Emanation thermal analysis study of Na-montmorillonite and montmorillonite saturated with various cations.

Emanation thermal analysis (ETA) and thermogravimetry measured in the range 20-1000 degrees C was used to characterize the thermal behaviour of Na-montmorillonite (Upton Wyoming, USA) and homoionic montmorillonite samples prepared by saturation with cations Li+ , Mg2+, Al3+, respectively. It was confirmed that the presence of cations used for montmorillonite saturation (Li+, Mg2+, Al3+) influenced the thermal behaviour of the samples. The results that indicated the decrease of radon release rate corresponding to a collapse of the interlayer space between the silicate sheets after water release and the crystallization of meta-montmorillonite in the respective temperature intervals were compared. From the ETA results it followed that the thermal stability of intermediate microstructure depends on the type of exchanged cation. A mathematical model was used to evaluate the ETA data