High-temperature dehydration of talc: a kinetics study using<i>in situ</i>X-ray powder diffraction

Abstract

High-temperature in situ X-ray powder diffraction patterns were used to study the dehydration kinetics of natural talc with a size of 10–15 µm. The talc was annealed from 1073 to 1223 K, and the variations in the characteristic peaks corresponding to talc with the time were recorded to determine the reaction progress. The decomposition of talc occurred, and peaks corresponding to talc and peaks corresponding to enstatite and quartz were observed. The enstatite and talc exhibited a topotactic relationship. The dehydration kinetics of talc was studied as a function of temperature between 1073 and 1223 K. The kinetics data could be modeled using an Avrami equation that considers nucleation and growth processesα=1−exp(−ktn),where n varies from 0.4 to 0.8. The rate constant (k) equation for the natural talc islnk=ln(3.2E+14)−366.5RT.The reaction mechanism for the dehydration of talc is a heterogeneous nucleation and growth mechanism.