Tie-line Compositions Research Articles

Evaluation of the impact of phosphate salts on the formation of ionic-liquid-based aqueous biphasic systems

The present study aims at evaluating the capability of phosphate-based salts, whose anions can coexist in water depending on the media pH, to promote aqueous biphasic systems (ABS) formation with 1-butyl-3-methylimidazolium-based ionic liquids, as well as to infer on the influence of the ionic liquid anion in the overall process of liquid–liquid demixing. In this context, novel phase diagrams of ABS composed of several imidazolium-based ionic liquids and three phosphate salts and a mixture of salts (K3PO4, K2HPO4, K2HPO4+KH2PO4, and KH2PO4) were determined by the cloud point titration method at 298K and atmospheric pressure. The corresponding tie-line compositions, tie-line lengths, and pH values of the coexisting phases were also determined. The ionic liquids ability to promote ABS is related with the hydrogen-bond basicity of the composing anion – the lower it is the higher the ability of the ionic fluid to undergo liquid–liquid demixing. Moreover, similar patterns on the ionic liquids sequence were observed with the different phosphate salts. The phosphate anion charge plays a determinant role in the formation of ABS. The two-phase formation aptitude (with a similar ionic liquid) decreases in the rank: K3PO4>K2HPO4>K2HPO4+KH2PO4>KH2PO4. Yet, besides the charge of the phosphate anion, the pH and ionic strength of the aqueous media also influence the phase separation ability.

(Liquid + liquid) equilibria for the ternary system of (N-formylmorpholine + ethylbenzene + 2,2,4-trimethylpentane) at temperatures (303.15, 313.15, and 323.15) K

Being an extraction solvent, N-formylmorpholine (NFM) is widely used to separate aromatic and aliphatic hydrocarbons. In order to get the LLE data and the interaction parameters of the ternary system of (NFM+ethylbenzene+2,2,4-trimethylpentane), the (liquid+liquid) equilibrium (LLE) data were measured for the ternary system under atmospheric pressure and at temperatures (303.15, 313.15, and 323.15) K in this work. The data can also demonstrate the ability for NFM to remove ethylbenzene from the mixture with 2,2,4-trimethylpentane. The complete phase diagrams were obtained by determining the solubility and the tie-line data. The tie-line compositions were correlated by Othmer–Tobias equation. The correlation factors r2 are bigger than 0.981. The universal quasi-Chemical activity coefficient (UNIQUAC) and the nonrandom two liquids equation (NRTL) were used to calculate the phase equilibrium data of the system with the interaction parameters fitted from the experimental data. It is found that both UNIQUAC and NRTL models could provide good correlations for the LLE data of the system. The root mean square deviation (RMSD) values for the NRTL and UIQUAC models are less than 0.0083 at all temperatures. In addition, the distribution coefficients, separation factors and selectivity were evaluated for the immiscibility region and the extracting capability of the solvents.

Binodal Curves and Tie-Lines of Aliphatic Alcohols + Diammonium Hydrogen Citrate + Water Ternary Systems: Measurement and Modeling

The liquid–liquid equilibrium of 1-propanol, 2-propanol, 2-methyl-2-propanol, or 2-butanol + diammonium hydrogen citrate aqueous biphasic systems was studied at 298.15 K. The binodal curves of investigated systems at (298.15 and 308.15) K were measured; the dielectric constant and densities were used to modify the empirical Merchuk equation, and the obtained equation was used for the correlation of all measured binodal data simultaneously. The temperature effect on the studied systems in the (293.15 to 323.15) K temperature range was discussed using the measured cloud-point data at constant salt-to-water mole fraction ratios. Additionally, tie-line compositions are reported at 298.15 K, and the electrolyte nonrandom two-liquid (NRTL) model was satisfactorily used for the correlation of these data; the restricted binary interaction parameters were also obtained. An acceptable agreement between the calculated and the experimental tie-line data was obtained.

