Absorption solvents water

Sodium sulfate (anhydrous). Has a large capacity for absorption of water, forming the decahydrate below 33°, but drying is slow and inefficient, especially for solvents that are sparingly soluble in water. It is suitable for the preliminary drying of most types of organic compounds. 

For gas absorption, the water or other solvent must be treated to remove the captured pollutant from the solution. The effluent from the column may be recycled into the system and used again. This is usually the case if the solvent is costly (e.g., hydrocarbon oils, caustic solutions, amphiphilic block copolymer). Initially, the recycle stream may go to a treatment system to remove the pollutants or the reaction product. Make-up solvent may then be added before the liquid stream reenters the column. 

The simple relation (6.1) is quite useful. It allows an estimate of the gain or loss in yield strength if the glass transition temperature is changed, as for instance by the progress of the curing reaction, by radiation damage, or by absorption of water and of solvents. The ATe is determined fairly easily by thermoanalytical measurements. 

In 1941, Mackinney ° published the first specific absorption coefficients for chlorophyll a and chlorophyll b in 80% acetone, quickly followed by other reports citing different solvents. Chlorophylls form aggregates in various organic solvent-water mixtures that may interfere strongly with the absorbance maximum wavelength and the shapes of spectra. 

In a typical process, the conversion of isobutene in the reactor stage is 97 per cent. The product is separated from the unreacted methanol and any C4 s by distillation. The essentially pure, liquid, MTBE leaves the base of the distillation column and is sent to storage. The methanol and C4 s leave the top of the column as vapour and pass to a column where the methanol is separated by absorption in water. The C4 s leave the top of the absorption column, saturated with water, and are used as a fuel gas. The methanol is separated from the water solvent by distillation and recycled to the reactor stage. The water, which leaves the base of the column, is... 

If an organic solvent is used to dissolve the chemical, water should be added to reduce the dehydrating effect of the solvent within the gut lumen. The volume of water or solvent-water mixture used to dissolve the chemical should be kept low, since excess quantities may distend the stomach and cause rapid gastric emptying. In addition, large volumes of water may carry the chemical through membrane pores and increase the rate of absorption. Thus, if dose- dependent absorption is suspected, it is important that the different doses are given in the same volume of solution. 

Figure 3.4-2 Enthalpy of absorption for water vapor in various solvents at 25 °C.

Reservoir capacity is, in our view, an attempt by a polymer to dissolve. Because of cross-linking and molecular weight, the system does not fully dissociate into a true solution. Rather than dissolving in the normal sense, the polymer is said to swell in the solvent. Absorption of a solvent, water or organic, is a volumetric phenomenon controlled by the relative polarities of polymer and solvent. A nonpolar backbone is preferred for absorbing nonpolar solvents. The molecule we call polyurethane, however, is not entirely nonpolar but is close enough for use as an absorbing matrix. 

AP571 66AP817), and the absorption bands of both tautomers (17R) and (17C) could be detected in a more polar solvent (water or methanol) in the case of the dimethoxy derivative 17 (R = MeO, R1 = Me) (66AP817). The unsubstituted derivative 17 (R = R1 = H) also existed in the ring form in methanol (62AP571). 

Phase separation membranes. This category includes membranes made by the Loeb-Sourirajan technique involving precipitation of a casting solution by immersion in a nonsolvent (water) bath. Also covered are a variety of related techniques such as precipitation by solvent evaporation, precipitation by absorption of water from the vapor phase, and precipitation by cooling. 

Water precipitation (the Loeb-Sourirajan process) The cast polymer solution is immersed in a nonsolvent bath (typically water). Absorption of water and loss of solvent cause the film to rapidly precipitate from the top surface down... 

Precipitation of the cast liquid polymer solution to form the anisotropic membrane can be achieved in several ways, as summarized in Table 3.1. Precipitation by immersion in a bath of water was the technique discovered by Loeb and Souri-rajan, but precipitation can also be caused by absorption of water from a humid atmosphere. A third method is to cast the film as a hot solution. As the cast film cools, a point is reached at which precipitation occurs to form a microporous structure this method is called thermal gelation. Finally, evaporation of one of the solvents in the casting solution can be used to cause precipitation. In this technique the casting solution consists of a polymer dissolved in a mixture of a volatile good solvent and a less volatile nonsolvent (typically water or alcohol). When a film of the solution is cast and allowed to evaporate, the volatile good solvent evaporates first, the film then becomes enriched in the nonvolatile nonsolvent, and finally precipitates. Many combinations of these processes have also been developed. For example, a cast film placed in a humid atmosphere can precipitate partly because of water vapor absorption but also because of evaporation of one of the more volatile components. 

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