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A combined synchrotron powder diffraction and vibrational study of the thermal treatment of palygorskite–indigo to produce Maya blue

Sánchez del Río, Manuel and Boccaleri, Enrico and Milanesio, Marco and Croce, Gianluca and Beek, Wouter van and Tsiantos, Constantinos and Chyssikos, Georgios D. and Gionis, Vassilis and Kacandes, Georges H. and Súarez Barrios, Mercedes and García Romero, Emilia (2009) A combined synchrotron powder diffraction and vibrational study of the thermal treatment of palygorskite–indigo to produce Maya blue. Journal of materials science, 44 . pp. 5524-5536. ISSN 0022-2461

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Official URL: http://www.springer.com/materials/journal/10853

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Abstract

The heating process (30–200 ºC) of a palygorskite-
indigo mixture has been monitored in situ and
simultaneously by synchrotron powder diffraction and
Raman spectroscopy. During this process, the dye and the
clay interact to form Maya blue (MB), a pigment highly
resistant to degradation. It is shown that the formation of a
very stable pigment occurs in the 70–130 ºC interval; i.e.,
when palygorskite starts to loose zeolitic water, and is
accompanied by a reduction of the crystallographic a
parameter, as well as by alterations in the C=C and C=O
bonds of indigo. Mid- and near-infrared spectroscopic
work and microporosity measurements, employed to study
the rehydration process after the complex formation, provide
evidence for the inhibition of the rehydration of MB as
compared with palygorskite. These results are consistent
with the blocking of the palygorskite tunnel entrance by
indigo molecules with a possible partial penetration inside
the tunnels. The surface silanols of palygorskite are not
perturbed by indigo, suggesting that MB is not a surface
complex.

Item Type:Article
Uncontrolled Keywords:Palygorskite–indigo; Maya blue; Diffraction and Raman spectroscopy
Subjects:Sciences > Geology > Mineralogy
ID Code:13480
Deposited On:25 Oct 2011 11:36
Last Modified:25 Oct 2011 11:36

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