Sparsely soluble compounds

Some silicate minerals are also formed in a similar manner. The process is very slow, slower than even carbonate formation, because of the very low solubility of silicate minerals. In clay minerals, or in lateritic soils, silicates dissolve very slowly to form an intermediate product, silicic acid (H4Si04), which subsequently will react with other sparsely soluble compounds and form silicate bonding phases. Thus, a dissolution-precipitation process seems to be crucial to forming some silicate minerals. 

To evaluate the leaching performance of the waste streams, we assume that soluble and sparsely soluble compounds will leach out and fail the TCLP and, hence, should be target contaminants for stabilization. These soluble or sparsely soluble components may directly be treated with phosphates and converted to their insoluble, nonleachable forms. The literature is full of studies on stabilization of such divalent hazardous metal contaminants (Pb, Cd, and Zn, in particular), where treatment with various phosphates has been elfective. These studies are summarized in Section 16.3. 

Other isotopes (I, Co, etc.) or their oxides and soluble salts can also be present. Stabilization of such contaminants is handled in a manner similar to the stabilization of hazardous metals, as discussed in Chapter 16, because most of them are sparsely soluble compounds. 

Nonaqueous capillary electrophoresis is a new technique that matured over the last couple of years to complement the electrophoretic techniques performed under aqueous conditions. Consequently, it extends the applicability of CE to those analytes that are insoluble or only sparsely soluble in water, including several classes of pharmaceutical compounds and long-chain fatty acids, vitamins, and surfactants, to name only a few. 

Arsenates have very low solubility, but AS2O3 is sparsely soluble. Like HgO, its solubility in the entire acidic range is almost constant and relatively high. Because of its higher solubility, phosphate treatment should be able to stabilize this compound. However, because other arsenates are nearly insoluble, they can be encapsulated in the phosphate matrix and will not be available for leaching. 

Prussian blue analogs are here defined as polynuclear transition metal cyanides of the composition M [M (CN)6]i xHzO a retallizing with a cubic unit cell. They are easily obtained as sparsely soluble precipitates by mixing solutions of a cyano complex M (CN)e with an appropriate salt of The compounds prepared by using the hexacyanometalate in the form of the most common potassium salt invariably contain different amounts of potassium, which in some cases can be exchanged by cesium... 

Since part of the ethos of SFC is to extend high resolution analysis to high molecular weight, reactive and thermolabile compounds not accessible to GC without derivatization, and to use universal detection, applications of derivatization in SFC have been sparse. They fall into two main groups derivatization to increase solubility in the supercritical mobile phase, and hence to extend further the molecular weight range of SFC and derivatization to provide selectivity and increase sensitivity in detection. 

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