On the Lattice Shrinkage and Structure of Montmorillonite

Nagelschmidt, G.

doi:10.1524/zkri.1936.93.1.481

Cited by 42 publications

(26 citation statements)

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“…Ross and Shannon (1926) were the first to suggest that smectite swells because water enters the structure between the 2:1 silicate layers. Nagelschmidt (1936) and Bradley et al (1937) demonstrated that the 001 spacing of smectite increases in distinct steps as the amount of water in the environment is increased. The latter workers suggested that the steps represented the formation of distinct hydrates containing one, two, and three layers of water molecules.…”

Section: Introductionmentioning

confidence: 99%

Ordered Interstratification of Dehydrated and Hydrated Na-Smectite

Moore

Hower²

1986

Clays and clay miner.

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Abstract--The 001 spacing of Na-smectite was found to vary from 9.6 ,~ at 0% relative humidity (RH) to 12.4 ~ at 60-65% RH. The 9.6-,~ spacing corresponds to dehydrated Na-smectite, and the 12.4-,~ corresponds to Na-smectite with one water layer. A regular series of intermediate values resulted from ordered interstratification of the 9.6-and 12.4-~ units. Ordered interstratification was confirmed by the presence of a 001 spacing of 9.6 + 12.4 A = 22 A. This peak appeared under experimental conditions at about 35% RH. It appeared for calculated simulations of ordered stacking of 50/50 mixtures (_+ 10%) of 9.6-and 12.4-,~ units. The 004 peak of this 22-,~ spacing interacted with the 002 of the 9.6-A spacing of ordered mixtures of more than 50% 9.6-/k units and with the 002 of the 12.4-~ spacing of ordered mixtures of more than 50% 12.4-~ units. The result of this interaction was a complex peak, the position of which was a function of the ratio of 9.6-and 12.4-,~ units. This complex peak was noted for experimental and for calculated conditions. Calculated tracings assuming ordered stacking matched the experimental tracings closely, whereas those assuming random stacking did not.Ordering was apparently due to the interaction of the positive charge of the interlayer cation repelling the positive charge of the hydrogens of the hydroxyl ions, one above and one below, closest to the interlayer space. The collapse of a single interlayer space (dehydration) brought the interlayer cation closer to the hydrogens of the hydroxyls causing the hydroxyls to rotate such that the hydrogens shifted toward the adjacent interlayer spaces. Collapse of these two interlayer spaces was therefore more difficult. This same mechanism helps explain ordering in illite/smectite. The difference is that hydration/dehydration is quick and reversible, whereas the change from smectite to illite is slow and irreversible.

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Section: Introductionmentioning

confidence: 99%

Ordered Interstratification of Dehydrated and Hydrated Na-Smectite

Moore

Hower²

1986

Clays and clay miner.

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“…[10][11][12][13][14] Different layer types were thus defined for smectite: dehydrated (0W, d 001 ) 9.7-10.2 Å), monohydrated (1W, d 001 ) 11.6-12.9 Å), bihydrated (2W, d 001 ) 14.9-15.7 Å), and trihydrated (3W, d 001 ) 18-19 Å) layers, the latter being less common. However, it was soon recognized that different hydration states/layer types usually coexist even under controlled conditions due to structural heterogeneities affecting the layer charge distribution (from one interlayer to the other or within a given interlayer) and/or location.…”

Section: Introduction and Background Informationmentioning

confidence: 99%

Hydration Properties and Interlayer Organization of Water and Ions in Synthetic Na-Smectite with Tetrahedral Layer Charge. Part 1. Results from X-ray Diffraction Profile Modeling

Ferrage¹,

Lanson²,

Michot³

et al. 2010

J. Phys. Chem. C

210

246

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The dehydration of two Na-saturated synthetic saponites with contrasting layer charge was studied by modeling the X-ray diffraction (XRD) patterns recorded along a water vapor desorption isotherm. The interlayer configurations used to reproduce the XRD data over a large angular range include Na + cations located in the interlayer midplane and H 2 O molecules normally distributed about one or two main positions for mono-and bihydrated layers, respectively. Although strongly reduced in comparison to natural smectites, hydration heterogeneity was systematically observed for these synthetic saponites, especially along the transition between two hydration states. Using improved models for the description of the interlayer organization, the influence of layer charge on the structure of interlayer water can be precisely assessed. In addition, the comparison with water contents obtained from water vapor gravimetry experiments allows discriminating the relative contributions of H 2 O molecules from 1W and 2W interlayers (crystalline water) and from the pore space network.

