Solute Distribution Coefficient Research Articles

Liquid–Liquid Equilibria for Ternary Systems n-Hexane + 1-Hexene + Furfural (or N,N-Dimethylformamide) at 298.2, 308.2, and 318.2 K

The liquid–liquid equilibrium (LLE) data of ternary systems n-hexane + 1-hexene + solvents (furfural and N,N-dimethylformamide) were determined experimentally at 298.2, 308.2, and 318.2 K under 101.3 kPa. The solvents’ extraction capacity was assessed by the solute distribution coefficient and selectivity. Othmer-Tobias and Hand equations were used to correlate the measured data to test the correlation of the experimental data, which the linear correlation is (R2) ≥ 0.99. Experimental LLE data was correlated utilizing the NRTL and UNIQUAC thermodynamic models with all of the RMSD and AARD values below 0.01 meaning that each ternary system satisfactory agreement at temperatures studied and the NRTL model gives a better agreement than the UNIQUAC model for ternary systems.

Experimental determination and modeling of liquid-liquid equilibrium for water + diethoxymethane + methyl tert-butyl ether (or methyl isobutyl ketone) at 298.15, 308.15, and 318.15 K

The liquid-liquid equilibrium (LLE) data of ternary systems water + diethoxymethane (DEM) + Methyl tert-butyl ether (MTBE) and water + DEM + Methyl isobutyl ketone (MIBK) were determined experimentally at 298.15, 308.15, and 318.15 K under the atmospheric pressure condition. The solvents' extraction capacity was assessed by the solute distribution coefficient and selectivity. Othmer-Tobias and Hand equations were utilized to validate the accuracy and reliability of the measured data, which the linear correlation (R2) ≥ 0.99. Experimental LLE data was correlated utilizing the NRTL and UNIQUAC thermodynamic models with all of the RMSD values below 0.002 meaning that each ternary system satisfactory agreement at temperatures studied. Also, the reliability of binary interaction parameters was validated by the topological analysis based on the Gibbs tangent plane test using a graphical user interface.

On the behavior of the osmotic second virial coefficients of gases in aqueous solutions: Rigorous results, accurate approximations, and experimental evidence

We present a novel molecular-based approach for the determination of the osmotic second virial coefficients of gaseous solutes in dilute binary solutions, according to a recently proposed molecular thermodynamic formalism of gas solubility [A. A. Chialvo, J. Chem. Phys. 148, 174502 (2018) and Fluid Phase Equilib. 472, 94 (2018)]. We discuss relevant solvation fundamentals and derive new expressions including (i) the relations among infinite-dilution solvation quantities leading to a novel self-consistent route to the calculation of the osmotic second virial coefficients, (ii) the new microstructural interpretation of the resulting osmotic second virial coefficients based on Kirkwood-Buff integrals, the unambiguous discrimination between short- and long-range contributions, and their limiting behavior as the solvent approaches its critical conditions, (iii) new rigorous expressions for the calculation of the osmotic second virial coefficients using standard reference thermodynamic data, and (iv) their underlying interdependence based on the constrained state variable invoked in the density expansion. We then invoke the proposed formalism to shed some light on the inaccuracies behind current calculations of osmotic second virial coefficients from molecular theory and simulation as well as macroscopic correlations. To advance the microscopic understanding and illustrate the functional relationship between the osmotic second virial coefficients, Henry's law constant, and the solute-solvent intermolecular asymmetry as a source of solution non-ideality, we use data for the microstructural and thermodynamic behavior of infinitely dilute Lennard-Jones systems obtained self-consistently via integral equations calculations. The newly derived relationships leading to the proposed formalism offer novel routes for the accurate determination of osmotic second virial coefficients of any type of solutes in dilute solutions regardless of the type and nature of the intermolecular interactions. However, for illustration purposes in the current work, we dealt with aqueous solutions of simple gases to exploit the abundance of standard thermodynamic data for the orthobaric Henry's law constant and solute distribution coefficients, as well as the availability of results from molecular-based calculations and macroscopic correlations.

