DEHYDRATION AND REHYDRATION OF MAGADIITE AND KENYAITE

Dehydration and rehydration characteristics of synthetic magadiite and kenyaite were investigated in a temperature range from R.T. to 1000-degrees-C, and also under high vacuum at R.T. Magadiite and kenyaite lost inter-layered water in the range of R.T.-600-degrees-C accompanying the decrease of basal spacing. At 80-degrees-C-100-degrees-C, the "intermediate" step of dehydration was observed for both compounds with the basal spacing of 14.1 angstrom for magadiite and 18.8 angstrom for kenyaite. Reversible rehydration took place completely after heating up to 250-degrees-C. The layered structures decomposed at 550-degrees-C for magadiite and at 600-degrees-C for kenyaite. Under high vacuum, interlayered water of both compounds was eliminated completely from the interlayer space at 10(-5) Torr for 24 h at R.T. However, the reversible rehydration was observed, when the "collapsed" products were kept in atmospheric air for 24 h.