Solutions solubilization

The phase condition for concentrations in the range close to the cmc are found in Fig. 4A. For the lowest soap concentrations, a liquid isotropic alcohol solution separated, when the solubility limit of the alcohol was exceeded. This was changed at concentrations approximately one half the cmc, when a lamellar liquid crystalline phase appeared Instead. After the relatively narrow three-phase region had been transversed, this liquid crystalline phase was the only phase in equilibrium with the aqueous solution. Solubilization of the long chain alcohol Increased at the cmc, as expected. 

Replacing part of the soap with the dicarboxylic acid at a sufficiently high pH value to ensure its complete ionization gave the results in Fig. 4B. At the site for the onset of the 3-phase area in Fig. 4A with the liquid crystal, the alcohol and the aqueous solution, solubilization of the alcohol now showed a sudden maximum. 

A nonpolar solubilizate such as hexane penetrates deeply into such a micelle, and is held in the nonpolar interior hydrocarbon environment, while a solubilizate such as an alcohol, which has both polar and nonpolar ends, usually penetrates less, with its polar end at or near the polar surface of the micelle. The vapor pressure of hexane in aqueous solution is diminished by the presence of sodium oleate m a manner analogous to that cited above for systems in nonpolar solvents. A 5% aqueous solution of potassium oleate dissolves more than twice the volume of propylene at a given pressure than does pure water. Dnnethylaminoazobenzene, a water-insoluble dye, is solubilized to the extent of 125 mg per liter by a 0.05 M aqueous solution of potassium myristate. Bile salts solubilize fatty acids, and this fact is considered important physiologically. Cetyl pyridinium chloride, a cationic salt, is also a solubilizing agent, and 100 ml of its A/10 solution solubilizes about 1 g of methyl ethyl-butyl either m aqueous solution. 

The two principal methods for processing hemicellulose to increase the accessibility of cellulose to penetrating agents are to put the hemicellulose into a liquid phase and/or reduce its molecular weight (Figure 6). Such aqueous solvents as alkali solutions solubilize hemicellulose by sodium salt formation and by breaking ester cross-links. Either true solutions or colloidal dispersion may be the mechanism by which the attack the lignin that blocks accessibility to cellulose. 

Kreilgard, B., Higuchi, T., and Repta, A. J. 1975. Complexation of parenteral solutions solubilization of cytoxic agent hexamethylmelamine by complexation with gentisicacidspelcilSbarm. Sci.11 1850-1855. 

Goto, A., R. Sakura, and F. Endo. 1980. Gel Jtration of solubilized systems. V. Effects of sodium chloride on micellar sodium lauryl sulfate solutions solubilizing alkylparabtfMsem. Pharm. Bull. 28 14-22. 

Firstly, it is well known that micellar aggregates in water can solubilize and bind hydrophobic solute molecules that are typically insoluble or only sparingly soluble in bulk water. For example, although the solubility of pyrene and anthracene in water is in the 0.1-0.6 micromolar range, their solubility can easily be increased to the 10 millimolar range in the presence of micelles. The amount of solute solubilized and bound to the micellar aggregate in an aqueous solution is typically proportional to the surfactant concentration up to the limiting value. 

Via use of the SED technique, it is possible to determine solute solubilization equilibrium constants (activity coefficients of micellar bound solutes) as well as the surfactant concentration on both sides of the dialysis membrane among other parameters (458-460). 

Table 3. Examples of Polar Solutes Solubilized in Supercritical and Near-critical Fluid Microemulsions...

Bart HJ, Jiingling H, Ramaseder N, and Marr R. Water and solute solubilization and transport in emulsion hquid membranes. J Membr Sci 1995 102 103-112. 

The prediction of the activity coefficients of solutes (such as gases and large molecules of biomedical and environmental significance) in saturated solutions of multicomponent mixtures constitutes the main difficulty in calculating the solute solubil-... 

The paper discs (diameter 1 cm), cut from Whatman No. 1 chromatography paper (wear gloves ), are placed in a polystyrene microplate so that the center of the discs and of the wells coincide. One to 2 pi of the protein solution (solubilized in 60% ethanol) is spotted (marked with pencil). After drying, the discs can be stored or used directly for EIA detectability is 1-2 ng/spot. 

The experimental techniques vary in the sense that some will determine the partition coefficients directly and some will determine the fraction of solute solubilized in the micellar phase. The data are easily converted if the surfactant and solute concentrations are given. 

One quantity of interest is that discussed in the preceding section, i.e., the maximum possible solubilization of a solute by a micellar solution, which occurs when it is in equilibrium with a bulk phase of the solute. Data may be presented as the mole fraction of solute in the micelle as in the above equations. More commonly, however, we find a plot of the moles of solute dissolved in the micellar solution as a function of surfactant concentration. Above the CMC such a plot usually exhibits a straight line whose slope is the moles of solute solubilized per mole of surfactant in the micelles (see Figure 9.2). Below the CMC the amount solubilized is usually constant and equal to the solute solubility in water. 

Reaction rates may be improved if the reaction is run in the mixture critical region. A rate enhancement can potentially occur as a result of applied hydrostatic pressure and as a result of the unusual partial molar volume behavior of a heavy solute solubilized in a supercritical solvent. Numerous authors have used transition state analysis (Laidler, 1965 Eckert, 1972 Ehrlich, 1971) to explain the rate enhancement that can occur at high pressures. For a bimolecular reaction, a chemical equilibrium is assumed to exist between the reactants A and B and the transition state M. ... 

