Salt selective dissolving

There are certain compounds that have the remarkable characteristic of being able to selectively dissolve some compounds, while at the same time ignoring others. A familiar example might be to take a spoonful of table salt and drop it into a half a glass of paint thinner. The salt sinks to the bottom of the glass. Mix it, shake it, and it still settles down to the bottom because it wont dissolve in paint thinner. Having observed that, it would be tough to get that salt completely separated from the paint thinner. 

Elemental composition Ag 63.50%, N 8.25%, O 28.25%. The salt is dissolved in water, diluted, and analyzed for silver. The nitrate ion, NO3, can be analyzed in aqueous solution by nitrate ion-selective electrode, ion chromatography, or colorimetry after reduction to NO2 ion with cadmium. The nitrate content of the salt is 36.50%. 

Elemental composition Na 54.75%, F 45.25%. The salt is dissolved in water and analyzed for sodium and fluoride anion. The anion can be measured effectively with a fluoride ion-selective electrode or by ion chromatography. 

To evaluate the net riverine influx of dissolved species to the ocean, the river load has to be corrected for sea salts transported via the atmosphere from the ocean to the continents and rained out mainly in coastal precipitation. Table 9.7 shows the average concentration of selected dissolved and particulate elements in rivers from Martin and Meybeck (1979), and the corresponding net fluxes corrected for sea-salt cycling from Martin and Meybeck (1979). The corrections of fluxes for cyclic salts and pollution are still debatable estimates (e.g., Holland, 1978 Maynard, 1981), and affect mainly the evaluation of the net flux of Na+ by perhaps as much as 20%. 

The selection of a salt form directly influences the physicochemical and biopharmaceutical properties of a compound. The impact of salt selection has been reviewed. Nelson examined the dissolution of theophylline salts and commented on their impact on oral administration. The dissolution rates of the theophylline salts proceeded independently of the pH of the medium but was governed by the diffusion layer pH. The choline and isopropanolamine salts dissolved three to four times faster than the ethylenediamine salt and produced higher and prolonged blood levels. 

The block flow diagram presented in Figure 2 gives the major operations of the conceptual process. Feed to the process is one core-axial blanket or radial blanket fuel assembly. The fuel assembly hardware below the active section is removed prior to processing. The hardware above the active section is not introduced into the process. In this low decontamination process, the active section of the spent fuel is selectively dissolved into molten metals and molten salts from which coprocessing of uranium and... 

The distributions of Li and Bi between liquid Li-Bi alloys and molten LiCl have been measured at 650—800 °C. The extent of their distribution to LiCl increased at each temperature with a moderate increase in the Li concentration of the alloy at 650 °C, the Bi concentration in LiCl increased from ca. 5 to 4800 p.p.m. as the Li concentration in the alloy increased from 10 to 50 mol %. The ratio of excess Li to Bi in LiCl was generally ca. 3, suggesting that salt-like Li,Bi was selectively dissolved from the alloys. 

In terms of salt selection procedure, the critical relative humidity (CRH) of each salt should be identified. This is defined as the point at which the compound starts to sorb moisture. Clearly, compounds or salts that exhibit excessive moisture uptake should be rejected. The level of this uptake is debatable, but those exhibiting deliquescence (where the sample dissolves in the moisture that has been sorbed) should be automatically excluded from further consideration. 

General.—Liquid bismuth has been used as the solvent for calorimetry and data for the enthalpy of solution of copper, indium, and tellurium have been obtained. Enthalpy of formation data are also given for a series of copper selenides. Studies on the distribution of lithium and bismuth between liquid Li-Bi alloys and molten LiCl suggested that a salt-like species LijBi was being selectively dissolved from the alloys. The mutual solubility of thorium and the metallic lanthanides La, Nd, and Eu in bismuth over the range 350—700 °C shows evidence for the formation of solid compounds with the composition ThLnBij,. ... 

