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Étude de la dégradation photocatalytique sur des couches minces de dioxyde de titane de dépôts solides discrets d’acide stéarique

Abstract : Photocatalysis is widely used in a variety of applications in water and air purification. For those reasons, fundamentals research on the photocatalytical degradation processes of organic compounds on photocatalysts surfaces concern in most cases liquid and gaseous phases. The more recent development of self-cleaning surfaces has raised several issues concerning the mechanisms of photocatalytic degradation of solid deposits such as soot or fatty acids. These issues remain little addressed in the literature and therefore deserve further attention. This thesis work deals with the study of the photocatalytical degradation modes of solid deposits of stearic acid (SA) on the surface of titanium dioxide thin films. In this work, an original experimental approach based on the use of optical microscopy is implemented to monitor, on a microscopic scale, the SA deposits as a function of UV light exposure. Viewed under microscope, the SA deposits appear as microscopic islands presenting size and form distribution. On the basis of a new kinetic model we propose, the existing relationships between the degradation rate of the deposit and the initial size distribution of the islands population is demonstrated. The proposed kinetic model rationalizes our experimental results as well as several others from the literature. Additionally, an original study on the degradation of SA microcrystals, grown on microstructured TiO2 thin films, provides insight into the role of the photogenerated oxygenated radicals in the photocatalytical mechanisms. Furthermore, the anisotropy of the microcrystals structure is put in relation with that of the SA molecules orientations within the microcrystal. This explains the observed {hkl}-dependence of the degradation rate of the microcrystals
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https://tel.archives-ouvertes.fr/tel-01947579
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Submitted on : Friday, December 7, 2018 - 8:35:07 AM
Last modification on : Saturday, December 8, 2018 - 10:10:58 AM
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  • HAL Id : tel-01947579, version 1

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Fouad Araiedh. Étude de la dégradation photocatalytique sur des couches minces de dioxyde de titane de dépôts solides discrets d’acide stéarique. Science des matériaux [cond-mat.mtrl-sci]. Université de Lorraine; Université de Gabès (Tunisie), 2018. Français. ⟨NNT : 2018LORR0161⟩. ⟨tel-01947579⟩

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