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-crystal grains was prepared by precipitation from a concentrated sulfuric acid solution. The average grain size and the size distribution was 3.8±0.7μm. Thermal decomposition behavior of the anhydrous aluminum sulfate was investigated by thermogravimetric measurements. The kinetics of the thermal decomposition fitted to a contracting volume model with an apparent activation energy of 360 kJ/mol. The mobility of the reaction boundary of the thermal decomposition at 760°C was estimated to be about 7.0×10-5μm/s. The temperature dependence of the mobility was expressed by an Arrhenius type equation.