Kaolinite hydrates synthesis

Subsequent work showed that a modification of the synthesis procedure produced a 10A hydrate which> if dried carefully, would maintain the interlayer water in the absence of excess water (27). This material is optimal for adsorbed water studies for a number of reasons the parent clay is a well-crystallized kaolinite with a negligible layer charge, there are few if any interlayer cations, there is no interference from pore water since the amount is minimal, and the interlayer water molecules lie between uniform layers of known structure. Thus, the hydrate provides a useful model for studying the effects of a silicate surface on interlayer water. 

Characterization of Interlayer Water. X-ray diffraction studies of the 10A hydrate show no hkl reflections indicating a lack of regularity in the stacking of the kaolin layers. In addition to the 10A hydrate, two other less hydrated kaolinites were synthesized. Both have one molecule of water for each formula unit in contrast to the 10A hydrate which has two. These less hydrated clays consequently have smaller d(001) spacings of 8.4 and 8.6 A. The synthesis conditions for these two hydrates are described in (22.). By studying the interlayer water in the 8.4 and 8.6A hydrates, it was possible to formulate a model of the water in the more complicated 10A hydrate. 

Cordierite synthesis method based on mechanical activation of mixtures of hydrated oxides of calcium, aluminium and silicon, as well as natural hydrated compounds (talc, kaolinite and gibbsite), has been developed in [2, 3]. Mechanical activation of these mixtures does not lead to the formation of new phases but provides good mixing at the cluster level giving aggregates that form cordierite during the subsequent thermal treatment. 

---