Liquid—liquid equilibrium in methanol + gasoline blends

An investigation has been carried out to study the limited miscibility of methanol and gasoline blends over the temperature range −20 to 20°C. Two liquid phases in equilibrium were analysed by mass spectrometric methods and their composition reported, in addition to the methanol content, in terms of six principal classes of hydrocarbons. Liquid—liquid equilibrium was predicted using the UNIFAC group contribution model. In liquidliquid equilibrium calculations, gasoline was represented by a set of model compounds. The number of the different groups that comprise each model molecule was determined using the result of a distillation analysis and the paraffin—naphthene—aromatic composition. Estimation of conjugate phase composition using the UNIFAC model is reasonable at temperatures above 0°C. To describe correctly the limited miscibility of methanol+gasoline blends over the whole temperature range studied, we found that ‘specific’ UNIFAC interaction parameters were necessary.     

Liquid–liquid phase equilibrium of MgSO4 and PEG1500 aqueous two-phase system

In this work, PEG 1500, MgSO₄ and water were used to create an aqueous two-phase system and the effect of temperature was surveyed by obtaining binodal data and equilibrium data at 35, 40 and 45°C; compositions of mixture were obtained by atomic absorption spectrometer and refractometery method. Results showed that with increasing temperature, the solution tends to attain a two-phase region and the slope and length of tie lines increases. Modified Wilson equation was used to correlate this system, adjustable parameters were evaluated directly from experimental data and good agreement with experimental data was obtained. The overall average relative deviation was found to be less than 6%.     

Experimental investigation of the vapor–liquid equilibrium at 313.15 K of the ternary system tert-amylmethyl ether (TAME)+n-heptane+methanol

Experimental isothermal P–x data at 313.15 K for the ternary system (tert-amylmethyl ether (TAME)+n-heptane+methanol) and for one of the unmeasured constituent binary systems, (tert-amylmethyl ether (TAME)+methanol) are reported. Data reduction by Barker's method provides correlations for g^E using the Margules equation for the binary systems and the Wohl expansion for the ternary system. Wilson, NRTL and UNIQUAC models have been applied successfully to both the binary and the ternary systems. The presence of azeotropes in the ternary system and constituent binaries are studied as well as the presence of immiscible zones.     

Liquid–liquid equilibria for butyl tert-butyl ether + (methanol or ethanol) + water at several temperatures

Liquid–liquid equilibrium (LLE) data for butyl tert-butyl ether + (methanol or ethanol) + water were measured experimentally at 298.15, 308.15 and 318.15 K. The experimental data were correlated with the NRTL and UNIQUAC equations. The equations were used to perform the correlation of each temperature data set and for the three temperatures data set simultaneously. The best results were found with UNIQUAC and NRTL (α = 0.1), respectively. Data prediction was carried out using the UNIFAC method, however the results found were not quantitative.     

Liquid–liquid equilibrium calculations for methanol–gasoline blends using continuous thermodynamics

This work presents the application of continuous thermodynamics to investigate the limited miscibility of methanol–gasoline blends. To predict the liquid–liquid equilibrium of these systems, the Gaussian distribution function was used to represent the composition of paraffins in the gasoline. The naphthenes and aromatics were represented by model compounds. A model has been developed using three different continuous versions of the UNIFAC model. Methanol is an associating component, and association affects phase equilibria. Therefore, the CONTAS (continuous thermodynamics of associating systems) model based on the Flory–Huggins equation, for multicomponent methanol–gasoline blends has also been investigated. The predicted results including the cloud point curve, shadow curve and phase separation data have been compared with experimental data and good agreement was found for the two UNIFAC and CONTAS models.     

Liquid–liquid equilibrium data for binary alcohol + n-alkane (C10–C16) systems: methanol + decane,ethanol + tetradecane,and ethanol + hexadecane

Liquid–liquid equilibrium (LLE) data for three binary alcohol + n-alkane (C₁₀–C₁₆) systems—methanol + decane, ethanol + tetradecane, and ethanol + hexadecane—were measured using a laser scattering technique. The experimentally determined cloud points were satisfactorily correlated by three local composition models (NRTL, Tsuboka–Katayama’s modification of the Wilson equation, and the modified complete local composition model suggested by Nagata and Tamura). Prediction of vapor–liquid equilibria by means of these models with parameters obtained from the LLE data was also tested.     

