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Solubility antisolvent effects

Sodium carbonate is soluble in ambient water but is insoluble in supercritical water the microparticles are generated as a result of the antisolvent effect of supercritical water. Because the surface area per unit mass for sodium carbonate microparticles is high, only a small amount of sodium carbonate needs to be injected in the reactor. For example, only 0.5wt% sodium carbonate is able to provide a microparticle surface area about 100-fold that of the reactor wall. [Pg.2930]

The solubilities of pure 3-carotene in ethyl acetate and cholesterol in acetone, predicted by using Eq. (46), compare well with the corresponding experimental data reported in the literature (52,53). The behavior of the curve for Z3 vs Xi is similar to that for V2 vs Xi in that both are drastically reduced at high values of Xi, although both remain almost invariant at lower values of X. This was further validated by experimental data (54) from comparisons of the antisolvent effects on the reduction of solubility of pure 3-carotene in hexane and in ethyl acetate. This trend was also observed for a lecithin-hexane system (55). The solute solubility is negligible at zero or negative values of V2, which occur at a very high CO2 dissolution. [Pg.69]

As the driving force for the precipitation in the GAS process is the antisolvent effect caused by the solubilization of CO2 in the liquid phase, and the solvent power of a liquid is often proportional to its density it has been found that it is possible to select the optimum thermodynamic conditions for this process by studying the volumetric expansion in the solvent caused by CO2. De la Fuente et al. presented a definition of the volumetric expansion based on the variation of the partial molar volume of the solvent, which allows an optimum selection of the solvent and the operating pressure and temperature for a particular application. These authors also showed that a study of the solubility of the solute in the solvent-C02 mixtures allows predicting if the GAS process can yield satisfactory results in systems in which there is a sharp decrease in solubility at some concentration of CO2, the performance of the GAS process will be optimum, since in this case, the precipitation will take place very quickly and homogenously upon reaching this region systems that show a slow decrease in solubility as the CO2 amount increases are likely to yield worse results, since in this case, the precipitation will take place continuously and relatively slowly as CO2 is fed to the precipitator. [Pg.450]

Precipitation Poiymerization. As described in the previous section, ultrasound-induced bulk polymerizations are limited to relatively low conversions, because a strong viscosity increase upon reaction hinders cavitation. To obtain higher conversions, precipitation polymerization forms a potential soln-tion. Because the produced polymer precipitates from the reaction medium, the viscosity and consequently the radical formation rate are expected to remain virtually constant. In this perspective, liquid carbon dioxide is a suitable reaction medium, because most monomers have a high solubility in CO2, whereas it exhibits an antisolvent effect for most polymers. Moreover, CO2 is regarded as an environmentally friendly compound, which is nontoxic, nonflammable, and naturally abundant. Since higher pressures are required for CO2 to act as an antisolvent (31-33), the possibility of ultrasound-induced cavitation in pressurized carbon dioxide systems has been studied (34). [Pg.8675]

Once a set of potential solvents (and antisolvents) have been identified then the solubility behavior should be assessed in the laboratory, confirming the effect of temperature, the isolated solid form and the limits of purification. [Pg.48]

Besides these thermodynamic criteria, the most common approach used in the literature is based on the operation at pressures above the binary (liquid - SC-CO2) mixture critical point, completely neglecting the influence of solute on VLEs of the system. But, the solubility behavior of a binary supercritical COj-containing system is frequently changed by the addition of a low volatile third component as the solute to be precipitated. In particular, the so-called cosolvency effect can occur when a mixture of two components solvent+solute is better soluble in a supercritical solvent than each of the pure components alone. In contrast to this behavior, a ternary system can show poorer solubility compared with the binary systems antisolvent+solvent and antisol-vent+solute a system with these characteristics is called a non-cosolvency (antisolvent) system. hi particular, in the case of the SAS process, they hypothesize that the solute does not induce cosolvency effects, because the scope of this process lies in the use of COj as an antisolvent for the solute, inducing its precipitation. [Pg.135]

Although crystallization by antisolvent addition shares many characteristics with that caused by chemical reaction, the processes often differ in the rate of creation of supersaturation (e.g., a rapid reaction leading to a compound of very low solubihty). Reactive crystallization is also subject to other kinetic considerations which are sometimes less predictable than the known solubility effects caused by addition of an antisolvent. [Pg.207]

The temperature stability profile of imipenem effectively niles out cooling or evaporative crystallization. Antisolvent addition is the obvious choice. The preferred solvent is water because of the need for sterile filtration of the solution to be fed to the crystallizer. A good antisolvent is known to be acetone. In this case, the antisolvent has the important function of reducing the metastable zone width as well as the solubility. [Pg.239]

The Symyx solubility workstation has been integrated into the medicinal and process chemistry work flows at Amgen [60]. The technology has allowed for the investigation of numerous parameters that would otherwise not be assessed during a first-pass analysis. Experiments on lead optimization candidates to study single- and multiple-solvent effects (e.g., co-, tri-, antisolvent, etc.) as a function of temperature, time, and pH have been conducted. [Pg.423]

When a solid has been solubilized in the liquid prior to the introduction of the compressed gas, the volumetric expansion is accompanied by a decrease of the liquid solvent strength, which causes the solid to precipitate as ultra fine particles. The physicochemical properties of the solute of interest strongly influence the choice of a solvent/antisolvent pair. The antisolvent should have appreciable mutual solubility with the solvent and should have little or no affinity for the solute. As will be seen, the solute-solvent affinity is also an effective factor that can strongly influence the morphology of the end product. [Pg.167]

MiCoS shares similar pros and cons to solvent-casting methods. With parallel preparation, it is highly efficient and effective in evaluating polymer types, drug loadings and antisolvent/solvent ratio comprehensively. However, the residue solvent and antisolvent content, which are critical for amorphous stability, cannot be determined due to low amount of solid products. The kinetic solubility results can only be interpreted qualitatively rather than quantitatively, as the particle size of the miniaturized products are not tightly controlled. [Pg.184]

The final size of nanoparticles may also be influenced by Ostwald ripening, which leads to a gradual increase of the mean particle size. However, the effect can be made negligible by rapid dilution of the obtained suspension with the antisolvent, since the rate of ripening is proportional to the bulk solubility of the solid [46,47]. [Pg.234]


See other pages where Solubility antisolvent effects is mentioned: [Pg.16]    [Pg.1057]    [Pg.2004]    [Pg.23]    [Pg.1762]    [Pg.858]    [Pg.160]    [Pg.1345]    [Pg.183]    [Pg.3]    [Pg.27]    [Pg.263]    [Pg.378]    [Pg.290]    [Pg.298]    [Pg.298]    [Pg.841]    [Pg.2008]    [Pg.987]    [Pg.147]    [Pg.258]    [Pg.252]    [Pg.229]    [Pg.354]    [Pg.356]    [Pg.249]    [Pg.71]    [Pg.147]    [Pg.910]   
See also in sourсe #XX -- [ Pg.251 , Pg.276 ]




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