Ternary (liquid + liquid) equilibria for mixtures of (methanol + aniline + n-octane or n-dodecane) at T = 298.15 K

(Liquid + liquid) equilibrium (LLE) data for the ternary mixtures of (methanol + aniline + n-octane) and (methanol + aniline + n-dodecane) at T = 298.15 K and ambient pressure are reported. The compositions of liquid phases at equilibrium were determined and the results were correlated with the UNIQUAC and NRTL activity coefficient models. The partition coefficients and the selectivity factor of methanol for the extraction of aniline from the (aniline + n-octane or n-dodecane) mixtures are calculated and compared. Based on these comparisons, the efficiency of methanol for the extraction of aniline from (aniline + n-dodecane) mixtures is higher than that for the extraction of aniline from (aniline + n-octane) mixtures. The phase diagrams for the ternary mixtures including both the experimental and correlated tie lines are presented. From the phase diagrams and the selectivity factors, it is concluded that methanol may be used as a suitable solvent in extraction of aniline from (aniline + n-octane or n-dodecane) mixtures.     

Excess Gibbs energies and excess molar volumes for binary mixtures: (2-pyrrolidone + water), (2-pyrrolidone + methanol), and (2-pyrrolidone + ethanol) at the temperature 313.15 K

Total vapour pressures and excess molar volumes, measured at the temperature 313.15 K, are reported for three binary mixtures (2-pyrrolidone + water), (2-pyrrolidone + methanol) and (2-pyrrolidone + ethanol). The results are compared with previously obtained data for binary mixtures (amide + A), where amide=N-methylformamide, N,N-dimethylformamide and N-methylacetamide, and A= water, methanol, and ethanol.     

Evaluation of (vapor + liquid) equilibria for the binary systems (1-octanol + cyclohexane) and (1-octanol + n-hexane), at low alcohol compositions

Isobaric (vapor + liquid) equilibrium at p = 101.32 kPa of pressure has been determined for the systems (1-octanol + cyclohexane) and (1-octanol + n-hexane), at low alcohol mole fractions. These data were satisfactorily correlated, using ASPEN PLUS^® commercial software, with Wilson, NRTL, and UNIQUAC activity coefficient models to obtain the binary interaction parameters of both mixtures. Also, UNIFAC group contribution method was employed to predict the equilibrium of both mixtures. With regression values an accurate knowledge of (vapor + liquid) equilibrium for both mixtures can be reached in a range of 1-octanol mole fractions less than 0.1. UNIFAC method provides acceptable results for (1-octanol + n-hexane) system but not for (1-octanol + cyclohexane) system.     

Experimental and theoretical study of quaternary (liquid + liquid) equilibria for mixtures of (methanol or water + ethanol + toluene + n-decane)

Experimental (liquid + liquid) equilibrium data were obtained for the extraction of toluene from n-decane by mixed-solvents (ethanol + water) and (ethanol + methanol) at three temperatures (298.15, 303.15, and 313.15) K and ambient pressure.The measured tie-line data for two quaternary mixtures of {(ethanol +  water) + toluene + n-decane} and {(ethanol + methanol) + toluene + n-decane} are presented. The experimental quaternary (liquid + liquid) equilibrium data have been correlated using the NRTL activity coefficient model to obtain the binary interaction parameters of these components. The NRTL models predict the equilibrium compositions of the quaternary mixtures with small deviations. The partition coefficients and the selectivity factor of the mixed-solvents used were calculated and presented. From our experimental and calculated results, we conclude that for the extraction of toluene from n-decane mixtures the mixed-solvent (ethanol + methanol) has a higher selectivity factor than the other mixed-solvent at the three temperatures studied.     

Density and surface tension variation with temperature for n-nonane + 1-hexanol

New experimental densities and surface tensions for n-nonane + 1-hexanol at 288.15, 298.15 and 308.15 K are reported. Densities were measured with an Anton Paar DMA 4500 densimeter, and surface tensions using a Lauda TVT2 automated tensiometer, which uses the principle of the pending drop volume. The experimental data of pure liquids and mixtures have been used to calculate excess molar volumes and surface tension deviations of n-nonane + 1-hexanol as a function of mole fractions. A comparative study of these properties together with those available in the literature for the n-alkane + 1-alkanol mixtures has been performed. In addition, the magnitude of these experimental quantities is discussed in terms of the nature and type of intermolecular interactions in binary mixtures.     

