Abstract
Thermogravimetric studies on two varieties of calcium carbonate viz., analytical reagentgrade and insitu generated from calcium oxalate monohydrate, were carried out. The kinetics and mechanism of their solid-state thermal decomposition reaction were evaluated from the TG data using integral methods and the effect of procedural factors such as heating rate, sample mass and method of computation on them were also studied. The procedural variables in the range studied had no marked influence on the results; however the kinetic parameters were marginally higher for the insitu generated calcium carbonate. This trend is explained by the presence of more micropores in the insitu generated calcium carbonate as well as the mechanism of its decomposition following phase boundary reaction with cylindrical symmetry.
Zusammenfassung
An zwei verschiedenen Arten von Calciumcarbonat (analytisch rein bzw. in situ hergestellt aus Calciumoxalatmonohydrat) wurden thermogravimetrische Untersuchungen durchgeführt. Die Kinetik und der Mechanismus der thermischen Feststoffzersetzungsreaktionen wurde unter Anwendung integrativer Verfahren aus TG-Daten ermittelt. Auch der Einfluß experimenteller Bedingungen, wie z.B. von Aufheizgeschwindigkeit, Probenmasse und Rechenmethode wurden untersucht. Die experimentellen Bedingungen haben im untersuchten Intervall keinen sichtlichen Einfluß auf die Ergebnisse; in jedem Falle hatten die kinetischen Parameter für in situ hergestelltes Calciumcarbonat wesentlich höhere Werte. Dies wird durch die Anwesenheit von wesentlich mehr Mikroporen in dem in situ hergestellten Calciumcarbonat erklärt. Der Reaktionsmechanismus der Zersetzung wird mittels Phasengrenzreaktionen mit zylindrischer Symmetrie erklärt.
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Dedicated to Prof. Dr. H. J. Seifert on the occasion of his 60th birthday
We thank Director, VSSC for the kind permission to publish this work. Thanks are due to Mr. A. Natarajan for the support in SEM studies.
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Ninan, K.N., Krishnan, K. & Krishnamurthy, V.N. Kinetics and mechanism of thermal decomposition of insitu generated calcium carbonate. Journal of Thermal Analysis 37, 1533–1543 (1991). https://doi.org/10.1007/BF01913486
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DOI: https://doi.org/10.1007/BF01913486