Gas-liquid Partition Coefficients Research Articles

Infinite Dilution Activity Coefficients and Gas–Liquid Partition Coefficients of Organic Compounds in Ionic Liquid 1-Butyl-2,3-dimethylimidazolium Thiocyanate: Measurements and LFER Calculations

Infinite dilution activity coefficients (γi∞) of 31 organic solutes (alkanes, cycloalkanes, olefins, aromatics, chlorinated alkanes, alcohols, and other polar organic solutes) in the ionic liquid (IL) 1-butyl-2,3-dimethylimidazole thiocyanate ([BMMIM][SCN]) were determined by gas–liquid chromatographic (GLC) method in the temperature range of 313.15–353.15 K. The infinite dilution partial molar excess enthalpies (H̅iE, ∞), entropies (TrefS̅iE, ∞), and Gibbs free energies (G̅iE, ∞) of the organic solutes at the reference temperature T = 298.15 K and the solubility parameters (δ3) of [BMMIM][SCN] were derived from γi∞. The gas–liquid partition coefficients (KL) of solutes at different temperatures were calculated by referring to the densities of [BMMIM][SCN]. The linear free energy relationship solvation model was used to fit the KL values, and the KL prediction model was obtained. The selectivity (Sij∞) and capacity (kj∞) of n-hexane (i)/benzene (j) and cyclohexane (i)/benzene (j) at infinite dilution at 323.15 K were calculated. The results were compared with the values of ILs with the thiocyanate anion in the literature.

Measurements and correlation of activity coefficients at infinite dilution for organic solutes in 1-heptyl-3-methylimidazolium chloride

This work is a continuation of our studies on the determination of activity coefficients at infinite dilution (γi∞) for organic solutes (i) in ionic liquids (ILs) and their use in separation processes. The values of γi∞ for 31 organic solutes including alkanes, cycloalkanes, 1,4-dioxane, aromatic hydrocarbons, cyclohexene, chloromethanes, acetonitrile, acetone, tetrahydrofuran, ethyl acetate and alcohols in the IL 1-heptyl-3-methylimidazolium chloride ([C7MIm]Cl) at six temperatures in range of (313.15–363.15) K were determined by gas-liquid chromatography (GLC). The density of [C7MIm]Cl as a function of temperature at pressure p= 101.33 kPa was measured and the values of gas-liquid partition coefficients (KL) were obtained. The linear relationship between lnγi∞ and 1/T was fitted by the Gibbs-Helmholtz equation. The molar excess thermodynamic functions including the infinite dilution partial molar excess Gibbs free energies (G¯iE,∞), partial molar excess enthalpies (H¯iE,∞) and entropies (TrefS¯iE,∞) at Tref = 298.15 K were calculated. In addition, the solubility parameters (δi) of [C7MIm]Cl were obtained from the regular solution theory combined with Flory “combinatorial” equation. The interaction between the solute and the IL was quantified based on the linear free energy relationship (LFER) model. The infinite dilution selectivity coefficients (Sij∞) of n-hexane (i)/benzene (j) and cyclohexane (i)/benzene (j) were calculated at T = 323.15 K from γi∞ and compared to literature values for [Cl]-based ILs for the same separation problems.

Application of dicyanamide-based ionic liquid in separation of binary mixtures based on gamma infinity data measurements

In this research, the activity coefficients (γ13∞) at infinite dilution of 61 solutes were experimentally determined in the 1-(4-methoxy-4-oxobutyl)-3-methylimidazolium dicyanamide, [(C3COOMe)MIM][DCA]. The data were obtained using the gas-liquid chromatography technique (GLC). The experiment was carried out at a wide temperature range of (318.15 to 368.15) K, in 10 K intervals. The studied solutes included polar and non-polar compounds, as alkanes, alkenes, and alkynes, as well as aromatic hydrocarbons, alcohols, water, ethers, ketones, acetonitrile, pyridine, 1-nitropropane, thiophene, and esters. Density, ρ, measurements for a range of temperatures (298.15–368.15) K, in 10 K intervals, for the chosen ionic liquid (IL) were undertaken at pressure, p = 101 kPa. Values of the gas-liquid partition coefficients, KL at infinite dilution, as well as the basic thermodynamic functions, such as partial molar excess Gibbs energy, enthalpy and entropy at infinite dilution were calculated from the experimental data measurements. The values of selectivity and capacity for the three chosen separation problems as heptane/thiophene, heptane/pyridine and heptane/1-nitropropane were calculated from γ13∞ values and compared to literature data for dicyanamide-based, ILs. The results from the study indicate that [(C3COOMe)MIM][DCA] has attractive capacity for all of the studied separation cases. These measurements allow to verify the possibility of use of investigated ionic liquid as an entrainer in liquid-liquid extraction.

