Search

Benzene separation from hydrocarbon mixtures is a challenge in the refining and petrochemical industries. The application of liquid–liquid extraction process using ionic liquids (I.Ls) is an option for this separation. The selection of the most appropriate I.L. for this application is a challenging task due to the variety of anion and cation structures. In the current study, the benzene distribution between the aliphatic hydrocarbon-rich and I.L.-rich phases has been evaluated using the Quantitative Structure–Property Relationship (QSPR) method. A dataset comprising of 112 ternary systems (namely, I.L., benzene, and aliphatic hydrocarbon) was compiled after an extensive review of literature. The primary dataset consists of 17 anions, 20 cations, and 12 aliphatic hydrocarbons. Therefore, the impact of the structure of anion, cation, or aliphatic hydrocarbon on the benzene distribution between the aliphatic hydrocarbon-rich and I.L.-rich phases has been investigated. The linear QSPR models were constructed using Multiple Linear Regression (MLR). The statistical evaluation of the final linear model showed that the constructed model (R2 = 0.900) has an acceptable capability to predict the mole fraction of benzene in the I.L.-rich phase. Additionally, non-linear QSPR models were developed using Genetic Programming (GP) and Artificial Neural Network (ANN) machine learning methods. The statistical evaluation of the GP model (R2 = 0.927) and ANN model (R2 = 0.939) showed that non-linear models had slightly higher prediction accuracy compared to the linear model. The final QSPR model was developed using the BELe3 cation descriptor which is a 2D Burden eigenvalues descriptor and HTm anion descriptor which is a 3D GETAWAY descriptor. After model construction, the selected molecular descriptors of anion and cation structures has been interpreted. The results showed that the size and the electronegativity of the atoms in the anion and cation structure are probably important parameters that affect the benzene distribution between the aliphatic hydrocarbon-rich and I.L.-rich phases. Additionally, the anion shape can be considered as an effective parameter in the benzene extraction process. [ABSTRACT FROM AUTHOR]

In order to separate phenol from water, at 101.3 kPa, the liquid-liquid equilibria (LLE) data of water + phenol + solvents (trichloromethane, isoamyl alcohol) were obtained at 298.15, 303.15, and 313.15 K. The ability of the extractant to extract phenol from water was evaluated by the distribution coefficient (D) and selectivity coefficient (S). The Bachman and Hand equations were used to verify the reliability of the LLE data with the linear coefficient was greater than 0.98%. The LLE data was correlated with the NRTL and UNIQUAC models to obtain a binary interaction parameter with an RMSD not greater than 0.36%. [ABSTRACT FROM AUTHOR]

The composition of coexisting phases for liquid-liquid and solid-liquid-liquid equilibria were measured at 298.2 and 313.2 K and under atmospheric pressure for the following systems: {sodium bromide + formamide + ethyl acetate}, {sodium thiocyanate + ethanol + (R)-limonene}, and {sodium thiocyanate + methanol + dibutyl ether}. These concentrations were determined mainly by chromatography and, for the first system, with the help of argentometric titration. The standard uncertainties in mole fractions varied between 0.001 and 0.008. The tie-line data were reproduced by the NRTL model with medium accuracy. Several empirical equations were used and tested to correlate binodal curves. The rational form of the equation, based on the liquid–liquid–solid tie-line, turned out to be the most adequate. [ABSTRACT FROM AUTHOR]

The liquid–liquid equilibrium (LLE) of the mesityl oxide + diethoxymethane + water was determined at 303.15, 313.15 and 323.15 K under 101.325 kPa, which was consistent with the Treybal’s type II ternary phase behavior. The distribution coefficients (D) and selectivity coefficients (S) were used to evaluate the extraction ability of mesityl oxide to extract diethoxymethane from water. The experimental data were correlated with the NRTL and UNIQUAC thermodynamic models, and the RMSD values are both less than 0.47%, indicating that the two models can well correlate the experimental data. [ABSTRACT FROM AUTHOR]

