Rehydroxylation in smectites and other clay minerals observed in-situ with a modified thermogravimetric system

The conventional (time)1/4 power law and the logarithmic kinetic models of rehydroxylation produced good fits of the experimental data. Calculation of activation energies (Ea) for the rehydroxylation reaction produced values from 30 kJ/mol to 173 kJ/mol, highly dependent on the interlayer cation, 2:1 layer structure, and the experimental protocol. The kinetic models developed for rehydroxylation at temperature near ambient remain valid for the experiments up to 400 °C. At 500 °C the mechanism of rehydroxylation is influenced by other factors.