Exfoliation and Extraction of Nanoclay from Montmorillonite Mineral Rich Bentonite Soil

Abstract

Nanoclay is a fine-grained crystalline material, which contains a mineral of alumina and silica with high aspect ratio and at least one dimension of a particle in the nanometer (1 nm = 10⁻⁹ m) range. Nanoclays have various applications in many fields, including problematic soil treatment, pharmacy, medicine, catalysis, cosmetics, food packaging, and textile industry. The raw cost of Nanoclay is high due to its costly manufacturing process that involves heavy chemicals and machinery. Therefore, the aim of the current research is to extract Nanoclay from the montmorillonite-rich commercially available Bentonite soil using a cost-effective method. The process involves the exfoliation of the nanosized lamina from the stacked 2:1 tetrahedral–octahedral laminae of montmorillonite minerals with the help of surfactant. Three different types of surfactants (cationic, nonionic, and anionic) were chosen in the current study to evaluate their effect on the exfoliation process of highly expansive Bentonite soil. A series of chemical processes including solution preparation, sonication, centrifugation, and drying were performed using selected proportion of surfactant and Bentonite soil mixture. Physical and chemical properties of the end product were investigated by performing X-ray diffraction (XRD) technique and scanning electron microscope (SEM) image analysis. Nanoclay of the particle size range of 10–15 nm is successfully exfoliated from montmorillonite sheet structure by the chemical interaction between cationic surfactant and Bentonite soil. Nonionic surfactant was observed to be just intercalated between the sheets of montmorillonite mineral with additional growth of small needle-like structures. Anionic surfactant has no prominent effect on Bentonite soil.