Kinetics for thermal decomposition of anhydrous aluminum sulfate powder composed of single crystal rhombohedrons in shape

The anhydrous aluminum sulfate powder composed of rhombohedral single-cryst al grains was prepared by precipitation from a concentrated sulfuric acid s olution. The average grain size and the size distribution was 3.8+/-0.7 mu m. Thermal decomposition behavior of the anhydrous aluminum sulfate was inv estigated by thermogravimetric measurements. The kinetics of the thermal de composition fitted to a contracting volume model with an apparent activatio n energy of 360 kJ/mol. The mobility of the reaction boundary of the therma l decomposition at 760 degrees C was estimated to be about 7.0 x 10(-5) mu m/s. The temperature dependence of the mobility was expressed by an Arrheni us type equation.