Mónica B. Gramajo de Doz

Liquid-liquid equilibria for the system water + propionic acid + 1-butanol at 303.2 K. Effect of addition of sodium chloride

Abstract Solubility and tie-line data were obtained for the ternary system: water + propionic acid + 1-butanol at 303.2 K. The ‘salting-out’ effect was studied by using sodium chloride (NaCl) at three concentrations within its solubility limits. The effect of the addition of this salt on the liquid-liquid equilibrium data of the ternary system has been investigated at the same temperature, determining independently both the solubility curve and the tie lines. In all cases, the addition of salt enhances significantly the distribution coefficients and selectivities, while the region of heterogeneity increases as compared to the no-salt condition. Tie-line data were correlated by the method of Othmer and Tobias [R.E. Othmer, P.E. Tobias, Ind. Eng. Chem. 34 (1942) 690–700.] and their parameters were evaluated. From the experimental results, it is evident that NaCl is not distributed in the same proportion between the phases at equilibrium, and that 1-butanol is a good solvent for extraction purposes.

Liquid–Liquid equilibria of ternary and quaternary systems including 2,2,4-trimethylpentane, benzene, ethanol, and water at 303.15 K

Tie-line data for ternary systems including ethanol (C2H6O), water (H2O), benzene (C6H6), and 2,2,4-trimethylpentane (C8H18) were investigated. Phase diagrams of {w 1H2O + w 2C2H6O + (1 − w 1 − w 2)C6H6} and {w 1H2O + w 2C2H6O + (1 − w 1 − w 2)C8H18} ternary systems were obtained at 303.15K, while {w 1H2O + w 2C8H18 + (1 − w 1 − w 2)C6H6} ternary system was taken from literature. A quaternary system containing these four compounds {w 1C2H6O + w 2C6H6 + w 3C8H18 + (1 − w 1 − w 2 − w 3)H2O} was also studied at the same temperature. From our experimental results, we can conclude that this quaternary system presents a very low water tolerance. Small quantities of water from ambient humidity or infiltration into storage tanks could produce phase separation with a considerable loss of C2H6O drawn into the aqueous phase. On the other hand, the results also show that the aqueous phase contains a higher concentration of C6H6 compared to C8H18. The ternary experimental results were correlated with the NRTL and UNIQUAC equations, and predicted with the UNIFAC group contribution method. The three models lead to accurate results according to the two overall errors. In order to predict the equilibrium data for the quaternary system the UNIFAC method was used. This method predicts the binodal surface, satisfactorily although its prediction of the ethanol distribution ratio is rather poor.

Influence of temperature on the liquid-liquid equilibria containing two pairs of partially miscible liquids. Water + nitromethane + 1-butanol ternary system

Abstract In order to show the influence of the temperature on the liquid–liquid equilibria for water+furfural+1-butanol ternary system, the solubilities and equilibrium data starting at 298.15 K have been measured. Between 298.15 K and 376.6±0.5 K, binodal band type curves are present, but above this last value, two separate binodal curves appear. The solubility data for water+furfural binary system is also reported. From the solubility curve, the upper critical solution temperature (UCST) was interpolated: 396 K and mass fraction of water equal to 0.49. When the temperature is decreased below the lower CST, the ternary system presents two binodal curves expanding toward each other until they meet with a common plait point at the lowest point on the ridge (saddle point, or col), which is situated at 376.6±0.5 K with a ternary composition: w1=0.64; w2=0.21 and w3=0.15. Tie-line data were satisfactorily correlated by the Othmer and Tobias method on a mass fraction basis, and their plait point coordinates were estimated when two separate binodal curves were present. From experimental distribution coefficients and selectivities, 1-butanol appears to be a good solvent for extraction purposes, particularly when the process is carried out at room temperature.

Influence of temperature on the liquid-to-liquid extraction of 4-hydroxy-4-methyl-2-pentanone from aqueous solutions with benzyl alcohol

