Original paper
Thermal decomposition kinetics of Fe-rich tourmaline
Liu, Xiaowen; Yu, Changqiang; Yang, Weiqiang; Xie, Lan; Liang, Song
European Journal of Mineralogy Volume 31 Number 5-6 (2019), p. 919 - 928
71 references
published: Dec 20, 2019
published online: Jun 25, 2019
manuscript accepted: Dec 14, 2018
manuscript revision received: Dec 13, 2018
manuscript received: Jun 30, 2018
Abstract
The thermal behaviour of different types of tourmaline with varying Fe content has been reported in the literature, which makes comparison of analytical results difficult. The objective of this study was to throw light on the thermal behaviour and to carry out kinetics analysis for Fe-rich tourmaline (schorl). X-Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR) and Thermogravimetry-Differential Scanning Calorimetry (TG-DSC) were applied to characterize the thermal behaviour. The Friedman, Flynn-Wall-Ozawa, modified Coats-Redfern and Kissinger integral approaches were carried out to determine the decomposition mechanism. The deprotonation reaction occurred at ~700 °C with the formation of oxy-tourmaline. Subsequently, oxy-tourmaline decomposition resulted in the formation of hematite, mullite and aluminium boron oxide at ~890 °C. Good linearity was observed using the Friedman, Flynn-Wall-Ozawa, modified Coats-Redfern and Kissinger integral approaches. The activation energy determined here was in the range 350–530 kJ mol−1, which offered a simplified approach in understanding the thermal decomposition properties of Fe-rich tourmaline.
Keywords
activation energy • kinetic analysis • thermal decomposition • tourmaline • schorl • deprotonation • oxy-tourmaline