Liquid–liquid equilibria of water + 2,3-butanediol + isobutanol at several temperatures

(Liquid–liquid) equilibrium (LLE) data for the ternary system of water+2,3-butanediol+isobutanol have been determined at 298.2, 308.2 and 318.2K and atmospheric pressure. Solubility curves were obtained by the cloud point method, while compositions of tie-lines were obtained by gas chromatography. Distribution coefficients and separation factors have been evaluated for the immiscibility region. The reliability of the experimental tie-lines has been confirmed by using Othmer–Tobias correlation. The LLE data of the ternary systems have been correlated by both the NRTL model and UNIQUAC model. Root mean square deviations between experimental and calculated compositions were considered satisfactory.

Equilibrium Phase Behavior of Poly(ethylene glycol) 4000 and Biodegradable Salts at Various Temperatures [(20, 30, and 40) °C

Liquid–liquid equilibrium data for the PEG 4000 (poly(ethylene glycol)) + salt [sodium citrate (Na3C6H5O7), potassium citrate (K3C6H5O7), or ammonium citrate ((NH4)3C6H5O7)] + water systems have been determined experimentally at different temperatures. The effects of temperature on the binodal curves and tie-lines were studied, and it was observed that an increase of the temperature generally led to an increase of the two-phase area. The salting-out ability of the cations follows the ordering sodium citrate > potassium citrate > ammonium citrate. Finally, the Setschenow-type, Othmer–Tobias, and Bancroft equations have been successfully used to correlate the tie-line compositions.

Liquid–liquid equilibria of systems containing cottonseed biodiesel + glycerol + ethanol at 293.15, 313.15 and 333.15 K

Liquid–liquid equilibrium (LLE) data for the ternary system (cottonseed biodiesel+glycerol+ethanol) have been determined at T=293.15, 313.15 and 333.15K and atmospheric pressure. The solubility (binodal) curves and tie-line compositions were obtained by means of density measurements. The reliability of the data has been tested by using Othmer–Tobias equation, with a squared correlation coefficient better than 0.99 for all systems studied. Selectivity and distribution coefficients have been determined from equilibrium data. Experimental LLE data have been correlated using NRTL model with an average global deviation of 0.89%. Additionally, binary interaction parameters of ternary systems components have been calculated.

(Liquid +Liquid) Equilibrium for Ternary Systems Containing of an Ionic Liquid, n-Hexane and an Organic Compound Involved in the Kinetic Resolution of rac-2-Pentanol

In this paper, (liquid +liquid) equilibrium (LLE) data for 12 ternary systems containing an ionic liquid + n-hexane +an organic compound involved in the racemic resolution of rac-2-pentanol (rac-2-pentanol, vinyl butyrate, rac-2-pentyl butyrate, or butyric acid) have been experimentally determined at 298.2 K and atmospheric pressure. The ionic liquids used were i. 1-ethyl-3-methylimidazolium ethylsulfate, [emim+] [EtSO4 −]; ii. 1-butyl-3–methylimidazolium tetrafluoroborate, [bmim+][BF4 −] and iii. 1-butyl-3-methylimidazolium bis{(trifluoromethyl)sulfonyl}imide, [bmim+][NTf2 −]. The binodal curves and the tie line compositions of the conjugate solutions were obtained by means of refractive index (ionic liquid rich phase) and by gas cromatography (hexane rich phase) to determine their potential for selectively extracting organic compounds from an ionic liquid reaction mixture. The tie line data were correlated through the use of the Non-Random Two-Liquid (NRTL) model for statistical consistency, which provides excellent agreement with the experimental measurements. There are no literature data for the mixtures discussed in this paper.

Liquid–Liquid Phase Behaviors of Geraniol in Aqueous Alcohol Mixtures

Liquid–liquid equilibrium (LLE) data of the binodal curves and tie-line compositions were examined for ternary mixtures of (water + methanol + geraniol) and (water + ethanol + geraniol) at T = (283.15, 298.15, and 313.15) K. The immiscible area of the (water + methanol + geraniol) system is wider than that for the ethanol system at the same temperature. The experimental liquid–liquid equilibrium data have been represented by using the original UNIQUAC, extended UNIQUAC, and modified UNIQUAC models.

