MONTMORILLONITE GROUP MINERALS: STRUCTURE, PROPERTIES, AND APPLICATIONS

Аннотация

Montmorillonite group minerals, which belong to the smectite family, are layered silicates known for their high cation-exchange capacity, swelling ability, and adsorption properties. This paper provides a comprehensive overview of their crystal structure, chemical composition, and physicochemical characteristics. It also explores the practical applications of montmorillonite in catalysis, environmental remediation, pharmaceuticals, and nanocomposite materials. Special attention is given to their modification through intercalation, acid activation, andion exchange to enhance theirfunctionality. Keywords: montmorillonite, smectite, structure, adsorption, cation exchange, clay minerals, intercalation Montmorillonite is one of the most widely studied clay minerals due to its exceptional physicochemical properties. It is a member of the smectite group of phyllosilicates and is characterized by a 2:1 layer structure consisting of two tetrahedral sheets sandwiching one octahedral sheet. The ability of montmorillonite to absorb water and various organic/inorganic substances into itsinterlayer spacemakes itvaluable in various fields. Found abundantly in bentonite clays, montmorillonite plays a significant role in environmental and industrial processes. Its cation exchange capacity (CEC), swelling behavior, and high surface area make it an ideal candidate for use in soil conditioning, pollutant adsorption, drillingfluids, and even as adrug delivery agent in biomedicine. Montmorillonite’s high cation exchange capacity (CEC) and swelling properties originate from its unique 2:1 layered silicate structure, which enables water and ions to enter between its layers. This characteristic makes it highly reactive and useful in a variety of industrial and environmental applications. Besides natural occurrences, montmorillonite can be chemically modified by acid activation or organic intercalation to tailor its surface chemistry forspecific purposes. Given its versatile properties, montmorillonite is widely utilized in environmental cleanup as an adsorbent for heavy metals and organic pollutants, in catalysis as a solid acid catalyst, and in the pharmaceutical industry as a carrier for controlled drug release. Recent advances in nanotechnology have further expanded its applications in nanocomposite materials, improvingmechanical strength and thermal stability. page1499 INTERNATIONAL JOURNAL OF ARTIFICIAL INTELLIGENCE ISSN:2692-5206,ImpactFactor:12,23 AmericanAcademicpublishers,volume05,issue06,2025 Journal: https://www.academicpublishers.org/journals/index.php/ijai Despite extensive studies, there is ongoing interest in optimizing the synthesis and modification of montmorillonite to enhance its efficiency and selectivity. Therefore, this study aims to characterize natural montmorillonite samples and investigate the effects of acid activation ontheirstructural andphysicochemical properties. Natural bentonite samples rich in montmorillonite were characterized using various analytical techniques. X-ray diffraction (XRD) was used to identify the crystal structure, while Fourier-transform infrared spectroscopy (FTIR) provided information onfunctional groups. The surface area and porosity were measured using the BET method. Samples were also subjected to acid activation and intercalation with organic cations to observe structural and property changes. SamplePreparation: Natural bentonite clay samples containing montmorillonite were obtained from [specify location or supplier]. The samples were dried at 105°C for 24 hours, ground to a fine powder, andsieved to obtain particle sizes below 63µm. Acid Activation: Acid activation was carried out by treating the montmorillonite samples with sulfuric acid (H₂SO₄) solutions of varying molarities (0.5 M, 1 M, and 2 M). The clay-to-acid ratio was maintained at 1:10 (w/v). The mixture was stirred continuously at 60°C for 4 hours. After treatment, samples were washed repeatedly with deionized water until neutral pH was achieved, then dried and ground. Characterization Techniques:  X-ray Diffraction (XRD): Used to identify crystalline phases and measure basal spacing (d001) changes. Measurements were taken using a Cu-Kα radiation source at 40 kVand 30mA.  Fourier-transform Infrared Spectroscopy (FTIR): Conducted to analyze functional groups and structural changes before and after acid activation. Spectra were recorded from 4000to 400cm⁻¹.  Brunauer–Emmett–Teller (BET) Surface Area Analysis: Performed using nitrogen adsorption at 77Ktodeterminespecific surfacearea andpore sizedistribution.  Cation Exchange Capacity (CEC): Determined by the ammonium acetate method to assess theion-exchange potential ofthesamples.  Thermogravimetric Analysis (TGA): Used to assess thermal stability and decompositionbehavior. 1.Structure andComposition: Montmorillonite has a layer charge resulting from isomorphic substitution, such as Mg²⁺ for Al³⁺ in the octahedral sheet. This negative layer charge is balanced b