Thermogravimetric study of the dehydration kinetics of talc

The dehydration kinetics of nearly pure talc, (Mg_0.99Fe_0.01)₃Si₄O₁₀(OH)₂, and of pure synthetic talc to enstatite and SiO₂ was studied as a function of temperature between 777 and 977°C and of grain size by thermogravimetry experiments. In the grain-size range of 15-1 μm, the rate of dehydration of talc increased with decreasing grain size, but further decrease of grain size did not significantly affect the dehydration rate. The kinetic data can be adequately modeled by a second-order phenomenological rate law. Compared with talc of the same grain size, the synthetic talc was found to have a significantly faster dehydration rate. TEM images showed topotactic growth of enstatite on talc, with a concomitant formation of tridymite. -from Authors