Enzymatic Formation of Long-Chain Fatty Aldehydes in a Green Seaweed U. pertusa. In preliminary experiments, they were found to increase during incubations of unsaturated fatty acids with homogenates of U. pertusa fronds. The acetone powder preparations from the homogenates were shown to retain this activity (20). Thus, enzyme solutions solubilized from the acetone powders with 0.1% Triton X-100 were used as a source of the enzyme activity. The products, (Z)-8-heptadecenal, (Z, Z)-8, 11-heptadecadienal and (Z, Z, Z)-8, 11, 14-heptadecatrienal and pentadecanal, were identified by GC and GC-MS analysis using authentic specimens... 

The bisulfite adducts of electrophilic pyrimidines are relatively stable, and several have been isolated. Thus, iV-substituted 5-chloro-2(l/7)-pyrimidinones readily form bisulfite adducts in aqueous solution. Both the 3,4- (329) and the 3,6-bisulfite (330) adducts are formed, with the former as the predominant isomer. In water, the 3,4-isomer was significantly less soluble and was precipitated selectively from concentrated solutions. Solubilization in more dilute aqueous solution, and addition of TFA, precipitates the parent heterocycle <87ACS(B)448,91ACS177). 

An alternative competitive impedimetric assay for analyzing neomycin B was demonstrated (de-los-Santos et al., 2007) (Figure 3.10A). A gold electrode was modified with neomycin B, and the respective RNA aptamer was linked to the surface. The resulting neomycin B-aptamer complex introduced an electron-transfer barrier to the solution-solubilized redox label FeCCN) , and this resulted in high interfacial electron-transfer resistance. In the presence of neomycin B, partial displacement of the aptamer occurred, and this resulted in a decrease in the interfacial electron-transfer resistance. Since the extent of the aptamer displacement was controlled by the concentration of neomycin B, the quantitative analysis of the substrate was achieved (Figure 3.10B). The method was applied successfully to analyze neomycin B in milk. 

The effects of SCFs on the catalytic activity of methanol synthesis are shown in Table 3. It is obvious that the gas phase (He) exhibited the lowest total carbon conversion (about 16.4%). As methanol synthesis is a highly exothermic reaction, the low conversion in gas phase possibly resulted from the heat of reaction which cannot be removed rapidly from the catalyst bed. The total carbon conversion increased to 45.6% when SC-Ce was introduced into the reaction. This illustrates that the SCF enhanced the reaction activity of methanol synthesis. The rate of reaction was possibly enhanced while the experiment was operated in the mixture critical region because of a favorable pressure dependence of the reaction rate constant as well as the imusual volumetric behavior of heavy solutes solubilized in an SCF solvent [16]. 

The fourth group comprises the acidic salts, LiBF4 and LiPF. These salts always contain unavoidable HF contamination. LiPFg may slowly decompose to LiF and PF5, which readily hydrolyze with trace water to POF3 and HF. Both species are highly reactive on the Li surfaces, and surface LiF and LijPOFy species are thus formed. HF, when present in alkyl carbonates or ethereal solutions, solubilizes carbonate and alkoxy species formed on the lithium surfaces... 

Hemoglobin and many enzymes are covalent polymers with a globular shape. This shape is enforced by the tendency of hydrophobic amino acids to form a hydrophobic droplet in aqueous solutions solubilized by hydrophilic side-chains around them. The same is true for synthetic block polymers made of hydrophobic and hydrophilic segments. " Spherical biopolymers thus usually appear as micelles, with a core made of organic material. Covalency allows the construction of fully organized micelles, e.g. dendrimeric spheres, where one half has a hydrophilic, the other a hydrophobic surface. Block polymers may not only form micelles, but they may also arrange to form vesicles which entrap a water volume. Such spheres have a thick polymer wall." Both the polymer micelles and vesicles can be removed from solution without collapsing. 

Polar and neutral solutes Solubilization and mobility of neutral compounds Formation of pseudostationary phase by MEKC or by MEECC Utilization of a stationary phase by CEC... 

Substances that are solubilized in surfactant micelles can be separated by ultrafiltration through membranes whose pores are smaller in diameter than the micelle size. For a membrane molecular weight cutoff from 1 to 50kDa, the rejections are 98%. The stream of water-containing monomeric molecules of surfactant (permeate) flows through the membrane. The remaining solution (retentate) contains solutes solubilized in micelles. The MEUF process is used for the separation of organic substances and various ions, the latter after their previous complexation. 

Hoshino and Saji [7] first reported the preparation of azo-dye thin films using FTMA. These films were prepared by controlled-potential electrolysis of the FTMA micelle aqueous solution solubilizing the azo dye at 4-0.3 V versus SCE. The azo-dye molecules exist as sol-ubilizate in the micelles, and are then released from the micelles and deposited... 

From Stockmann and Schwarz (1999). Oil-in-water emulsions were prepared with 20% corn oil and 1% emulsifier in 0.2 M acetate buffer (pH 5). SDS = sodium dodecyl sulfate, CTAB = cetyltrimethyl ammonium bromide, Brij 58 = polyoxyethylene 20 cetyl ether, PHLC = partially hydrolysed soybean lecithin. Amount of solute solubilized in oil lipid phase of emulsions was calculated from the difference between the total amount in the system and the amount of oil solubilized in the aqueous phase determined by ultrafiltration and semiequiUbrium dialysis. 

To design and evaluate scale-up feasibility, the development of a reliable mathematical model to describe the process is important. In a packed bed extraction, the extraction fluid first penetrates and diffuses into the solid matrix. Then the solute solubilizes and moves from the solid matrix to the pores where diffusion inside the pores takes place. At the end, the fluid with the dissolved extract axially diffuses back along the extraction bed and leaves the extractor. 

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