Liquid–Liquid Equilibrium for Ternary Mixtures of Biodiesel (Soybean or Sunflower) + Glycerol + Ethanol at Different Temperatures

Biodiesel has many advantages because it is a biodegradable, nontoxic fuel and its production results in less particulate matter. For this reason it has been studied in many fields of science as a substitute for mineral fuels. Short chain alcohols such as ethanol have been used for extraction of soybean and sunflower biodiesel in the literature. The present paper reports liquid–liquid equilibrium data for systems containing soybean biodiesel + glycerol + ethanol at (293.15 and 323.15) K and sunflower biodiesel + glycerol + ethanol at (298.15 and 313.15) K. Binodal curves were obtained by the cloud-point method, while tie-line compositions were obtained by density measurements. The values of distribution coefficients and selectivities indicate that the ethanol is a good solvent for the extraction of soybean biodiesel and sunflower biodiesel from glycerol. The reliability of experimentally measured tie-line data can be ascertained by applying the Othmer–Tobias equation. The experimental data were correlated...

Study of the liquid–liquid equilibrium of 1-propanol + manganese sulphate and 2-propanol + lithium sulphate aqueous two-phase systems at different temperatures: Experiment and correlation

Phase equilibrium data for 1-propanol + manganese sulphate and 2-propanol + lithium sulphate aqueous two-phase systems were measured at T = 298.15, 308.15 and 318.15 K. The salting-out effect was discussed on the bases of the salting-out coefficient of the Setschenow-type equation. Furthermore, the experimental tie-line compositions were successfully correlated to the generalized electrolyte-NRTL model for mixed solvent electrolyte system (e-NRTL), and the binary interaction parameters of the e-NRTL model were obtained. Correlation of the tie-lines data shows that the calculated values and experimental data are in good agreement and the performance of the e-NRTL model in the correlation of the tie-lines data is good.

(Liquid + liquid) equilibrium of (imidazolium ionic liquids + organic salts) aqueous two-phase systems at T = 298.15 K and the influence of salts and ionic liquids on the phase separation

(Liquid + liquid) equilibrium for the {1-ethyl-3-methylimidazolium tetrafluoroborate ([C 2mim]BF 4)/1-propyl-3-methylimidazolium tetrafluoroborate ([C 3mim]BF 4) + organic salt + H 2O} aqueous two-phase systems (ATPSs) have been experimentally ascertained at T = 298.15 K. Three empirical equations were used to correlate the binodal data. On the basis of the empirical equation of the binodal curve with the highest accuracy and lever rule, the (liquid + liquid) equilibrium data were calculated by MATLAB. The reliability of the tie line compositions was proved by the empirical correlation equations given by the Othmer–Tobias and Bancroft equations. The effective excluded volume (EEV) values obtained from the binodal model for these systems were determined. The EEV and the binodal curves plotted in molality both indicate that the salting-out abilities of the four salts follow the order: Na 3C 6H 5O 7 > (NH 4) 3C 6H 5O 7 > Na 2C 4H 4O 4 ≈ Na 2C 4H 4O 6, while the phase-separation abilities of the investigated ILs are in the order of [C 3mim]BF 4 > [C 2mim]BF 4. In the systems investigated, the effect of salts on the phase-forming capability was also evaluated in the shape of the salting-out coefficient obtained from fitting the tie-line data to a Setschenow-type equation. The phase-forming ability increases with the increase of salting-out coefficient.

Liquid–liquid equilibrium for the ternary system isopropenyl acetate + water + acetic acid at 298.2 K, 313.2 K, 323.2 K and 333.2 K

Liquid–liquid equilibrium data for the ternary system isopropenyl acetate + water + acetic acid were measured at 298.2 K, 313.2 K, 323.2 K, 333.2 K and atmospheric pressure. Binodal curves were obtained by the cloud point method, while compositions of tie-lines were obtained by gas chromatography. The plait points were calculated by a convenient method described by Treybal and the consistency of the tie-line data were ascertained by Ishida correlation. In addition, the experimental data were correlated by the NRTL model and UNIQUAC model. Root mean square deviations between experimental and calculated compositions were considered satisfactory.