The influence of the ionic liquids functionalization on interaction in binary systems with organic solutes and water – Thermodynamic data of activity coefficients at infinite dilution

In this work, the effect of IL’s functionalization of the interaction of IL with organic solutes and water at infinite dilution has been investigated. Based on the experimental activity coefficients at infinite dilution, (γ13∞) the possibility of using ionic liquids (ILs) in different separation processes, such as aliphatic from aromatic hydrocarbon (heptane/benzene, or cyclohexane/benzene), desulfurization and denitrification of model fuel (heptane/thiophene and heptane/pyridine) were investigated based on the experimental study of the activity coefficients at infinite dilution. The (γ13∞) values were determined for more than fifty different solutes including alkanes, cycloalkanes, alkenes, alkynes, aromatic hydrocarbons, alcohols, ethers, ketones, thiophene, acetonitrile, pyridine, 1-nitropropane and water in two ionic liquids: 4-(3-cyanopropyl)-4-methylmorpholinium tricyanomethanide, [Mo1,3CN][TCM] and 4-(3-hydroxypropyl)-4-methylmorpholinium tricyanomethanide, [Mo1,3OH][TCM]. The experiment was performed using inverse gas–liquid chromatography at a wide temperature range from T = (308.15 to 358.15) K. From the experimental data, the partial molar excess Gibbs energy (ΔG1E,∞), enthalpy (ΔH1E,∞) and entropy (Tref ΔS1E,∞) at infinite dilution were determined. The gas–liquid partition coefficients of the solutes, KL were also calculated. Finally, two the values of two factors important from separation point of view: selectivity (S12∞) and capacity (k2) at infinite dilution for few separation problems as hexane/benzene, cyclohexane/benzene, heptane/thiophene, and heptane/pyridine were calculated from γ13∞ and compared to literature values for other ionic liquids taken from available literature. Moreover, physicochemical properties of pure IL including liquid density and dynamic viscosity data, important from the technological point of view was determined at a wide temperature range.

DCA]-based ionic liquids for the extraction of sulfur and nitrogen compounds from fuels: Activity coefficients at infinite dilution

Some petroleum processes need the removal of low level aromatic-sulfur and nitrogen compounds for many products, which are extremely important according to the new strict environmental regulations to reduce sulfur and nitrogen content compounds in liquid fuels. Thus the new, alternative solvents such as ionic liquids (ILs) have been proposed. ILs reveal a high selectivity and capacity of extraction of sulfur- and nitrogen-compounds from alkanes with little solvent loss during the process. The measurements of activity coefficients γ13∞ at infinite dilution of different solutes in the IL shows the effect of interactions between organic solutes, or water on the interfacial and bulk properties of the IL. The new (3-cyanopropyl)pyridinium dicyanamide, [N–C3CNPy][DCA] and (3-cyanopropyl)methylpyrrolidinium dicyanamide, [N–C3CNMPyr][DCA] were investigated in this work. The data were obtained using the gas-liquid chromatography technique. Measurements were undertaken at six temperatures, in 10 K intervals, in the range of (318.15–368.15) K. The solutes studied included both non-polar and polar compounds, as alkanes, alkenes, alkynes, as well as aromatic hydrocarbons, alcohols, water, ethers, ketones, and esters. The most important solutes used were thiophene, pyridine, and 1-nitropropane. Densities, ρ, measurements for a range of temperatures, T (298.15–368.15) K for the chosen ILs were undertaken at pressure, p = 101 kPa. The gas-liquid partition coefficients, KL at infinite dilution were calculated. The fundamental thermodynamic functions such as partial molar excess Gibbs energy, enthalpy and entropy at infinite dilution were calculated from the experimental data measurements to discuss the interaction between solutes and the ILs. The values of selectivity and capacity for three separation cases, viz. heptane/thiophene, heptane/pyridine, and heptane/1-nitropropane were calculated from γ13∞ values and compared to literature data for dicyanamide-based ILs. The Abraham solvation parameter model was presented for all solutes. The obtained results indicated that [N–C3CNPy][DCA] has large selectivity and capacity values for all three of the separation cases studied.

Experimental and theoretical study on infinite dilution activity coefficients of various solutes in ionic liquid 1-propyl-2,3-dimethylimidazolium bis(trifluoromethylsulfonyl)imide

The infinite dilution activity coefficients (γi∞) and gas–liquid partition coefficients (KL) of solutes in the ionic liquids (ILs) are important parameters of thermodynamic properties. They can evaluate the separation selectivity (Sij∞) of ILs and screen out suitable extractants for difficult separation systems. The retention times of solutes in IL 1-propyl-2,3-dimethylimidazolium bis(trifluoromethylsulfonyl)imide [PMMIM][NTf2] were measured by gas chromatography (GC) to calculate the γi∞ and the ΚL values of organic solutes (eg. n-alkanes, alkyl benzenes, acetonitrile, tetrahydrofuran, ethyl acetate, etc.) in [PMMIM][NTf2] at 303.15 K-353.15 K. The density of [PMMIM][NTf2], as a function of temperature, was measured at p = 101.3 kPa. The values of the partial molar excess enthalpies at infinite dilution (H-iE,∞) were derived from the T dependence of the lnγi∞. The entropies (TrefS-iE,∞) and Gibbs free energies (G-iE,∞) of organic solutes in [PMMIM][NTf2] at a reference temperature Τref = 298.15 K can be calculated from the γi∞ values. The Hildebrand’s solubility parameters of the IL [PMMIM][NTf2] were obtained from the regular solution theory (RST) combined with Flory “combinatorial” equation. At 323.15 K, the selectivity (Sij∞) of n-hexane (i)/benzene (j) and cyclohexane (i)/benzene (j) and the capacity (kj∞) at infinite dilution of benzene have been determined. The results were analyzed by comparing with literature data for alkylimidazolium-based ILs with [NTf2]−.

