Immiscibility Region Research Articles

Liquid–Liquid Equilibrium in Ternary Systems Present in Biodiesel Purification from Soybean Oil and Castor Oil at (298.2 and 333.2) K

Liquid–liquid equilibrium (LLE) data for the soybean oil biodiesel (BIO-SO) + ethanol + water and castor oil biodiesel (BIO–CO) + ethanol + water systems at (298.2 and 333.2) K and atmospheric pressure were determined by gas chromatography and volumetric Karl Fischer titration. The degree of consistency of the experimental LLE data was ascertained by applying the Hand and Othmer-Tobias correlations. Ethanol distribution coefficients and water selectivity were evaluated for the immiscibility region. The experimental data were also compared with the values correlated by the NRTL and UNIQUAC activity coefficient models. For all systems studied, the average deviations found for the UNIQUAC model are larger than those found for the NRTL model.

Ternary liquid–liquid equilibrium data for the (water + butyric acid + n-hexane or n-hexanol) systems at T = (298.2, 308.2, and 318.2) K

In this study, liquid–liquid equilibrium (LLE) values for the (water+butyric acid+n-hexane) and (water+butyric acid+n-hexanol) ternary systems were experimentally obtained at T=(298.2, 308.2, and 318.2) K and atmospheric pressure for the first time. The cloud point method was used to determine the solubility data. The concentration of each phase was determined by acidimetric titration, the Karl-Fischer technique, and refractive index measurements. Both the ternary systems exhibit type-1 behaviour of LLE. The experimental tie-line data were correlated using the UNIQUAC and NRTL models. The Othmer–Tobias and the Hand correlation equations were used to check the consistency of the obtained tie-line data for each system. Distribution coefficients and separation factors were calculated over the immiscibility regions. Finally, the Katritzky LSER multi-parameter equation was used to correlate the separation factors.

Thermodynamic Study of the Liquid-Liquid Equilibrium Water-Chloroform-Acetic Acid

Experimental liquid-liquid equilibria of the water-chloroform-acetic acid system were studied at temperature of 298.15 K. Complete phase diagrams were obtained by determining solubility and tie-line data. Data for the construction of ties-lines were determined by preparing mixtures of known mole fraction of components in the region of formation of two phases. Separation factors were evaluated for the immiscibility region.

Tie-line data for the aqueous solutions of phenol with organic solvents at T = 298.2 K

Solubility and tie-line data for the (water+phenol+1-octanol), (water+phenol+cyclohexanone), (water+phenol+2-ethyl-1-hexanol), and (water+phenol+isobutyl acetate) ternary systems were obtained at T=298.2K and atmospheric pressure. The solubility data were determined by the cloud point method. The tie-line data were experimentally determined by the Karl-Fischer and refractive index measurement methods. The ternary systems exhibit type-2 LLE behaviour. Distribution coefficients and separation factors were calculated for the immiscibility region to evaluate the extracting capability of the solvents. For each system, the Othmer–Tobias equation was used to ascertain the quality of the LLE results. The experimental values were correlated using the NRTL and UNIQUAC models, and the binary interaction parameters were calculated.

Experimental study of phase equilibria in aqueous mixtures of phosphoric acid with isoamyl acetate and methyl isoamyl ketone at T = (298.2, 308.2, and 318.2) K

This study demonstrates the experimental solubility and tie-line data for (water+phosphoric acid+isoamyl acetate or methyl isoamyl ketone) ternary systems at T=(298.2, 308.2, and 318.2)K and atmospheric pressure for the first time. The concentration of each phase was determined by acidimetric titration, the Karl Fischer technique, and refractive index measurements. The experimental tie-line data were correlated using the UNIQUAC and NRTL models. The reliability of the experimental data was determined through the Othmer–Tobias and Hand plots. Distribution coefficients and separation factors were evaluated over the immiscibility regions.

(Liquid + liquid) equilibria of aqueous solutions of butyric acid with n-heptane and toluene at T = (298.2, 308.2, and 318.2) K

Solubility and tie line data for the (water+butyric acid+n-heptane) and (water+butyric acid+toluene) ternary systems were determined at T=(298.2, 308.2, and 318.2)K and atmospheric pressure. Solubility data were obtained by the cloud-point titration method. The concentration of each phase was determined by acidimetric titration, the Karl-Fischer technique, and refractive index measurements. The experimental tie-line data were correlated using the UNIQUAC and NRTL thermodynamic models. The reliability of the experimental data was determined through the Othmer–Tobias and Hand plots. Distribution coefficients and separation factors were evaluated for each system over the immiscibility regions.