Liquid–Liquid Equilibrium of Poly(ethylene glycol) 2000 + Diammonium Hydrogen Citrate + Water System at Different Temperatures

Phase diagrams and liquid–liquid equilibrium (LLE) data of the aqueous poly(ethylene glycol) (PEG-2000) + diammonium hydrogen citrate system (aqueous two-phase system) has been determined experimentally at (298.15, 303.15, 308.15, 313.15, and 318.15) K. The effects of temperature on the binodal curve and tie-lines have been studied. The binodal curve was fitted to an empirical equation relating the concentrations of PEG 2000 and diammonium hydrogen citrate, and the coefficients were estimated for the respective temperatures. Tie line compositions were estimated and correlated using Othmer–Tobias and Bancroft equations, and the parameters are reported. The effect of temperature on the phase-forming ability in the investigated system has been studied based on a salting-out coefficient; obtained from fitting the binodal data to a Setschenow-type equation for each temperature. The effective excluded volume values were also calculated from the binodal data.

Extraction of Benzene from Aliphatic Compounds Using Commercial Ionic Liquids as Solvents: Study of the Liquid–Liquid Equilibrium at T = 298.15 K

In this paper, the liquid extraction of benzene from aliphatic compounds (heptane, octane, cyclooctane, and methylcyclohexane) using commercial ionic liquids (ILs; 1-propyl-3-methylimidazolium bis{trifluoromethylsulfonyl}imide, [PMim][NTf2], and 1-butyl-3-methylimidazolium bis{trifluoromethylsulfonyl}imide, [BMim][NTf2]) as solvents was studied. The liquid–liquid equilibrium (LLE) data for five ternary systems (aliphatic compound + benzene + IL) are reported at T = 298.15 K and atmospheric pressure. The cloud point method was used to determine the solubility curves, and the tie-line compositions were obtained by density measurements. From the experimental LLE data, the selectivity and the solute distribution ratio were calculated. The degree of consistency of the tie-lines was tested using the Othmer–Tobias equation, and the experimental LLE data were correlated using nonrandom two-liquid (NRTL) and universal quasichemical (UNIQUAC) thermodynamic models. Moreover, a systematic study about the influence of the size of the aliphatic and IL on the aromatic extraction was carried out.

Liquid−Liquid Equilibria of Water + 3-Hydroxy-2-butanone + 1-Butanol

Liquid−liquid equilibrium (LLE) data of the solubility curves and tie-line compositions have been determined for mixtures of (water + 3-hydroxy-2-butanone +1-butanol) at 298.15 K, 308.15 K, and 318.15 K and 101.3 kPa. Distribution coefficients and separation factors have been evaluated for the immiscibility region. The reliability of the experimental tie-lines has been confirmed by using Othmer−Tobias correlation. The LLE data of the ternary systems have been predicted by the UNIFAC method.

Liquid–liquid equilibria of water + 3-hydroxy-2-butanone + ethyl ethanoate

(Liquid–liquid) equilibrium (LLE) data of the solubility curves and tie-line compositions have been determined for mixtures of (water + 3-hydroxy-2-butanone + ethyl ethanoate) at 298.15 K, 308.15 K and 318.15 K and 101.3 kPa. Distribution coefficients and separation factors have been evaluated for the immiscibility region. The reliability of the experimental tie-lines has been confirmed by using Othmer–Tobias correlation. The LLE data of the ternary systems have been predicted by UNIFAC method.

