2,4,5-T and its degradation intermediates by means of the electrogeneration of the highly reactive hydroxyl radicals. The evolution of the chemical oxygen demand (COD) and the instant current efficiency (ICE) during the degradation process is perfectly predicted by a theoretical mathematical model. HPLC and GC-MS have also been performed to highlight the evolution of the mother product and its degradation intermediates. Kinetic analysis of the obtained results has shown a fast destruction of the mother herbicide asserting a diffusion-controlled process. 2,4,5-trichlorophenol and quinone-based organic compounds have been depicted as aromatic intermediates, all of them transformed into short chains carboxylic acids before complete mineralization happens.

                                                         

KEY WORDS: Electrochemical decontamination, Cyclic voltammetry, 2,4,5-T herbicide, Mineralization,  BDD electrodes

 

 

Bull. Chem. Soc. Ethiop. 2004, 18(2), 205-214.
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eISSN: 1726-801X
print ISSN: 1011-3924