Effects of liquid separation on the microstructure formation and hardness behavior of undercooled Cu–Co alloy

Applying a melt-fluxing method, a substantial degree of undercooling up to 220 K has been obtained for Cu50Co50 immiscible alloy and the non-equilibrium solidification microstructure is investigated considering the successive processes of undercooling, liquid separation, non-equilibrium and near-equilibrium solidification. For samples undercooled by 62, 79 and 105 K, grain refinement occurs and becomes more serious without the occurrence of liquid separation and peritectic transformation. In contrast, metastable liquid demixing occurs upon the undercooling reaching 125 K, and it proceeds completely with the further increase of undercooling to 188 and 220 K, which can be ascribed to the sufficient time through the immiscible region. After liquid separation, versatile solidification microstructure for Co-rich and Cu-rich regions can be observed due to the different non-equilibrium effect. Moreover, second liquid separation becomes more serious for higher undercooling because of the enhanced immiscible effect. Finally, the solute content of primary Co-rich phase was analyzed with the consideration of solute trapping and liquid immiscible effects, which gives an excellent explanation for the variation of hardness behavior.

Experimental determination and correlation of tie line data for the system (water + butyric acid + methylcyclohexane) at four temperatures

This study demonstrates the experimental solubility and tie line data for (water+butyric acid+methylcyclohexane) system at temperatures of 298.2, 308.2, 318.2, and 328.2K and atmospheric pressure. The cloud-point titration method was used to determine solubility data (binodal curves). The tie line data were determined by acidimetric titration, the Karl–Fischer technique, and refractive index measurements. The investigated ternary system exhibits type-1 behavior of liquid–liquid equilibrium. The thermodynamic models UNIQUAC and NRTL were used to correlate the experimental tie-line data. The consistency of the tie-line data was determined through the Othmer Tobias and Hand correlation equations. Distribution coefficients and separation factors were calculated over the immiscibility regions. A comparison of the extracting capability of the solvent at different temperatures was made with respect to separation factors. The Katritzky multiparameter scale was applied to correlate distribution coefficients and separation factors in this ternary system.

Ternary liquid–liquid phase equilibria of (water–carboxylic acid–1-undecanol) systems at 298.15 K

Liquid–liquid equilibrium (LLE) data for the ternary systems of (water–formic acid–1-undecanol), (water–acetic acid–1-undecanol), (water–propionic acid–1-undecanol), (water–butyric acid–1-undecanol), and (water–valeric acid–1-undecanol) were investigated at 298.15K and atmospheric pressure. Complete phase diagrams were obtained by determining solubility and tie-line data. The tie-line data were compared with the results predicted by the UNIFAC, modified UNIFAC (Dortmund), and modified UNIFAC (Lyngby) methods and correlated by means of UNIQUAC model. The reliability of the experimental tie-line data was confirmed by using the Othmer–Tobias correlation. Distribution coefficients and separation factor values were evaluated for the immiscibility region.

Structure and properties of melt-quenched manganese- and nickel-diamagnetic element systems

The choice of melt quenching temperatures from a single-phase region is justified by theoretical calculations of the positions of maxima of the immiscibility regions in liquid Mn-Pb, Ni-Pb, and Mn-Bi alloys, and the influence of an alloy composition and a high cooling rate on the phase formation in these alloys and their magnetic properties is studied. The coercive force of an Mn-Bi alloy is shown to be increased by increasing the melt quenching temperature to 1923 K to form nanocrystals of the α-MnBi phase.

Tie-line data for aqueous mixtures of butyric acid with isobutyl acetate at various temperatures

Experimental liquid-liquid equilibrium (LLE) data for the system of (water+butyric acid+iso-butyl acetate) were obtained at T=(298.2, 303.2, 308.2, and 313.2) K and atmospheric pressure. This ternary system exhibits type-1 behavior of LLE. The experimental tie-line data were correlated using the UNIQUAC and NRTL models. The reliability of the experimental tie-line data was determined by applying the Othmer-Tobias and Hand correlations. Distribution coefficients and separation factors were calculated over the immiscibility regions.

