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Kinetics of thermal transformation of Mg 3(PO 4) 2 8H 2O to Mg 3(PO 4) 2
Author(s)
Date Issued
February 1, 2010
Type
Article
Abstract
The kinetics of thermal dehydration of Mg 3(PO 4) 2 8H 2O was investigated using thermogravimetry at four different heating rates. The activation energies of the dehydration step of Mg 3(PO 4) 2 8H 2O were calculated through the isoconversional Ozawa and Kissinger-Akahira-Sunose (KAS) methods and iterative methods, which were found to be consistent and indicate a single mechanism. The possible conversion function of the dehydration reaction for Mg 3 (PO 4) 2 8H 2O has been estimated through the Coats and Redfern integral equation, and a better kinetic model such as random nucleation of the "Avrami-Erofeev equation (A 3/2 model)" was found. The thermodynamic functions (ΔH *, ΔG *, and ΔS *) of the dehydration reaction are calculated by the activated complex theory and indicate that it is a non-spontaneous process when the introduction of heat is not connected. © Springer Science+Business Media, LLC 2010.
Citation
International Journal of Thermophysics, 31(2), 416-429, 2010