Thermal analysis and infrared emission spectroscopy of the borate mineral colemanite (CaB3O4(OH)3H2O) : implications for thermal stability.
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Date
2016
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Abstract
Colemanite CaB3O4(OH)3H2O is a secondary
borate mineral formed from borax and ulexite in evaporate
deposits of alkaline lacustrine sediments. The basic structure
of colemanite contains endless chains of interlocking
BO2(OH) triangles and BO3(OH) tetrahedrons with the
calcium, water and extra hydroxide units interspersed
between these chains. We have studied the thermal
decomposition of colemanite by using a combination of
thermal analysis (TG/DTG) and infrared emission spectroscopy
(IES). Thermogravimetric analysis of the colemanite
mineral was obtained by using TA Instruments Inc.
Q50 high-resolution TGA operating at a 10 C min-1 ramp
with data sample interval of 0.50 s pt-1 from room temperature
to 1000 C in a high-purity flowing nitrogen
atmosphere (100 cm3 min-1
). Thermogravimetric analysis
shows a sharp mass loss at 400.9 C. Only a single mass loss
is observed. IES shows a sharp band at 3610 cm-1 assigned
to the stretching vibration of hydroxyl units. Intensity in this
band is lost by 350 C. A broad spectral feature is observed
at 3274 cm-1 attributed to water stretching vibrations.
Intensity in this band is lost by 300 C. A combination of
thermogravimetry and IES is used to study the thermal
stability of the borate mineral colemanite. It is important to
characterize the very wide range of borate minerals
including colemanite because of the very wide range of
applications of boron-containing minerals.
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Keywords
Thermogravimetric analysis, Colemanite, Infrared spectroscopy, Borate, Evaporite
Citation
FROST. L. et al. Thermal analysis and infrared emission spectroscopy of the borate mineral colemanite (CaB3O4(OH)3H2O): implications for thermal stability. Journal of Thermal Analysis and Calorimetry, v. 124, n. 1, p. 131-135, abr. 2016. Disponível em: <https://link.springer.com/article/10.1007/s10973-015-5128-5>. Acesso em: 10 jul. 2017.