Comparative analysis of Na+ and Ca2+ ion effects on the physical-chemical properties of Bentonite: Implications for industrial applications

Abstract

This study investigates the potential industrial applications of two types of bentonite - Calcium Bentonite (Ca-B) and Sodium Bentonite (Na-B) - from the Kert Basin in northern Morocco. The bentonite samples' structural characteristics, inclusions, and microcracks were examined using scanning electron microscopy. X-ray diffraction analysis of both the whole rock and clay fractions was conducted to determine the bentonite type and mineralogical composition. The chemical composition was assessed through X-ray fluorescence. The physico-chemical properties analyzed included cation exchange capacity, swelling index, colloidality index, water content, and pH. The plasticity index and liquid limit were determined using Atterberg limits tests. The results indicate that sodium bentonite exhibits superior absorption and plasticity compared to calcium bentonite, with a higher cation exchange capacity, particularly after activation. The analyzed bentonites contain high amounts of iron and silica, with moderate levels of calcium and aluminum. Quartz, feldspars, and clay minerals were identified in all samples, with smectite being the dominant clay mineral phase (80 %), along with traces of kaolinite, illite, and interstratified illite-smectite. These bentonites generally display high plasticity, making them well-suited for hydraulic drilling applications. Additionally, their low organic matter and calcium carbonate (CaCO₃) content may indicate mechanical strength, water sensitivity, and purity.