Density measurements on binary mixtures (nitrogen + carbon dioxide and argon + carbon dioxide) at temperatures from (298.15 to 423.15) K with pressures from (11 to 31) MPa using a single-sinker densimeter

A single-sinker densimeter was built to specifically investigate the (p, ρ, T, x) behavior of fluid mixtures relevant for carbon capture and storage (CCS). Due to the use of a magnetic-suspension coupling, the densimeter enables measurements over the temperature range from (273.15 to 423.15) K with pressures up to 35 MPa. A comprehensive analysis of the experimental uncertainties was undertaken. The expanded uncertainties (k = 2) are 35 mK for temperature, 3.39 kPa for pressure, and 0.033% for density determination. The apparatus was used for measurements on the binary systems (nitrogen + carbon dioxide) and (argon + carbon dioxide). The compositions for both systems were (0.05 and 0.01) mole fraction carbon dioxide. Density measurements were carried out at temperatures from (298.15 to 423.15) K with pressures from (11 to 31) MPa. The relative combined expanded uncertainty (k = 2) in density was 0.15% for the (nitrogen + carbon dioxide) mixtures and 0.12% for the (argon + carbon dioxide) mixtures. A major contribution to this uncertainty emerged from the uncertainty in the gas mixture composition. The new experimental data were compared to the GERG-2008 equation of state (EOS) for natural-gas mixtures as implemented in the NIST REFPROP database and to the EOS-CG, another new Helmholtz energy model for CCS mixtures as implemented in the TREND software package of Ruhr-University Bochum. Relative deviations were mostly within 0.5%. The agreement of the new density values with the only available literature data closest to the composition range under study was better than 0.1%.     

Excess volumes of mixing in (N,N-dimethylacetamide + methanol + water) and (N,N-dimethylacetamide + ethanol + water) at the temperature 313.15 K

Precise excess volumes of mixing measurements at T = 313.15 K are reported over the whole composition range for binary mixtures: (N,N-dimethylacetamide + water), (N,N-dimethylacetamide + methanol), (N,N-dimethylacetamide + ethanol) and for the ternary mixtures (N,N-dimethylacetamide + methanol + water) and (N,N-dimethylacetamide + ethanol + water). For all the systems, large negative deviations from ideality are observed. The binary results have been fitted using the Redlich–Kister type polynomial. The possibility of predicting the ternary results from the binary ones was examined.     

(Vapour + liquid) equilibria and excess molar enthalpies for mixtures with strong complex formation. Trichloromethane or 1-bromo-1-chloro-2,2,2-trifluoroethane (halothane) with tetrahydropyran or piperidine

Isothermal (vapour  +  liquid) equilibria were measured for (trichloromethane  +  tetrahydropyran or piperidine) at T =  333.15 K and {1-bromo-1-chloro-2,2,2-trifluoroethane (halothane)  +  tetrahydropyran or piperidine} atT =  323.15 K with a circulation still. The results were verified by effective statistical procedures and used to calculate activity coefficients and excess molar Gibbs free energiesG_m^E . Excess molar enthalpiesH_m^E for these mixtures were determined at T =  298.15 K by means of an isothermal CSC microcalorimeter equipped with recently reconstructed flow mixing cells. Reliable performance of the calorimetric setup was proved by the good agreement of H_m^Efor (hexane  +  cyclohexane), (2-propanone  +  water), and (methanol  +  water), with the best literature results. The trichloromethane- or halothane-containing mixtures exhibit strong negative deviations from Raoult’s law and are highly exothermic, thus indicating that complex formation via hydrogen bonding is a governing nonideality effect. A close similarity in the behaviour of corresponding mixtures with trichloromethane and halothane is observed, but for halothane-containing mixtures,G_m^E and H_m^Eare consistently more negative, confirming that halothane is a more powerful proton donor than chloroform.     

(Liquid + liquid) equilibria for ternary mixtures of (methanol or ethanol + toluene or m-xylene + n-dodecane)

(Liquid + liquid) equilibrium (LLE) results for the ternary mixtures of (methanol or ethanol + toluene or m-xylene + n-dodecane) at three temperatures (298.15, 303.15 and 313.15) K are reported. The compositions of liquid phases at equilibrium were determined by g.l.c. measurements and the results were correlated with the UNIQUAC and NRTL activity coefficient models. The partition coefficients and the selectivity factor of methanol and ethanol are calculated and compared to suggest which alcohol is more suitable for extracting the aromatic hydrocarbons (toluene or m-xylene) from n-dodecane. The phase diagrams for the ternary mixtures including both the experimental and correlated tie lines are presented. From the phase diagrams and the selectivity factors it is concluded that methanol has a higher efficiency as a solvent in extraction of aromatic hydrocarbon from alkane mixtures.     