Separation of ethanol from n-decane-ethanol mixtures using imidazolium based ionic liquids

Great features of ionic liquids (ILs) lead to consider them as new generation of solvents in liquid-liquid extraction process. In present work, 1-ethyl-3-metylimidazolium thiocyanate ([Emim][SCN]) and 1-ethyl-3-methylimidazolium trifluoromethanesulfonate ([Emim][Otf]) were utilized as solvents for separation of ethanol from n-decane-ethanol mixtures. The experiments were conducted to obtain liquid-liquid equilibria (LLE) data of n-decane/ethanol/[Emim][SCN] and n-decane/ethanol/[Emim][Otf] systems at two different temperatures (T = 298.15 K and T = 313.15 K) and the pressure of 101.3 kPa. The solute distribution coefficients (β) and selectivities (S) were calculated to investigate the efficiencies of [Emim][SCN] and [Emim][Otf] as solvents. Moreover, the temperature dependencies of β and S were investigated in this study. The non-random two liquid (NRTL) model was used to correlate the recorded experimental data of studied systems.

Liquid–Liquid Extraction of Alcohols from Their Azeotropic Mixtures with Hexane Using Ionic Liquid

The phase behavior of alkane/alcohol/ionic liquid ternary systems is essential for designing the separation process of alcohol from its mixture with alkane. In this work, 1-ethyl-3-metylimidazolium thiocyanate ([Emim][SCN]) has been experimentally studied as an extractive agent for this process. New experimental liquid–liquid equilibria (LLE) data for four ternary systems (hexane/ethanol/[Emim][SCN], hexane/1-propanol/[Emim][SCN], hexane/2-propanol/[Emim][SCN], and hexane/1-butanol/[Emim][SCN]) are presented under standard conditions (pressure = 101.3 kPa and temperature = 298.15 K). The selectivity (S) and solute distribution coefficient (β) are measured to investigate the effectiveness of ionic liquid as a solvent to separate alcohol from its azeotropic mixtures with hexane. Furthermore, the effect of alcohol chain length has been investigated. Finally, nonrandom two-liquid model is utilized and tuned to model the experimental LLE data.

Study of Deep Eutectic Solvent on the Base Choline Chloride as Entrainer for the Separation Alcohol–Ester Systems

Choline chloride-based deep eutectic solvent (DES) was tested for the separation of azeotropic mixtures of ethanol–ethyl acetate, n-propanol–n-propyl acetate and n-butanol–n-butyl acetate via liquid–liquid extraction. The mixture of choline chloride with malonic acid with a molar ratio of 1:1 was used. Extraction experiments were conducted with the ternary mixture ethanol–ethyl acetate–DES at temperatures 293.15, 303.15, and 313.15 K and with ternary mixtures n-propanol–n-propyl acetate–DES and n-butanol–n-butyl acetate–DES at 293.15, 303.15, 313.15, and 323.15 K. Liquid–liquid tie-lines for studied systems were determined. The extraction performance of DES was characterized with solute distribution coefficients and values of selectively respectively to alcohol. The influence of the alkyl chain length of the alcohol and ester on the phase equilibria was investigated. Experimental data were fitted using the nonrandom two liquids model.

Liquid-liquid equilibrium for the system of ionic liquid [BMIm][HSO 4 ] catalysed isobutyl isobutyrate formation

Isobutyl isobutyrate is an important chemical which can be formed in a reactive extraction process with ionic liquid as dual solvent-catalyst. To design such an intensified process, the liquid-liquid equilibria (LLE) data for the esterification system involving ionic liquid are essential. In this work, the LLE of ternary systems {isobutyl isobutyrate (IBIBE) + isobutyric acid (IBAc) or isobutanol (IBOH) + 1-butyl-3-methylimidazolium hydrogen sulfate ([BMIm][HSO4])} and the quinary system {IBAc + IBOH + IBIBE + H2O + [BMIm][HSO4]} were measured at temperature T = (298.2, 323.2 and 353.2) K, T = (323.2, 333.2, 343.2 and 353.2) K and atmospheric pressure, respectively. Based on the experimental data, the solute distribution coefficient and the selectivity were determined, which confirms the feasibility of the ionic liquid for isobutyl isobutyrate formation. The phase behaviour was explained by the molecular interaction using σ-potential analysis. Moreover, the binary parameters of the NRTL model for [BMIm][HSO4] catalysed isobutyl isobutyrate formation system were fitted.

