Decomposition kinetic characteristics of calcium carbonate containing organic acids by TGA

Abstract

By means of thermogravimetric analysis (TGA), influences of organic acids such as citric acid, oxalic acid and tartaric acid on decomposition process and thermal behaviors of calcium carbonate were investigated in non-isothermal condition. Experiments were conducted from the ambient temperature to 1273K at a heating rate of 10Kmin−1. Moreover, the kinetic parameters (activation energy and pre-exponential factor) of the mixtures of calcium carbonate and organic acids were determined using the Coats–Redfern method. It is indicated that the decomposition process of calcium carbonate containing different organic acids includes three or four weight loss processes. In the zone of 370–450°C, energy is released due to the combustion of organic products decomposed from organic salts, and energy increases with the increase of molecular weight of organic acid. Activation energy of the samples containing citric acid, oxalic acid and tartaric acid is decreased by 34.9%, 28.8% and 31.9%, respectively. The results may be used to provide a useful basis for further applying industrial wastes containing different organic acids in cement industries with high-efficiency.