Partially-miscible liquids

Purified monomer is usually inhibited before shipment by such materials as copper resinate, diphenylamine or hydroquinone, which are generally removed before polymerisation. The monomer is a sweet-smelling liquid partially miscible with water and with the following properties boiling point at 760mmHg, 72.5°C specific gravity at 20°C, 0.934 refractive index 1.395 vapour... 

Liquid, determination of density and refractive index of, 1029-1034 Liquid ammonia, reactions in, 895-902 Liquids, partially miscible, 17-19 Liquids, supercooled, 22, 23 Liquidus, 26, 33... 

As positive deviations (7.56) increase (as in oil-water mixtures), the tendency toward immiscibility and phase separation increases. In this case, the simple liquid region of (7.61) may separate into two distinct liquid phases one A-rich and one B-rich in composition. Such liquid-liquid partial miscibility is a ubiquitous feature of aqueous solutions of hydrophobic solutes, particularly at lower temperatures. 

The three systems show liquid-liquid partial miscibility by decreasing the temperature at constant pressure, and thus present upper critical solution temperature (UCST) behavior as depicted in Figure 20.4.11. As can be observed from Figure 20.4.12, the addition of oleic acid, which is a naturally occurring olive oil constituent, significantly improves the mutual solubility. The presence of 11.60 wt% of oleic acid in olive oil decreases the UCST 11.2K (see Tables 20.4.8 and 20.4.9). 

An adequate prediction of multicomponent vapor-liquid equilibria requires an accurate description of the phase equilibria for the binary systems. We have reduced a large body of binary data including a variety of systems containing, for example, alcohols, ethers, ketones, organic acids, water, and hydrocarbons with the UNIQUAC equation. Experience has shown it to do as well as any of the other common models. V7hen all types of mixtures are considered, including partially miscible systems, the... 

For systems of type II, if the mutual binary solubility (LLE) data are known for the two partially miscible pairs, and if reasonable vapor-liquid equilibrium (VLE) data are known for the miscible pair, it is relatively simple to predict the ternary equilibria. For systems of type I, which has a plait point, reliable calculations are much more difficult. However, sometimes useful quantitative predictions can be obtained for type I systems with binary data alone provided that... 

Best ternary predictions are usually obtained for mixtures having a very broad two-phase region, i.e., where the two partially miscible liquids have only small mutual solubilities. Fortunately, this is the type of ternary that is most often used in commercial liquid-liquid extraction. 

To illustrate the criterion for parameter estimation, let 1, 2, and 3 represent the three components in a mixture. Components 1 and 2 are only partially miscible components 1 and 3, as well as components 2 and 3 are totally miscible. The two binary parameters for the 1-2 binary are determined from mutual-solubility data and remain fixed. Initial estimates of the four binary parameters for the two completely miscible binaries, 1-3 and 2-3, are determined from sets of binary vapor-liquid equilibrium (VLE) data. The final values of these parameters are then obtained by fitting both sets of binary vapor-liquid equilibrium data simultaneously with the limited ternary tie-line data. 

BLIPS calculates equilibrium phase compositions for a partially miscible liquid system of N components (N 20). 

Equilibrium between a Hydrocarbon Liquid and a Partially Miscible Liquid... 

Partially miscible liquids. Critical solution temperature. 

Some liquids are practically immiscible e.g., water and mercury), whilst others e.g., water and ethyl alcohol or acetone) mix with one another in all proportions. Many examples are known, however, in which the liquids are partially miscible with one another. If, for example, water be added to ether or if ether be added to water and the mixture shaken, solution will take place up to a certain point beyond this point further addition of water on the one hand, or of ether on the other, will result in the formation of two liquid layers, one consisting of a saturated solution of water in ether and the other a saturated solution of ether in water. Two such mutually saturated solutions in equilibrium at a particular temperature are called conjugate solutions. It must be mentioned that there is no essential theoretical difference between liquids of partial and complete miscibility for, as wdll be shown below, the one may pass into the other with change of experimental conditions, such as temperature and, less frequently, of pressure. 

