A Thermogravimetric study of the alunites of sodium, potassium and ammonium
Frost, Ray L., Wain, Daria L., Wills, Rachael-Anne, Musumeci, Anthony W., & Martens, Wayde N. (2006) A Thermogravimetric study of the alunites of sodium, potassium and ammonium. Thermochimica Acta, 443(1), pp. 56-61.
Thermogravimetry in tandem with mass spectrometry has been used to characterise the thermal decomposition of synthetic alunites of potassium, sodium and ammonium. Three mechanisms of decomposition are observed a) dehydration b) dehydroxylation c) desulphation. The thermal decomposition of the three alunites is different. For NH4-alunite, an additional process of de-ammoniation is observed which occurs simultaneously with dehydration. Dehydroxylation takes place in a series of four steps. De-sulphation occurs for K-alunite at 680 degrees C in a single step in comparison with Na and NH4 alunites where de-sulphation is observed in a series of four steps. The temperature of desulphation is cation dependent. The thermal decomposition is not completed until around 800 degrees C.
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|Item Type:||Journal Article|
|Additional Information:||This paper is one of a series of papers on alunites and jarosites. The interest in such minerals rests with their possible identification on the planet mars. Such minerals on only formed from solution. The paper reports the stability of a series of alunites.|
|Keywords:||alunite, natroalunite, ammonioalunite, jarosite, thermogravimetry, sulphate|
|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 2006 Elsevier|
|Copyright Statement:||Reproduced in accordance with the copyright policy of the publisher.|
|Deposited On:||23 Mar 2006|
|Last Modified:||29 Feb 2012 13:23|
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