Solubility enhancement factor

From Table 1, it can be seen that the order of ligand solubilities in aqueous solution is PADA < Dimbipy Bipy, so that Bipy is considerably more hydrophilic than the other two ligands. From solubility measurements in 0.1 mol dm SDS, a solubility enhancement factor (SHF) can be determined. The order of values obtained is PADA Dimbipy Bipy. 

To understand the role of solute-solvent interac tions on solubilities and selectivities, it is instructive to define an enhancement factor, E, as the ac tual solubility, y9, divided by the solubility in an ideal gas, so that E = where P is the vapor pressure. This factor is a normahzed... 

Since a is small for sparingly soluble gases, the enhancement factor can be quite large. 

Solid-Fluid Equilibria The solubility of the solid is very sensitive to pressure and temperature in compressible regions, where the solvent s density and solubility parameter are highly variable. In contrast, plots of the log of the solubility versus density at constant temperature often exhibit fairly simple linear behavior (Fig. 20-19). To understand the role of solute-solvent interactions on sofubilities and selectivities, it is instructive to define an enhancement factor E as the actual solubihty divided by the solubility in an ideal gas, so that E = ysP/Pf, where P is the vapor pressure. The solubilities in CO2 are governed primarily by vapor pressures, a property of the solid... 

PAHs are widely distributed in the environment as evidenced by their detection in sediments, soils, air, surface waters, and plant and animal tissues. However, the ecological impact of PAHs is uncertain. PAHs show little tendency for bioconcentration despite their high lipid solubility (Pucknat 1981), probably because most PAHs are rapidly metabolized. Sims and Overcash (1983) list a variety of research needs regarding PAHs in soil-plant systems. Specifically, research is needed to establish the rates of PAH decomposition in soils the soil PAH levels above which PAH constituents adversely affect the food chain and enhancement factors that increase degradation rates of PAHs, especially PAHs with more than three rings. Once these factors have been determined, PAH disposal into soils may become feasible at environmentally nonhazardous levels. 

The addition of powdered-activated carbon (PAC) to the activated sludge process has received considerable attention, particularly with respect to the removal of specific organics. The applicability of activated carbon in removing specific substrates depends on the molecular weight, solubility, polarity, location of functional groups, and overall molecular configuration. Investigations of PAC systems have centered around process enhancement factors. These include ... 

The fugacity coefficient of the solid solute dissolved in the fluid phase (0 ) has been obtained using cubic equations of state (52) and statistical mechanical perturbation theory (53). The enhancement factor, E, shown as the quantity in brackets in equation 2, is defined as the real solubility divided by the solubility in an ideal gas. The solubility in an ideal gas is simply the vapor pressure of the solid over the pressure. Enhancement factors of 104 are common for supercritical systems. Notable exceptions such as the squalane—carbon dioxide system may have enhancement factors greater than 1010. Solubility data can be reduced to a simple form by plotting the logarithm of the enhancement factor vs density, resulting in a fairly linear relationship (52). 

The quantity contained in square bracketts represents the ratio between the real solubility and the ideal solubility (the supercritical phase is described by the ideal gas law) it is always greater than 1 and it is also called the enhancement factor (E). E can have values of 10+3 or higher. 

In the Raman experiments, an excitation wavelength of 785 nm (intensity 1.8 105 W/cm2) was used. The sample, i.e. a drop of Au nanoparticle suspension with soluble pollen content was placed under a (60x) water immersion objective. Raman spectra were recorded with 1 s acquisition time. The control preparations (pollen supernatant with water) did not yield any spectral features. A spectrum of rye pollen supernatant with Au nanoparticles is shown in Fig. 4.9, together with a normal Raman spectrum of a rye pollen grain. The difference in spectral information that can be obtained by both approaches is evident from a comparison of these two spectra. Although an estimate of an enhancement factor is not possible from this experiment, it is clear that... 

Based on Eq. (4.4), the enhancement factor E is defined as the enhancement on the maximum flux J"max of a drug across skin by increasing the (kinetic) diffusivity and/or the (thermodynamic) solubility in the stratum corneum.79 Thus... 

