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Kinetics and thermodynamics of thermal decomposition of synthetic AlPO 4•2H2O
Author(s)
Danvirutai, Chanaiporn
Date Issued
December 1, 2009
Type
Article
Abstract
The non-isothermal kinetics of dehydration of AlPO4•2H 2O was studied in dynamic air atmosphere by TG-DTG-DTA at different heating rates. The result implies an important theoretical support for preparing AlPO4. The AlPO4•2H2O decomposes in two step reactions occurring in the range of 80-150 °C. The activation energy of the second dehydration reaction of AlPO4•2H2O as calculated by Kissinger method was found to be 69.68 kJ mol-1, while the Avrami exponent value was 1.49. The results confirmed the elimination of water of crystallization, which related with the crystal growth mechanism. The thermodynamic functions (ΔH*, ΔG*and ΔS*) of the dehydration reaction are calculated by the activated complex theory. These values in the dehydration step showed that it is directly related to the introduction of heat and is non-spontaneous process. © 2009 Akadémiai Kiadó, Budapest, Hungary.
Citation
Journal of Thermal Analysis and Calorimetry, 98(3), 771-777, 2009