Thermal decomposition of jarosites of potassium,sodium and lead |
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Authors: | R L Frost M L Weier W Martens |
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Institution: | (1) Inorganic Materials Research Program, School of Physical and Chemical Sciences, Queensland University of Technology, GPO Box 2434, Brisbane Queensland 4001, Australia;(2) Inorganic Materials Research Program, School of Physical and Chemical Sciences, Queensland University of Technology, GPO Box 2434, Brisbane Queensland 4001, Australia;(3) Inorganic Materials Research Program, School of Physical and Chemical Sciences, Queensland University of Technology, GPO Box 2434, Brisbane Queensland 4001, Australia |
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Abstract: | Summary Jarosites are a group of minerals formed in evaporite deposits and form a component of efflorescence. As such the minerals
can function as cation and heavy metal collectors. Thermogravimetry coupled to mass spectrometry has been used to study three
Australian jarosites which are predominantly K, Na and Pb jarosites. Mass loss steps of K-jarosite occur over the 130 to 330
and 500 to 622°C temperature range and are attributed to dehydroxylation and desulphation. In contrast the behaviour of the
thermal decomposition of Na-jarosite shows three mass loss steps at 215 to 230, 316 to 352 and 555 to 595°C. The first mass
loss step for Na-jarosite is attributed to deprotonation. For Pb-jarosite two mass loss steps associated with dehydroxylation
are observed at 390 and 418°C and a third mass loss step at 531°C is attributed to the loss of SO3. Thermal analysis is an excellent technique for the study of jarosites. The analysis depends heavily on the actual composition
of the jarosite. |
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Keywords: | dehydration dehydroxylation high-resolution thermogravimetry Raman spectroscopy jarosite |
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