It should be noted that the modern view is that all partially miscible liquids should have both a lower and upper critical solution temperature so that all such systems really belong to one class. A closed solubility curve is not obtain in all cases because the physical conditions under normal pressure prevent this. Thus with liquids possessing a lower C.S.T., the critical temperature (the critical point for the liquid vapour system for each component, the maximum temperature at which liquefaction is possible) may be reached before the consolute temperature. Similarly for liquids with an upper C.S.T., one or both of the liquids may freeze before the lower C.S.T. is attained. 

Many pairs of partially miscible liquids possess neither a lower nor an upper C.S.T. for reasons outlined in the previous paragraph. Thus consider the two liquid phases from the two components water and diethyl ether. Upon cooling the system at constant pressure, a point will be reached when a third phase, ice, will form, thus rendering the production of a lower C.S.T. impossible, likewise, if the temperature of the two layers is raised, the critical point for the ether rich layer will be reached while the two liquid phases have different compositions. Above the critical point the ether-rich layer will be converted into vapour, and hence the system will be convert into a water rich liquid and an ether rich vapour the upper C.S.T. cannot therefore be attained. 

Influence of added substances upon the critical solution temperature. For a given pressure the C.S.T. is a perfectly defined point. It is, however, affected to a very marked extent by the addition of quite a small quantity of a foreign substance (impurity), which dissolves either in one or both of the partially miscible liquids. The determination of the consolute temperature may therefore be used for testing the purity of liquids. The upper consolute temperature is generally employed for this purpose. 

If the system represented by the point D be heated, the solid A will disappear and two partially miscible liquids will remain. The curve ETD is the ordinary solubility curve for two partially miscible liquids (compare Section 1,8, Fig. I, 8, 1). As the temperature rises, the mutual... 

The first system is characterized by a partial miscibility of the liquid phases, the second one is instable with incongruent melting points at -54... 

Robbins ( Oquid-Liquid Extraction, in Schweitzer, Handbook of Separation Techniques for Chemical Engineers, McGraw-Hill, New York, 1979, sec. 1.9) reported that most liquid-liquid extrac tion systems can be treated as having either (A) immiscible solvents, (B) partially miscible solvents with a low solute concentration in the extract, or (C) partially miscible solvents with a high solute concentration in the extract. 

Bonhote and co-workers [10] reported that ILs containing triflate, perfluorocar-boxylate, and bistrifylimide anions were miscible with liquids of medium to high dielectric constant (e), including short-chain alcohols, ketones, dichloromethane, and THF, while being immiscible with low dielectric constant materials such as alkanes, dioxane, toluene, and diethyl ether. It was noted that ethyl acetate (e = 6.04) is miscible with the less-polar bistrifylimide and triflate ILs, and only partially miscible with more polar ILs containing carboxylate anions. Brennecke [15] has described miscibility measurements for a series of organic solvents with ILs with complementary results based on bulk properties. 

Addition of co-solvents can also change the co-miscibility characteristics of ionic liquids. As an example, the hydrophobic [BMIM][PFg] salt can be completely dissolved in an aqueous ethanol mixture containing between 0.5 and 0.9 mole fraction of ethanol, whereas the ionic liquid itself is only partially miscible with pure water or pure ethanol [13]. The mixing of different salts can also result in systems with modified properties (e.g., conductivity, melting point). 

Renon s [58] technique for predicting vapor-liquid relationships is applicable to partially miscible systems as well as those with complete miscibility. This is described in the reference above and in Reference 54. 

If two partially miscible liquids are shaken together, two saturated solutions, one of A in B, and the other of B in A, will in general result. If now a third substance is added, which dissolves in either pure liquid, it will go into solution in both layers. Thus, if ether and water are agitated together, the lower layer will consist mainly of water, and the upper mainly of ether. If iodine is now added, it will nearly all go to the ethereal layer, but a little dissolves in the aqueous layer, as is evident from the colour. 

Partially Miscible Liquids (water and ether), which exhibit a total pressure practically equal to that of the more volatile component (ether). 

Vapour-Pressure Curves of Partially Miscible Liquids. 

Liquids, miscible, 382 partially miscible, 406 immiscible, 409 Litre-atmosphere, 48 Luther s rule, 480... 

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