Liquid–liquid phase behaviour,liquid–liquid density,and interfacial tension of multicomponent systems at 298 K

Experimental liquid–liquid phase diagrams are presented for the multicomponent systems isooctane–benzene–(80 mass% methanol + 20 mass% water)–5 mass% isobutyl alcohol (2-methyl-1-propanol) and isooctane–benzene–(80 mass% methanol + 20 mass% water)–15 mass% isobutyl alcohol, at 298.15 K. The density and interfacial tension of conjugate phases of concentration located in the isothermal binodal have been determined at 298.15 K for the partially miscible systems: isooctane–benzene–methanol, isooctane–benzene–(80 mass% methanol + 20 mass% water), isooctane–benzene–(80 mass% methanol + 20 mass% water)–5 mass% isobutyl alcohol, and isooctane–benzene–(80 mass% methanol + 20 mass% water)–15 mass% isobutyl alcohol. The experimental tie-line data define the binodal or coexistence curve of the two studied multicomponent systems and depending on the initial isobutyl alcohol concentration the liquid–liquid phase diagram is either of type II, with low alcohol concentration, or type I, with high concentration of alcohol, which is a clear indication that the solubility of the partially miscible systems is greatly enhanced via the co-solvency phenomenon. It is observed that both the density of each conjugate phase and the interfacial tension of each tie-line are valuable indicators of the degree of solubility of the multicomponent systems. Furthermore the experimental tie-lines data were correlated with the NRTL and UNIQUAC solution models with satisfactory quantitative results.     

Liquid–liquid equilibria of the ternary system water + acetic acid + dimethyl adipate

Liquid–liquid equilibrium (LLE) data of water + acetic acid + dimethyl adipate have been determined experimentally at 298.15, 308.15 and 318.15 K. Complete phase diagrams were obtained by determining binodal curve and tie-lines. The reliability of the experimental tie-line data was confirmed by using the Othmer-Tobias correlation. UNIFAC and modified UNIFAC models were used to predict the phase equilibrium in the system using the interaction parameters determined from experimental data of CH₂, CH₃COO, CH₃, COOH, and H₂O functional groups. Distribution coefficients and separation factors were evaluated for the immiscibility region.     

Liquid phase equilibria of (water + propionic acid + oleyl alcohol) ternary system at several temperatures

(Liquid–liquid) equilibrium (LLE) data are investigated for mixtures of (water + propionic acid + oleyl alcohol) at 298.15, 308.15 and 318.15 K and atmospheric pressure. The solubility curves and the tie-line end compositions of liquid phases at equilibrium were determined, and the tie-line results were compared with the data predicted by the UNIFAC method. The phase diagrams for the ternary mixtures including both the experimental and correlated tie-lines are presented. The distribution coefficients and the selectivity factors for the immiscibility region are calculated to evaluate the effect of temperature change. The reliability of the experimental tie-lines was confirmed by using Othmer–Tobias correlation. It is concluded that oleyl alcohol may serve as an adequate solvent to extract propionic acid from its dilute aqueous solutions. The UNIFAC model correlates the LLE data for 298.15, 308.15 and 318.15 K with a root mean square deviation of 5.89, 6.46, and 6.69%, respectively, between the observed and calculated mole concentrations.     

Liquid–liquid equilibria for pseudo-ternary systems: (Sulfolane + 2-ethoxyethanol) + octane + toluene at 293.15 K

Liquid–liquid equilibrium data, both binodal and tie lines are presented for the pseudo-ternary systems: {(sulfolane + 2-ethoxyethano) (1) + octane (2) + toluene (3)} at 293.15 K. The experimental liquid–liquid equilibrium data have been correlated using NRTL and UNIQUAC models, and the binary interaction parameters of these components have been presented. The correlated tie lines have been compared with the experimental data. The comparisons indicate that both NRTL and UNIQUAC models satisfactorily correlated the equilibrium compositions. The tie-line data of the studied systems also were correlated using the Hand method.     