In order to separate o-cresol from wastewater and supplement the related parameters of o-cresol + solvent (isoamyl alcohol), the liquid–liquid equilibrium (LLE) data of isoamyl alcohol + o-cresol + water was determined at 298.2, 308.2 and 318.2 K, under 101.3 kPa. Comparing the distribution coefficients (D) and separation factors (S) of isoamyl alcohol, it is found that the isoamyl alcohol was great for extracting o-cresol from water. The consistency was verified by the Othmer–Tobias and Hand equations. Meanwhile, the NRTL and UNIQUAC thermodynamic models of this system were correlated using Aspen Plus 8.4. The root mean square deviation (RMSD) values were less than 0.42%. In addition, the reliability of regression parameters was verified using the GUI-MATLAB tool. [ABSTRACT FROM AUTHOR]

For separation of the azeotropes of water + 2-methyl-3-buten-2-ol by liquid–liquid extraction, methyl tert-butyl ether or butyl acetate or 4-methyl-2-pentanone or 2-ethyl-1-hexanol was selected as the extraction solvent. The liquid–liquid equilibrium (LLE) data for water + 2-methyl-3-buten-2-ol + (methyl tert-butyl ether/butyl acetate/4-methyl-2-pentanone/2-ethyl-1-hexanol) ternary systems at 308.2 K under 101.3 kPa were determined. The distribution coefficient and the separation factor were calculated to evaluate the extraction ability of different solvents. The Othmer–Tobias, Bachman, and Hand equations were applied to verify the reliability of the experimental LLE data. Meanwhile, the experimental LLE data were successfully correlated by the NRTL and UNIQUAC models with the root-mean-square deviations (RMSD) were less than 0.42%. [ABSTRACT FROM AUTHOR]

Liquid–liquid phase equilibria in ethanol–n-propyl acetate and n-propanol–ethyl acetate systems with deep eutectic solvents (DESs) at temperatures of 293.15 and 313.15 K and atmospheric pressure have been studied. DESs based on choline chloride, namely, choline chloride–glycerol and choline chloride–urea at a molar ratio of 1 : 2, have been investigated. An internal consistency check for experimental data has been performed using the Othmer–Tobias equation. Based on the data, the distribution coefficients and the values of selectivity have been calculated. The effect of an alcohol and an ester on the position of the region of phase equilibrium has been found. The nonrandom two-liquid (NRTL) model has been used to correlate experimental data on liquid–liquid equilibria. [ABSTRACT FROM AUTHOR]

The phase equilibria for CsCl in three polyethylene glycols (PEG) with molecular weights of 1000, 4000, 6000 g⋅mol−1 and water (H2O) mixed solvent were investigated at 288.15 and 308.15 K. The isothermal dissolution equilibrium method was applied for the solid–liquid equilibria experiments; the turbidimetric method was used for the liquid–liquid equilibria experiments. Results show that there is only solid–liquid equilibrium for the ternary system CsCl–PEG1000–H2O at 288.15 K, both solid–liquid and liquid–liquid equilibria coexist in ternary systems CsCl–PEG1000–H2O at 308.15 K and CsCl–PEG4000/6000–H2O at 288.15 and 308.15 K. For liquid–liquid equilibrium, the binodal curve and compositions of the tie-lines were obtained experimentally, and the effect of temperature and molecular weight of PEG on liquid–liquid equilibrium was discussed. It shows that the liquid–liquid equilibrium formed easily at higher temperature and larger molecular weight of PEG. Moreover, three nonlinear expressions were applied to correlate the binodal curve, and the experimental values of tie-line were correlated with a good agreement by using Othmer–Tobias, Bancroft and NRTL models. [ABSTRACT FROM AUTHOR]

Liquid–liquid equilibrium (LLE) data for the ternary systems composed of water, C1–C4 monocarboxylic acids, and dibutyl ether were determined at three different temperatures (293.15, 303.15, and 313.15 K) and atmospheric pressure. The experimental solubility curves and mutual solubilities of (water + dibutyl ether) were determined by the cloud-point method, whereas the tie-lines of conjugate phases were obtained via GC analysis. The examined C1–C4 monocarboxylic acids are valuable components for estimating the effect of acid structure on LLE. The separation factor calculated from experimental LLE data is indicative of the ability of the solvent to effectively recover the acid. Equilibrium distribution of C1–C4 acids is better for more structured propionic and butyric acids as compared to less structured formic and acetic acids, and the general ranking with respect to the separation factor (S) follows the order: C4 > C3 > C2 > C1, and T293.15 < T303.15 ≤ T313.15. The LLE data were predicted with the group-contribution method A-UNIFAC with the newly estimated parameters, which shows an appropriate consistency with the experimental data. [ABSTRACT FROM AUTHOR]

