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Etude d'élimination de trois herbicides : Atrazine, Sulcotrione et Mésotrione, en milieu aqueux par les procédés électrochimiques d'oxydation avancée

Abstract : This study concerns the application of an electrochemical advanced oxidation process, namely the "electro-Fenton process", to treatment of waste water containing the persistent organic pollutants such as herbicides. A very strong oxidant, the hydroxyl radical, is generated in situ in electrocatalytic way. This radical is able to oxidize any organic molecule until the ultimate oxidation stage, i.e. mineralization (transformation into CO2 and H2O).Degradation/mineralization of three herbicides (atrazine, sulcotrione and mesotrione) was the subject of this work. Atrazine was very largely used herbicide in the past and prohibited recently in France because of its negative impact on the environment. During the two last decades atrazine constituted the chronic pollutants of surface and underground waters. Atrazine and its metabolites will be present in water still during several years. Atrazine are well-known as problematic herbicides for their treatment. Atrazine is one of the rare molecules which resist to mineralization by the advanced oxidation processes. Mesotrione and sulcotrione are molecules designed to replace the atrazine as weed-killers. After having optimized the operational parameters of the electro-Fenton process (nature and concentration of the catalyst, the use of a boron doped diamond (BDD) instead of Pt, etc.) in order to increase its efficiency, we applied it to treatment of the aqueous solutions of selected herbicides. Initially, we identified and carried out the quantitative follow-up of the aromatic and aliphatic reaction intermediates formed during current controlled electrolysis. The release of the mineral ions was measured by ion chromatography and their evolution during electrolysis was followed. The mineralization efficiency of treated solutions was determined in term of total organic carbon (TOC) measurements. In the case of the atrazine, a mineralization ratio of 96% was obtained. Such mineralization efficiency was never reported by an advanced oxidation process. The degradation kinetics study of the herbicides under examination permitted to determine the apparent rate constants (kapp) of the reactions between herbicides and hydroxyl radical. The absolute rate constants (kabs) of degradation reactions of studied herbicides were determined by employing the competition kinetics method using a standard molecule for which kabs is known. The values of (1,53 x 108 M-1 s-1 ) ,(1.01 x 109 M-1 s-1 ) and ( 8.20 x 108 M-1 s-1) were found respectively for the atrazine, the sulcotrione and the Mesotrione
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Submitted on : Friday, December 14, 2012 - 10:37:11 AM
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  • HAL Id : tel-00740108, version 2

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Minir Murati. Etude d'élimination de trois herbicides : Atrazine, Sulcotrione et Mésotrione, en milieu aqueux par les procédés électrochimiques d'oxydation avancée. Sciences de la Terre. Université Paris-Est; Univerzitet Kiril i Metodiǰ (Skopje, Macédoine), 2012. Français. ⟨NNT : 2012PEST1030⟩. ⟨tel-00740108v2⟩

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