Montmorillonite solubility

This group includes materials such as various clay minerals including kaolinites and montmorillonites soluble sulfates and sulfuric acid sodium silicates calcium aluminate cements soluble phosphates, polyphosphates, and phosphoric acid and borates and boric acid. 

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. 

Englezos, P. and S. Hull, Phase Equilibrium Data on Carbon Dioxide Hydrate in the Presence of Electrolytes, Water Soluble Polymers and Montmorillonite , CanJ. Chem. Eng, 72, 887-893 (1994). 

Fig. 5. Relationship between the distribution (partition) coefficient on dimethyl dihydrogenated tallow montmorillonite for a range of non-ionic organic pollutants and their corresponding solubility in water. BHC is benzene hexachloride, the y-isomer of which is known as lindane aroclor 1232 and aroclor 1252 denote mixtures of polychlorinated biphenyls containing about 32 and 52% chlorine, respectively. After Beall (2003).

In adsorption studies from saline environments it is necessary to prepare the water-soluble polymer and peptized montmorillonite in fresh water at high concentrations and to add each to a saline solution. Polyelectrolytes will frequently not "yield" the same viscosity as when they are dissolved in fresh water. Montmorillonite will flocculate in saline solutions. With fresh water mixing of components, reproducible results are obtained in the saline studies. After component mixing, agitation of the slurry is maintained with gentle stirring via... 

While the high solubility of aminotriazole in water (28g per 100ml at 23°C) suggests ready leaching from whole soil, Russell et al. [106] showed if the soil contains a montmorillonite-type mineral, the aminotriazole might be resistant to leaching as a result of adsorption by the montmorillonite. 

No interaction between ferrihydrite and kaolinite was found at pH 9 because both compounds are negatively charged at this pH (Fig. 16.20b, c). Boiling kaolinite and montmorillonite in a Fe(N03)3 solution for 8 min resulted in clays containing up to ca. 55 mg oxalate soluble Fe/g clay. The BET surface area of kaolinite increased from 18 to 34 m /g and that of montmorillonite from 11 to 62 m g . Whereas kaolinite shows only a small decrease in > 10 pm pores, montmorillonite lost about half of its >10 pm pores even with the lowest Fe oxide content (6.6 mg ECq g clay). It has been speculated that in contrast to kaolinite, the Fe oxide, in the presence of montmorillonite, remained highly disorderd and active due to A1 and Si dissolved from... 

Modified clays comprise a commercially available ex situ technology that can remove low-solubility organics from groundwater. Smectites (including montmorillonite and bentonite clays). 

Certain manganese porphyrins adsorbed on silica or alumina, or intercalated in different mineral matrices such as montmorillonite, are also very efficient in alkane hydroxylation.150 151 Alcohol yields and alcohol ketone ratios are remarkably higher than those obtained with the corresponding soluble manganese porphyrins. Manganese tetra(4-Al-methylpyridiniumyl)porphyrin supported on montmorillonite, for instance, is efficient in the hydroxylation of compounds of low reactivity such as n-pentane and n-heptane.151... 

Normally, when such an experiment is carried out, it may not be possible to cover as wide a range of concentration of the nuclide shown in this hypothetical case Solubility or other constraints may limit the accessible range In the case of tri-valent ions like Eu(III), it is not possible to increase the concentration of the ion much above tracer levels at higher pH because of the possibility of precipitation and the formation of hydrolyzed and polynuclear species which would change the nature of the sorption process We have so far not been able to determine a reproducible sorption isotherm for Eu(III) on our samples of montmorillonite above about pH 5-6. 

Structural formulas of montmorillonites before and after extraction of easily soluble Si and Al (After Osthaus, 1955)... 

Most kaolinites contain appreciable amounts of MgO (range 0.01—1.0% modal value between 0.2—0.3%). Bundy et al. (1965) found that MgO as well as total iron and soluble iron were directly related to the C.E.C. and suggested that the Mg and Fe were present in montmorillonite which they believe is commonly present, in amounts less than 5%, in kaolinites. This may be true in part, but electron probe studies (Weaver,1968) indicate that some of the MgO is related to the Ti02-Fe203 material and some is present in biotite. 

Englezos P, Hall S (1994) Phase equilibrium data on carbon dioxide hydrate in the presence of electrolytes, water soluble polymers and montmorillonite. Can J Chem Eng 72 887-893... 

Fit . 3.5. Activity-ratio diagram for smectite (montmorillonite), kaolinite, and gibbsite based on Eq. 3.22. Solubility windows for kaolinite and gibbsite are shown bounded from below by dashed lines. The range of silicic acid activity expected in soils is indicated by the two short vertical lines labeled Si(),(am)" and "quart/."... 

Figure 8.18. Adsorption isotherm of six. v-triazines on Na-montmorillonite. Order of solubility simetone > atratone > promatone > atrazine > trietazine > propazine (from Bailey et al., 1968, with permission).

Inskeep, W. P. and J. Baham. 1983. Competitive complexation of Cdll and Cull by water soluble organic ligands and Na-montmorillonite, Soil Sci. Soc. Am. J. 47 1109. 

To summarize, calcium ions in the solution can be present as hydrated Ca2+ions, and CaHEDTA and CaEDTA2 complexes, of which only the positive calcium aqua complexes (Ca2+) participate in the ion-exchange reaction. In the process, calcium ions dissolve from montmorillonite to the solution, and mostly hydrogen ions get into the interlayer space of montmorillonite. In addition, sodium ions are also present in the system (EDTA is added as disodium salt H4EDTA is hardly soluble in water), which also affects the ion-exchange process. The ratio of cCa aCa can be plotted as a function of the concentration of Ca2+ (Figure 2.11). 

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