Kinetic and thermodynamic studies of MgHPO4 •A 3H2O by non-isothermal decomposition data

The thermal decomposition of magnesium hydrogen phosphate trihydrate MgHPO4 center dot A 3H(2)O was investigated in air atmosphere using TG-DTG-DTA. MgHPO4 center dot A 3H(2)O decomposes in a single step and its final decomposition product (Mg2P2O7) was obtained. The activation energies of the decomposition step of MgHPO4 center dot A 3H(2)O 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 center dot A 3H(2)O is the F (1/3) model as a simple n-order reaction of chemical process or mechanism no-invoking equation. The thermodynamic functions (Delta H*, Delta G* and Delta S*) 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.