Unprecedented total mineralization of atrazine and cyanuric acid by anodic oxidation and electro-Fenton with a boron-doped diamond anode |
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Authors: | Nihal Oturan Enric Brillas Mehmet A Oturan |
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Institution: | (1) Laboratoire G?omat?riaux et Environnement (LGE), Universit? Paris-Est, 5 bd Descartes, 77454 Marne-la-Vall?e Cedex 2, France;(2) Laboratori d’Electroqu?mica dels Materials i del Medi Ambient, Departament de Qu?mica F?sica, Universitat de Barcelona, Mart? i Franqu?s 1-11, 08028 Barcelona, Spain; |
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Abstract: | This article reports the complete mineralization of atrazine. Atrazine has been the most widely used s-triazine herbicide.
Atrazine occurs in natural waters and presents a potential danger for public health because atrazine is considered as an endocrine
disruptor. The use of chemical, photochemical and photocatalytic advanced oxidation processes (AOPs) to decontaminate waters
containing atrazine only allowed its conversion into the cyanuric acid as ultimate end products, since it cannot be completely
degraded by hydroxyl radicals (•OH) produced by these techniques. The same behavior was previously reported for anodic oxidation and electro-Fenton with Pt
anode, although better performances were found using boron-doped diamond (BDD) anode but without explaining the role of generated
•OH. Here, the oxidative action of these radicals in such electrochemical AOPs has been clarified by studying the mineralization
process and decay kinetics of atrazine and cyanuric acid in separated solutions by anodic oxidation with BDD and electro-Fenton
with Pt or BDD anode using an undivided cell with a carbon-felt cathode under galvanostatic conditions. Results showed that
electro-Fenton with BDD anode was the more powerful treatment to degrade both compounds. Almost total mineralization, 97%
total organic carbon (COT) removal, of atrazine was only feasible by this method with a faster removal of its oxidation intermediates
by •OH formed at the BDD surface than that formed in the bulk from Fenton reaction, although the latter process caused a more
rapid decay of the herbicide. Cyanuric acid was much slowly mineralized mainly with •OH produced at the BDD surface, and it was not degraded by electro-Fenton with Pt anode. These results highlight that electrochemical
advanced oxidation processes (EAOPs) using a BDD anode are more powerful than the classical electro-Fenton process with Pt
or PbO2 anodes. |
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