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Kinetic and thermodynamic studies of MgHPO4 • 3H 2O by non-isothermal decomposition data
Author(s)
Date Issued
December 1, 2009
Type
Article
Abstract
The thermal decomposition of magnesium hydrogen phosphate trihydrate MgHPO4 • 3H2O was investigated in air atmosphere using TG-DTG-DTA. MgHPO4 • 3H2O decomposes in a single step and its final decomposition product (Mg2P 2O7) was obtained. The activation energies of the decomposition step of MgHPO4 • 3H2O were calculated through the isoconversional methods of the Ozawa, Kissinger-Akahira-Sunose (KAS) and Iterative equation, and the possible conversion function has been estimated through the Coats and Redfern integral equation. The activation energies calculated for the decomposition reaction by different techniques and methods were found to be consistent. The better kinetic model of the decomposition reaction for MgHPO4 • 3H2O is the F 1/3 model as a simple n-order reaction of "chemical process or mechanism no-invoking equation". The thermodynamic functions (ΔH*, ΔG*and ΔS*) of the decomposition reaction are calculated by the activated complex theory and indicate that the process is non-spontaneous without connecting with the introduction of heat. © 2009 Akadémiai Kiadó, Budapest, Hungary.
Citation
Journal of Thermal Analysis and Calorimetry, 98(3), 863-871, 2009