Bentonites Wyoming

In a similar investigation Sastry and Fuerstenau (S4) used up to 1.5% Wyoming bentonite in a teconite feed with 48.4, 50.3, and 52.3% volume moisture. The water retention capacity was calculated as 0.47 0.11, independent of the water and bentonite contents. An evaluation of bentonites from three sources by Nicol and Adamiak (N3) indicates that the Wyoming bentonite has the highest cation exchange capacity and also the maximum retardation effect on the balling rate. 

Thermodynamic data for alkali metal cation exchange at 25 °C (in kJ equiv ) Camp Berteau and Wyoming Bentonite... 

Laponite (27), Camp Berteau (28) and Wyoming Bentonite (29). Reproduced with permission from Ref. 17, 26 and 27. 

Cu (en) + xchange in ig. 4. For the case of Wyoming bentonite the Ag(en), - Cu(en) reaction is endothermic (12.5 kJ Eq ), while AG 9.665 kJ (see table IV), showing that enthalpic factors also rule the exchange among complex ions. 

The aluminosilicates examined were chosen as end members of those groups of phyl losil icates that commonly occur in soils muscovite and biotite mica, Fithian and Morris illite, Montana vermicul ite, montmoril Ionites from Upton (Wyoming bentonite), Camp Berteau, Redhill and New Mexico, and kaolinites from St. Austell, England, and Georgia, U.S.A. 

Figure 1. Integral (aHx) and differential (d(aHx)/dx) enthalpies of Ca - 2K ( ) and 2K + Ca (0) exchange on Wyoming bentonite as a function of the fractional K saturation of the exchange capacity.

If mica-type sites are truly indicative of mica surfaces, and so on for montmoril Ionite etc., then of the clays examined, only the mica could be regarded as pure. The Montana vermiculite contained much montmoril Ionite, the Fithian illite contained mica and montmoril Ionite, the Wyoming bentonite contained some mica,... 

Thus, the variations in composition appear to be primarily due to environmental differences whereas the consistant composition of Wyoming bentonites is related to the uniformity of the shallow marine environment in which they were deposited. The data indicate that Texas bentonites fix more K than Wyoming bentonites. This likely means that they also have a larger amount of tetrahedral Al. Tetrahedral A1 increases... 

The apparent density of both native and sodium Wyoming bentonite in a number of nonpenetrating liquids is 2.694 grams per cc. (11 determinations, standard deviation 0.006 gram per cc.). 

We have also determined the apparent density of a sodium Wyoming bentonite clay with a small amount of preadsorbed water (approximately 300 mg. per gram of clay), using n-decane as the pycnometer fluid. Assuming normal densities for both n-decane and the preadsorbed water, we found that the apparent density of the clay in this experiment is identical with the apparent density of the clay when completely immersed in water (2.786 grams per cc.). This particular experiment will be discussed in more detail later. 

The above interpretation is probably valid for most expanding montmoril-lonite clays, of which only sodium hectorite was studied in addition to sodium Wyoming bentonite. An exceptional behavior is shown by sodium vermiculite clay, an expanding clay differing essentially from the other expanding clays in the charge density, which is about twice as high. 

Two additional experiments were carried out with very thin flakes of sodium Wyoming bentonite. According to x-ray analysis, two-layer complexes were formed, and the water uptake was 275 and 304 mg. per gram, respectively, and the apparent densities were 2.768 and 2.786, respectively. The higher value... 

Sposito, G., K. M. Holtzclaw, L. Charlet, C. Jouany, and A. L. Page. 1983. Sodium-calcium and sodium-magnesium exchange on Wyoming bentonite in perchlorite and chloride background ionic media. Soil Sci. Soc. Am. J. 47 51-56. 

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