Controlled Solubility

Characteristics due to chemical functionalities (e.g., carboxyl groups) of sample components that control solubility of the sample in aqueous media, viscosity of carbohydrate/polysaccharide solutions, and stability of obtained solutions. 

Reduction-oxidation is one of the most important processes controlling solubility and speciation of trace elements in soils, especially for those elements with changeable values, such as Cr, As and Se. Within normal ranges of redox potentials and pH commonly found in soils, the two most important oxidation states for Cr are Cr(III) and Cr(VI). Cr(III) is the most stable form of chromium and less soluble and nontoxic, but Cr(VI) is mobile, soluble and toxic. The main aqueous species of Cr(III) are Cr3+, Cr(OH)2+, Cr(OH)3° and Cr(OH)4" and the major aqueous species of Cr(VI)... 

Solution pH is an important variable, as it controls solubility, the deposition potential, and precursor speciation [140], As noted, one of the advantages of using an ALE process is that very different solutions can be used for each step in the cycle. For instance, pH 4 Cd solutions have been used with pH 10 Te solutions to form CdTe. Some care must be taken rinsing between solutions, however. On the other hand, Foresti et al. have used the same pH for both the metal and chalcogenide in the formation of II-VI compounds, such as CdS and CdSe on Ag single crystals [115, 116, 123, 143], To keep the Cd from precipitating in the basic solution, they complexed it with pyrophosphate. 

Changes in metal solubility with respect to physico-chemical parameters controlling solubility ... 

This follows the convention that the solubility product is written as the lowest common ratio of the species involved. However, when there are significant quantities of an aggregate in the solution, it might be more correct to express the controlling solubility product in terms of the aggregate. This would change the interpretation of the calculated parameters but it should not have an effect on the equations used to determine the solubility. 

There are probably several mineral phases, particularly for the highly alkaline systems, that remain to be discovered. Mixed hydroxides may control solubility. Calcium zincate (CaZn2(OH)6), for example, is thermodynamically more stable than Zn(OH)2 above pH 11.5 and may be important in cementitious systems. Another group of minerals is that of the hydrotalcite-like minerals, the layered double hydroxides (LDH, M2+2M3+l/yXy (OH)6 where X is an anion). Cobalt, Ni and Zn can form such minerals (Johnson Glasser 2003) under neutral to alkaline conditions. For the majority of species, however, solubility-limiting phases do not appear to control dissolved concentrations. 

Algae and bacterial slime Algae and bacterial control Solubility control... 

Quite often, a vendor will not promote a product on the basis of a particular inhibitor category but rather, may promote the benefit of an individual component within the product (such as the ability of a constituent polymer to control soluble iron) and across product categories. So, a range of products within different categories, may therefore be marketed under a particular brand name that is common to all inhibitors containing the same iron polymer. 

Solvation in supercritical fluids depends on the interactions between the solute molecules and die supercritical fluid medium. For example, in pure supercritical fluids, solute solubility depends upon density (1-3). Moreover, because the density of supercritical fluids may be increased significantly by small pressure increases, one may employ pressure to control solubility. Thus, this density-dependent solubility enhancement may be used to effect separations based on differences in solute volatilities (4,5). Enhancements in both solute solubility and separation selectivity have also been realized by addition of cosolvents (sometimes called entrainers or modifiers) (6-9). From these studies, it is thought that the solubility enhancements are due to the increased local density of the solvent mixtures, as well as specific interactions (e.g., hydrogen bonding) between the solute and the cosolvent (10). 

Controlled solubility and ionic diffusion of the antimicrobial agent, such as, chlorhexidine, to the microorganisms (see Figs. 2.23 and 2.24), and... 

The horizontal lines in the lower part of the figure show the range of dominance of solids controlling solubility and aqueous species as functions of Eh. Figures 3 through 7 are interpreted similarly. See text for further explanation.)... 

Included in the figures are the specific solid phases that control solubility and those dissolved species that dominate the aqueous solution as a function of Eh for each radionuclide. The criterion used for listing soluble species is that, collectively, they account for >90% of the total solubility of the element over the range of Eh values considered. 

A number of studies have been reported in the literature in which theoretical aqueous speciation of key radionuclides has been determined from available thermodynamic data (4.9.21-25). In general, where comparisons are possible, one finds reasonably close agreement in the calculated dominant dissolved species, the solids controlling solubility, and computed total solubilities for this study and those listed above. 

The next step is to produce nearly perfect single-crystal boules of silicon from the ultrapure polycrystalline silicon. Many techniques have been developed to accomplish this, and they all rely on a similar set of concepts that describe the transport process, thermodynamically controlled solubility, and kinetics [8]. Three important methods are the vertical Bridgman-Stockbarger, Czochralski, and floating zone processes, fully described in Fundamentals of Crystal Growth by Rosenberger [9]. 

Dixit S., Cappellen P. V., and Bennekom A. J. V. (2001) Processes controlling solubility of biogenic sihca and pore water build-up of silicic acid in marine sediments. Mar. Chem. 73, 333-352. 

---