Quaternary Liquid–Liquid Equilibria for Aqueous Systems Containing Dimethyl Carbonate at 298.15 K

Experimental tie-line data for two ternary systems, water + dimethyl carbonate + methanol or ethanol, and two quaternary systems, water + dimethyl carbonate + toluene + methanol or ethanol were investigated at 298.15 K and atmospheric pressure. The experimental liquid–liquid equilibrium data were correlated using a modified UNIQUAC activity coefficient model with binary and ternary as well as quaternary parameters. The calculated results were further compared with those obtained from an extended UNIQUAC model.     

Isobaric vapor–liquid equilibria for acetone + methanol + lithium nitrate at 100 kPa

Isobaric vapor–liquid equilibria for the ternary system acetone + methanol + lithium nitrate have been measured at 100 kPa using a recirculating still. The addition of lithium nitrate to the solvent mixture produced an important salting-out effect and the azeotrope tended to disappear for small contents of salt. The experimental data sets were fitted with the electrolyte NRTL model and the parameters of the Mock's model were estimated. These parameters were used to predict the ternary vapor–liquid equilibrium which agreed well with the experimental one.     

Measurement and correlation of excess molar enthalpies for the partially miscible systems 2-butanone+water and methanol+hexane

The excess molar enthalpies of the systems 2-butanone+water and methanol+hexane which show limited miscibility were measured at 283.15–298.15 K using a flow microcalorimeter. The experimental data were correlated using three local-composition (LC) models (NRTL, modified Wilson and modified EBLCM). These models were also used to predict the liquid–liquid equilibria for both systems with the parameters obtained from the excess enthalpy data.     

Liquid–liquid equilibria of ternary systems (water + carboxylic acid + cumene) at 298.15 K

(Liquid–liquid) equilibrium data for the ternary systems [water + formic acid or acetic acid or propionic acid + cumene (2-phenylpropane, isopropylbenzene)] at 298.15 K are reported. Complete phase diagrams were obtained by determining solubility and the tie-line data. The reliability of the experimental tie-lines was determined through the Othmer–Tobias plots. Distribution coefficients and separation factors were evaluated for the immiscibility region. The tie-line data were compared with the results predicted by the UNIFAC method.     

Liquid–liquid equilibria for binary systems of tert-amyl ethyl ether (TAEE), isopropyl tert-butyl ether (IPTBE) and di-sec-butyl ether (DSBE) with water and for ternary systems with methanol or ethanol

The liquid–liquid equilibria for binary systems of tert-amyl ethyl ether (TAEE) + water, isopropyl tert-butyl ether (IPTBE) + water and di-sec-butyl ether (DSBE) + water are analytically determined in the temperature range 278.65–358 K. Additionally, tie-lines for six ternary systems of TAEE, IPTBE and DSBE with methanol and water or with ethanol and water are also measured at 298.15 K. All the measured binary and ternary data were correlated with the NRTL and UNIQUAC model. The reliability of the experimental tie-line data for ternary systems was ascertained by using the Othmer–Tobias correlation.     

Vapor–liquid equilibria and excess volumes of the binary systems ethanol + ethyl lactate, isopropanol + isopropyl lactate and n-butanol + n-butyl lactate at 101.325 kPa

Isobaric vapor–liquid equilibrium data have been experimentally determined at 101.3 kPa for the binary systems ethanol + ethyl lactate, isopropanol + isopropyl lactate and n-butanol + n-butyl lactate. No azeotrope was found in any of the systems. All the experimental data reported were thermodynamically consistent according to the point-to-point method of Fredenslund. The activity coefficients were correlated with the NRTL and UNIQUAC liquid-phase equations and the corresponding binary interaction parameters are reported. The densities and derived excess volumes for the three mixtures are also reported at 298.15 K.     

(Liquid + liquid) equilibria of (water + propionic acid + alcohol) ternary systems

(Liquid + liquid) equilibrium (LLE) data of the solubility (binodal) curves and tie-line end composition were examined for mixtures of {water (1) + propionic acid (2) + octanol or nonanol or decanol or dodecanol (3)} at T = 298.15 K and 101.3 ± 0.7 kPa. The reliability of the experimental tie-line data was confirmed by using the Othmer-Tobias correlation. The LLE data of the ternary systems were predicted by UNIFAC method. Distribution coefficients and separation factors were evaluated for the immiscibility region.     

