Physico - Chemical and Mineralogical Characterization of a Moroccan Bentonite (Azzouzet) and Determination of its Nature and its Chemical Structure

Abstract

This study concerns the results of Physicochemical and mineralogical characterization of a Moroccan bentonite (bentonite Azzouzet) and determination of its nature and its chemical structure. Several techniques were used; in particular X-ray diffraction (XRD), scanning electron microscopy coupled with EDX microanalysis (SEM-EDX), differential thermal and gravimetric analyses (DTA-TGA) and finally infrared Fourier transform (FTIR) and X-ray fluorescence (XRF). The bentonite fine fraction (< 2 µm in size), was characterized by BET method for specific surface area, and a cation- exchange capacity.The X-ray diffraction analysis supplemented by gravimetric analysis showed that Azzouzet bentonite is primarily (smectite) (49 wt %) with the presence of feldspar (34 wt %), Quartz (5 wt %), magnetite (7 wt %) and amorphous iron oxide (3 wt %). It has a cation- exchange capacity of 73,3 meq/100g and a specific surface area by using surface area analyser and N2 gaz was used as adsorbate under atmosphere of 31 m²/g.the structural formula calculated for bentonite has shown that the montmorillonite has a high charge density. SEM-EDX, X-ray, chemical analysis and Infrared spectroscopy demonstrated that this montmorillonite contains iron Fe3 + in the octahedral sheet. The origin of the charge sheets is tetraedral (Si4) (Al2.12 Mg0.15), with the montmorillonite character of the bentonite (15%) is present (less than 50% octahedral charge) with a phase rich in iron.