SECTION 17.6 Comparison of the ion product, Q, with the value of K p can he used to judge whether a precipitate will form when solutions are mixed or whether a slightly soluble salt will dissolve under various conditions. Precipitates form when Q > K p. If two salts have sufficiently different solubilities, selective precipitation can be used to precipitate one ion while leaving the other in solution, effectively separating the two ions. 

Most of the liquid electrolytes used in the commercial lithium-ion cells are the nonaqueous solutions, in which roughly 1 mol (tar (= M) of lithium hexafluoro-phosphate (LiPF ) salt is dissolved in the mixture of carbonate solvents selected from cyclic carbonates - ethylene carbonate (EC), and propylene carbonate (PC) and linear carbonates - dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) -, whose chemical structures are displayed in Fig. 4.2. Recently, another type of liquid electrolyte based on 1.5 M LiBFyy-butyrolactone (GBL) + EC came onto the market for the laminated thin Uthium-ion ceUs with an excellent safety performance. Many other solvents and Uthium salts have limited appUcations, although much effort has been made to develop new materials. Into the above baseline electrolyte solutions, a small amount of the additives are dissolved, which are so-called functional electrolytes. ... 

Most liquid electrolytes used in commercial lithium-ion cells are nonaqueous solutions, in which roughly 1 mol dm of lithium hexafluorophosphate (LiPF ) salt is dissolved in a mixture of carbonate solvents selected from cyclic carbonates, e.g., ethylene carbonate (EC) and propylene carbonate (PC), and linear carbonates, e.g., dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC), as listed in Table 2.1 [1]. 

Small particles, with their high surface/volume ratio, pick up water more readily and are especially liable to caking. Vacuum salts and potash, as suggested by Fig. 7.13, are therefore the most sensitive. They are frequently treated with an anticaking additive before shipping. The one most widely used is sodium ferrocyanide, or yellow prussiate of soda (YPS). By the nature of the addition process, YPS also tends to concentrate at the surfaces of the particles. Therefore, when a batch of treated salt is dissolved, the first brine formed has a high concentration of YPS. Rain also selectively removes YPS from the salt, and this is one reason not to store such salts in the open. 

Selective Dissolving. Brine quality improves if NaCl can be dissolved selectively, leaving some of the impurities behind. Selective dissolving techniques usually are aimed at partial rejection of calcium sulfate, the major impurity in salt. These techniques can be divided into three categories ... 

Later, the liquid state measuring membrane was changed by an elastic plastic disk. This made the electrode form mechanically more stable. In the early times, well working potassium [16] and ammonium [17] ISEs were made with a silicon rubber matrix. Later, however, plasticized polyvinyl chloride (PVC) matrices became the most popular in ISE fabrication. Their preparation procedure was well worked out and clearly described by Shatkay [18] and Thomas [19], The high molecular weight PVC used in membrane preparation can be dissolved in tetrahydrofurane. In this solution, the plasticizer, the selective ionophore, and other ingredients like special lipophilic salt are dissolved. The solution is transferred into a ring-shaped flat bottomed mold. Care is taken to let the tetrahydro furane (THE) slowly evaporate. In a few days, a circular, flexible membrane is obtained. A disk with appropriate diameter is cut from the membrane and pasted on the tubular electrode body. 

A number of the morphologically stable alloy systems (for example, Ag-Au, Cu-Au, Ag-Pd, Cu-Pd [30]) selectively dissolving in the solution of the corresponding salts satisfies such conditions. The solid state diffusion coefficient was varied in a wide range of 10 ° 10 cm Vs, whereas the diffusional mobility of ions in the liquid phase was unchanged and equal to 10 cm Vs. 

Atomic absorption spectroscopy instruments place a sample in a high temperature flame that yields atomic species and passes selected, element specific, illumination through the flame to detect what wavelengths of light the sample atoms absorb. Either acetylene or nitrous oxide fuels the analytical flame. This process again demands that solid samples be digested (dissolved in an acid or fused with a salt) and dissolved to form a solution that can be aspirated or sprayed into the instrument s flame, while protecting the sample material from contamination or adulteration. 

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