Liquid−Liquid Equilibria of the (Water + Ethanol + Linalyl Acetate) Ternary System at Different Temperatures

Liquid−liquid equilibrium (LLE) data of the solubility curves and tie-line compositions were examined of the (water + ethanol + linalyl acetate) system at T = (298.2, 308.2, and 318.2) K and P = 101.325 kPa. The relative mutual solubility of ethanol is higher in the water phase than in the linalyl acetate phase. The consistency of the experimental tie lines was determined through the Bachman correlation equation. The experimental LLE data were satisfactorily correlated with the nonrandom two-liquid model (NRTL), and the binary interaction parameters so obtained are reported. The best results were obtained with the NRTL method, using nonrandomness parameter (α = 0.3) for the correlation. Distribution coefficients (D) and separation factors (S) were evaluated over the immiscibility region. The influence of temperature on the LLE characteristics was found to be significant at the temperatures studied.

Liquid–liquid equilibrium for the ternary systems of water + acetyl acetone + propyl acetate at several temperatures

Liquid–liquid equilibrium data of the solubility curves and tie-line compositions were determined for ternary systems of water + acetyl acetone + propyl acetate at 288.15 K, 298.15 K and 313.15 K and atmospheric pressure. Distribution coefficients were evaluated for the immiscibility region. The reliability of the experimental tie-lines has been confirmed by using Othmer–Tobias and Bachman correlation. The experimental data were fitted using the NRTL and UNIQUAC equations, parameters of these two models were regressed.

Tie-Line Compositions of the σ and (γ,δ) Phases in the Re-Cr-Ni System at 1573 K

Compositions with tie lines between the σ and (γ,δ) phases in a ternary Re-Cr-Ni system were investigated by heat treating various ternary Re-Cr-Ni alloys at 1573 K in vacuum for up to 2000 h. The microstructures of the Re-containing alloys that had been water quenched after various heat treatment for times were observed and their concentration profiles for Re, Cr, and Ni were measured using an electron probe microanalyzer. The Re-Cr-Ni alloys consisted of the σ phase with either the γ or δ phase. The concentration profiles of the γ phase became flat after short heat treatment, whereas longer times of up to 2000 h were required to achieve the same effect for the σ and δ phases.The tie-line composition (at%) of each phase at 1573 K was experimentally determined as follows. The σ phase tie-line with the γ phase (17.3 Re, 20.6 Cr, and 62.1 Ni) consists of 53.1 Re, 25.5 Cr, and 21.4 Ni. The σ phase tie-lined with the γ phase (16.9 Re, 19.2 Cr, and 63.9 Ni) consists of 53.0 Re, 24.6 Cr, and 22.4 Ni. The σ phase tie-line with the γ phase (12.7 Re, 24.8 Cr, and 62.5 Ni) consists of 48.4 Re, 30.9 Cr, and 20.7 Ni. The σ phase tie-line with the γ phase (6.1 Re, 46.2 Cr, and 47.7 Ni) consists of 28.1 Re, 52.3 Cr, and 19.6 Ni. The σ phase tie-line with the δ phase (85.6 Re, 5.2 Cr, and 9.2 Ni) consists of 61.1 Re, 27.7 Cr, and 11.2 Ni.

Separation of toluene from cyclic hydrocarbons using 1-butyl-3-methylimidazolium methylsulfate ionic liquid at T = 298.15 K and atmospheric pressure

In this paper the extraction of toluene from cyclic hydrocarbons (cyclohexane, or methylcyclohexane, or cyclooctane, or cyclohexene) was analyzed by liquid extraction with 1-butyl-3-methylimidazolium methylsulfate ionic liquid, [BMim][MSO 4], as solvent. The experimental (liquid + liquid) equilibrium (LLE) data were determined at T = 298.15 K and atmospheric pressure. Solubility curves were obtained by the cloud point method and tie-line compositions were determined by density measurement. An analysis of the influence of different cyclic hydrocarbons on the extraction was performed. The effectiveness of the extraction of toluene from cyclic hydrocarbons was evaluated by means of the solute distribution ratio and selectivity values. The degree of consistency of the experimental LLE data was ascertained using the Othmer–Tobias and Hand equations. The experimental data for the (liquid + liquid) equilibria of the ternary systems were correlated with the Non-Random Two-Liquid (NRTL) and UNIversal QUAsi-Chemical (UNIQUAC) thermodynamic models.