In recent years, considerable attention has been given to the capability of deep eutectic solvents (DESs) to replace ionic liquids in extraction processes. The objective of this study is to determine the physicochemical parameters of heterogeneous systems and phase equilibria in industrially important mixtures that contain DESs. Ethanol–ethyl acetate–DES, n-propanol–n-propyl acetate–DES, and n-butanol–n-butyl acetate–DES systems have been investigated at a temperature of 293.15 K and atmospheric pressure. DESs based on choline chloride, namely, its mixtures with glycerin and urea, have been studied. An analysis of the capability of DESs to separate the specified mixtures of alcohols and esters has been performed using data on the equilibrium compositions of coexisting liquid phases. The nonrandom two-liquid (NRTL) model has been used to correlate experimental data on liquid–liquid equilibria. [ABSTRACT FROM AUTHOR]

The selection of the extractant is an important consideration for the design of liquid–liquid extraction processes. Researchers are paying more attention to a priori predictions of liquid–liquid equilibria. The predictive and fully open-source thermodynamic model COSMO-SAC (conductor-like screening model-segment activity coefficient) uses quantum chemical calculations for calculating activity coefficients and thermodynamic properties. Through a brief review of the recent advances of COSMO-SAC in predicting liquid–liquid equilibrium of ionic liquid systems, this work assessed the accuracy of prediction for different chemical family combinations and generated directions for future improvement. [ABSTRACT FROM AUTHOR]

Abstract: Liquid-liquid equilibrium data for the n-heptane + phenol + sulfolane system were obtained at 323.15 and 343.15 K under 101.35 kPa pressure. The distribution coefficient (K) and separation factor (S) were calculated to assess the effectiveness of extracting phenol from n-heptane, and the consistency of LLE date were verified by the Othmer-Tobias, Hand as well as Bachman equations. The experimental data were correlated by using NRTL and UNIQUAC models, and the root-mean-square deviation (RMSD) values of both models were below 0.59%, demonstrating the two models were successfully describe the experimental data. [ABSTRACT FROM AUTHOR]

The ability of binary deep eutectic solvent choline chloride+1,2-propanediol (DES1; 1 : 3 mole ratio) and ternary deep eutectic solvent choline chloride+1,2-propanediol+water (DES2; 1 : 3 : 3 mole ratio) for breaking the azeotropes hexane/heptane+ethanol by means of liquid-liquid extraction was evaluated. Liquid-liquid equilibrium experiments were performed at 298.15 K, at atmospheric pressure, and data were correlated by NRTL and UNIQUAC models. Thermodynamic properties (density, viscosity, refractive index and speed of sound) of DES1 and DES2 were determined in temperature range from 288.15 K to 333.15 K and at atmospheric pressure. Extraction ability of the investigated eutectics yielded promising results in comparison with conventional solvents. Besides a high selectivity towards ethanol, an advantage of DES2 is its lower viscosity and higher distribution ratio values, which is an important aspect for a potential industrial application. Another advantage of both investigated eutectics is their easy and high recoverability from the extract layer based on their negligible vapor pressure. [ABSTRACT FROM AUTHOR]

Both 1-benzyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [BzMeIM][NTf2], and 1-benzylpyridinium bis(trifluoromethylsulfonyl)imide, [BzPY][NTf2], were used to separate toluene from heptane through liquidliquid equilibria (LLE). The LLE of two ternary systems of toluene, n-heptane, and [BzMeIM][NTf2] and [BzPY][NTf2], were experimentally determined at temperature of 293.2 K and 0.1MPa. The LLE experiments were also performed at 303.2 and 313.2 K to investigate the effect of temperature on toluene recovery. The distribution ratio of toluene and the selectivity in these two ternary systems were calculated and compared with different ternary mixtures. The LLE measured data were well correlated with nonrandom two-liquid (NRTL). [ABSTRACT FROM AUTHOR]

