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Materials 2013, 6(4), 1452-1466; doi:10.3390/ma6041452
Article

Dehydration Process of Hofmann-Type Layered Solids

1
,
2
,
3,*  and 1
1 Centro de Investigación en Ciencia Aplicada y Tecnología Avanzada Unidad Legaria, Instituto Politécnico Nacional, Legaria 694, Colonia, Irrigación, México D.F. 11500, Mexico 2 Mexican Petroleum Institute, Eje Central 152, México D.F. 07730, Mexico 3 Center for Research and Advanced Studies of the National Polytechnic Institute, Km 6 Antigua Carretera Progreso, Cordemex, Mérida 97310, Yucatán, Mexico
* Author to whom correspondence should be addressed.
Received: 14 December 2012 / Revised: 8 March 2013 / Accepted: 22 March 2013 / Published: 9 April 2013
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Abstract

In the present work the dehydration process of layered solids with formula unit M(H2O)2[Ni(CN)4nH2O, M = Ni, Co, Mn; n = 1, 2, 4 is studied using modulated thermogravimetry. The results show that water molecules need to overcome an energetic barrier (activation energy between 63 and 500 kJ/mol) in order to diffuse through the interlayer region. The related kinetic parameters show a dependence on the water partial pressure. On the other hand, X-ray diffraction results provide evidence that the dehydration process is accompanied by framework collapse, limiting the structural reversibility, except for heating below 80 °C where the ordered structure remains. Removal of water molecules from the interlayer region disrupts the long-range structural order of the solid.
Keywords: kinetics parameters; hi-res/modulated-TG; porous lattices; dehydration of lamellar solids kinetics parameters; hi-res/modulated-TG; porous lattices; dehydration of lamellar solids
This is an open access article distributed under the Creative Commons Attribution License (CC BY 3.0).

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Reyes-Martinez, O.; Torres-García, E.; Rodríguez-Gattorno, G.; Reguera, E. Dehydration Process of Hofmann-Type Layered Solids. Materials 2013, 6, 1452-1466.

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