Minimum water solubilization

The lamellar spacing of a monoglyceride gel phase as a function of water content is plotted in Figure 14. The gel phase of the neutral monoglyceride has a lipid bilayer thickness of 49.5 A, and it swells to a unit layer thickness of 64 A (20). If an ionic amphiphilic substance (e.g. a soap) is solubilized in the lipid bilayer, it is possible to obtain a gel phase with high water content. As with the gel phases with infinite swelling that were discussed above, there is, however, a minimum water layer thickness which in this monoglyceride gel is about 40 A. 

The change of solubility areas with electrolyte content is shown in Figure 2. The solubility area for the pentanol solution of potassium oleate and water (—. —. —, Figure 2) shows a minimum water amount for solubilization. The minimum amount of water is proportional to the amount of soap present the solubility limit to the right gives a molecular water potassium oleate ratio of three, the minimum number of water molecules to bring the soap into solution. The solubility area is approximately triangular with maximum water solubilization at 12% (w/w) potassium oleate, 33% pentanol, and 55% water. The potassium oleate pentanol ratio is. 36 at that point. 

Palit and Venkateswarlu investigated the solubilization of water by a series of organic acid salts of n-dodecylamine in xylene and reported maximum solubilization with butyrate salts [204]. A similar trend was observed with salts of n-octadecylamine in xylene, maximum solubilization being observed with the propionate salt. The amount of water solubilized by w-dodecylamine and n-octadecylamine salts of several carboxylic acids in benzene or cyclohexane was greatest for the shortest chain carboxylate [205]. The effect of electrolyte in decreasing the minimum temperature of solubilization and increasing the maximum amount of water solubilized in dodecylammonium carboxylates in... 

A carboxylate derivative of a fully aromatic, water-soluble, hyperbranched polyphenylene is considered as a unimolecular micelle due to its ability to complex and solubilize non-polar guest molecules [23]. The carboxylic acid derivative of hyperbranched polyphenylene polymer (HBP) (My,=5750-7077, Mn=3810-3910) consists of 40-60 phenyl units that branch outward from a central point forming a roughly spherical molecule with carboxylates on the outer surface. The free acid form of HBP was suspended in distilled water and dissolved by adding a minimum quantity of NaOH. The solution was adjusted to pH 6.2 with aqueous HCl. Calcium carbonate crystals were growth from supersaturated calcium hydrogencarbonate solution at room temperature. HBP gave... 

In n-octane/aqueous systems at 27°C, TRS 10-80 has been shown to form a surfactant-rich third phase, or a thin film of liquid crystals (see Figure 1), with a sharp interfacial tension minimum of about 5x10 mN/m at 15 g/L NaCI concentration f131. Similarly, in this study the bitumen/aqueous tension behavior of TRS 10-80 and Sun Tech IV appeared not to be related to monolayer coverage at the interface (as in the case of Enordet C16 18) but rather was indicative of a surfactant-rich third phase between oil and water. The higher values for minimum interfacial tension observed for a heavy oil compared to a pure n-alkane were probably due to natural surfactants in the crude oil which somewhat hindered the formation of the surfactant-rich phase. This hypothesis needs to be tested, but the effect is not unlike that of the addition of SDS (which does not form liquid crystals) in partially solubilizing the third phase formed by TRS 10-80 or Aerosol OT at the alkane/brine interface Til.121. 

Pretreatment of Substrate. Several different lignocelluloses were pretreated with NaOH. This pretreatment partially solubilizes the hemicelluloses and lignin and swells the cellulose so that the organism can utilize it for its growth and for production of a cellulase system in SSF. The treated lignocelluloses were not washed. The NaOH treatment is done with a minimum amount of water so that, after the addition of nutrient solution and inoculum, the moisture content is less than 80% wt/wt and there is no free water in the medium. More water was added to make suspensions of different lignocellulosic substrates of the desired concentration (1% or 5%) for liquid-state (submerged) fermentation (LSF). 

