The kinetics of thermal dehydration of copper(II) acetate monohydrate in air

Abstract

The thermal decomposition of copper(II) acetate monohydrate was studied in air using TG-DTG/DTA, DSC, XRD techniques. TG-DTA curves show that the decomposition occurs in four steps. TG and XRD data indicate the reduction of Cu(II) during the decomposition of CuAc 2·H 2O. DTG and DSC data imply at least two steps contained in dehydration reaction, which is verified by the activation energy values estimated with Friedman and Flynn–Wall–Ozawa (FWO) methods. The dependence of activation energy on conversions indicates the dehydration reaction contains an additional initial reversible step. The most-probable kinetic model has been estimated with multivariate non-linear regression method assuming a two-step consecutive reaction. Bna (expanded Prout–Tompkins equation) → Cn ( n order autocatalytic reaction) model fits the original data best with a high correlation coefficient of 0.9998, and the calculated apparent activation energies of the fitted models are consistent with those calculated by isoconversional methods using original data. The corresponding function f( α), activation energy E and preexponential factor A of Bna, are (1 − α) 0.7593 α 0.2867, 128.5 kJ/mol and 1.6 × 10 15, respectively. Those of Cn, are (1 − α) 1.0534(1 + 2.712 α), 80.5 kJ/mol and 6.9 × 10 7, respectively. The combination of model free isoconversional methods and multivariate non-linear regression can give more reasonable and applicable models than commonly used model fitting methods.