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Title: Influence of chelation on the Fenton-based electrochemical degradation of herbicide tebuthiuron
Author: Gozzi, Fábio
Sirés Sadornil, Ignacio
de Oliveira, Silvio César
Machulek Jr., Amílcar
Brillas, Enric
Keywords: Oxidació electroquímica
Complexos metàl·lics
Electrolytic oxidation
Metal complexes
Issue Date: 12-Feb-2018
Publisher: Elsevier Ltd
Abstract: This study describes the performance of electro-Fenton (EF) and photoelectro-Fenton (PEF) processes to degrade the herbicide tebuthiuron (TBH) in 0.050 M Na2SO4 at pH = 3.0. Experiments were performed in an undivided cell equipped with a boron-doped diamond (BDD) or Pt anode and an air-diffusion cathode that produces H2O2. Physisorbed hydroxyl radicals (M(●OH)) generated from water oxidation at the anode and/or free ●OH formed from Fenton's reaction acted as main oxidants. All processes became much more effective using a BDD anode because of the higher oxidation power of BDD(●OH). Sulfate and nitrate were the predominant ions released during TBH destruction. In both, EF and PEF treatments, two distinct kinetic regimes were observed, the first one corresponding to the oxidation of free TBH by ●OH and the second one to that of the Fe(III)-TBH complex by M(●OH). The effect of Fe2+ and TBH concentrations on the kinetics of both regions has been examined. Moreover, a poor mineralization was reached with Pt anode, whereas almost total mineralization was attained by EF and PEF with BDD. Both processes showed analogous mineralization rates because the intermediates produced could not be photodegraded by UVA light. Gas chromatography-mass spectrometry analysis of electrolyzed solutions revealed the generation of eight heteroaromatics along with 1,3-dimethylurea, which have been included in a reaction pathway proposed for the initial degradation of TBH.
Note: Versió postprint del document publicat a:
It is part of: Chemosphere, 2018, vol. 199, p. 709-717
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ISSN: 0045-6535
Appears in Collections:Articles publicats en revistes (Ciència dels Materials i Química Física)

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