Deep eutectic solvents (DESs) are promising alternative for ionic liquids due to their low cost and sustainability. Considerable attention is paid on the ability of DES to replace ionic liquids in the separation of organic liquid mixtures via extraction. In this sense, it is important to determine the physicochemical parameters of liquid-liquid equilibrium for the industrially significant mixtures and deep eutectic solvents. In the present work a mixture of n-octane, toluene and DES based on choline chloride and malonic acid was studied at 293.15, 313.15 K and atmospheric pressure. Tie-lines were obtained and ability of deep eutectic solvents to separate aliphatic-aromatic mixture was analyzed. Experimental liquid-liquid equilibrium data were fit with the NRTL model, and interaction parameters of components were obtained and discussed. [ABSTRACT FROM AUTHOR]

Liquid-liquid equilibrium (LLE) data for the methyl isobutyl ketone + o-cresol + water ternary system have been experimentally measured from 298.2 to 323.2 K below 101 kPa. The measured LLE data were verified to be highly consistent through the Othmer-Tobias and Hand equations. The extraction efficiency of methyl isobutyl ketone for o-cresol was assessed by the distribution coefficient and separation factor. The experimental results correlated well with two excess Gibbs energy models: non-random two-liquid and universal quasi chemical, which also yielded binary interaction parameter. [ABSTRACT FROM AUTHOR]

Aqueous two phase systems (ATPS), consisting of two incompatible aqueous solutions, are widely used in biological extraction. In recent years, many experimental studies on the phase behavior of ionic liquid(IL)-inorganic salt ATPS systems have been reported but few investigations of the thermodynamics of the IL-based ATPS have been reported. In this work, the Extended UNIQUAC model is modified to calculate the equilibrium of [Bmim]Cl-KHPO-HO ATPS at 298.15 K. All the interaction parameters of the model are salt specific. The results show that the experimental compositions of tie lines are correlated successfully using the proposed model. The root mean square deviation of the mass fraction is 0.0256. [ABSTRACT FROM AUTHOR]

The phase equilibrium data for methanol + ethanol + isooctane systems were obtained at 303.15 K. Data for methanol + ethylbenzene + isooctane system were taken from literature. The effect of ethanol addition on the system equilibrium was investigated at the same temperature. The distribution curves for ternary and quaternary system was analyzed. The experimental results for ternary systems were correlated with UNIQUAC and NRTL equations. For the ternary systems studied here, the NRTL equation is more accurate than the UNIQUAC. The equilibrium data for the three ternary systems were used to determine interactions parameters for the UNIQUAC equation. For the quaternary system, the experimental data can be fitted more accurately to UNIQUAC equation than by the UNIFAC method. [ABSTRACT FROM AUTHOR]

In this work, liquid-liquid equilibrium data for the ternary system, 2-pentanone + phenol + water, were determined at temperatures of 298.15, 313.15 and 323.15 K under atmospheric pressure. The consistency of the experimental data was confirmed by using empirical equations such as the Bachman and Hand equations. The distribution coefficients and selectivities were calculated from the experimental data, indicating 2-pentanone is an excellent solvent to extract phenol. The experimental LLE data were correlated with NRTL and UNIQUAC thermodynamic models, which gave good representation for the experimental data. [ABSTRACT FROM AUTHOR]

Tie line data of {methanol + methyl tert-butyl ether + isooctane} ternary systems were obtained at T = 303.15 K, while data for {methanol + ethylbenzene + isooctane} were taken from literature. The ternary system {methanol + methyl tert-butyl ether + ethylbenzene} and {methyl tert-butyl ether + ethylbenzene + isooctane} were completely miscible. A quaternary system {methanol + ethylbenzene + isooctane + methyl tert-butyl ether} was also studied at the same temperature. In order to obtain equilibium data of the quaternary system, four quaternary sectional planes with several methyl tert-butyl ether/methanol ratios were studied. The effect of the addition of methyl tert-butyl ether on the liquid-liquid equilibrium data of {methanol + ethylbenzene + isooctane} ternary system has been investigate at the same temperature. The distribution curves for ternary and quaternary system was analysed. For the quaternary system {methanol + ethylbenzene + isooctane + methyl tert-butyl ether}, experimental data demonstrated that the distribution coefficient of ethylbenzene between the hydrocarbon and methanol phase on a methyl tert-butyl ether-free basis slightly increases with the increase of methyl tert-butyl ether/methanol ratio. Ternary experimental results were correlated with the UNIQUAC and NRTL equation. The NRTL equation is more accurate than the UNIQUAC equation for the ternary systems studied here. The equilibrium data of three ternary systems were used for determining interactions parameters for the UNIQUAC equation. The UNIQUAC equation fitted to the experimental data appeared to be more accurate than the UNIFAC method for the same quaternary system. [ABSTRACT FROM AUTHOR]