We have begun to characterize the retinoid enhancement factor. Reconstitution studies clearly show that the factor is present in the post-microsomal soluble fraction (Table III) in rat liver (there is a factor(s) present in the 17,000xg pellet which normally inhibits this factor (Table III)). The retinoid enhancing factor is heat sensitive, since its activity in the presence of retinol is lost when supernatant is incubated for 15 minutes at 45°C (Figure 3). Similar results were obtained by incubating the supernatant at 50°C for five minutes. 

The postmicrosomal supernatant was filtered through Amicon membrane filters of varying pore size, and assayed for its effectiveness in the presence of retinol. These results are summarized in Table IV which shows that the enhancing factor has a molecular weight between 50,000 and 100,000 daltons. Finally, this factor is not precipitated from the soluble fraction by (NH )aSO in the range from 1.0 to 2.0 M. 

The solubility data for naphthalene in ethylene and in CO2 are consistent with the data in Figure 3. The proper way to make the comparison is to use the enhancement factor instead of the solubility. The enhancement factor equals y2P/P2 which is simply the actual solubility divided by the solubility in an ideal gas. The enhancement factor removes the effect of vapor pressure which is useful for comparing fluids at constant reduced temperature but at different actual temperatures. In terms of the fugacity coefficient of the solute, 2, the enhancement factor is given by... 

The effect of solid structure on the solubilities of n-alkanes in supercritical ethane has been investigated at a temperature just above the critical point of ethane. Solubilities of n-alkanes containing 28 to 33 carbon atoms in ethane at 308.15K and pressures up to 20 MPa are reported in this work. The enhancement factor is shown to exhibit a regular trend with the number of carbon atoms in the n-alkane, although different trends are exhibited by the odd and even members of the series. 

Enhancement factors are given In Table 2. Solid densities and sublimation pressures used In the solubility calculations (Eq. 2) are given In Table 3. The densities were supplied by the manufacturers whereas the sublimation pressures were extrapolated... 

The shape of the solubility curve is characterized in part by the behavior of the derivative dyJdP (constant T). A general expression is found from Eq. (14.98), y = P XP/F, where the enhancement factor F depends (at constant T) on P and y. Thus,... 

The exothermic absorption gives rise to complex behaviour of the Enhancement Factor. As Fig. 7 shows, for y,. = 4.9, G=2.3 mol s 1 and N=400 rpm, the flux and T fall continuously with time, but the Enhancement Factor passes through a maximum value of 27 after 50 minutes. This results from interference of solubility decrease with rate constant increase, where E is defined by... 

Water-soluble cyclophane 86145 exhibited a well-defined fluorescence band at 290 nm with a 210 nm excitation. The emission intensity was markedly increased by complexation with Zn2+ which forms a 2 1 (metal-ligand) complex. The fluorescence emission is pH-independent to pH 2. The fluorescence enhancement factor is 5.0 at pH 6 and 50 at pH 8.6 (due to the pH dependence of the free ligand). Ni2+ and Cu2+ ions quenched the ligand fluorescence via a PET mechanism. Furthermore, when cyclophane 86 was coordinated to Cu2+, the molar absorptivity of the transition band observed at 260 nm was increased by a factor of about 10. Such a large spectral change was not observed for the Zn2+ and Ni2+ complexes. In the Cu2+ complex, the two phenyl rings of the cyclophane are expected to be... 

The high solubility of solid substances in supercritical fluids compared to those in ideal gases (enhancement factors of lO -lO are common) allows their use as solvents in pharmaceutical, biomedical and food industries. Sections 2.4-2.7 are devoted to predictions of the entrainer effect, and of solubility in supercritical fluids with and without entrainer. Reliable predictive methods for solid solubilities in mixtures of a supercritical solvent -i- cosolvent were developed (2.4-2.6). These apply not only to the usual cosolvents such as organic liquids (2.4-2.5), but also to cases in which the cosolvent is a gas or another supercritical fluid (2.6). Our methods provided good agreement with experimental data in all of these cases (2.4-2.6). 

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