The Intercalation of Kaolinite by Alkali Halides in the Solid State: A Systematic Study of the Intercalates and their Derivatives

Abstract

Kaolinite : alkali halide intercalates have been successfully prepared by grinding the salt with kaolinite in the absence of water. Rate of intercalation is shown to correlate negatively with melting point of the salt. The basal dimensions of the intercalates increase with increasing size of the ion. As shown recently for kaolinite : NaC1 intercalate, the layered structure survives the dehydroxylation of the kaolinite at 500"-600~ at which point the excess alkali halide can be removed by rinsing to give an XRD- amorphous material. This amorphous material, of approximate stoichiometry MA1SiO4, reacts at sur- prisingly low temperatures to give crystalline phases, apparently of the same stoichiometry, with structures closely related to eucryptite (M = Li), carnegieite (M = Na), kalsilite (M = K), and leucite (M = K, Rb, Cs). The relationships between the structures of the reaction products are discussed.