Liquid-liquid equilibrium (LLE) data for the 2-methoxy-2-methylpropane (methyl tert-butyl ether) + m-cresol + water ternary system were measured at 298.15 and 313.15 K and atmospheric pressure. The resulting distribution coefficients and selectivity show 2-methoxy-2-methylpropane is an efficient solvent for the extraction of m-cresol from waste water. The consistency of experimental tie-line data was assessed through the Othmer-Tobias, Hand and Bachman equations. The NRTL and UNIQUAC models were used to correlate the LLE data and to calculate binary interaction parameters for the ternary system. Both models describe the system's phase behavior accurately with very small average deviations. [ABSTRACT FROM AUTHOR]

Liquid-liquid equilibria were determined at 305.15 K for aqueous two-phase systems (ATPSs) containing 1-butyl-4-methylpyridinium tetrafluoroborate + inorganic salts (NaHPO·2HO, (NH)SO, NaSO, and NaHPO·12HO) + water. Four nonlinear equations were used to correlate the binodal data, and the binodal curves were used to describe and display the effect of different experimental salts on phase separation. Furthermore, a simple, two-parameter equation, along with the Othmer-Tobias and Bancroft equations, was used to correlate the tie-line data. All the results showed good agreement between the fitting equations and the experimental data. The effect of temperature on the binodal curves and tie-lines for 1-butyl-4-methylpyridinium tetrafluoroborate + NaSO + water systems was studied at T = 298.15, 311.15 and 338.15 K. Additionally, the effect of Gibbs energy on the salting-out ability of the different inorganic salts was discussed. From this study, we concluded that these salting-out abilities decline in the following order: NaHPO > NaSO > (NH)SO > NaHPO. These data may be helpful for the further investigation of ATPSs based on the ionic liquid 1-butyl-4-methylpyridinium tetrafluoroborate. In summary, our study determined the basic extraction data for this aqueous two-phase system and developed a fundamental method for the further study of material separation. [ABSTRACT FROM AUTHOR]

In this work, liquid-liquid equilibria data for the methyl tert-butyl ketone (MTBK) + phenol + water ternary system at 298.15, 313.15 and 323.15 K, under atmospheric pressure, were measured. The experimental tie-line data's reliability was verified by the Hand and Bachman equations. The distribution coefficient, together with the selectivity, was used to assess the extraction performance of MTBK. The experimental data were correlated with the nonrandom two-liquid and universal quasi-chemical activity coefficient models to yield binary interaction parameters for relevant process simulations. [ABSTRACT FROM AUTHOR]

Tie line data of the {methanol + methylcyclohexane + hexane} and {methanol + toluene + hexane} ternary systems were obtained at T = 303.15 K, while data for {methanol + toluene + methylcyclohexane} were taken from the literature. A quaternary system {methanol + methylcyclohexane + hexane + toluene} was also studied at the same temperature. In order to obtain the binodal surface of the quaternary system, four quaternary sectional planes with several hexane/methylcyclohexane ratios were studied. Experimental results show that the binodal surface in the solid diagram is small and that the highest toluene mass fraction values, beyond which only one phase is present for the methanol-rich phase and hydrocarbon-rich one, respectively, are: 0.052 and 0.064 for P1, 0.068 and 0.052 for P2, 0.047 and 0.107 for P3, 0.029 and 0.030 for P4. So, if this quaternary system contains the correct methanol and hydrocarbon concentrations, this blend can be used as a reformulated gasoline, because no phase separation should be observed. Ternary experimental results were correlated with the UNIQUAC and NRTL equations. The equilibrium data for the three ternary systems were used to determine interaction parameters for the UNIQUAC equation. The NRTL equation is more accurate than the UNIQUAC for the ternary systems studied here. The UNIQUAC equation fitted to the experimental data is more accurate than the UNIFAC method for this quaternary system. [ABSTRACT FROM AUTHOR]