Caution should be exercised when considering temperature effects on solubilization by micelles, since the aqueous solubility of the solute and thus its micelle/water partition coefLcient can also change in response to temperature changes. For example, it has been reported that although tt solubility of benzoic acid in a series of polyoxyethylene nonionic surfactants increases with temperature, the micelle/water partition coefLci rt, shows a minimum at 2C, presumably due to the increase in the aqueous solubility of benzoic acid (Humphreys and Rhodes, 1968). The increasr in Km with increasing temperature was attributed to an increase in micellar size, as the cloud point temperature of the surfactant is approached (Humphreys and Rhodes, 1968). 

The solubilization of an aqueous sodium chloride solution by potassium oleate in the pentanol isotropic solution was determined. The presence of sodium chloride increased the minimum concentration for solubilization, reduced the maximum solubilization at high pentanohpotassium oleate ratios, and altered this ratio to lower values for maximal solubilization of the electrolyte solution. The increased minimum amount of electrolyte solution for solubilization arose from the fact that no micelles were present at the lowest fractions of water in the pentanol solution. The increased potassium oleate. pentanol ratio for maximal solubilization of the electrolyte was related to the destabilization of the lamellar liquid crystal with which the inverse micellar pentanol solution of high water content was in equilibrium. 

The solubilities of R and S in the reaction mixture were determined and an appropriate volume of water/isopropyl acetate was found that could solubilize S but allow R to crystallize soon after the star of addition of B to A. The reaction is nin in the fed batch (semibatch) mode with B added to A. Two critical crystaUization parameters are controlled to ensure the minimum concentration of R (maximum crystallization) during the addition ... 

Solubilization is the increase in solubility of a poorly water-soluble substance with surface-active agents. The mechanism involves entrapment (adsorbed or dissolved) of molecules in micelles and the tendency of surfactants to form colloidal aggregations at critical micelle concentration levels. Thus, the critical micelle concentration is the minimum surfactant concentration that begins solubilization of the insoluble molecule. Increases in the concentration of micelles lead to increases in drug solubility. 

From the above discussion, it should be apparent that for POE nonionics, there is a particular temperature where the hydrophilic and lipophilic characters of the surfactant balance each other and yow is at, or close to, its minimum value. It is usually defined operationally, for example, as the temperature where the surfactant phase solubilizes equal volumes of water and nonpolar material or the temperature at which an emulsion (Chapter 8) of the surfactant, water, and nonpolar material inverts. In the latter case, it is known as the phase-inversion temperature (PIT) (Chapter 8, Section IVB). Similarly, there is an electrolyte content at which the hydrophilic and lipophilic characters of ionic surfactants balance. The point at which equal volumes of water and nonpolar material are solubilized into the surfactant is known as the optimal salinity (Healy, 1974) and has been extensively investigated for enhanced oil recovery (Healy, 1977 Hedges, 1979 Nelson, 1980). The optimal salinity or PIT is at or close to the point where the parameter Vh/lcao (Chapter 3, Section II) equals 1 and lamellar normal and reverse micelles are readily interconvertable. 

The prevalent view is that the feed olefins of the aqueous biphase technique require a certain minimum solubility in the aqueous catalyst phase for adequate conversion. The reactivity differences in hydroformylation between, for example, propene and octene are readily explained by the solubility differences between the two olefins (Figure 7) [28, 29]. This is also the basis of the many proposals for solubilizing solvents or cosolvents, which are meant to make possible the reaction of higher and hence less water-soluble olefins in the bulk of the catalyst solution. In Figure 8, the two possibilities for the hydroformylation of propene (a liquified gas under reaction conditions) and syngas are shown. 

The next step in method development is the solubilization of the sample. The first solvent that is always tried is distilled/or deionized water, although the type of solvent is determined by the analytical method that has been chosen. There are some solid substances that must first be desegregated. They cannot be dissolved in any other way in any of the solvents. The best quality and reliability can be obtained in this step by utilization of a micro-wave digestion system.332 This system of desegregation produces the minimum contamination of the sample. Usually, the solvents and reagents used for desegregation of solids also constitute the blank for the analysis. 

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