Abstract Solubilities between 323.15 and 413.15 K and equilibrium data between 323.15 and 373.15 K for the water + 4-hydroxy-4-methyl-2-pentanone + benzyl alcohol ternary system are reported in order to obtain the extractive properties of benzyl alcohol for separating 4-hydroxy-4-methyl-2-pentanone from aqueous solutions, and the influence of temperature. Solubility data of the binary system water + benzyl alcohol are also reported. The effect of temperature on liquid-liquid phase equilibrium was determined, and its consequences are discussed. Tie-line data were satisfactorily correlated by the Othmer and Tobias method [Othmer, D.F. and Tobias, P.E., 1942. Tie line correlation. Ind. Eng. Chem., 34: 693–696]. The experimental data were compared with values calculated by the NRTL and UNIQUAC equations for the ternary mixture, and the predictions obtained by the UNIFAC method are also included. While the water + benzyl alcohol system has a binary upper critical solution temperature at 421.65 K, no ternary one was observed. It is concluded that benzyl alcohol is appropriate for the extraction process when the mass fraction of the consolute component in the extract phase is less than 0.22, not as suitable when this concentration is greater. The small difference in the extractive properties between 348.15 K and room temperature shows that it is unnecessary to carry out the extraction at a higher temperature.

Aqueous phase diagrams containing t-aconitic acid + (1-pentanol or +isobutyl acetate or + methyl isobutyl ketone) at 303.15 K

Abstract Phase diagrams of ternary systems, water+t-aconitic acid (AA)+(1-pentanol (P) or +isobutyl acetate (iBuAc) or +methyl isobutyl ketone (MIK)), were obtained at 303.15±0.05 K. Experimental results show that all aqueous AA systems have one liquid–liquid equilibria region and three solid–liquid equilibria zones, where the solid is the AA. The recovery of this acid from aqueous solutions was evaluated by analyzing its distribution coefficients, selectivities, and distribution curves on a solvent-free basis. Although the experimental distribution coefficients are practically always less than unity for the three systems, the selectivities are higher due to the lower solubility of the non-consolutes, particularly for MIK, which appears as the best solvent among those studied here. The experimental data were also compared with values calculated by the NRTL and UNIQUAC equations for these ternary mixtures.

Aqueous phase diagrams containing oxalic acid at 303.15 K

Abstract Phase diagrams of ternary systems: water + oxalic acid + (1-pentanol or + isobutyl acetate or + methyl isobutyl ketone) were obtained at 303.15 K. The system containing 1-pentanol was revised [Faizal et al., J. Chem. Eng. Data 35 (1990) 352–354] in order to show the presence of the dihydrate of oxalic acid, by means of the analysis of the solid phase using FT-IR spectrum, melting point data, and acid-base titration. Experimental results show that all aqueous oxalic acid systems have one region where both acid forms are mixed, and three solid-liquid zones where the solid is the hydrated oxalic acid. The recovery of oxalic acid from aqueous solutions was evaluated analyzing their distribution coefficients, selectivities and distribution curves on a solvent-free basis. None of the three solvents studied here were found suitable for oxalic acid extraction processes, because distribution coefficients are always smaller than 1 and selectivities are not high enough.

Excess Molar Volume and Excess Viscosity of Benzyl Alcohol + 4-Hydroxy-4-Methyl-2-Pentanone and Water +4-Hydroxy-4-Methyl-2-Pentanone Binary Systems at 298.15K

Densities, viscosities and refractive indices have been measured at 298.15K for water + 4-hydroxy-4-methyl-2-pentanone and benzyl alcohol + 4-hydroxy-4-methyl-2-pentanone binary mixtures over the whole concentration range. From experimental densities and viscosities, excess molar volumes and excess viscosities, respectively have been calculated. These results are fitted with a Redlich-Kister polynomial relation and their coefficients were estimated. The experimental and calculate excess quantities are used to discuss the mixing behaviour of the components.

Liquid-Liquid Equilibria for Water + Nitromethane + (1-Propanol, or + Acetone, or + p-Dioxane) Ternary Systems at 303.15 K

Abstract Liquid-liquid equilibria, distribution coefficients, and selectivities of ternary systems of the type: (water + K + nitromethane), where Kis 1-propanol, acetone, or p-dioxane, have been determined at (303.15 ± 0.05) K, in order to evaluate the suitability of nitromethane for extracting preferentially the second components from their aqueous solutions. The line data were satisfactorily correlated by the Othmer and obias method, and the plait point coordinates for the three systems were estimated. The experimental data were compared with values calculated using the NRTL and UNIQUAC models, and with those predicted by the UNIFAC group contribution method. This last method predicts qualitative and quantitative behaviour which are in disagreement with experimental results, while the values calculated using the other two models are in agreement but only when the concentration of component K is low. The three ternary systems studied have distribution coefficients higher than unity, and high selectivities. Therefore, nitromethane could be considered as a potential solvent for the extraction of K from its aqueous solutions