(Liquid + liquid) equilibria for the ternary system of (N-formylmorpholine + ethylbenzene + 2,2,4-trimethylpentane) at temperatures (303.15, 313.15, and 323.15) K

Being an extraction solvent, N-formylmorpholine (NFM) is widely used to separate aromatic and aliphatic hydrocarbons. In order to get the LLE data and the interaction parameters of the ternary system of (NFM+ethylbenzene+2,2,4-trimethylpentane), the (liquid+liquid) equilibrium (LLE) data were measured for the ternary system under atmospheric pressure and at temperatures (303.15, 313.15, and 323.15) K in this work. The data can also demonstrate the ability for NFM to remove ethylbenzene from the mixture with 2,2,4-trimethylpentane. The complete phase diagrams were obtained by determining the solubility and the tie-line data. The tie-line compositions were correlated by Othmer–Tobias equation. The correlation factors r2 are bigger than 0.981. The universal quasi-Chemical activity coefficient (UNIQUAC) and the nonrandom two liquids equation (NRTL) were used to calculate the phase equilibrium data of the system with the interaction parameters fitted from the experimental data. It is found that both UNIQUAC and NRTL models could provide good correlations for the LLE data of the system. The root mean square deviation (RMSD) values for the NRTL and UIQUAC models are less than 0.0083 at all temperatures. In addition, the distribution coefficients, separation factors and selectivity were evaluated for the immiscibility region and the extracting capability of the solvents.

Liquid–liquid equilibria of water + 2,3-butanediol + isobutanol at several temperatures

(Liquid–liquid) equilibrium (LLE) data for the ternary system of water+2,3-butanediol+isobutanol have been determined at 298.2, 308.2 and 318.2K and atmospheric pressure. Solubility curves were obtained by the cloud point method, while compositions of tie-lines were obtained by gas chromatography. Distribution coefficients and separation factors have been evaluated for the immiscibility region. The reliability of the experimental tie-lines has been confirmed by using Othmer–Tobias correlation. The LLE data of the ternary systems have been correlated by both the NRTL model and UNIQUAC model. Root mean square deviations between experimental and calculated compositions were considered satisfactory.

Miscibility of 1-alkyl-3-methylimidazolium bis(trifluoromethyl)sulfonyl imides with benzene and deuterated benzene

The liquid–liquid phase diagrams of 1-alkyl-3-methylimidazolium bis(trifluoromethyl)sulfonyl imides ([CnMIM][NTf2], n=6,7,8) with C6H6 and C6D6 have been obtained. As the length of the alkyl chain decreases, the immiscible region is significantly enlarged and the phase diagram changes its shape from the most popular type that exhibits upper critical solution temperature to the “hourglass” type. The values of isotope effects on miscibility increase when the carbon chain length decreases and reach 4.4K, 5.5K, 7.1K and even 50.1K for n=12,10,8,7, respectively.

Binodal curves and tie line data of the water–propionic acid–iso-butyl acetate at T = (298.2, 308.2, 318.2, and 328.2) K

Experimental liquid–liquid equilibrium (LLE) data for the system of (water+propionic acid+iso-butyl acetate) were obtained at T=(298.2, 303.2, 308.2, and 313.2)K and atmospheric pressure. This ternary system exhibits type-1 behavior of LLE. The experimental tie-line data were correlated using the UNIQUAC and NRTL models. The reliability of the experimental tie-line data was determined by applying the Othmer–Tobias and Hand correlations. Distribution coefficients and separation factors were calculated over the immiscibility regions. The influence of temperature on the equilibrium characteristics and separation factor was found to be minor at the temperatures studied. The average rmsd values between the observed and calculated mass fractions were 0.92% and 0.98% for the UNIQUAC and NRTL models, respectively. The thermodynamic models showed good agreement to the experimental results.

