Study of the interactions between caesium bromide and kaolinite by photoacoustic and diffuse reflectance infrared spectroscopy

Abstract

The mechanochemical reactions between CsBr and kaolinite that occur during shaking, grinding at ambient atmosphere (air grinding), and grinding in the presence of a few drops of water (wet grinding), were investigated by photoacoustic and diffuse reflectance infrared spectroscopy and by thermal weight loss. An intercalation complex was formed by the wet grinding technique but not by mixing or air grinding. For comparison, the mechanochemical reactions of kaolinite with CsCl and CsI were also investigated. No complex of CsI was formed but CsCl gave an intercalation complex by air or wet grinding and, after an aging period of 3 months, also by mixing. A structure is suggested for the intercalation complex in which a water molecule coordinated to the large caesium cation donates one proton to an inner surface oxygen and another proton to the halide, while accepting a proton from an inner surface hydroxyl group. Key words: kaolinite, infrared spectroscopy, intercalation.