Experimental study and Monte-Carlo simulation of the nucleation and growth processes during the dehydration of Li2SO4.H2O single crystals.

A kinetic model for the dehydration of lithium sulfate monohydrate is proposed in order to account for experimental data obtained on single crystals by thermogravimetry at 80 degrees C under fixed water vapour pressure, and by optical microscopy. This model is based on the assumptions of Mampel's model, the nucleation takes place randomly at the surface of the solid and is followed by isotropic growth toward the centre of the crystal. Calculated rates dalpha/dt are obtained by means of Monte-Carlo simulations and compared to the experimental ones, which leads to the determination of two kinetic constants: the areic frequency of nucleation (in number of nuclei m(-2) s(-1)) and the areic reactivity of growth (in mol m(-2) s(-1)).