Ternary (liquid + liquid) equilibria for β-citronellol in aqueous alcohol at different temperatures

(Liquid+liquid) equilibrium (LLE) data for {water (1)+methanol (2)+β-citronellol (3)} and {water (1)+ethanol (2)+β-citronellol (3)} ternary systems at T=(283.15, 298.15, and 313.15)K are reported. The immiscible region of (water+methanol+β-citronellol) system was found to be larger than that for the ethanol system at the same temperature. The effect of the temperature on the ternary (liquid+liquid) equilibria was examined and discussed. The experimental (liquid+liquid) equilibrium data have been satisfactorily represented by using extended UNIQUAC and modified UNIQUAC models.

(Liquid + liquid) equilibrium data of (water + phosphoric acid + solvents) systems at T = (308.2 and 318.2) K

Ternary equilibrium data for the mixtures of {water+phosphoric acid+organic solvent (cyclohexane, methylcyclohexane, and toluene)} were determined at T=(308.2 and 318.2)K and atmospheric pressure. Solubility data were determined by the cloud-point titration method. In order to obtain the tie-line data, the concentration of each phase was determined by acidimetric titration, the Karl–Fischer technique, and refractive index measurements. The experimental tie-line data were correlated using the UNIQUAC and NRTL models. The reliability of the experimental data was determined through the Othmer–Tobias and Hand plots. Distribution coefficients and separation factors were evaluated over the immiscibility regions. The Katritzky LSER model was applied to correlate distribution coefficients and separation factors in these ternary systems.

Phase equilibria and critical phenomena in the Li2SO4-K2SO4-H2O system at 380-400°C: Specifics of ternary phase diagrams with type 2 (p-Q) boundary subsystems

Phase equilibria in Li2SO4-KLiSO4-H2O and K2SO4-KLiSO4-H2O ternary systems, which contain type 2 salts (Li2SO4, KLiSO4, and K2SO4), were studied at temperature of 380 to 400°C and pressures up to 90 MPa. Homogeneous supercritical (SC) fluids, which propagate from type 2 water-salt subsystems into a three-component region, change to heterogeneous liquid-phase equilibria as a result of the transformation of metastable immiscibility regions into stable equilibria. The heterogenization of SC fluids starts with critical phenomena in saturated solutions. In the K2SO4-KLiSO4-H2O system, the monovariant critical curve $(l_1 = l_2 - s_{KLiSO_4 } )$ reveals a temperature maximum at the invariant double critical end point (DCE).

Phase equilibria in the Cu-Tl-Ge system

The Cu-Tl-Ge system has been studied by DTA and powder X-ray diffraction. Several polythermal sections, the isothermal section at 400 K, and the liquidus surface projection have been constructed for the phase diagram of this system. Primary phase fields and the types and coordinates of invariant and monovariant equilibria have been determined. An immiscibility region of the Cu-Tl binary subsystem considerably (up to 60 at % Ge) protrudes into the triangular diagram and crosses peritectic and eutectic curves that originate from the Cu-Ge subsystem. This gives rise to a number of four-phase monotectic equilibria in the ternary system. Crystallization ends with peritectic equilibrium and eutectic equilibria, which are all degenerate in the vicinity of thallium. Intermediate ternary phases are not formed in the system. Solubilities in the initial components and in binary phases of the Cu-Ge system do not exceed 0.5 at %.

Structural variation and optical properties of ZnO–LiGaO2 pseudo-binary system

The structural variation in the x(LiGaO2)1/2(1−x)ZnO alloy system was studied by powder XRD, TEM-SAD and Raman spectroscopy. It was elucidated that the phase varied upon increasing the alloying level was the wurtzite-type for 0≤x<0.2, the Zn2LiGaO4-type for 0.2≤x≤0.5 and the β-LiGaO2-type for 0.8≤x≤1, and the 0.5<x<0.8 region was the immiscible region of ZnO with LiGaO2. The solubility limit of LiGaO2 in ZnO was explained by the c0/a0 ratio based on the fact that there is no binary wurtzite phase for a c0/a0 less than 1.6. The optical phonons of wurtzite and its derived phase were simply explained by the lattice shrinkage and reduced mass upon reduction the alloying of ZnO with LiGaO2. The bowing parameter of the optical band gap of y(Zn2LiGaO4)1/4(1−y)ZnO was determined to be 0.67eV. The value was very low, and it was related to the small lattice and chemical mismatches between the Zn2LiGaO4 and ZnO.