A study on the liquid–liquid equilibria of 1-alkyl-3-methylimidazolium hexafluorophosphate with ethanol and alkanes

This work demonstrates the ability of the 1-alkyl-3-methylimidazolium hexafluorophosphate to act as an extraction solvent in petrochemical processes for the removal of alkanes from their azeotropic mixture with ethanol. LLE (liquid–liquid equilibrium) of the ternary systems hexane + ethanol + 1-hexyl-3-methylimidazolium hexafluorophosphate (HMIM PF₆) or 1-octyl-3-methylimidazolium hexafluorophosphate (OMIM PF₆) and heptane + ethanol + OMIM PF₆ are carried out at 298.15 K and atmospheric pressure. Experimental liquid–liquid data are correlated by using different equations. The solute distribution ratio and the selectivity, determined from tie-line data, suggest the efficiency of the ILs used as solvents. A comparison with other IL, in terms of solvent capacity, is included. The liquid–liquid extraction process is simulated by using conventional software and the obtained results are shown.     

Liquid–Liquid Equilibria of Some Aliphatic Alcohols + Disodium Hydrogen Citrate + Water Ternary Systems at 298.15 K

In this paper, the liquid?Cliquid equilibria for 1-propanol, 2-propanol or 2-methyl-2-propanol + disodium hydrogen citrate aqueous two-phase systems at 298.15 K were studied. The experimental binodal curves at 298.15?K are reported, and the parameters of the Merchuk equation, modified as a nonlinear function of mixed solvent properties and used for the simultaneous correlation of the experimental binodal data. Moreover, the salting-out ability of different salts and different alcohols with different anions is discussed. Additionally, experimental tie-line data are reported at 298.15 K. The generalized electrolyte-NRTL model of the mixed solvent electrolyte systems (e-NRTL) satisfactorily used for the correlation of the tie-line compositions; restricted binary interaction parameters were also obtained.     

Phase equilibria of liquid (water + butyric acid + oleyl alcohol) ternary system

(Liquid + liquid) equilibrium (LLE) data for the ternary system of (water + butyric acid + oleyl alcohol) at T = (298.15, 308.15, and 318.15) K are reported. Complete phase diagrams were obtained by determining solubility and the tie-line data. The reliability of the experimental tie lines was confirmed by using Othmer-Tobias correlation. The UNIFAC method was used to predict the phase equilibrium data. The phase diagrams for the ternary mixtures including both the experimental and correlated tie lines are presented. Distribution coefficients and separation factors were evaluated for the immiscibility region. A comparison of the solvent extracting capability was made with respect to distribution coefficients, separation factors, and solvent-free selectivity bases for T = (298.15, 308.15, and 318.15) K. It is concluded that oleyl alcohol may serve as an adequate solvent to extract butyric acid from its dilute aqueous solutions.     

Liquid–Liquid Equilibria of Oxygenate Fuel Additives with Water: Two Quaternary Aqueous Systems of Diisopropyl Ether + 2,2,4-Trimethylpentane with Methyl <Emphasis Type="Italic">tert</Emphasis>-Butyl Ether or Toluene

Experimental tie-line data for two quaternary systems, water + diisopropyl ether + 2,2,4-trimethylpentane + methyl tert-butyl ether or toluene, were investigated at 298.15 K and atmospheric pressure. The experimental liquid–liquid equilibrium data were correlated using a modified UNIQUAC activity coefficient model with ternary and quaternary parameters, in addition to the binary ones. The calculated results were further compared with those obtained with an extended UNIQUAC model from Nagata [Fluid Phase Equilib. 54, 191–206 (1990)].     

Vapor–liquid equilibria and excess molar volumes of diethylamine(1) + acetone(2) and diethylamine(1) + acetonitrile(2) binary systems

Isothermal vapor–liquid equilibrium (VLE) data for diethylamine(1)+acetone(2) and diethylamine(1)+acetonitrile(2) binary systems were obtained at 323.15 K by dynamic method. Excess molar volumes at 298.15 K for these systems were measured by a dilution dilatometer. VLE data have been checked for thermodynamic consistency and correlated by Wilson, NRTL and UNIQUAC equations. UNIFAC group interaction parameters for CH₂NH---CH₃CO and CH₂NH---CH₃CN pairs are also obtained from the experimental VLE data.     