The object of this study was to measure the liquid-liquid equilibria (LLE) data of binary mixtures containing ionic liquids and citrus essential oil. We investigated linalool as the citrus essential oil, and 1-alkyl-3-methyl-imidazolium bis(trifluoromethanesulfonyl)imide ([CMIM][TFSI]) as the ionic liquid. Firstly, the experimental apparatus and procedure for the LLE measurement of mixtures containing ionic liquids were verified by measuring the LLE of the binary mixture 1-hexyl-3-methyl-imidazolium bis(trifluoromethanesulfonyl)imide ([CMIM][TFSI]) + 1-hexanol as a reference test system recommended by Marsh et al. (Pure Appl Chem 81:781-789, ). Next, the LLE data for IL + linalool were obtained, and the LLE data of two binary mixtures 1-butyl-3-methyl-imidazolium bis(trifluoromethanesulfonyl)imide ([CMIM][TFSI]) or [CMIM][TFSI] + linalool were determined. The experimental LLE data were satisfactorily represented by the non-random two-liquid model. [ABSTRACT FROM AUTHOR]

Liquid-liquid equilibria data have been determined for the ternary system of water + phosphoric acid + solvent entrainer (1,4-dimethylbenzene, 1,2-dichloroethane, and n-hexane) at 313.15 and 333.15 K. Experiments were carried out at atmospheric pressure using stirred and thermo-regulated cells. The ternary phase diagrams were obtained by the experimental solubility and tie-line data. The Othmer-Tobias equation was used to correlate the tie-line compositions. The measured liquid-liquid equilibrium data were compared with the non-random two liquid activity coefficient model. Root mean square deviations between experimental and calculated compositions were considered satisfactory. It was showed that the non-random two liquid model of all ternary systems presented very good satisfactory results with root mean square deviations so that this model was highly appropriate to calculate thermodynamic properties of the ternary solutions. The liquid-liquid equilibrium thermodynamic properties of water + phosphoric acid + solvent entrainer can be used in research on the nature of mixing behavior of the ternary system for molecular models and industrial applications in concentration the phosphoric acid aqueous solution. [ABSTRACT FROM AUTHOR]

The study concentrates on the separation of aromatic hydrocarbons from aliphatic hydrocarbon mixtures using ionic liquids as a new alternative of extraction solvents. Influence of the phase equilibrium description accuracy on the separation equipment design using different thermodynamic models was investigated. As a model system, a heptane-toluene binary mixture was chosen, employing 1-ethyl-3-methylimidazolium ethyl sulfate (EMIES) ionic liquid as an extractive solvent. Liquid-liquid equilibrium (LLE) data of the ternary system were calculated using NRTL equations with different quality model parameters. Model 1 corresponds to the NRTL equation with the original binary parameters evaluated independently from the respective binary equilibrium data. Model 2 is represented by an NRTL equation extended by the ternary correction term (with the original binary parameters and ternary correction term parameters evaluated from the ternary tie-lines). Model 3, i.e. the NRTL equation with binary model parameters determined via ternary LLE data regression using ASPEN Plus, was taken from Meindersma et al. (2006). Continuous-flow liquidphase extraction was simulated considering a cascade of mixer-settler type extractors according to the Hunter-Nash scheme (Hunter & Nash, 1934). Based on the simulation results, for a preset separation efficiency criterium, different accuracies of the equilibrium description caused serious discrepancies in the separation equipment design, e.g. in the number of theoretical stages, solvent to feed ratio, and product purity. [ABSTRACT FROM AUTHOR]

Liquid-liquid equilibria of the methanol + ethylbenzene + methylcyclohexane ternary system are reported at 278.15, 283.15, and 293.15 K. The effect of the temperature on the liquid-liquid equilibrium is discussed. All chemical concentrations were quantified by gas chromatography using a thermal conductivity detector. Experimental data for the ternary system are compared with values calculated by the NRTL and UNIQUAC equations. It was found that both equations gave comparable quality representations of the experimental data for this ternary system. Distribution curves were also analyzed. Data for the ternary system is available from the literature at 303.15 K. [ABSTRACT FROM AUTHOR]

In this paper, the liquid-liquid 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. [ABSTRACT FROM AUTHOR]

We present the results from measuring the solubility of 18-crown-6 in isobutanol in the temperature interval of 280-308 K and information about liquid-liquid equilibria in water-(1-, 2-, iso-)butanol-18-crown-6 systems at 298 K. The parameter values of the extended UNIQUAC model were determined on the basis of information about the thermodynamic properties and phase equilibria in the binary systems. It is shown that we must use parameters of ternary interaction in addition to binary parameters to adequately describe the miscibility gap on the basis of the results of turbidimetric titration in ternary water-(1-,2-, iso)butanol-18-crown-6 systems. [ABSTRACT FROM AUTHOR]

