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Comportement photochimique dans l'eau d'une famille d'antibiotiques : devenir et élimination

Abstract : Nowaday the emergence of pharmaceuticals in the aquatic and terrestrial environment have been a major concern. They have been detected in sewage-treatment plants, sediments, and soils as well as at surface and drinking water. So far, there is limited information in the literature on the fate of these compounds once they are exposed to solar light in the various environmental compartments. In the present work we have been interested in studying the behavior of antibiotics from Sulfonamide family: Sulfamethoxazole (STZ), Sulfathiazole (STL), Sulfamethazine (STN) and Hydrochlorothiazide (HCD) in aqueous solutions upon exposure to simulated solar light. We mainly concentrate our effort on the kinetic studies by evaluating the degradation quantum yield as well as the effect of various parameters such as oxygen concentration, pH and the presence of inorganic ions. The main effect was observed by molecular oxygen parameter. We also make an important effort in the elucidation of the main intermediate and stable by-products. A lot of information is available on the stability and fate of parent compounds and not so many on their transformation products. These may present a toxicity level higher than the precursor substrate and should be identified and analysed. The chemical structure elucidation was obtained by using the HPLC/ESI/MS and HPLC/ESI/MS2 techniques in negative as well as positive modes and through the complete study of the various fragmentation pathways. The main involved photochemical processes were identified as i) the scission of the bridge through a photohydrolysis process, ii) selective hydroxylation of the aromatic moiety iii) Desulfonation process and iiii) in the case of HCD to dechloration reaction. A mechanism was then proposed in the light of the kinetics and analytical studies.
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  • HAL Id : tel-01919334, version 1

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Soumaya Mezghich. Comportement photochimique dans l'eau d'une famille d'antibiotiques : devenir et élimination. Chimie théorique et/ou physique. Université Clermont Auvergne, 2017. Français. ⟨NNT : 2017CLFAC095⟩. ⟨tel-01919334⟩

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