Thermal decomposition of syngenite, K2Ca(SO4)2.H2O

Kloprogge, J. Theo, Ding, Zhe, Martens, Wayde N., Schuiling, Roelof D., Duong, Loc V., & Frost, Ray L. (2004) Thermal decomposition of syngenite, K2Ca(SO4)2.H2O. Thermochimica Acta, 417(1), pp. 143-155.

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The thermal decomposition of syngenite, K2Ca(SO4)2.H2O, formed during the treatment of liquid manure has been studied by Thermal Gravimetric Analysis, Differential Scanning Calorimetry, high temperature X-ray diffraction and Infrared Emission Spectroscopy. Gypsum was found as a minor impurity resulting in a minor weight loss due to dehydration around 100 degrees Celsius. The main endothermic dehydration and decomposition stage of syngenite to crystalline K2Ca2(SO4)3 and amorphous K2SO4 is observed around 200 degrees Celsius. The reaction involves a solid-state recrystallization, while water and the K2SO4 diffuse out of the existing lattice. The additional weight loss steps around 250 and 350 degrees Celsius are probably due to presence of larger syngenite particles, which exhibit slower decomposition due to the slower diffusion of water and K2SO4 out of the crystal lattice. A minor endothermic sulphate loss around 450 degrees Celsius is not due to the decomposition of syngenite or its products or of the gypsum impurity. The origin of this sulphate is not clear.

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ID Code: 921
Item Type: Journal Article
Refereed: Yes
Keywords: differential scanning calorimetry, infrared emission spectroscopy, sulphate double salt, syngenite, thermogravimetry, mass spectroscopy
DOI: 10.1016/j.tca.2003.12.001
ISSN: 0040-6031
Subjects: Australian and New Zealand Standard Research Classification > CHEMICAL SCIENCE (030000) > INORGANIC CHEMISTRY (030200)
Divisions: Past > QUT Faculties & Divisions > Faculty of Science and Technology
Copyright Owner: Copyright 2004 Elsevier
Copyright Statement: Reproduced in accordance with the copyright policy of the publisher: This journal is available online.
Deposited On: 13 Oct 2005 00:00
Last Modified: 09 Jun 2010 12:23

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