Experimental tie-line data were investigated for two quaternary systems of water + n-hexane + diethyl carbonate + dimethyl carbonate and water + toluene + isooctane + dimethyl carbonate, and two related ternary systems of water + n-hexane + diethyl carbonate and water + n-hexane + dimethyl carbonate at 298.15 K and ambient pressure. The experimental tie-line data have been correlated using a modified UNIQUAC model and an extended UNIQUAC model, both with multicomponent interaction parameters in addition to the binary ones. [ABSTRACT FROM AUTHOR]

Liquid–liquid equilibrium tie line data were determined for three quaternary systems water + ethanol + diethyl carbonate+ n-heptane, water + ethanol + 1,1-dimethylethyl methyl ether + diethyl carbonate, and water + 1,1-dimethylethyl methyl ether + diethyl carbonate+ n-heptane at 298.15 K and atmospheric pressure. The experimental liquid–liquid equilibria results have been correlated using a modified UNIQUAC model and an extended UNIQUAC model, both with multicomponent interaction parameters in addition to the binary ones. [ABSTRACT FROM AUTHOR]

Our Laboratory has synthesized a novel light-sensitive and recycling copolymer P NBC . The P NBC copolymer could form recycling aqueous two-phase systems with Dextran. Recycling aqueous two-phase systems have important application in bioseparation engineering. Phase diagram prediction of the novel aqueous two-phase systems also is an important aspect in engineering. This article applied the Cabezas model and effective excluded volume (EEV) model to the experimental data of light-sensitive recycling aqueous two-phase systems. It has been found that the EEV model could consist with experimental data very well. The maximum absolute error and average absolute error is 0.81% (wt%) and 0.23% (wt%), respectively. [ABSTRACT FROM AUTHOR]

Binary interaction parameters used in the UNIQUAC activity coefficient model are found to be dependent on each other and related by a linear relation termed as the closure equation. For a ternary system, six binary interaction parameters are related by one closure equation. Similarly for quaternary systems, three independent closure equations are obtained for the twelve binary interaction parameters and for quinary systems there are six closure equations for twenty parameters. Each closure equation consists of six parameters. The binary interaction parameters that do not satisfy the closure equations may lead to a less accurate prediction of liquid-liquid equilibria. In this work the binary interaction parameters have been estimated with and without closure equations for few ternary and quaternary systems. Parameters that satisfy the closure equations exhibit better root mean square deviation than those that do not satisfy the closure equations in most of the cases. A similar behavior is observed for NRTL model also. [ABSTRACT FROM AUTHOR]

The NFM ( N-formylmorpholine) extractive distillation process is used for the purpose of recovering aromatics, such as benzene, toluene, and xylene. The thermodynamic equation used in the simulation is the NRTL equation, and NRTL interaction binary parameters were obtained by experimental data. The missing thermodynamic properties are predicted by group contribution method. Simulation results of the extractive distillation column were in good agreement with the operation data. [ABSTRACT FROM AUTHOR]

Experimental tie-line data have been determined for the ternary system water + methyl tert-butyl ether + tert-amyl methyl ether and the quaternary systems water + methanol + methyl tert-butyl ether + tert-amyl methyl ether, and water + ethanol + methyl tert-butyl ether + tert-amyl methyl ether at 25°C and ambient pressure. The experimental results have been satisfactorily correlated using the modified UNIQUAC and extended UNIQUAC models with ternary and quaternary, in addition to binary parameters. [ABSTRACT FROM AUTHOR]

A model with nonclassical exponents is developed for phase equilibria of a Type 2 mixture with vapor–liquid equilibrium (VLE) and liquid–liquid equilibrium (LLE). Starting with a Leung–Griffiths model for a Type 1 mixture with only VLE, the model adds a Schofield parametric construction to describe LLE and a three-phase locus. Care is taken to suppress a spurious and artificial phase boundary. The model is applied to VLE data of carbon dioxide+methane. It is conjectured that this mixture upon cooling would undergo liquid–liquid separation, but it freezes before such “virtual LLE” can be observed. Experimental bubble curves and the LLE structure from a classical equation of state are accurately modeled. [ABSTRACT FROM AUTHOR]