Liquid–liquid–solid equilibria for the quaternary system water+ethanol+1-pentanol+sodium chloride at 25°C

Salting-out effect can be used to improve the extraction of some solutes by modifying the solute distribution between two liquid phases. In this work we report the results obtained for the quaternary system water+ethanol+1-pentanol+sodium chloride at 25°C. All equilibrium regions (one liquid, two liquids, one liquid+one solid and two liquids+one solid zones) have been systematically studied. Tie lines and tie-triangles data were measured, after separating the conjugated phases, determining the liquid components by Chromatography, and sodium chloride by gravimetrical methods and titration with AgNO₃ depending on its concentration. Distribution and selectivity curves are represented to analyse the sodium chloride salt effect. Tie-lines and tie-triangles data have been correlated using a modification of the Eisen–Joffe equation.     

The influence of the temperature on the liquid–liquid equilibrium of the ternary system 1-pentanol–ethanol–water

Liquid–liquid equilibrium data for the ternary system 1-pentanol–ethanol–water have been determined experimentally at 25, 50, 85 and 95°C. These results have been correlated simultaneously by the uniquac method obtaining two sets of interaction parameters: one of them independent of the temperature and the other with a linear dependence. Both sets of parameters fit the experimental results well.     

Liquid–liquid phase equilibrium in ternary immiscible Al–Bi–Sn melts

In this paper, the liquid-phase separation of ternary immiscible Al–Bi–Sn melts was studied with resistivity and thermal analysis methods at different temperatures. The resistivity–temperature curves appear anomalous and abrupt change as rising temperature, corresponding to the distinctive and low peak of melting process in the differential scanning calorimetry (DSC) curves, indicative of the occurrence of the liquid-phase separation. The anomalous behaviour of the resistivity temperature dependence is attributable to concentration–concentration fluctuations. The microheterogeneity–microhomogeneity transformation causes large fluctuations in concentration, which make the randomness and chaos of the atoms larger, leading to the greater impediment to electron movement and the sharp rise of resistivity. The addition of tin to the Al–Bi immiscible alloys decreases the monotectic reaction. It is concluded that concentration–concentration fluctuations are responsible for the anomalous behaviour of resistivity and DSC methods.     

Vapor—liquid equilibrium measurements for the methanol—acetone system at 372.8, 397.7 and 422.6 K

A static high pressure equilibrium facility has been used to obtain P − x − y measurements for the methanol—acetone binary for the three isotherms 372.8, 397.7 and 422.6 K. These measurements show that maximum pressure azeotropic behaviour exists at each of these temperatures. The data obtained have been correlated satisfactorily using the three suffix Margules equation. A comparison has been made between the information resulting from this study and the high pressure data of Griswold and Wong. Parameters of the three suffix Margules equation have been correlated with temperature over the range 285–425 K using additional vapor—liquid equilibrium and excess enthalpy data available in the literature. These correlations have been used to predict isobaric behavior. Auxiliary expressions have been developed which relate azeotropic pressure and composition to temperature.     

Influence of inorganic salts on the liquid–liquid equilibrium of water + furfuryl alcohol + cyclopentanone system at 298.15 K

Influence of inorganic salts on the system of liquid phase equilibrium of water + furfuryl alcohol + cyclopentanone at 298.2 K was studied. Different salt concentrations (0, 1 and 2 wt%) and the type of salt (LiCl, NaCl, KCl, and RbCl) were investigated. The results showed that the two-phase region of the ternary system enlarged by addition of salt. NRTL model was applied, and good correlation between the experimental data and the model was achieved as confirmed by the low rmsd values.     

