Kinetic analysis of the thermal decomposition of Zn(II) 2-chlorobenzoate complex with caffeine

Abstract

Kinetics of the first two thermal decomposition steps of the complex [Zn(2-Clbenz)2(caf)2] (where 2-Clbenz = (C6H4Cl)2COO− and caf = caffeine) has been studied using differential thermogravimetry under non-isothermal conditions in air. Although the two studied processes partially overlap, it was found that apparent activation energy may be determined directly from the raw data using both, isoconversional and non-isoconversional methods. The original Kissinger method appears to perform better due to its robustness, however, the isoconversional methods on the other hand provide information about the onsets and endsets of the overlapping peaks. In order to complete kinetic analysis the peaks needed to be deconvoluted – the Fraser–Suzuki function was utilized in this approach. Based on the characteristic kinetic functions z(α) and y(α) it was found that both decompositions follow first order kinetics and can be described using the Johnson–Mehl–Avrami kinetic model.