Solubihty limit

Niobium Oxides. The solubihty of oxygen in niobium obeys Henry s law to the solubiHty limit of the first oxide phase of 850—1300°C (123). The amount of oxygen in solution in niobium is 1.3 at. % at 850°C and nearly 2 at. % at 1000°C (124). Only three clearly defined anhydrous oxides of niobium have been obtained in bulk, ie, NbO, Nb02, and Nb20. Niobium monoxide, NbO, is obtained by hydrogen reduction of the pentoxide at... 

In the United States, Hquid HLW from the reprocessing of defense program fuels was concentrated, neutralized with NaOH, and stored in underground, mild steel tanks pending soHdification and geologic disposal (see Tanks AND PRESSURE VESSELS). These wastes are a complex and chemically active slurry. Suspended in the supernatant Hquid are dissolver soHds which never went into solution, insoluble reaction products which formed in the tank, and salts which have exceeded their solubiHty limit. The kinetics of many of the reactions taking place are slow (years) so that the results of characterization... 

Sihcate solutions of equivalent composition may exhibit different physical properties and chemical reactivities because of differences in the distributions of polymer sihcate species. This effect is keenly observed in commercial alkah sihcate solutions with compositions that he in the metastable region near the solubihty limit of amorphous sihca. Experimental studies have shown that the precipitation boundaries of sodium sihcate solutions expand as a function of time, depending on the concentration of metal salts (29,58). Apparently, the high viscosity of concentrated alkah sihcate solutions contributes to the slow approach to equihbrium. 

Specia.lty Coppers. Additions are made to copper to satisfy specific needs. Tellurium at a nominal 0.5 wt % addition, sulfur at 0.35 wt %, and lead at 1 wt % enhance machinabiHty. These alloys are identified as C145, C147, and C187, respectively. The solubiHty limit for each element is <0.001%, so that the excess is present as second-phase particles which assist in fracture of chips and lubrication during machining. 

Experience in air separation plant operations and other ciyogenic processing plants has shown that local freeze-out of impurities such as carbon dioxide can occur at concentrations well below the solubihty limit. For this reason, the carbon dioxide content of the feed gas sub-jec t to the minimum operating temperature is usually kept below 50 ppm. The amine process and the molecular sieve adsorption process are the most widely used methods for carbon dioxide removal. The amine process involves adsorption of the impurity by a lean aqueous organic amine solution. With sufficient amine recirculation rate, the carbon dioxide in the treated gas can be reduced to less than 25 ppm. Oxygen is removed by a catalytic reaction with hydrogen to form water. 

Antisealants Precipitation of salts can form a scale on the membrane surface when solubihty limits (Table 20-22) are exceeded in the retentate. This decreases flux. 

The main function of the ink is to bring a functional molecule, usually a colorant, to a substrate. If the colorant is a dye molecule (or combination of various molecules) it should be present at a concentration much below its solubihty limit, otherwise slight variations during storage (e.g., temperature, pH) could cause precipitation. In such inks it is essential to determine the dye solubility in presence of all the components, especially at low temperatures. The optical properties... 

It is possible to separate more polar components by introducing a gradient from a low concentration (0-10%) of a polar modifier to a higher concentration of the same polar solvent (to 90%, for example). The important consideration is the solubihty limit of the polar component. Thus, methanol is only soluble in hexane to about 5 %, but ethanol can be brought up to 20% before reaching maximum solubility. If more polar samples are to be separated, then hexane can be replaced by ethyl acetate or chloroform. 

In the modified procedure, the organic solution was distilled under vacuum until the batch concentration exceeded the solubihty limit. In order to avoid undesited spontaneous nucleation, seed was charged at this point and the batch was aged to develop a seed bed. Following the seed age, toluene was fed and THF was distilled continuously under vacuum while maintaining the same batch volume. On completion of the distillation, additional hexane was added to minimize product loss in the mother hquor. The key parameters for this process are construction of the solubility map, determination of the seeding point, and control of the solvent evaporation rate to release the supersatrrration at the proper rate. 

Condition for equilibrium as the solubihty limit is / L = /4 which implies... 

The ranges of solid solutions of MgO and AI2O3 remained unchanged and are 2 % and 1 % respectively. The solubihty limit of AJ2O3 does not depend on temperature whereas for MgO is highly increasing with temperature (1.5% at 1420 °C). 

From a process point of view, higher recovery results in higher salt concentration in the feed-reject charmel that in turn results in sparingly soluble salts exceeding their solubiHty limits faster. Hence, high recovery is only an option when operating a second-pass RO unit or when the feed water is pure. 

Solid solubilities of binary compounds in most cases extend in the direction of a Fe/Si exchange at a fixed Y concentration. In some cases solubihty limits were... 

The alternative approach to modeling micelle formation is to think in terms of a phase separation model in which, at the cmc, the concentration of the free surfactant molecules becomes constant (like a solubihty limit or Ksp), and all additional molecules go into the formation of micelles. Analysis of the two approaches produces the same general result in terms of the energetics of micelle formation (with some slight differences in detail), so that the choice of model is really a matter of preference and circumstances. There is evidence that the activity of free surfactant molecules does increase above the cmc, which tends to support the mass-action model however, for most purposes, that detail is of little consequence. 

Bal] Dynamic gas equilibrimn technique to derive solubihty limits, cahn microbalanee 1000-1200°C up to 1.6 mass% C (7Fe)-NbCi x... 

Jon] Jonsson, S., Assessment of the C-Fe-Ti System, Calculation of the Fe-Ti-N System, and Prediction of the Solubihty Limit of Ti(C,N) in Liquid Fe , Metall. Mater. Trans. B, 29B, 371-384 (1998) (Assessment, Phase Diagram, Phase Relations, Thermodyn., 53)... 

At low concentration, the impurities X dissolve in solid solution in the matrix phase M (Figure 8.22a) however, with increasing concentration the solubihty limit will be exceeded so that a second (or third) phase exists at the grain boundaries (Figure 8.22b and c). 

As a first step, we will look at the equilibrium compositions in the parent phase Cjjoo = Cp R —> 00) and in the new phase C oo = Cn R —> 00), corresponding to the full separation in the infinite bulk material (at every fixed temperature T). The conditions for optimal concentration C oo and Cp co and solubihty limits can be found according to the common tangent rule ... 

What Is the solubility limit for the protein In water at 25 °C The horizontal line at 25 °C intersects the left side of the coexistence curve at about 50 mg mL This is the solubihty limit, the most crystallin that can dissolve in water (at 25 °C). 

The above calculation assumes that the liquid makes only a single pass through the tower. In practice, a more effective way of treating the gas would be to recirculate the hquid with a small feed of concentrated acid to the recirculation loop and a small bleed of the recirculation loop contents. This would permit the NH4 concentration to build up in the recirculation loop. However, even if this concentration built up to the solubihty limit of ammonium nitrate (NH4 NO3), about 30 (g mol)/L, the partial pressure exerted by the dissolved ammonia at the top of the tower would still be nearly two orders of magnitude below the partial pressure of ammonia in the gas at the top of the tower. Therefore, for all practical conditions, the reaction is effectively irreversible, given the acid concentrations calculated in step 4. 

Example 11.1 A common way to measure small solubilities like those shown in Table 11.1 is to add one species from a buret, one drop at a time, to a large mass of the other species. After each drop is added the mixture is shaken and observed to see if it has turned cloudy, indicating that the solubihty limit has been reached. If we begin with 1L... 

---