Investigation of Cation-Substituted Vermiculite Deformation upon Water Vapor Sorption

Structural Perturbations in the Solid–Water Interface of Redox Transformed Nontronite

“…These mutual structural modifications at the clay-water interface evidently are insensitive to the type or concentration of monovalent electrolyte surrounding the mont-morillonite layers (4). Earlier studies, using other analytical methods, also indicated that the structure of montmorillonite (5,6) and vermiculite (7,8) can be modified through interaction of the crystal layers with water molecules. Recently, we observed that changes in the oxidation state of structural Fe in montmorillonite greatly perturbs structural Si-O and interlayer H-O-H bending vibrations (9), indicating that the solidwater interfacial interactions depend on both the interlayer water content and the composition and structure of the clay mineral.…”

Adsorptive Deformation of Organo-Substituted Laminar Silicates

“…A detailed description of the dilatometric part of the apparatus was given in our earlier work (17). Briefly, the main part of the dilatometer was a linear differential transformer, whose core was connected to the adsorbent by means of a rod.…”

“…For example, the interlaminar adsorption of water on the Na samples of vermiculite (17) and fluorohectorite is similar (17,21). This permitted us to compare the extent of deformation of organofluorohectorite (Fig.…”

“…The interlaminar adsorption of water molecules in these packets in the first stage leads, as in the case of vermiculite (17), to contraction of the system (see Figs. 5 and 6) and then to expansion of the crystals.…”

“…A consequence of the structural perfection of vermiculite is the almost simultaneous intracrystalline swelling of vermiculite packets at certain water vapor pressures. Previously (17), we used a dilatometric method to determine the deformations of Na, Ca, and Ba-vermiculites upon the adsorption of water vapor. These results were compared with the adsorption, microcalorimetric, and X-ray diffraction data.…”