TY - JOUR
T1 - A combined synchrotron powder diffraction and vibrational study of the thermal treatment of palygorskite-indigo to produce Maya blue
AU - Sánchez Del Río, Manuel
AU - Boccaleri, Enrico
AU - Milanesio, Marco
AU - Croce, Gianluca
AU - Van Beek, Wouter
AU - Tsiantos, Constantinos
AU - Chyssikos, Georgios D.
AU - Gionis, Vassilis
AU - Kacandes, George H.
AU - Suárez, Mercedes
AU - García-Romero, Emilia
N1 - Funding Information:
Acknowledgements We acknowledge the ESRF for beamtime used for this experiment, and the experimental staff of BM01B for technical support and helpful discussions. Financial support from the Spanish CICYT (project CGL2006-09843) and Italian PRIN edition 2007 is also acknowledged.
PY - 2009/10
Y1 - 2009/10
N2 - The heating process (30-200 °C) 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 °C 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.
AB - The heating process (30-200 °C) 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 °C 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.
UR - http://www.scopus.com/inward/record.url?scp=69549107497&partnerID=8YFLogxK
U2 - 10.1007/s10853-009-3772-5
DO - 10.1007/s10853-009-3772-5
M3 - Article
SN - 0022-2461
VL - 44
SP - 5524
EP - 5536
JO - Journal of Materials Science
JF - Journal of Materials Science
IS - 20
ER -