Characterization, Kinetic Using Deconvolution Techniques and Thermodynamic Study of Synthetic MgHPO[sub.4]·3H[sub.2]O

MgHPO[sub.4]·3H[sub.2]O was synthesized via a simple wet reaction and transformed to its final decomposed product, Mg[sub.2]P[sub.2]O[sub.7] at 873 K. The thermal properties, vibrational modes of block units, and solid phases of the synthetic compounds have been investigated by TG/DTG/DTA, FTIR, and XRD techniques. The temperature dependence of thermodynamic properties estimated from the DSC data occurred in two regions (before and after the dehydration reaction) indicating a characteristic of the prepared MgHPO[sub.4]·3H[sub.2]O sample. The dehydration reactions of 3.5 mol of water molecules in the structure overlapped in the temperature of 363-823 K and showed the phase transition at 921 K as revealed by TG/DTG/DTA. The deconvolution technique using the newly modified co-mathematical functions was used to separate the overlapped dehydration steps in the DTG curve, which obtained the three steps. Only the first and second steps were estimated using kinetic triplet parameters (E[sub.a], A, and model), which indicate the single dehydration mechanism with the A[sub.1.25] model and the multi-step of a parallel mechanism with the A[sub.1.6] model, respectively. The data of kinetics and thermodynamics play key points in theoretical study, application development, and industrial production of magnesium phosphates as a theoretical basis.