On the following subject: Modified bentonite and diatomite versus ion-imprinted polymers: towards new materials for extracting nickel and silver from contaminated effluents
Co-supervised thesis: Sidi Mohammed Ben Abdallah University
Faculty of Sciences Dhar El Mahraz - Fez
Centre for doctoral studies in Science and Technology
Doctoral training: Materials Science and Industrial Processes
Specialism: Materials science for energy and the environment
&
Toulon University
Doctoral school: ÉCOLE DOCTORALE MER ET SCIENCES (ED 548)
Discipline: Chemistry
Speciality: Materials and Environmental Engineering
Composition of the jury :
Prof. Mohammed LACHKAR Université Sidi Mohamed Ben Abdellah Fès, Chairman
Prof. Nicolas MARMIER University of Nice Sophia Antipolis, Rapporteur
Prof. Abdeljalil BENLHACHEMI Ibn Zohr University, Agadir, Rapporteur
Pr. Fouad KHALIL Faculty of Science and Technology Fez, Rapporteur
Prof. Pascale PRUDENT University of Aix-Marseille, Examiner
Prof. Véronique LENOBLE University of Toulon, Co-supervisor
Pr. Catherine BRANGER University of Toulon, Thesis supervisor
Pr. Abdelkrim OUAMMOU Université Sidi Mohamed Ben Abdellah Fès, Thesis supervisor
Summary:
The copper smelting plants in the city of Fez produce effluent that is highly contaminated with metallic elements such as nickel, silver, lead, copper and zinc. This effluent, discharged directly into the public sewer system, has a negative impact on the nearby wastewater treatment plant. It is therefore necessary to decontaminate this effluent before it is treated. In this context, the objectives of this work were to recover natural mineral substances, bentonite and diatomite, ores that are abundant in the national soil and little exploited in Morocco, for use as nickel and silver adsorption phases. The aim of this work was to modify the physico-chemical properties of these natural materials to maximise their adsorption capacity. In the first stage, diatomite was modified by heat treatment at various temperatures (from 550 to 950°C). Diatomite calcined at 550°C showed the best adsorption capacity for nickel and silver. The second stage involved modifying the bentonite by heat treatment (550°C and 750°C), chemical activation with sodium carbonate and combined chemical and thermal activation at 450°C. Bentonites modified by chemical activation with sodium carbonate and by combined chemical and thermal activation at 450°C show the best results. In addition, nickel ion imprinted polymers (IIPs) were considered as alternative materials to replace natural materials in order to improve selectivity. The final part consisted in comparing the performances of these materials, in order to select the best material for future application in the depollution of contaminated effluents prior to their treatment by the wastewater treatment plant of the city of Fez. Residual nickel and silver concentrations became negligible in the natural samples after adsorption by the materials studied in this work, which meets Environmental Quality Standards perfectly. These results have successfully validated the use of natural and synthetic materials for extracting nickel and silver from contaminated effluents.