Phase behaviour of binary and ternary mixtures for the poly(methyl methacrylate-co-hexafluorobutyl methacrylate) [P(MMA-co-HFBMA)] in supercritical fluorine solvents

In this study, the poly(methyl methacrylate-co-2,2,3,4,4,4-hexafluorobutyl methacrylate) [P(MMA-co-HFBMA)] as a fluoric copolymer was prepared using dispersion polymerization in supercritical carbon dioxide. The characterization for the prepared P(MMA-co-HFBMA) was investigated with varied ratios of MMA vs HFBMA (30:1, 25:1, 22:1 and 20:1), 2,2′-azobisisobutyronitrile (AIBN) amounts (1.0, 2.0, 3.0, and 4.0) wt% and the weight average molar mass (M_w).Experimental cloud-point data at temperatures to 454 K and pressures up to 184 MPa are reported for binary and ternary mixtures of P(MMA-co-HFBMA) in supercritical CH₂F₂, CHF₃ and CHClF₂. Experiments are performed in order to determine phase behaviour of binary system for the P(MMA-co-HFBMA) (mole ratio: 25:1, AIBN: (1.0, 2.0, 3.0 and 4.0) wt%) + supercritical solvents (CH₂F₂, CHF₃ and CHClF₂) mixtures at temperature range from (333 to 454) K and pressure up to 184 MPa. It appears that the {P(MMA-co-HFBMA) + CH₂F₂} mixtures show the upper critical solution temperature (UCST) type behaviour with negative slope, while the {P(MMA-co-HFBMA) + CHF₃} and {P(MMA-co-HFBMA) + CHClF₂} mixtures show lower critical solution temperature (LCST) type curve with positive slope. Cloud-point curves for the P(MMA-co-HFBMA) [mole ratio: 30:1 (M_w = 186,000 g · mol⁻¹), 25:1 (M_w = 176,000 g · mol⁻¹), 22:1 (M_w = 158,000 g · mol⁻¹) and 20:1 (M_w = 126,000 g · mol⁻¹); AIBN: 1.0 wt%) + supercritical (CH₂F₂, CHF₃ and CHClF₂) mixtures show a negative slope for the {P(MMA-co-HFBMA) + CH₂F₂}, and a positive slope for the {P(MMA-co-HFBMA) + CHF₃} and {P(MMA-co-HFBMA) + CHClF₂} mixtures at temperatures to 454 K and pressure up to 184 MPa. Also, the impact of MMA on phase behaviour for the {P(MMA-co-HFBMA) (mole ratio: 25:1; AIBN: (1.0 and 2.0) wt%) + CH₂F₂} mixtures are measured in changes of the (pressure + temperature) slope from UCST behaviour to LCST behaviour, and with MMA co-solvent concentrations of (0.0 to 40.1) wt%.     

Salt effect on (liquid + liquid) equilibrium of (water + tert-butanol + 1-butanol) system: Experimental data and correlation

(Liquid + liquid) equilibrium data for the quaternary systems (water + tert-butanol + 1-butanol + KBr) and (water + tert-butanol + 1-butanol + MgCl₂) were experimentally determined at T = 293.15 K and T = 313.15 K. For mixtures with KBr, the overall salt concentrations were 5 and 10 mass percent; for mixtures with MgCl₂, the overall salt concentrations were 2 and 5 mass percent. The experimental results were used to estimate molecular interaction parameters for the NRTL activity coefficient model, using the Simplex minimization method and a concentration-based objective function. The correlation results are extremely satisfactory, with deviations in phase compositions below 1.7%.     

Dynamic viscosities of the ternary liquid mixtures (dimethyl carbonate + methanol + ethanol) and (dimethyl carbonate + methanol + hexane) at several temperatures

Densities, ρ speeds of sound, u and dynamic viscosities, η of the ternary mixtures {dimethyl carbonate (DMC) + methanol + ethanol} and (dimethyl carbonate + methanol + hexane) were gathered at T = (293.15, 298.15, 308.15, and 313.15) K. From experimental data viscosity deviations, Δη of the ternary mixtures were evaluated. These results have been correlated using the Cibulka equation. The fitting parameters and the standard deviations of the ternary viscosity deviations are given. UNIFAC-VISCO group contribution method was used to predict the dynamic viscosities of the ternary mixtures at several temperatures.     

