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The Diffusion of Interlamellar Water in the 23.3 Å Na-Montmorillonite:Pyridine/H2O Intercalate by Quasielastic Neutron Scattering

Published online by Cambridge University Press:  01 July 2024

J. M. Adams
Affiliation:
Edward Davies Chemical Laboratories, University College of Wales, Aberystwyth, SY23 1NE, U.K.
C. Breen
Affiliation:
Edward Davies Chemical Laboratories, University College of Wales, Aberystwyth, SY23 1NE, U.K.
C. Riekel
Affiliation:
Institut Laue-Langevin, 156X, Grenoble, Cedex, France

Abstract

The diffusion of water in the title intercalate has been measured by quasielastic neutron scattering. The diffusion coefficient (6.1 × 10−7 cm2 s−1 at 23.5°C) is one order less than that found previously for a sodium-exchanged montmorillonite which, however, contained 4 times as much water in the interlamellar space. The activation energy for the motion has been deduced to be 18 kJ mol−1. Also it has been demonstrated that upon the time scale of the neutron scattering events (faster than 10−9 s) the hydroxyl groups of the clay lattice are not in motion.

Резюме

Резюме

Диффузия воды в прослойку 23,3 Å Ыа-монтмориллонит:пиридии/Н2O измерялась с помошью квази-эластичного рассеивания нейтронов. Диффузионный коеффициент (6,1 × 10-7 cm2/s при 23,5°С) на один порядок меньше, чем было обнаружено ранее для монтмориллонита с обменным натрием, который однако содержал в четыре раза больше воды в межслойных промежутках. Была вычислена активационная энергия для перемещения, которая оказалась равной 18 кдж/мол. Было также продемонстрировано, что в масштабе временных событий нейтронного рассеивания (быстрее, чем 10−9 сек) гидроксильные группы решетки глины не находятся в движении.

Resümee

Resümee

Die Diffusion von Wasser in der Titeleinschiebung wurde mit quasi-elastischer Neutronenstreuung gemessen. Der Diffusionskoeffizient (6,1 × 10-7 cm2/s bei 23,5°C) ist um eine Ordnung niedriger als der welcher voher für ein Natriumausgetauschtes Montmorillonit gefunden wurde, welches allerdings viermal soviel Wasser im interlamellaren Raum enthält. Die Aktivierungsenerdie für die Bewegung wurde auf 18 kj/mol geschätzt. Es wurde auch demonstriert, daß auf der Zeitskala der Neutronénstreuungsereignisse (schneller als 10-9s), die Hydroxylgruppen des Tongitters sich nicht bewegen.

Résumé

Résumé

La diffusion d'eau dans la matière intercalée mentionée dans le titre a été mesurée par dispersion quasi-élastique de neutrons. Le coefficient de diffusion (6,1 × 10-7 cm2/s à 23,5°C) est un ordre de grandeur plus bas que celui trouvé dans le passé pour une montmorillonite échangée pour du sodium qui, pourtant, contenait quatre fois plus d'eau dans l'espace interfeuillet. On a déduit que l’énergie d'activation pour le mouvement était 18 kj/mol. Il a aussi été démontré que sur l’échelle de temps des événements de la dispersion de neutrons (plus rapide que 10-9 s) les groupes hydroxyles du réseau cristallin de l'argile n’étaient pas en mouvement.

Type
Research Article
Copyright
Copyright © 1979, The Clay Minerals Society

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