A new facile synthesis, kinetic mechanism and some thermodynamic studies of thermal transformation of α-LiZnPO4·H2O

Abstract

α-LiZnPO4·H2O was successfully synthesized via a new simple route in an aqueous media at ambient temperature. The as-prepared and the calcined powders were confirmed by standard characterization methods. The SEM micrographs of the title compound and its dehydration product were studied. The experimental enthalpy of dehydration was evaluated from DSC data, which was found to be close to the standard enthalpy of water vaporization. α-LiZnPO4·H2O dehydrates in a single step. Therefore, this compound is an additional ideal case for studying the decomposition kinetics. Non-isothermal dehydration kinetics was studied from TG data using Ozawa–Flynn–Wall (OFW) and Kissinger–Akahira–Sunose (KAS) methods including their iterative procedures, as well as some reliable solid-state kinetic equations of Coats–Redfern, Madhysudanan–Krishnan–Ninan (MKN), Tang and Wanjun. The most probable mechanism function was determined using the master plots method. The dehydration mechanism was found to be the chemical reaction with the one-third order reaction or the type F1/3 reaction model with the differential form of f(α)\u2009=\u20093/2 (1\u2009−\u2009α)1/3 and the integral form of g(α)\u2009=\u20091\u2009−\u2009(1\u2009−\u2009α)2/3. The calculated activation energy value is exact and reliable. The discussions about the results of XRD, SEM, DSC, FTIR and the most probable mechanism function of dehydration are consistent.