Liquid–liquid extraction of toluene from its mixtures with aliphatic hydrocarbons using an ionic liquid as the solvent

ABSTRACTThe knowledge of liquid–liquid equilibria (LLE) of the ternary systems (alkane/toluene/ionic liquid) is essential to develop thermodynamic models for liquid–liquid extraction of aromatics such as toluene from its mixtures with aliphatic hydrocarbons. In this study, new experimental LLE data for the ternary systems (hexane and heptane/toluene/1-methyl-3-octylimidazolium tetraflouroborate) are measured at T = 298.15 K and atmospheric pressure. The capability of ionic liquid for extracting toluene from its azeotropic mixture with aliphatic hydrocarbons (hexane and heptane) has been evaluated by the selectivity and solute distribution coefficients. The Othmer–Tobias equation has been applied to check the consistency of the experimental tie-lines. Finally, the obtained experimental LLE data are satisfactorily correlated by the nonrandom two-liquid model.

Liquid–Liquid Extraction of Lower Alcohols Using Menthol-Based Hydrophobic Deep Eutectic Solvent: Experiments and COSMO-SAC Predictions

The lower alcohols tend to form azeotropic solution with water which makes the separation challenging. The current work primarily focuses on the synthesis and application of a menthol-based hydrophobic deep eutectic solvent (DES) for the removal of lower alcohols from its aqueous solutions. The DES is synthesized by the addition of DL-menthol and lauric acid (dodecanoic acid) with a molar ratio of 2:1. Liquid–liquid equilibria (LLE) experiments are then performed to evaluate the performance of the synthesized DES for the extraction of lower alcohols such as ethanol, 1-propanol, and 1-butanol. LLE corresponding to the pseudo ternary systems of lower alcohols (1-butanol, ethanol, and 1-propanol) + hydrophobic DES + water are measured at T = 303.15 K and p = 1 atm. The composition of the tie lines were evaluated using 1H NMR analysis for both extract and raffinate phases. Thereafter, the extraction efficiency of the DES is analyzed and compared by determining the solute distribution coefficients and the sele...

Experimental measurement and thermodynamic modelling of liquid-liquid equilibria for the separation of 1,2-dichloroethane from cyclohexane using various extractants

Experimental liquid-liquid equilibrium (LLE) data for the cyclohexane +1.2-dichloroethane+solvent ternary systems were determined at T=313.15K and p=101.3kPa, where the extracting agents are sulfolane, dimethyl sulfoxide, 1,4-butanediol and N,N-dimethylmethanamide. According to the experimental values, solute distribution coefficient and selectivity were obtained to estimate the feasibility of the utilization of the selected solvents for extraction of 1,2-dichloroethane from cyclohexane. The reliability and consistency of the experimentally measured LLE results were then corroborated by employing the Hand and Bachman equations. In addition, the experimental tie-line compositions were successfully regressed with the universal quasi-chemical (UNIQUAC) and nonrandom two-liquid (NRTL) thermodynamic models, and the values of relevant binary energy parameters were reported as well. Further, the solvent cost analysis indicated that dimethyl sulfoxide was a desirable extractant for separation of 1,2-dichloroethane from cyclohexane.

Phase equilibrium measurements and thermodynamic modelling of {water + phenol + [Hmim][NTf 2 ]} ionic liquid system at several temperatures

Abstract Experimental liquid–liquid equilibrium (LLE) data of the ternary chemical system of {water + phenol + 1-hexyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, [Hmim][NTf2], ionic liquid (IL)} were obtained under different temperatures of (293.2, 298.2 and 308.2) K and ambient pressure of 81.5 kPa. The cloud point method, based on refractive index measurement, was employed. The results indicate that the solubility of phenol in the IL is considerably higher than in water, especially at high level concentrations. Meanwhile, due to very low miscibility of the IL in water and strong hydrogen bonding between the IL and phenol, high level solute distribution coefficient and separation factor were obtained within (5.586–25.001) and (105.05–1476.23), respectively. The reliability of the tie-line data was examined with Hand and Bachman equations. Further, the well-known NRTL and UNIQUAC models were used to correlate the experimental data. For this aim, the thermodynamic properties of the IL were determined by the Density Functional Theory (DFT) calculations, carried out at the M05-2X/6-311++G∗∗ level of theory. Low levels of root mean square deviations indicate the capability of the both models to correlate data with a preference for NRTL model.

