Mineralogical and Physicochemical Characterization of Three Natural Bentonite Samples from the Tahoua Sites (Niger)

Abstract

This study evaluated the physicochemical, mineralogical, structural and textural characteristics of three natural bentonite samples collected from Adoua (BN-G₁), Mougia (Madaoua) (BN-G₂) and Bouza (BN-G₃) in the Tahoua region of Niger, with the aim of assessing their potential relevance to catalytic applications. The samples were characterized through preliminary physicochemical analyses, X-ray fluorescence, X-ray diffraction, Fourier-transform infrared spectroscopy, scanning electron microscopy and nitrogen adsorption using the Brunauer–Emmett–Teller method. Mineralogical analysis showed that the samples contained quartz, montmorillonite, kaolinite and calcite, with quartz particularly prominent in the Mougia and Bouza samples. X-ray fluorescence indicated that BN-G₁ contained 61.27% SiO₂ and 20.12% Al₂O₃, whereas BN-G₂ contained 85.45% SiO₂ and 7.93% Al₂O₃ and BN-G₃ contained 85.84% SiO₂ and 6.76% Al₂O₃. BN-G₁ had a specific surface area of 87.2959 m²/g, substantially higher than those of the other samples, together with the highest swelling index and cation-exchange capacity. Scanning electron microscopy of BN-G₁ showed a layered smectite morphology consistent with montmorillonite, while its SiO₂/Al₂O₃ ratio was 3.045. Overall, the comparative characterization distinguished Adoua bentonite from the Mougia and Bouza samples and identified BN-G₁ as the material with the most favourable measured properties for subsequent evaluation in the proposed catalytic application. These findings provide a comparative basis for selecting local bentonite for further catalytic testing.