Ternary mixtures fractionation

The use of a ternary mixture in the drying of a liquid (ethyl alcohol) has been described in Section 1,5 the following is an example of its application to the drying of a solid. Laevulose (fructose) is dissolved in warm absolute ethyl alcohol, benzene is added, and the mixture is fractionated. A ternary mixture, alcohol-benzene-water, b.p. 64°, distils first, and then the binary mixture, benzene-alcohol, b.p. 68-3°. The residual, dry alcoholic solution is partially distilled and the concentrated solution is allowed to crystallise the anhydrous sugar separates. 

Katz et al. tested the theory further and measured the distribution coefficient of n-pentanol between mixtures of carbon tetrachloride and toluene and pure water and mixtures of n-heptane and n-chloroheptane and pure water. The results they obtained are shown in Figure 17. The linear relationship between the distribution coefficient and the volume fraction of the respective solvent was again confirmed. It is seen that the distribution coefficient of -pentanol between water and pure carbon tetrachloride is about 2.2 and that an equivalent value for the distribution coefficient of n-pentanol was obtained between water and a mixture containing 82%v/v chloroheptane and 18%v/v of n-heptane. The experiment with toluene was repeated using a mixture of 82 %v/v chloroheptane and 18% n-heptane mixture in place of carbon tetrachloride which was, in fact, a ternary mixture comprising of toluene, chloroheptane and n-heptane. The chloroheptane and n-heptane was always in the ratio of 82/18 by volume to simulate the interactive character of carbon tetrachloride. 

A ternary mixture of mole fraction ethanol of 0.15, ethyl acetate of 0.6 and methanol 0.25 is to be separated into relatively pure products. Sketch a system of distillation columns and mixer arrangements in the triangular diagram to carry out the separation by exploiting the shift in the distillation boundary with pressure. Sketch the flowsheet corresponding with this mass balance. 

Equation (8) expresses the relation of the approximated variance of fraction X, as a function of the composition of the mixture and the square of the coefficient of variation. For example for a ternary mixture ... 

The virial equation of state discussed in Section 7.2 is applicable to gas mixtures with the condition that n represents the total moles of the gas mixture that is, n = f= l n,. The constants and coefficients then become functions of the mole fractions. These functions can be determined experimentally, and actually the pressure-volume-temperature properties of some binary mixtures and a few ternary mixtures have been studied. However, sometimes it is necessary to estimate the properties of gas mixtures from those of the pure gases. This is accomplished through the combination of constants. 

The procedure for processing a given batch charge of mixture m (operation m), can be viewed as a sequence of NTm distillation tasks to produce one or more main-cuts, possibly some intermediate off-cuts and a final bottom residue or product (Figure 7.1). For a ternary mixture this can be represented in the form of a STN shown in Figure 7.2. Each state s is characterised by a name (e.g. Dl), an amount Ss (e.g. SDi) and a composition vector xs (e.g. xD1). The molar fraction of an individual component j in state 5 is denoted by The sets of external feed states, main-cuts and off-cuts states in operation m are defined as EFm, MPm, and OPm, respectively. For example, Figure 7.2 shows operation 1 for a ternary mixture distillation with NTt=4 tasks, EFj= F0, MPt= Dl, D2, Bf] and OP/=[Rl, R2. Several feed states could occur, for example in the preparation of a mixed charge or... 

Figure A.l illustrates the graphical interpretation in a right-angle triangle. Pure components are marked in the vertices A, B, C. The molar fractions xA and xB are represented on the edges CA and CB, while xc is visualized by the height of the point representing the ternary mixture with respect to AB. In Figure A.1 the chemical equilibrium curve is displayed too drawn by means of the relation ...

For example, the AB mixture expressed in Figure A.1 by XA and XB mole fractions on the AB edge leads at equilibrium to a mixture (xA, xB, xc) obtained by intersecting the equilibrium curve with the stoichiometric line passing through the initial mixture. Conversely, a ternary mixture where a chemical reaction at equilibrium takes place may be described only by two transformed composition variables. 

The ternary mixture can be separated into three relatively pure fractions by the use of varying reflux to obtain high overhead concentrations, with intermediate slop cuts being taken during the transition between components. 

The present paper is devoted to the local composition of liquid mixtures calculated in the framework of the Kirkwood—Buff theory of solutions. A new method is suggested to calculate the excess (or deficit) number of various molecules around a selected (central) molecule in binary and multicomponent liquid mixtures in terms of measurable macroscopic thermodynamic quantities, such as the derivatives of the chemical potentials with respect to concentrations, the isothermal compressibility, and the partial molar volumes. This method accounts for an inaccessible volume due to the presence of a central molecule and is applied to binary and ternary mixtures. For the ideal binary mixture it is shown that because of the difference in the volumes of the pure components there is an excess (or deficit) number of different molecules around a central molecule. The excess (or deficit) becomes zero when the components of the ideal binary mixture have the same volume. The new method is also applied to methanol + water and 2-propanol -I- water mixtures. In the case of the 2-propanol + water mixture, the new method, in contrast to the other ones, indicates that clusters dominated by 2-propanol disappear at high alcohol mole fractions, in agreement with experimental observations. Finally, it is shown that the application of the new procedure to the ternary mixture water/protein/cosolvent at infinite dilution of the protein led to almost the same results as the methods involving a reference state. 

Combining Eq. (14) with Eqs. (B. 19)-(B.24) of Appendix B allowed us to obtain expressions at infinite dilution for the derivatives of the activity coefficients with respect to the mole fractions in ternary mixtures. They are... 

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