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Synthèse, propriétés physicochimiques et réactivité vis-à-vis de l’arsenic (III) et (V) de nanoparticules de magnétite fonctionnalisées par de l’amidon

Abstract : This thesis work focused on the synthesis of starch-functionalized magnetite Fe3O4 nanoparticles with the final objective of arsenic (III) and (V) removal in waters. Two "one pot" synthesis methods were applied and the influence of the mass ratio R = mstarch/miron on the physicochemical properties and reactivity of magnetite was systematically studied. The first synthesis method is based on partial oxidation of iron (II) followed by co-precipitation of iron (II) and iron (III) and the second method is based on direct co-precipitation of iron (II) and iron (III). Magnetite synthesis and starch functionalization were performed in a single step. The results of the analyses combining TEM, XRD, Raman, FTIR, XPS and Mössbauer spectroscopies showed differences in the microstructural, structural and magnetic properties of magnetite depending on the synthesis method used. For the first synthesis method, the ratio R influences the crystallite size of magnetite which varies from ~ 70 to 10 nm between R = 0 and 10 while the size decrease is less important using the second method (from ~13 to 9 nm) for the same R values. The size decrease clearly influences the magnetic properties of magnetite by inducing the appearance of the superparamagnetism phenomenon highlighted by Mössbauer spectroscopy. The reactivity of magnetite towards arsenic (III) and (V) was studied by evaluating the influence of parameters such as adsorbent dose, contact time, arsenic concentration at equilibrium, pH and presence of competing ions. Functionalized magnetite have shown higher adsorption capacities than bare magnetite regardless of the synthesis method used. The decrease in crystallite size and the dispersion of nanoparticles in the presence of starch explain these results.
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https://hal.univ-lorraine.fr/tel-02559232
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Submitted on : Thursday, April 30, 2020 - 11:43:52 AM
Last modification on : Wednesday, November 3, 2021 - 7:57:53 AM

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  • HAL Id : tel-02559232, version 1

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Mbolantenaina Rakotomalala Robinson. Synthèse, propriétés physicochimiques et réactivité vis-à-vis de l’arsenic (III) et (V) de nanoparticules de magnétite fonctionnalisées par de l’amidon. Matériaux. Université de Lorraine, 2019. Français. ⟨NNT : 2019LORR0290⟩. ⟨tel-02559232⟩

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