(Vapour + liquid) equilibrium in (N,N-dimethylacetamide + ethanol + water) at the temperature 313.15 K

Total vapour pressures, measured at the temperature 313.15 K, are reported for the ternary mixture (N,N-dimethylacetamide + ethanol + water), and for binary constituent (N,N-dimethylacetamide + ethanol). The present results are also compared with previously obtained data for (amide + ethanol) binary mixtures, where amide = N-methylformamide, N,N-dimethylformamide, N-methylacetamide, 2-pyrrolidinone, and N-methylpyrrolidinone. We found that excess Gibbs free energy of mixing for binary (amide + ethanol) mixtures varies roughly linearly with the molar volume of amide.     

Liquid viscosity of low-GWP refrigerant mixtures (R32 + R1234yf) and (R125 + R1234yf)

In this work, the viscosity of R1234yf, (R32 + R1234yf), and (R125 + R1234yf) in one-phase liquid was measured. The combined expanded uncertainty of viscosity measurement apparatus of confidence of 0.95 (k = 2) is about 2.0%. The measurements of mixtures containing (30.0, 50.0, and 70.0) wt% R32 or R125 were carried out between T = (283.0 and 323.0) K (at intervals of T = 5 K) and P = (1.58 and 2.74) MPa, with a moving piston viscometer (VISCOpro 1600, accuracy ±1.0%) and a Coriolis flowmeter (Ultramass MKII, accuracy ±0.001 g/ml). The measured data were correlated with a hard-sphere (RSH) method and the Grunberg and Nissan method. The average absolute deviations are (2.2 and 3.3)% for the (R32 + R1234yf) and (R125 + R1234yf) mixtures by RSH method, (2.8 and 1.3)% for the (R32 + R1234yf) and (R125 + R1234yf) mixtures by Grunberg and Nissan method, while (3.5 and 2.4)% for the (R32 + R1234yf) and (R125 + R1234yf) mixtures by RefProp V9.1, respectively.     

Description of intra-diffusion in liquid mixtures

Employing a previously derived model to describe intra-diffusion coefficients in liquid mixtures based on molecular simulations of spherical Lennard–Jones particles [T. Merzliak, A. Pfennig, Mol. Simul. 30 (7) (2004) 459–468], an improved set of coefficients was obtained from optimized molecular dynamics simulations. In these simulations, the thermodynamic states were planned with the help of optimal experimental design, which allows to reduce the number of simulations necessary for significant determination of the coefficients by roughly a decade. The model was then applied to the real liquid mixtures toluene + cyclohexane, toluene + 1,4-dioxane, n-hexane + toluene, 1,4-dioxane + cyclohexane and cyclohexane + n-hexane, which have molecular properties that correspond to the model assumptions. Experimental intra-diffusion coefficients for the mixtures toluene + cyclohexane, toluene + 1,4-dioxane, n-hexane + toluene and 1,4-dioxane + cyclohexane were determined with nuclear magnetic resonance (NMR) techniques in this work. Even without additional parameters for the mixture the proposed model can describe the diffusion coefficients with an average accuracy of 5%. Allowing a deviation from Lorentz–Berthelot mixing rules leads generally only to slight improvement.     

Properties of pure 1-methylimidazolium acetate ionic liquid and its binary mixtures with alcohols

Densities and viscosities of the pure ionic liquid 1-methylimidazolium acetate ([Mim]Ac) and its binary mixtures with methanol, ethanol, 1-propanol, and 1-butanol were measured at temperature ranging from T = (293.15 to 313.15) K. The thermal expansion coefficient, molecular volume, standard entropy, and lattice energy of [Mim]Ac were deduced from the experimental density results. A simple linear equation was used to correlate the variation of viscosity of [Mim]Ac with temperature. Excess molar volumes V^E and viscosity deviations Δη for the binary mixtures at above mentioned temperature were calculated and fitted to the Redlich–Kister equation with satisfactory results. Excess molar volumes for {[Mim]Ac + 1-butanol} mixture have an S shape, while those for other mixtures have a negative deviation from ideal behaviour over the entire mole fraction range. Viscosity deviations are all negative deviation for {[Mim]Ac + alcohol} mixtures. The results were interpreted in terms of interactions and structural factors of binary mixtures.     