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“…As a 28 consequence, with increasing relative humidity the smectite structure "swells" in different 29 steps corresponding to the intercalation of 0, 1, 2 or 3 layers of H 2 O molecules 30 (Nagelschmidt, 1936;Bradley et al, 1937;Mooney et al, 1952;Norrish, 1954;Walker, 31 1956). From these early studies, it is now accepted that the hydration ability of 2:1 32 phyllosilicates is controlled by factors such as the nature of the interlayer cation and the 33 amount of layer charge and its location (octahedral vs. tetrahedral).…”

Section: Introduction 1mentioning

confidence: 99%

Influence of pH on the interlayer cationic composition and hydration state of Ca-montmorillonite: Analytical chemistry, chemical modelling and XRD profile modelling study

Ferrage

Tournassat

Rinnert

et al. 2005

Geochimica et Cosmochimica Acta

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To cite this version:Eric Ferrage, Christophe Tournassat, Emmanuel Rinnert, Bruno Lanson. Influence of pH on the interlayer cationic composition and hydration state of Ca-montmorillonite: analytical chemistry, chemical modelling and XRD profile modelling study.. Geochimica et Cosmochimica Acta, Elsevier, 2005Elsevier, , 69, pp.2797Elsevier, -2812Elsevier, . 10.1016Elsevier, /j.gca.2004 ABSTRACTThe hydration state of a <2 µm fraction of Ca-saturated SWy-2 montmorillonite was characterised after rapid equilibration (3 hours) under pH-controlled conditions (0.1-12.6 pH range). The solution composition was monitored together with the interlayer composition and X-ray diffraction (XRD) patterns were recorded on oriented preparations. Experimental XRD patterns were then fitted using a trial-and-error procedure to quantify the relative proportions of layers with different hydration states.The montmorillonite is mostly bi-hydrated in basic and near-neutral conditions whereas it is mostly mono-hydrated at low pH. The transition from the bi-hydrated to the mono-hydrated state occurs through very heterogeneous structures. However, the proportion of the different layer types determined from XRD profile modelling and that derived from chemical modelling using Phreeqc2 code strictly coincide. This correlation shows that the hydration modification is induced by a H 3 O + -for-Ca 2+ exchange at low pH, the two species being distributed in different interlayers. This layer-by-layer exchange process occurs randomly in the layer stack.Under alkaline conditions, results from XRD profile modelling and from near infrared diffuse reflectance spectroscopy (NIR-DRS) clearly demonstrate that there is no CaOH + -for-Ca 2+ exchange at high pH. The apparent increase in Ca sorption in smectite interlayers with increasing pH is thus probably related to the precipitation of CalciumSilicate-Hydrate (CSH) phases, which also accounts for the decrease in Si concentration under high-pH conditions. This precipitation is thermodynamically favoured.2

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On the Lattice Shrinkage and Structure of Montmorillonite

Cited by 42 publications

References 0 publications

Ordered Interstratification of Dehydrated and Hydrated Na-Smectite

Ordered Interstratification of Dehydrated and Hydrated Na-Smectite

Hydration Properties and Interlayer Organization of Water and Ions in Synthetic Na-Smectite with Tetrahedral Layer Charge. Part 1. Results from X-ray Diffraction Profile Modeling

Influence of pH on the interlayer cationic composition and hydration state of Ca-montmorillonite: Analytical chemistry, chemical modelling and XRD profile modelling study

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