Binary aqueous systems

D ans, J. Surawski, H. Synowietz, C. Schafer, K., Ed., Part IV "Densities of Liquid Systems and Their Heat Capacities. Part B. Densities of Binary Aqueous Systems... 

The work presented here is essentially a preliminary study of the solubilization of oil in simple binary aqueous systems which can be used as model systems for microemulsions. Still, it was demonstrated that the use of phase separation to recover the oil... 

In this expression xi and x / are the compositions of component 1 in the two phases. For most binary aqueous systems, when xi, the mole fractions of component 1 in water, is small, xi/, and therefore y f are both close to one. This results in the approximation yi = 1/xi. This approximation is valid at the solubility concentration xi. 

Once the interaction energies were obtained, they were used to calculate the parameters in the UNIQUAC and Wilson models given by Eq. (24). To test the validity of the method, low-pressure vapor-liquid equilibrium (VLE) predictions were made for several binary aqueous systems. The calculations were done using the usual method assuming an ideal vapor phase (Sandler, 1999). Figures 7 and 8 show the low-pressure VLE diagrams for the binary aqueous mixtures of ethanol and acetone [see Sum and Sandler (1999a,b) for results for additional systems and values of the... 

G3. Landolt-Bornstein. Densities of Binary Aqueous Systems and Heat Capacities of Liquid Systems, New Series, Group IV Springer-Verlag Berlin, 1977 Vol. lb. 

Yakoumis, l.V. et al.. Prediction of phase equilibria in binary aqueous systems containing alkanes, cycloalkanes, and alkenes with the CPA EoS, Ind. Eng. Chem. Res., 37, 4175, 1998. 

ZA2 Zafarani-Moattar, M.T., Hamzehzadeh, S., and Hosseinzadeh, S., Phase diagrams for liquid-hquid equilibrium of ternary poly(ethylene glycol) + disodium tartrate aqueous system and vapor-liquid equilibrium of constituting binary aqueous systems at r = (298.15, 308.15, and 318.15)K. Experiment and correlation, Fluid Phase Equil, 268, 142, 2008. 

Figure 5. Critical curves for several binary aqueous systems in the vicinity of the critical point of pure water. The shaded side of the curves indicates the two-phase regions. Tlie CeHn-curve is not shaded only because of clarity. The not shaded heavy solid line near the bottom left represents the vapour pressure curve of pure water, ending at the critical point (c.p.) [81]...

It is of course desirable to extend studies of binary aqueous systems to water-salt combinations over the complete composition range all the way up to the molten salt. Many salts have melting points that are too high. One electrolyte of choice, however, is sodium hydroxide, which above its melting point at 321 is completely miscible with high density water and thus offers a broad homogeneous region at moderate temperatures and pressures. 

The binary aqueous systems phase diagrams in the range of the crystallization of TBA carboxylate and isocarboxylate polyhydrates are given in Figures 1 and 2 respectively, and some properties of the hydrates are shown in Table I. Two hydrates with stable crystallization branches form in the TBA acetate - water system. One stable and several metastable hydrates have been discovered in each of the rest of the systems (from 1 (TBA formate) to 8 (TBA o-butyrate)). 

Densities of Binary, Aqueous Systems and Heat Capacities of Liquid Systems... 

Figure 1.42 p-T projection of two critical surfaces in the system C02-benzene (C6H6)-H20 (ternary class la-ld-ld ). High-pressure critical surface (L = G, Gi = G2 (Li = L2)) extends between the high-temperature high-pressure branches of binary critical curves CO2 - H2O and C6H6 -H2O. Low-pressure critical surface (L = G) extends between the low-temperature low-pressure branches of critical curves in binary aqueous systems and binary critical curve CO2 - CeHe, and ends in the ternary critical curve Rco2Rc6H6 (Li = G-L2) (Brandt, E., Franck, E.U., Wei, Ya S. and Sadus, RJ. (2000) Phys. Chem. Chem. Phys., 2, pp. 4157 164. Reproduced by permission of the PCCP Owner Societies). 

The systems are arranged in alphabetic order of nonaque-ous components for each of seven groups of aqueous mixtures. Binary aqueous systems were divided into three groups - Binary systems with electrolytes , Binary systems with nonelectrolytes and Binary systems with acids . There are also three groups of ternary aqueous systems - Ternary systems - electrolytes , Ternary systems - nonelectrolytes ... 

Chandler, K., Eason, B., Liotta, C.L. and Eckert, C.A., Phase equilibria for binary aqueous systems from a near-critical water reaction apparatus, Ind. Eng. Chem. Res., 1998, 37, 3515-3518. 

PEO/PPO/PEO triblock copolymers exhibit properties similar to typical surfactants, i.e. they reduce surface and interfacial tension of aqueous solutions and form micellar aggregates above a critical micellar concentration [74, 78]. For some compounds of this type, like P104 (EOigPOsgEOis), P123 (E02oP07oE02o)> 3nd F127 (EO106PO70EO106), a similarly located cubic phase like the one of the aminoxide systems has been found in tbe binary aqueous system [74, 79]. 

Perhaps because of its polyfunctionality and complex molecular structure, C12MG (and probably also its analogs) displays a high level of complexity in its physical behavior. Polymorphism exists in the dry material three different crystalline polymorphs that vary widely in their kinetic stabilities have been discovered. Nonequuilibrium phenomena exist in unary and in binary aqueous systems. The likelihood that similar complexity also exists in ternary systems is very high. Unfortunately, one cannot be sure that this behavior is unique to these molecules because few other systems have been studied in the depth that C12MG has been. It would have been desirable to have studied in depth one or two other analogs, but time did not allow this. 

Figure 4. Critical curves of binary aqueous systems...

Zou, M. Prausnitz, J. M. Vapor-liquid and liquid-liquid equilibria in binary aqueous systems. 

---