Interlayer porosity

G. Alberti, U. Costantiono, F. Marmottoni, R. Vivani, and P. Zappelli, Preparation of a Covalently Pillared a-Zirconium Phosphite-diphosphonate with a High Degree of Interlayer Porosity. Microporous Mesoporous Mater., 1998, 21, 297-304. 

Capkov, P., R.A.J. Driessen, H. Schenk, andZ. Weiss. 1997. Interlayer porosity in montmorillonite intercalated with keggin-like cations. Studies by molecular mechanics simulation. J. Molec. Model. 3 467-472. 

In the CSM model the total porosity n is divided into porosity between particles n/p and that within the particles or interlayer porosity tin.. 

Substituting equation (3) into equation (2) yields the maximal interlayer porosity niu. ... 

As the swelling effects occur chiefly in the expansive minerals like montmorillonite, therefore the apparent interlayer porosity should be modified with the expansive mineral fraction p. For an absolutely dry sample, the interlayer porosity should be zero. The maximal interlayer porosity can only be reached in the free swelling case. Therefore, it is reasonable to assume that is a function of water saturation The simplest correlation is linear functionary) =... 

The change of the effective void ratio due to moisture change can be calculated as the interlayer porosity variation ... 

Figure 2. Computed profiles with swelling (a) Gas pressure, (b) Liquid saturation (c) Interlayer porosity, (d) Permeability...

In case of free swelling, the volume change is equivalent to the change of interlayer porosity. 

In case of constrained swelling, the potential of interlayer porosity change turns out to be swelling pressure owing to the further swelling compaction effect. The effective void ratio (interparticle porosity) decreases with the increase of the moisture content, hence results in the decrease of the bentonite permeability. 

Given the size of clay particles (10-1,000 nm), they are found in solution as colloidal dispersions or gels. At low water content, they can be obtained as dry powders, and can form solid porous materials upon compaction. In all these regimes, their properties crucially depend on the charge density and on the nature of the counterions. Most counterions are mono- or divalent, usually alkaline (most commonly sodium Na" or potassium or alkaline earth cations (most commonly calcium Ca " ). They are not incorporated in the clay layers. Rather, they are located near the surface, either between different layers, in the so-called interlayer porosity, or on the external surfaces of clay stacks (typically 10 layers). Such stacks are called particles, and their assembly to form a porous material then leaves voids called interparticle porosity, with sizes between a few nanometers to tens of nanometers, which are usually saturated by an electrolyte solution. 

Two general cases were observed in which some interlayer porosity could be created." The first were situations in which secondary anions were included (e.g., Cl ). This served two functions, the first being to form effectively a divalent metal center as the Cl would typically nest atop on the triangular... 

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