Sound velocity during solidification in binary eutectic systems

We applied an ultrasound technique to an advanced material process by investigating the behavior of sound velocity during solidification of binary alloy melts over a wide range of temperatures and compositions. To gain a basic understanding of the relationship between the sound velocity and phase change in binary eutectic systems, the sound velocity was measured in Pb-Sn and Bi-Sn alloys by the pulse transmission method. Based on the measurement results, we established a link between the sound velocity variation and the complex solidification process, including the initial appearance of undercooling and eutectic reaction. During solidification, alloys usually pass through a transient mushy state between the liquid and solid phases. Since the solid fraction is uniquely related to the sound velocity, we demonstrate that it is possible to identify the solid fraction in the mushy state using the sound velocity. At the eutectic point, a sudden change was observed in relation to the eutectic reaction, in which the sound velocity exhibited an abrupt transition under isothermal conditions. This sudden change in the sound velocity was evident even when the initial composition was below the maximum solid-solution limit, such as when the solute distribution coefficient was relatively large. This result suggests that the presence of a eutectic in the final solidified texture can be predicted using our sound velocity measurement system. Finally, we present a novel sound velocity phase diagram that provides a real-time state determination system using ultrasound during solidification process, such as casting.

Liquid-liquid equilibrium data for extractive desulfurization using 1-butyl-3-methyl imidazolium thiocyanate, n-alkane and thiophene

The experimental liquid – liquid equilibrium (LLE) data for three ternary mixtures containing an ionic liquid (IL) (1-butyl-3-methyl imidazolium thiocyanate [Bmim][SCN]), alkanes (n-hexane, n-octane and n-decane) and sulfur compound (thiophene) have been measured experimentally. Distribution and selectivity coefficients have been calculated using experimental data. The LLE data have been obtained at 25 °C and ambient pressure. The experimental LLE data of ternary mixtures have been compared with our previous works. It has been shown that the IL with higher molecular weight of cation has higher solute distribution and lower selectivity coefficients. It has been found that the solubility decreases as the cation length decreases, meanwhile ILs cation chain length has a remarkable effect on solubility of alkanes. Moreover, the experimental data have been demonstrated that the selectivity decreases as alkane chain length of alkane decreases while the solubility of alkanes in the ILs increases, hence the removal costs of aromatic sulfur components will be increased. The results show that [Bmim][SCN] has the lowest alkane solubility and highest selectivity coefficient, in the system containing n-decane and thiophene. A comparative study reveals that compared to other ILs, [Bmim][SCN] is a more suitable solvent. Finally, the experimental data have been correlated utilizing non-randomness two liquid (NRTL) model. The binary energy parameters were obtained, it can be seen that the model can correlate the experimental data efficiently.

Liquid-liquid separation of hexane/hex-1-ene and cyclohexane/cyclohexene by dicyanamide-based ionic liquids

