Dehydration kinetics of some smectites: a thermogravimetric study

Abstract Weight-loss experiments for eight smectite samples, from various international localities, were followed by dynamic thermoģravimetry. Analysis of the curves was achieved by plotting log g(α) vs. 1/ T , according to Satava (1971), or by applying the methods of Coats and Redfern (1964). The estimated activation energies of dehydration ( E d below 300° C) were 10–17 and 8–14 kcal mol −1 , respectively. In the former method, the F 1 function (random nucleation mechanism) fits better to dehydration, whereas the first-order kinetics apply in the latter method. Nontronites do not show different E d values compared to montmorillonites. The different values of E d seem to be correlated with the water content lost through the dehydration region.