Sodium montmorillonite clays

To obtain a high viscosity at a much lower clay concentration, certain water-soluble vinyl polymers called clay extenders can be used. In addition to increasing the yield of sodium montmorillonite, clay extenders serve as flocculants for other clay solids. The flocculated solids are much easier to separate using solids control equipment. 

Sodium montmorillonite clay particles ot-Fe203 prepared in clay particles... 

The morphology of rubber-based nanocomposites also seems to change in the presence of compounding ingredients [89, 90]. HNBR, when melt-compounded with organo-modified sodium montmorillonite clays (o-MMTs) prior to sulfur curing, resulted in the formation of nanocomposites with exfoliated or intercalated structures. In stark contrast, under similar conditions HNBR compounded with unmodified sodium montmorillonite clays (NA) formed microcomposites [90]. This was traced to its reactivity with the sulfur in the presence of amine-type organomodifiers. 

Pojanavaraphan, T, Magaraphan, R., Chiou, B. S., and Schiraldi, D. A. (2010). Development of Biodegradable Foamlike Materials Based on Casein and Sodium Montmorillonite Clay, i22jfl 222J2(g y(g2,11,2640-2646. 

Combination of both molecular dynamics and Monte Carlo simulations were used to study the mechanism of swelling of sodium-montmorillonite clay by Karaborni and coworkers (110). Their molecular simulations wCTe performed in the grand-canonical ensemble, that is, at constant chemical potential, volume, and temperature (/tt, V, and T, respectively). In their simulation, the distance... 

Figure 1 depicts a typical configuration of a hydrated sodium montmorillonite clay [5]. The structure and partial charges of the model... 

To make a typical nanocomposite, Lin and Wu [37] combined 100 g of a sodium-montmorillonite clay with 30 g of hexadecyltrimethylammonium bromide in 5000 ml of hot water nsing a homogenizer. After drying and grinding, the treated clay was combined with 20 g of a bisphenol-based epoxy resin (MW = 360) in a dough mixer. The product is termed a co-intercalated clay since the organic moieties now have... 

The clay mineral bentonite (sodium montmorillonite) has an excellent ion exchange and adsorption capacity. Films can be applied to electrode surfaces from colloidal clay solutions by simple dip or spin coating that become electroactive after incorporation of electroactive cations or metal particles 136-143)... 

Osmotic swelling is a second type of swelling. Where the concentration of cations between unit layers in a clay mineral is higher than the cation concentration in the surrounding water, water is osmotically drawn between the unit layers and the c-spacing is increased. Osmotic swelling results in larger overall volume increases than surface hydration. However, only certain clays, like sodium montmorillonite, swell in this manner. 

A theoretical model for the adsorption of metals on to clay particles (<0.5 pm) of sodium montmorillonite, has been proposed, and experimental data on the adsorption of nickel and zinc have been discussed in terms of fitting the model and comparison with the Gouy-Chapman theory [10]. In clays, two processes occur. The first is a pH-independent process involving cation exchange in the interlayers and electrostatic interactions. The second is a pH-dependent process involving the formation of surface complexes. The data generally fitted the clay model and were seen as an extension to the Gouy-Chapman model from the surface reactivity to the interior of the hydrated clay particle. 

Gheyi, H. R., and Van Bladel, R., "Calcium-Sodium Exchange in Some Calcareous Soils and a Montmorillonite Clay as Compared with Predictions Based on a Double Layer Theory," Geoderma, (1976), 16, 159. 

Sodium bentonite with a cation exchange capacity (CEC) of 75 meq/100 g of clay, supplied by Commercial Minerals Ltd., Australia, was used as starting clay material, to prepare samples for SCD and surfactant treatments. Besides, sodium montmorillonite (Kunipia G), from Kunimine Industrial Company, Japan, was used as the starting clay for samples of pore opening modification. CEC of this clay is 100 meq/100 g of clay. 

Some experiments have been carried out with a sodium montmorillonite dispersion on an Sn02 electrode.77 The layer of clay adhered well to the surface and [Ru(bipy)3]2+ was successfully exchanged on to the clay. The film was electroactive but cracked readily. The addition of powdered platinum gave a more coherent layer. Other species exchanged on to the clay included [Fe(bipy)3]2+ and a trimethylammonium derivatized ferrocene. 

In these experiments a commercially available bentonite, marketed under the name Colclay A90 (Ankerpoort, Geertruidenberg, The Netherlands) was used. It is a sodium-montmorillonite with a third of the exchange complex occupied by calcium. 5.0 g of the air-dried powdered bentonite was weighed into a stainless steel mould with an ID of 50 mm between two porous stones of the same diameter. Then the clay was subjected to a compaction pressure of 20.3 MPa for 30 minutes. After compaction, the mould was placed in a bowl of NaCl-solution for five days in which the clay became saturated and swollen. Thus samples were obtained with thickness of 3.8 and 2.8 mm respectively and a diameter of 50 mm. 

---