The Upper Cretaceous-Paleogene of Phosphate Clays of the Ouled Bou Sbaa Deposit: Mineralogy, Geochemistry, and Beneficiation (Meskala, Morocco)

Abstract

This work aims first to characterize the Maastrichtian and Paleogene clays of the Ouled Bou Sbaa phosphate deposit located in the northern part of the Meskala Basin; and as a second goal, the most efficient clay fractions are tested and identified for organic dyes removal. Several techniques and methods have been adopted for the characterization of clays: X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), X-ray fluorescence (XRF), Scanning electron microscope (SEM), and thermogravimetric analysis (TGA). Tests for the removal of methylene blue from clays were carried out by adsorption. The XRD study shows that the clays of the Ouled Bou Sbaa deposit contain fibrous clay types of palygorskite and sepiolite, and phyllite clays such as montmorillonite and illite. Stratigraphically, the Maastrichtian sample yielded, mainly aluminous clays dominated by montmorillonites, while in the Paleogene clays, the palygorskite-types clays, also rich in magnesium, are more common. The results of FTIR, XRF and SEM analyses confirm the mineralogical data, respectively, by the presence of characteristic bands and the dominance of oxides of silica, aluminum, magnesium, and the large dominance of palygorskite which is presented in the form of bundles or platelets of long fibers and montmorillonite which is presented in the form of a stack of sheets. The adsorption of methylene blue (MB) on these clays showed very fast fixation kinetics and a very efficient purifying power for this organic pollutant. The equilibrium isotherms were determined using the Langmuir, Freundlich and Elovich models. The results show that the Freundlich isotherm had better agreement with the methylene blue on clay with a correlation coefficient of 0.959.