TG DTA studies of dehydration behaviors for montmorillonites

摘要

The dehydration properties for Na{sup}+-, K{sup}+-, Cu{sup}(2+)- and Co{sup}(2+)- saturated montmorillonites in the temperature range up to 1200℃ with TG-DTA were examined. The changes of the dehydration behaviors on the specimens were measured by TG-DTA. From the results of TG analysis, it was recognized that the amounts of water dehydrated for the water adsorbed in the interlayer until 200℃ were 8.10% (Na-mont.), 6.99% (K-mont.), 10.1% (Cu-mont.), 12.9% (Co-mont.), respectively. And the amounts of weight losses till 1200℃ were 13.7%(Na-mont.), 13.0%(K-mont.), 16.8%(Cu-mont.), 19.5% (Co-mont.), respectively. From the DTA curves, the endothermic peak causing by the water co-ordinated the divalent cations was observed around 172℃ for Cu-mont and the peak for Co-mont. was shifted to higher temperature around 200℃ That endothermic peaks by dehydration due to the water co-ordinated metal ions were not recognized for Na-mont., K-mont. These results was indicated that the valence number or the sorts of the cations in the interlayer the play an important role in its dehydration properties.