Isoconversional and Model-fitting Approaches to Kinetic and Thermoanalytic Study of Lanthanum Oxalate: Nonlinear Relationship between Kinetic Parameters

Abstract

The data for the nonisothermal and isothermal thermal decompositions of lanthanum oxalate have been analysed using the model-free and model-fitting kinetic techniques. When applied to nonisothermal data using the Coat-Redfern(CR) equation, the widely used model-fitting approach that results excellent fitting for both isothermal and nonisothermal data but produces very ambiguous values of the Arrhenius parameters. These values cannot be compared to those obtained from isothermal experiments. On the other hand, the model-free strategy represented by the iso-conversional method, such as Flynn-Wall-Ozawa (FWO) and Kissinger-Akahira-Sunose (KAS), emphasize propertionate  variation of the activation energy with the degree of conversion for both isothermal and nonisothermal experiments. The model free approach is recommended as a reliable way for obtaining consistent kinetic information from both isothermal and non-isothermal data. Despite their linear correlation, the kinetic parameters do not exhibit isokinetic behaviour. Thus, utilising Nonlinear Compensation Law, a greater association between kinetic triplets was examined.