The work presented focused on the experimental liquid-liquid phase equilibrium measurements in ternary systems {ionic liquid (1)+hex-1-ene (2)+hexane (3)} and (ionic liquid (1)+cyclohexene (2)+cyclohexane (3)} at temperature T=298.15K and ambient pressure. The dicyanamide-based ionic liquids (ILs) were discussed as solvents for two types of separation problems of hexane/hex-1-ene and cyclohexane/cyclohexene. The objective of this work was to explore the feasibility of six ILs, namely N-ethyl-N-methylmorpholinium dicyanamide, [EMMor][DCA], (3-hydroxypropyl)-1-methylmorpholinium dicyanamide, [N-C3OHMMor][DCA], 1-(3-hydroxypropyl)-3-methylimidazolium dicyanamide, [N-C3OHMIM][DCA], 1-(3-hydroxypropyl)pyridinium dicyanamide, [N-C3OHPy][DCA], (3-cyanopropyl)pyridinium dicyanamide, [N-C3CNPy][DCA] and (3-cyanopropyl)methylpyrrolidinium dicyanamide,[N-C3CNMPyr][DCA]. The separating ability of the investigated ILs was compared with the previously measured by us in ternary LLE ILs for these chosen separation problems. The effect of cation for the same anion was examined with respect to the selectivity and solute distribution ratio in these processes. The separation effectiveness of the [N-C3CNMPyr][DCA] in comparison with other ILs used in this work is the best for hexane/hex-1-ene separations but lower than those presented by us earlier for [EMIM][DCA], however with better solute distribution coefficient. The experimental tie-lines were correlated with the non-random two liquid NRTL model. The proposed [N-C3CNMPyr][DCA] may be used as an alternative solvent for the separation of alkenes from alkanes and [EMMor][DCA] for cyclohexane/cyclohexene separation.

On the Nonequilibrium Interface Kinetics of Rapid Coupled Eutectic Growth

Nonequilibrium interface kinetics (NEIK) is expected to play an important role in coupled growth of eutectic alloys, when solidification velocity is high and intermetallic compound or topologically complex phases form in the crystallized product. In order to quantitatively evaluate the effect of NEIK on the rapid coupled eutectic growth, in this work, two nonequilibrium interface kinetic effects, i.e., atom attachment and solute trapping at the solid–liquid interface, were incorporated into the analyses of the coupled eutectic growth under the rapid solidification condition. First, a coupled growth model incorporating the preceding two nonequilibrium kinetic effects was derived. On this basis, an expression of kinetic undercooling (∆T k), which is used to characterize the NEIK, was defined. The calculations based on the as-derived couple growth model show good agreement with the reported experimental results achieved in rapidly solidified eutectic Al-Sm alloys consisting of a solid solution phase (α-Al) and an intermetallic compound phase (Al11Sm3). In terms of the definition of ∆T k defined in this work, the role of NEIK in the coupled growth of the Al-Sm eutectic system was analyzed. The results show that with increasing the coupled growth velocity, ∆T k increases continuously, and its ratio to the total undercooling reaches 0.32 at the maximum growth velocity for coupled eutectic growth. Parametric analyses on two key alloy parameters that influence ∆T k, i.e., interface kinetic parameter (μ i ) and solute distribution coefficient (k e ), indicate that both μ i and k e influence the NEIK significantly and the decrease of either these two parameters enhances the NEIK effect.

Choline chloride based deep eutectic solvents as extraction media for separation of n-hexane–ethanol mixture

Two different choline chloride based deep eutectic solvents (DES) were tested for the separation of azeotropic mixture of n-hexane and ethanol via liquid-liquid extraction. The simplest mixtures of choline chloride with dibasic acids: oxalic (DES1) or malonic (DES2) with molar ratio 1:1 were used. The selected DESs were characterized by differential scanning calorimetry (DSC). Extraction experiments were conducted with pseudo-ternary mixtures n-hexane–ethanol–DES. Tie-lines were obtained at temperatures 293.15 K, 313.15 K and atmospheric pressure. The extraction performance of DES was characterized with solute distribution coefficients and values of selectively for ethanol. It has been shown that the most successful component for the separation of a mixture of n-hexane-ethanol is water. It was found that DES1 is more effective then DES2 for extraction of ethanol. The higher efficiency of separation of DES as compared to conventional ionic liquids (IL) makes it possible to consider them as an alternative promising solution in the separation of multicomponent mixtures. Experimental data was fitted using the nonrandom two liquids (NRTL) model.