Liquid–liquid–solid equilibrium for the water + sodium chloride + potassium chloride + 1-butanol quaternary system at 25 °C

The methodology for the study of the liquid–liquid–solid equilibrium of quaternary systems including two inorganic salts, water and an organic solvent has been reviewed and applied to the water + sodium chloride + potassium chloride + 1-butanol quaternary system at 25 °C. The different equilibrium regions have been systematically studied.The experimental equilibrium data have been used to check the accuracy of the predictions using the electrolyte NRTL model (MNRTL) and the parameters obtained by correlation of ternary systems. The results obtained with the model are satisfactory.     

Ternary phase equilibrium studies of the water—ethanol—1,8-cineole system

Ternary liquid—liquid equilibrium data at 25°C were obtained for the water—ethanol—1,8-cineole system, 1,8-cineole being the main component of eucalyptus oil. This study formed one aspect of a project utilizing solar energy stored in plants as liquid fuel components. Experimental results confirmed the absence of phase separation problems in the use of this system as a liquid fuel. The tie-line data for the system were well correlated by the methods of Hand and Othmer—Tobias. The solubility of 1,8-cineole in water was determined over a range of temperatures.     

Liquid–liquid equilibria for the ternary system water+n-dodecane+2-(2-n-hexyloxyethoxy)ethanol

Experiments of the fish-shaped phase diagram for the ternary system water+n-dodecane+2-(2-n-hexyloxyethoxy)ethanol (abbreviated by C₆E₂ hereafter) under atmospheric pressure were performed at constant water/n-dodecane weight ratio (1/1) to locate the critical end points. The upper and lower critical consolute temperatures for the system of interest are 307.80 K and 282.30 K, respectively. Compositions of two- and three-phase liquid–liquid equilibrium for the ternary system water+n-dodecane+C₆E₂ at 293.15 K and 303.15 K under atmospheric pressure are presented in this paper.     

Isobaric vapor–liquid–liquid equilibrium and vapor–liquid equilibrium for the system water–ethanol-1,4-dimethylbenzene at 101.3 kPa

An all-glass, dynamic recirculating still equipped with an ultrasonic homogenizer has been used to determine vapor–liquid (VLE) and vapor–liquid–liquid (VLLE) equilibria. Consistent data have been obtained for the ternary water + ethanol + p-xylene system at 101.3 kPa for temperatures in the range of 351.16–365.40 K. Experimental results have been used to check the accuracy of the UNIFAC, UNIQUAC and NRTL models in the liquid–liquid region of importance in the dehydration of ethanol by azeotropic distillation.     

Molecular thermodynamics of salt effect in vapor–liquid equilibrium of ethanol–water systems

Scaled particle theory was used to derive a general expression for the salt effect parameter, K, of isobaric vapor–liquid equilibrium for ethanol–water-1-1 type electrolytic systems, which appears in the Furter equation. This expression was essentially a sum of two terms: 1, the hard sphere interaction term calculated by Masterton–Lee's equation, 2, the soft sphere interaction term calculated by Y. Hu's molecular thermodynamical model, in which the diameters of nacked ions were replaced by that of solvated ions, the solvation coefficients (i.e., in the radio of the latter to the former) were taken to be adjustable parameters, their magnitude implies the ionic solvation rules. A correlation equation for the local dielectrical constant around central ions with liquid concentration was obtained by mapping out experimental points. The calculated salt effect parameters of 9 ethanol–water-1–1 type electrolytic systems were in good agreement with the literature values within the wide range of liquid concentration.     

Vapour—liquid equilibrium of the system benzene + cyclohexane + 1-propanol at 760 mm Hg

Arce, A., Blanco, A. and Tojo, J., 1986. Vapour—liquid equilibrium of the system benzene + cyclohexane + 1-propanol at 760 mm Hg. Fluid Phase Equilibria, 26: 69–81.Vapour—liquid equilibrium data for the mixture benzene + cyclohexane + 1-propanol at a constant pressure of 760 mm Hg have been determined experimentally and predicted using the group contribution methods UNIFAC and ASOG and the NRTL, UNIQUAC and Wilson equations (with correlation parameters obtained from data for the corresponding binary mixtures). The various predictions are compared and evaluated in the light of the experimental results.