Kinetics and thermodynamics of zinc phosphate hydrate synthesized by a simple route in aqueous and acetone media

Abstract

Zinc phosphate (Zn3(PO4)2·4H 2O) was prepared by a simple route using ZnO and H3PO 4 in aqueous and acetone media at ambient temperature. Zn 3(PO4)2·4H2O decomposes to Zn3(PO4)2 by three dehydration reactions, as revealed by thermal analytical (TG/DTG/DTA) and differential scanning calorimetry (DSC) techniques. The synthesized Zn3(PO 4)2·4H2O and its dehydration product Zn3(PO4)2 were characterized by powder X-ray diffraction, Fourier transfer infrared, and scanning electron microscopy. Kinetic triplet parameters (activation energy, E; preexponential, A; Avrami exponent, n) and thermodynamic functions (ΔH*, ΔG*, and ΔS*) of three dehydration reactions are calculated by DSC experiments. Evaluation and control of the specific characteristics of three dehydration processes of Zn3(PO4)2· 4H2O are essentially important in the variously oriented studies, which were discussed from the viewpoints of thermal stability based on kinetics and thermodynamics. © 2010 American Chemical Society.