Methanol-water vapor composition difference

The experimental and predicted results for the ternary system carbon dioxide-methanol-water are listed in Table 7. Chang and Rousseau [47] have measured the solubilities of carbon dioxide in methanol-water mixtures at differents pressures and at temperatures below the critical temperature of carbon dioxide while Yoon [51] have measured the liquid and vapor phase equilibrium composition but overestimates shightly these of carbon dioxide in the liquid phase. 

The mobile phases consisting of acetonitrile/methanol [16] or acetoni-trile/methanol/water [18] in different ratios with a few drops of ammonia solution were found to discriminate between two enantiomers of these three -blockers in one-dimensional (ID) ascending development mode. The mobile phase composition and values of chiral separation factor a are listed in Table 11.3. The zones of separated antipodes were detected using iodine vapor and the detection limit of both alprenolol and propranolol racemates was 2.6 ng, while that of metoprolol was 0.26 /rg [16]. The effects of temperature on the separation of these three jS-blockers were also investigated [16]. It was observed that no resolution of atenolol racemate was achieved at the temperatures higher than 15" C, as well as below 8°C. The best resolution of propranolol and metoprolol racemates was achieved at 22°C. Increase of the temperature above 22°C led to the tailing, while a decrease up to 6°C had little or no effect on the quality of resolution. 

A procedure is presented for correlating the effect of non-volatile salts on the vapor-liquid equilibrium properties of binary solvents. The procedure is based on estimating the influence of salt concentration on the infinite dilution activity coefficients of both components in a pseudo-binary solution. The procedure is tested on experimental data for five different salts in methanol-water solutions. With this technique and Wilson parameters determined from the infinite dilution activity coefficients, precise estimates of bubble point temperatures and vapor phase compositions may be obtained over a range of salt and solvent compositions. 

Distillation For separation to occur during distillation, the composition of the vapor must differ from that of the liquid. For example (Figure 22-2, left), the vapor from a solution of methanol and water contains a larger proportion of methanol than does the liquid. According to Figure 22-2, if 40% methanol is distilled, the first vapor to be condensed contains about 72% methanol. If the 72% vapor were condensed and a second distillation performed, the first part of the condensate would be about 88% methanol. To obtain near 100% methanol, a distillation with many such stages is required. In some systems the composition changes not toward the pure... 

It is useful now to illustrate how the descriptive treatment of a particular separation process, e.g. distillation, has been implemented in an evolutionary fashion via the different chapters as identified in row 7 of Table 1. In Section 1.1, Example I of Figure 1.1.2 illustrates the result of heat addition to an equimolar liquid mixture of benzene-toulene a benzene-rich vapor phase and a toluene-rich liquid phase. Using definitions of compositions etc. introduced in Section 1.3, separation indices such as the separation factor (also the equilibrium ratio Ki) describe the separation achieved in a closed vessel for the benzene-toluene system and a methanol-water system for various liquid-phase compositions. Section 1.5 illustrates via Example 1.5.1 and the values of various separation indices, i2 and f, the... 

Another interesting ramification of binary systems that exhibit azeotropes is that in some cases T and P no longer uniquely specify the vapor and liquid compositions of the system in phase equilibrium. For example, there are two different states that the chloroform-n-hexane system can take at 59 kPa and 3f8 K, one on the left side of the azeotrope with Xa = 0.65 and = 0.68 and another to the right of the azeotrope with Xa = 0.90 and j/a = 0.88. In contrast, the methanol-water system depicted in Figure 8.3 exhibits a unique solution of liquid and vapor mole fractions for any T and P. Problems 8.22 through 8.24 provide cases where we can solve for vapor and liquid mole fractions given T and P. 

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