Vermiculite uses

Recently, it was noted that the addition of poly(vinyl methyl ether) to a clay-salt-water system induced the contraction of the interlayer separation between the clay platelets [18], The K-butylammonium vermiculite used in those experiments provided an ideal structure of regularly spaced and parallel charged colloidal platelets in a salt solution [19,20], Swenson et al. [21-23] studied the effect of the addition of poly(ethylene oxide) (PEO) on the distance between the vermiculite layers and observed that, with increasing PEO concentration, the distance between the vermiculite layers decreased. They estimated that the bridging force per bridge was 1.4 pN. 

The average density of the vermiculite crystals was found to be 1.86 0.01 g cm 3, and the volume of vermiculite used in the experiments was determined by weighing... 

The vermiculite used in this work originates from South Africa and contains some pyrophyllite as contaminant. Its chemical composition is Si02 39.37% AI2O3 12.08% MgO 23.37% Fe203 5.45% CaO 1.46% K2O... 

Soils Flood site with plenty of cold water. Build barriers (dikes and lagoons) to contain large spills. Allow small spills to vaporize and absorb with sand or vermiculite. Use carbon dioxide foams to neutralize spills. 

Because more than 90% of vermiculite used is in the low-density, expanded form, commercial vermiculite is differentiated according to whether or not it has been exfoliated. 

Concentration of dioctahedral mica and vermiculite using a fluoride solution. Clays... 

In view of the problems associated with the expanding 2 1 clays, the smectites and vermiculites, it seemed desirable to use a different clay mineral system, one in which the interactions of surface adsorbed water are more easily studied. An obvious candidate is the hydrated form of halloysite, but studies of this mineral have shown that halloysites also suffer from an equally intractable set of difficulties (JO.). These are principally the poor crystallinity, the necessity to maintain the clay in liquid water in order to prevent loss of the surface adsorbed (intercalated) water, and the highly variable morphology of the crystallites. It seemed to us preferable to start with a chemically pure, well-crystallized, and well-known clay mineral (kaolinite) and to increase the normally small surface area by inserting water molecules between the layers through chemical treatment. Thus, the water would be in contact with both surfaces of every clay layer in the crystallites resulting in an effective surface area for water adsorption of approximately 1000 tor g. The synthetic kaolinite hydrates that resulted from this work are nearly ideal materials for studies of water adsorbed on silicate surfaces. 

It is clear from this chapter that the coulombic attraction theory potential is much better adapted to explain the experimental phenomena described in Chapter 1 than the DLVO theory potential (Equation 1.2). Of course, if you predict an interaction potential, you predict force-distance curves along the swelling axis. There have been a lot of arguments about how direct measurements of forces between spherical colloidal particles refute the coulombic attraction theory. Let us get the facts first. We now examine the experimental curves for the n-butylammonium vermiculite system. 

Let us recall the schematic illustration of the raw phenomenon of the clay swelling in Figure 1.4. In the cases studied in Chapters 1 to 3, V was always much greater than V, the volume occupied by the macroions. We now define Vm to be the volume occupied by the macroions in the coagulated (crystalline) state, as in Figure 1.4a in the vermiculite system. This is an experimentally controlled variable. We define the sol concentration r by... 

But it was not to be. Try as we might, the difference in scattering lengths between the 6Li and 7Li isotopes was too small to permit us to measure the lithium ion distribution in the swollen state. We had to content ourselves with the results for the crystalline phase, where the behavior of the lithium ions is different from that of the larger alkali metal cations [27], Potassium and cesium ions bind directly to vermiculite clay surfaces rather than hydrating fully. Because only lithium-substituted vermiculites of the alkali metal series will swell macroscopically when soaked in water, it seems that interlayer cations must form fully hydrated ion-water complexes if the particles are to expand colloidally. This conclusion has since been supported... 

Van Gosen B. S., Lowers H. A., Bush A. L., Meeker G. P., Plumlee G. S., Brownheld 1. K., and Sutley S. J. (2002) Reconnaissance Study of the Geology of US Vermiculite Deposits—are Asbestos Minerals Common Constituents US Geological Survey Bulletin 2192, 8pp. 

Strong-Lite Products Corporation Emmett Sanders Road P.O. Box 8029 Pine Bluff, AR 71611, US A tel 1 501 536 3453 toll free 1 800 255 9057 fax 1 501 536 1033 perlite vermiculite 120 165... 

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