Ternary Liquid–Liquid Equilibrium of Azeotropes (Ester + Alcohol) with Different Ionic Liquids at T = 298.15 K

The liquid–liquid equilibria (LLE) for ternary systems of n-propyl acetate (PAC) + 1-propanol (NPA) + 1-butyl-3-methylimidazolium hexafluorophosphate ([Bmim][PF6]) or 1-hexyl-3-methylimidazolium hexafluorophosphate ([Hmim][PF6]) and n-butyl acetate (NBAC) + n-butanol (NBA) + [Bmim][PF6] or [Hmim][PF6] were measured at 298.15 K and 101.325 kPa. All the studied systems containing ionic liquids (ILs) show Treybal type I behavior of the LLE. The solute distribution coefficient (β) and the selectivity (S) were used to investigate the effect of the number of carbon atoms of cations, esters, and alcohols of ionic liquids on the liquid–liquid phase behavior for ester-alcohol-ILs. The measured data were correlated using both the NRTL model and the UNIQUAC model. Results indicate that all these systems can be correlated with reasonable accuracy by using both the NRTL model and the UNIQUAC model.

Homogenous multi-agent optimization for process systems engineering problems with a case study of computer aided molecular design

In this paper, we propose a novel homogenous multi-agent optimization (HMAO) framework for optimal design of large scale process system engineering problems. The platform is validated using a benchmark problems and a computer-aided molecular design (CAMD) problem. The molecular design problem is a solvent selection problem and it is formulated as a mixed integer nonlinear programming (MINLP) in which solute distribution coefficient of a candidate solvent is maximized subject to structural feasibility, thermodynamic property and process constraints. The model simultaneously determines the optimal decisions that include the size and the functional groups of the candidate solvents. In developing the HMAO framework, multiple efficient ant colony optimization (EACO) algorithms are considered as distinct algorithmic agents. We illustrate this approach through a real world case study of the optimal design of solvent for extraction of acetic acid from waste process stream using liquid–liquid extraction. The UNIFAC model based on the infinite dilution activity coefficient is used to estimate the mixture properties. The results show that quality of the objective function and the computational efficiencies are improved by a factor ranged from 1.475 to 4.137. The new solvents proposed in this work are with much better targeted thermodynamic properties compared to the solvents proposed so far in previous studies.

Measurements and prediction of ternary liquid–liquid equilibria for mixtures of IL + sulfur compound + hexadecane

For the practical application of ionic liquids as possible solvents for the removal of thiophenic compounds in the diesel fuel, the liquid–liquid equilibrium (LLE) data of such systems is necessary for the design and optimization of process equipment. In this work, LLE experiments were carried out on four ternary systems consisting of one of two pyrrolidinium or phosphonium-based ionic liquids (IL), one of two sulfur compounds and hexadecane as a representative for diesel fuel. For benzothiophene, the system consisting of the [HMPyrr][TFSI] IL as a solvent possesses the highest solute distribution coefficient (2.754) while a solute distribution coefficient of 3.722 was recorded for dibenzothiophene using the [P4444][MeSO3] as an extraction solvent. The LLE data were fairly correlated with the NRTL model especially at the region of low mole fraction of the sulfur compounds. The data presented in this work can therefore be integrated into process simulators and can be used for preliminary techno-economic evaluation of an ionic liquid-based deep extractive desulfurization of diesel fuel.

Ability of Single-Rate Models to Predict Solute Distribution Coefficients in Systems with Heterogeneous Sorption Kinetics

Several sorption nonequilibrium models have been developed to gain a better understanding of solute transport in porous media, among which are those that assume a single-rate behavior. In this study, two commonly used single-rate models were fitted to computer-simulated breakthrough data from hypothetical column experiments in which multirate sorption kinetics exist at the pore scale. The objective was to determine how the sorption distribution coefficient (K) predicted using these models depends on the conditions under which the data were obtained. Simulated cases covered a range of experimental conditions and involved compounds with different sorption characteristics and different degrees of sorption rate heterogeneity. Results revealed that, for a system with a multirate sorption behavior, the true K value is under-predicted if the parameter estimation is determined by curve fitting a single-rate model. The extent of deviation between the fitted and true K increases with the decrease in residence time and increase in sorption rate heterogeneity. Functional relationships were developed between the relative reduction in K and solute residence time. Analysis using the relationships developed suggests that a major potential cause of the previously reported discrepancy between batch- and column-determined K could be attributed to the use of single-rate models for parameter prediction.