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Bentonite et diatomite modifiées versus polymères à empreintes ioniques : vers de nouveaux matériaux pour l'extraction du nickel et de l'argent d'effluents contaminés

Abstract : The brassware manufacturing of Fez city produces effluents that are very contaminated by metals such as nickel, silver, lead, copper and zinc. These effluents are directly discharged into the environment with a negative impact on the ecosystems and nearby wastewater treatment plant. Therefore, there is an urgent need for decontaminating these effluents before their treatment. In this context, the objectives of this work were the valorisation of natural mineral substances, bentonite and diatomite, widespread minerals in Moroccan soil although little exploited, for their use as adsorbent phases for nickel and silver extraction. A considerable part of this work has been directed toward modifying the physicochemical properties of these natural materials to maximize their adsorption capacity. In a first step, the modification of the diatomite was carried out by heating treatment at different temperatures (550 to 950 °C). The diatomite calcined at 550 °C showed the best adsorbing capacity towards nickel and silver. The second step was dedicated to the modification of the bentonite by heating treatment (550 °C and 750 °C) and chemical activation by sodium carbonate and by a combined chemical and thermal activation at 450 °C. Bentonites modified by chemical activation with sodium carbonate and by combined chemical and thermal activations at 450 ° C showed the best results. In addition, Ion Imprinted Polymers (IIPs) have been considered as alternative materials to replace these natural materials to improve the selectivity. The last part of this study consisted in comparing the performance of these materials, in order to select the best material for a future application in the remediation of contaminated effluents before their depollution by the treatment plant of Fez city. The nickel and silver concentrations become negligible in the natural samples after adsorption by the studied materials, which perfectly meets the Environmental Quality Standards. These results successfully validated the use of natural and synthetic materials for the extraction of nickel and silver from contaminated effluents.
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Submitted on : Thursday, June 24, 2021 - 5:00:25 PM
Last modification on : Saturday, June 26, 2021 - 3:03:35 AM

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EL_OUARDI_2020TOUL0013.pdf
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  • HAL Id : tel-03270385, version 1

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Youssef El Ouardi. Bentonite et diatomite modifiées versus polymères à empreintes ioniques : vers de nouveaux matériaux pour l'extraction du nickel et de l'argent d'effluents contaminés. Matériaux. Université de Toulon; Université Sidi Mohamed ben Abdellah (Fès, Maroc). Faculté des sciences, 2020. Français. ⟨NNT : 2020TOUL0013⟩. ⟨tel-03270385⟩

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