Volumetric and viscometric behaviour of the binary systems of N-methyldiethanolamine and diethanolamine with 1-butyl-3-methylimidazolium acetate at various temperatures

In the present work, density and viscosity of two binary mixtures of N-methyldiethanolamine (MDEA) and diethanolamine (DEA) with 1-butyl-3-methylimidazolium acetate ([bmim][acetate]) are measured. The experiments were carried out at atmospheric pressure and at T = (293.15 to 343.15) K for density and from 293.15 K to 353.15 K for viscosity over the whole range of mole fraction. Using the density and viscosity results, several physical and thermodynamic properties such as excess molar volumes (V^E), coefficients of thermal expansions (α), viscosity deviation (Δη),molar activation entropy (ΔS), molar activation enthalpy (ΔH) and molar activation Gibbs free energy (ΔG) for these binary mixtures are calculated.The experimental results of the density and viscosity for the pure systems as well as the binary systems show a decrease with increasing temperature as expected. The results of density measurements show that over all ranges of temperatures investigated the density of the pure components show the following trend: DEA > [bmim][acetate] > MDEA. Therefore, in the binary mixtures of the (MDEA + [bmim][acetate]), the density of the mixture reduces with decreasing concentration of the ionic liquid and for the (DEA + [bmim][acetate]) mixture the density of the blend enhances to reduce the concentration of the ionic liquid. Moreover, the calculated excess molar volumes show a positive deviation from ideality for the two binary mixtures. The behaviour of change of viscosity against concentration for the (MDEA + [bmim][acetate]) system is different from the (DEA + [bmim][acetate]) mixture so that for the first system the value of the viscosity rises with increasing [bmim][acetate] mole fraction, but in the second system there is a minimum viscosity point in the DEA-rich region.     

Interfacial tensions of binary mixtures of ethanol with octane,decane, dodecane,and tetradecane

This contribution is devoted to the experimental characterization of interfacial tensions of a representative group of binary mixtures pertaining to the (ethanol + linear hydrocarbon) series (i.e. octane, decane, dodecane, and tetradecane). Experimental measurements were isothermically performed using a maximum differential bubble pressure technique, which was applied over the whole mole fraction range and over the temperature range 298.15 K < T/K < 318.15 K.Experimental results show that the interfacial tensions of (ethanol + octane or decane) negatively deviate from the linear behavior and that sharp minimum points on concentration, or aneotropes, are observed for each isotherm. The interfacial tensions of (ethanol + dodecane or tetradecane), in turn, are characterized by combined deviations from the linear behavior, and inflecting behavior observed on concentration for each isotherm. The experimental evidence also shows that these latter mixtures are close to exhibit aneotropy.For the case of (ethanol + octane or decane) mixtures, aneotropy was clearly induced by the similarity of the interfacial tension values of the constituents. The inflecting behavior of the interfacial tensions of (ethanol + dodecane or tetradecane), in turn, was observed in the vicinity of the coordinates of the critical point of these mixtures, thus pointing to the fact that the quasi-aneotropic singularity that affects these mixtures was provoked by the proximity of an immiscibility gap of the liquid phase.Finally, the experimental data of interfacial tensions were smoothed with the Scott–Myers expansion, from which it is possible to conclude that the observed aneotropic concentrations weakly depend on temperature for all the analyzed mixtures.     

The potential of head-space gas chromatography for VLE measurements

Head-space gas chromatography (HS-GC) is thought to allow the performance of (vapour + liquid) equilibrium (VLE) measurements in a fast and automated way. However, two decades after the first applications of HS-GC for this purpose, the potential of this technique is not fully developed yet. Measurements of isothermal VLE and activity coefficients of mixtures can be obtained in a high throughput scenario. However, several considerations have to be taken into account before starting the analysis, such as the equilibration time or the minimum sample volume and the GC response factors. These aspects can strongly influence on the validity of the results and should therefore be determined for each mixture.In this paper, four azeotropic mixtures of interest in the pharmaceutical and chemical industry, i.e., (ethylacetate + water), which forms a heterogeneous azeotrope, (ethylacetate + isooctane), (acetonitrile + toluene) and the ternary mixture (acetonitrile + toluene + tetrahydrofuran), are considered to show the potential of HS-GC for VLE measurements. The thermodynamic analysis of VLE data leads to activity coefficients for the mixtures at (35, 50, and 70) °C. In addition, the experimental data are compared with thermodynamic models and data from the literature, when available.     

Phase equilibria for mixtures containing nonionic surfactant systems: Modeling and experiments

Surfactants are important materials with numerous applications in the cosmetic, pharmaceutical, and food industries due to inter-associating and intra-associating bond. We present a lattice fluid equation-of-state that combines the quasi-chemical nonrandom lattice fluid model with Veytsman statistics for (intra + inter) molecular association to calculate phase behavior for mixtures containing nonionic surfactants. We also measured binary (vapor + liquid) equilibrium data for {2-butoxyethanol (C₄E₁) + n-hexane} and {2-butoxyethanol (C₄E₁) + n-heptane} systems at temperatures ranging from (303.15 to 323.15) K. A static apparatus was used in this study. The presented equation-of-state correlated well with the measured and published data for mixtures containing nonionic surfactant systems.