Influence of water vapor pressure on the induction period during Li 2SO 4·H 2O single crystals dehydration

Abstract

The dehydration of Li 2SO 4·H 2O single crystals at 80 °C has been studied by means of both isothermal thermogravimetry at 2.6, 3.6 and 4.6 hPa of water vapor and environmental scanning electron microscope. Thermogravimetric experiments allowed the determination of induction periods. Distributions of these isoconversion induction periods for a large number of single crystals showed that increasing the water vapor pressure produced a longer induction period. Moreover, the shape of the distributions of the induction periods over a large number of single crystals changed from one mode at 2.6 hPa to two modes at 3.6 and 4.6 hPa. Using an environmental scanning electron microscope, this result could be attributed to differences in nucleation rates at edges and faces of the single crystals.