Isothermal vapour–liquid equilibria in the ternary system tert-butyl methyl ether + tert-butanol + 2,2,4-trimethylpentane and the three binary subsystems

Vapour–liquid equilibrium data are reported for the ternary tert-butyl methyl ether+tert-butanol+2,2,4-trimethylpentane and the three binary tert-butyl methyl ether+tert-butanol, tert-butyl methyl ether+2,2,4-trimethylpentane, tert-butanol+2,2,4-trimethylpentane subsystems. The data were measured isothermally at 318.13, 328.20, and 339.28 K covering pressure range 15–100 kPa. Azeotropic data are presented for the tert-butanol+2,2,4-trimethylpentane system. Molar excess volumes at 298.15 K are given for the three binary systems. The binary vapour–liquid equilibrium data were correlated using Wilson, NRTL, and Redlich–Kister equations; the parameters obtained were used for calculation of phase behaviour in ternary system and for subsequent comparison with experimental data.     

Vapour–liquid equilibria, azeotropic data, excess enthalpies, activity coefficients at infinite dilution and solid–liquid equilibria for binary alcohol–ketone systems

Isothermal vapour–liquid equilibria (VLE), solid–liquid equilibria and excess enthalpies have been measured for the systems cyclohexanone + cyclohexanol and 2-octanone + 1-hexanol. Additionally in this paper binary azeotropic data at different pressures for 1-pentanol + 2-heptanone and 1-hexanol + 2-octanone have been determined with the help of a wire band column. Furthermore activity coefficients at infinite dilution for methanol, ethanol, 1-butanol and 1-propanol in 2-octanone at different temperatures have been measured with the help of the dilutor technique. These data together with literature data for alcohol–ketone systems were used to fit temperature-dependent group interaction parameters for the group contribution method modified UNIFAC (Dortmund) and the group contribution equation of state VTPR.     

Phase equilibria of (water + levulinic acid + dibasic esters) ternary systems

Liquid–liquid equilibrium (LLE) data of the solubility (binodal) curves and tie-line end compositions were examined for mixtures of {(water (1) + levulinic acid (2) + dimethyl succinate or dimethyl glutarate or dimethyl adipate (3)} at 298.15 K and 101.3 ± 0.7 kPa. The reliability of the experimental tie-line data was confirmed by using the Othmer–Tobias correlation. The LLE data of the ternary systems were predicted by UNIFAC method. The LLE data were correlated fairly well with UNIQUAC and NRTL models, indicating the reliability of the UNIQUAC and NRTL equations for these ternary systems. The best results were achieved with the NRTL equation, using non-randomness parameter (α = 0.3) for the correlation. Distribution coefficients and separation factors were measured to evaluate the extracting capability of the solvents.     

Revision of the volumetric method for measurements of liquid–liquid equilibria in binary systems

A theoretical analysis of the accuracy of the volumetric method for the determination of liquid–liquid equilibrium was carried out. The results show that, under certain conditions, this method can be used to investigate systems showing relatively small mutual solubilities. Relations were derived to estimate standard deviations of the equilibrium compositions determined by the volumetric method.

In the experimental part of the work, an apparatus for measurements of mutual solubilities of liquids was constructed. A procedure that enabled us to determine precisely volumes of liquid phases was developed. This procedure and apparatus present the advantage that relatively small amounts of samples are required (approximately 2 × 20 ml). Theoretical conclusions concerning the applicability of the volumetric method were checked by measuring mutual solubilities at 303.15 K in systems methylcyclohexane + N,N-dimethylformamide, 1-butanol + water and dimethyl phthalate + water. Further, the method was used to measure systematically the liquid–liquid equilibrium in systems ethyl acetate + ethylene glycol and phenyl acetate + ethylene glycol at temperatures from 293 to 323 K. Data for these systems were acquired by means of other methods as well and a good agreement was observed on comparison.