A modified form of the UNIQUAC model is presented to accurately reproducebinary phase equilibria and ternary and quaternary liquid-liquid equilibria ofaqueous and organic solutions. The model gives a good representation in thereproduction of binary coexistence curves over a wide temperature range usingtemperature-dependent parameters and of binary vapor-liquid equilibria usingtwo binary energy parameters, and in the correlation of ternary and quaternaryliquid-liquid equilibria using ternary and quaternary parameters, in addition tobinary parameters. The quaternary calculated results are compared with thoseobtained from the modified Wilson and extended UNIQUAC models. [ABSTRACT FROM AUTHOR]

A ground based (1 g) experiment is in progress that measures the turbidity of the density-matched, binary fluid mixture methanol–cyclohexane extremely close to its liquid–liquid critical point. By covering the range of reduced temperatures t ≡ ( T− Tc)/ Tc from 10−8 to 10−2, the turbidity measurements should allow the Green–Fisher critical exponent η to be determined. This paper reports measurements showing ±0.1 % precision of the transmitted and reference intensities, and ±4μK temperature control near the critical temperature of 320 K. Preliminary turbidity data show a nonzero η consistent with theoretical predictions. No experiment has precisely determined a value of the critical exponent η, yet its value is significant to theorists in critical phenomena. Relatively simple critical phenomena, as in the liquid–liquid system studied here, serve as model systems for more complex behavior near a critical point. [ABSTRACT FROM AUTHOR]

This paper presents liquid liquid equilibria and densities of the coexisting phases for the system water-methanol-dichloromethane in the temperature range between 20 and 90 °C. 63 connodes, structured in isothermal datasets, have been measured. For each of the isothermal datasets a regression with the UNIQUAC as well as the NRTL model has been made. Both models describe the data within the experimental error. Simultaneous fit of all datas leads to unacceptable high deviations from experimental values for both the UNIQUAC and the NRTL modell. The extension of the UNIQUAC equation with a two parameter hyperbolic temperature function for the interaction parameters yields significantly better results as the original equation when applied to the fit of all available data. [ABSTRACT FROM AUTHOR]

Liquid-liquid equilibria of the ternary system 1,2-dichloroethane/ n-propanol/water were measured at 20, 30, and 40 °C. In the plot of the system for 20 °C are shown the results of 'titration' (i. e. addition of increasing quantities of water resp. 1,2-dichloroethane to the homogenous mixture of the other components). These results geree well with the plot of extraction results. The binary homogeneous systems n-propanol/water and n-propanol/1,2-dichloroethane exhibit an non-ideal behaviour. Vapor-liquid equil. of these systems were measures at 133.32 and 666.6 mbar (100 and 500 Torr). The azeotropic points at these pressures are in good agreement with the literature. In addition to this, measurements of the values of surface-tension, viscosity and refractive index were performed. Aqueous solutions of n-propanol can be determined by the micromethod of R. Fischer. [ABSTRACT FROM AUTHOR]

A newly developed laser light scattering technique was used for the determination of mutual solubilities in the aniline+cydohexane system at moderate pressures. The liquid-liquid equilibria (LLE) were measured from the region of solid-liquid equilibria (SLE) to the upper critical solution temperature. Freezing points in this system were determined by a cooling curve method. The solubility data were correlated with the NRTL equation. [ABSTRACT FROM AUTHOR]

Prediction of liquid-liquid phase equilibria is an important goal in the physical chemistry of solutions. Quantum chemistry methods, combined with a dielectric continuum description of the solvent, has received attention as a first principle approach. In this work, the performance of the continuum solvation model based on density (SMD) for prediction of γ∞ in binary liquid mixtures, using 46 values of γ∞, was evaluated. We found the mean uncertainty of RTln γ∞ to be 0.92 kcal mol−1. Based on the calculated γ∞ and the two parameters of the Redlich-Kister expansion, we calculated the liquid-liquid phase equilibria. Based on 26 values of solubility, an uncertainty of 0.66 was found in the logarithm of molar fraction of the smallest component in each phase. Our results suggest this approach can be used for fast and semi-quantitative prediction of phase behavior. More reliable predictions could be obtained with improvements in the SMD model.Prediction of liquid-liquid phase equilibriaᅟ [ABSTRACT FROM AUTHOR]