Synthetic nanoclays with the structure of montmorillonite: Preparation, structure, and physico-chemical properties

Nanosized layered silicates with a montmorillonite structure of varying composition were synthesized under hydrothermal conditions (350°C, 700 atm). The hydrothermal treatment was applied to gels with the compositions calculated with the use of an ideal formula of the final product Na2x (Al2(1 − x), Mg2x ) Si4O10(OH)2 · nH2O (0 ≤ x ≤ 1). The obtained samples were investigated by X-ray diffraction, IR and NMR spectroscopy, electron microscopy, and mercury porosimetry. The values of the cation-exchange capacity and specific surface are determined. The mean size of the particles of the synthesized samples is 40 ± 7 nm. A gradual substitution of aluminum for part of the magnesium in the initial gel made it possible to obtain samples with well-defined composition-dependent characteristics.