ORGANOPHILIC BENTONITES OF UKRAINE. PART II. STRUCTURE AND HYDROPHILIC-ORGANOPHILIC NATURE OF THE SURFACE

Using the methods of adsorption from solutions and X-ray analysis, structural changes in montmorillonites from various Ukrainian deposits after their modification with cationic surfactants (salts of quaternary ammonium bases) were studied depending on their structure, chain length, degree and conditions of modification. Based on the change in basal interplanar distances d001 in montmorillonite crystals, conclusions were drawn about the structure of organomontmorillonite derivatives and the orientation of adsorbed cations relative to the silicon-oxygen surface. The dependences of d001 of organomontmorillonite from the Pyzhivsk and Neporotovsk deposits on the degree of modification with octadecyl-benzyl-dimethylammonium and hexadecyl-trimethylammonium chlorides were obtained, on the basis of which it was concluded that at low surface filling, organic cations are located flat on the surface. At higher filling, their reorientation is observed at a certain angle £ 55°, similarly to that in organic crystals. It is assumed that the difference in the values of the interplanar distances of organocomplexes with the same organic cation for montmorillonites from different Ukrainian deposits is explained by the different magnitude of the layer charge and the unequal nature of the charge distribution in the structural layers of the studied layered silicates, which are associated with different geological origins. By adsorption of water vapor and benzene on modified montmorillonites, the mosaic hydrophilic-hydrophobic nature of their surface was estimated and its connection with the structure of organo-derivatives and the chemical nature of the surfactants used was discussed. An integral picture of the change in the lyophilic properties of montmorillonite under the influence of modification by cationic surfactants was obtained. Bibl.47, Fig. 15, Tab. 9.