The intercalation of several highly polar organic compounds into kaolinite and the formation of interlamellar complexes has been examined by X-ray diffraction. Some compounds intercalate directly into kaolinite, while others can only be intercalated by the displacement of a previously intercalated compound. The formation of the complexes is strongly dependent on the properties of the organic compound, and generally a large dipole moment favours the formation of a complex. A large dipole moment may however cause extensive association in the liquid state and this decreases the rate of intercalation. The addition of water to highly associated compounds increases the rate of intercalation by breaking up the structure of the associated liquid, and the rate passes through a maximum with increasing water content. Thus the rate of intercalation is found to depend on the extent of association in the liquid or solution, the temperature and the molecular size. The d(001) spacings of the complexes are given and the orientation and packing of the intercalated molecules in relation to the A -values is discussed.
Abstract-The i.r. spectra of interlamellar kaolinite complexes with formamide, N-methylformamide and dimethylformamide have been examined. The spectra show that the amides hydrogen-bond, through the C= O group of the amide to the inner surface kaolinite hydroxyls and decrease the intensity of the kaolinite v(OH) bands. Hydrogen-bonded kaolinite hydroxyl bands appear at lower frequencies and these have been correlated to the original kaolinite v(OH) bands. Other kaolinite bands in the complexes show smaller perturbations of the kaolinite vibrations. Each amide hydrogen-bonds to different groups of hydroxyls. Formamide hydrogen-bonds to the 3690 and 3664 cm -1 hydroxyls, N-methylformamide to the 3690 and 3648 cm -~ hydroxyls. The interpretation for the dimethylformamide complex is less clear. The v(NH) frequencies of formamide and N-methylformamide in the complexes are intermediate between that in dilute non-polar solution and in the liquid. This could arise from either or both a degree of intermolecular association of the amide when between the kaolinite lamellae, or to weak N--H... O hydrogen bonds to the tetrahedral oxygen sheet of the lamellae.
Abstract--The crystalline and osmotic swelling of N~, Cs-, Mg-and Ca-montmorillonite has been measured in dimethyl sulphoxide and in formamide, N-methyl formamide, dimethyl formamide, N-methyl acetamide and dimethyl acetamide. These liquids have similar dipole moments but their relative permittivities vary appreciably from values less than water to values greater than water.Na montmorillonite exhibits osmotic swelling (diffuse double layer development -d(001) ~ 19 A) in formamide and N-methyl formamide and Cs gives osmotic swelling behavior in formamide. Cs-montmorillonite in the crystalline swelling region give spacings greater than those found for water with all liquids. Mg-and Ca-montmorillonite did not give spacings greater than 19 A in any of the liquids studied.The swelling behavior of montmorillonite is affected by relative permittivity but for liquids with a similar relative permittivity methyl substitution in the molecule may prevent the development of diffuse double layers on the particle surfaces.
INTRODUCTIONThe swelling of montmorillonites in water has received considerable attention (e.g. Norrish and Quirk, 1954;Norrish, 1954;Warkentin and Schofield, 1962; Norfish and Raussel-Colom, 1963; Posner and Quirk, 1964a,b;Quirk, 1968)with the result that the swelling behavior of montmorillonites in relation to factors such as exchangeable cation, hydrostatic pressure and electrolyte concentration, is relatively well described. There still exists, however, some uncertainty in the detailed interpretation of the swelling behavior (Quirk, 1968) particularly in relation to the exchangeable cation and its polarizing power in affecting the properties of water in the neighborhood of the cation and the surface.The literature reveals that montmorillonites show limited expansion [d(001) < 19 A,] with a wide variety of polar organic compounds; swelling in relation to the properties of organic compounds has previously been examined by Barshad (1952) and Greene-Kelly (1955a,b) and, although some very polar organic liquids have been used, for instance nitrobenzene (Yariv, Russell and Farmer, 1966), basal spacings greater than 15.2/k have not been reported except for glycerol and ethylene glycol. Most of the earlier work deals with the bonding and mechanism of adsorption of organic compounds in montmorillonite or simply the spacing of the interlayer complexes.
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