Determination of gas–liquid partition coefficients of several organic solutes in trihexyl (tetradecyl) phosphonium dicyanamide using capillary gas chromatography columns

We report here gas-liquid partition constants and activity coefficients for thirty-seven volatile organic solutes in ionic liquid trihexyl(tetradecyl)phosphonium dicyanamide measured by gas-liquid chromatography using capillary columns. Four capillary columns with exactly known phase ratios were constructed and employed to measure the solute retention factors at four temperatures between 313.15 and 343.15 K. The partition coefficients were calculated from the slopes of the linear regression between solute retention factors and the reciprocal of phase ratio at a given temperature. The partition coefficients thus calculated are free from errors due to the contribution to retention from gas-liquid interphase adsorption. For these reason, reliable solute’s infinite dilution activity coefficients can be obtained, as well as partition enthalpies and entropies. A thorough discussion of the uncertainties of the experimental measurements and the main advantages of the use of capillary columns to acquire the aforementioned relevant thermodynamic information was performed.

Determination of the thermodynamic parameters of ionic liquid 1-propyl-3-methylimidazolium bromide by gas-liquid chromatography

The measurements of activity coefficients at infinite dilution (γi∞) for 33 solutes including alkanes, cycloalkanes, alkenes, aromatic hydrocarbons, acetonitrile, acetone, tetrahydrofuran, ethyl acetate, 1,4-dioxane, chloromethanes, alcohols in the ionic liquid (IL) 1-propyl-3-methylimidazolium bromide, [PMIM][Br], were determined by gas-liquid chromatography at five temperatures at 10 K intervals in range of (323.15–363.15) K. The densities of [PMIM][Br] were measured at the temperature range from 323.15 K to 363.15 K. The gas-liquid partition coefficients, KLat infinite dilution from 323.15 K to 363.15 K and the fundamental thermodynamic functions, such as the partial molar excess enthalpies at infinite dilution (H-iE,∞), Gibbs free energies (G-iE,∞) and entropies (TrefS-iE,∞) were calculated at a reference temperature Tref = 298.15. The Hildebrand’s solubility parameters of the IL [PMIM][Br] were also determined by the regular solution theory (RST) combined with Flory ‘‘combinatorial’’ equation. The values of selectivity and capacity for n-hexane (i)/benzene (j), cyclohexane (i)/benzene (j) at T = 323.15 K were calculated from γi∞ and compared to literature values for [Br]-based ILs for the same separation problems.

Separation of binary mixtures based on gamma infinity data using [OMMIM][BF4] ionic liquid and modelling of thermodynamic functions

The activity coefficients at infinite dilution (γi∞), gas-liquid partition coefficients (KL) of organic solutes (n-alkanes, alkenes, alkyl benzenes, acetonitrile, acetone, tetrahydrofuran, ethyl acetate, 1,4-dioxane, chloromethanes, alcohols and cycloalkene) in the ionic liquid 1-octyl-2,3-dimethylimidazolium tetrafluoroborate ([OMMIM][BF4]) have been measured using the gas-liquid chromatographic method (GLC) at five temperatures (313.15 K–353.15 K). The density of [OMMIM][BF4], as a function of temperature, was determined in atmosphere pressure p = 101.3 kPa. The values of the partial molar excess enthalpies at infinite dilution (H-iE,∞) were derived from the temperature dependence of the lnγi∞ values at a reference temperatureTref = 298.15 K. The entropies (TrefS-iE,∞) and Gibbs free energies (G-iE,∞) of organic solutes in [OMMIM][BF4] at a reference temperatureTref = 298.15 K were calculated from the γi∞ values. The Hildebrand’s solubility parameters of [OMMIM][BF4] were determined by the regular solution theory (RST) combined with Flory ‘‘combinatorial’’ equation. The interaction between the IL and the individual solutes can be disclosed and the nature of force for IL was explored by the linear free energy relationship (LFER) analysis. Selectivity (Sij∞) and capacity (kj∞) at infinite dilution at 323.15 K have been determined for n-hexane (i)/benzene (j), cyclohexane (i)/benzene (j). The results were analysed in comparison to literature data for alkylimidazolium ionic liquids (ILs) with [BF4]-.

Thermodynamics and activity coefficients at infinite dilution for organic compounds in the ionic liquid 1-hexyl-3-methylimidazolium chloride

The activity coefficients at infinite dilution,γi∞, for 33 solutes, including alkanes, cycloalkanes, alkenes, aromatic hydrocarbons, acetonitrile, acetone, tetrahydrofuran, ethyl acetate, 1,4-dioxane, chloromethanes, alcohols in the ionic liquid 1-hexyl-3-methylimidazolium chloride, [HMIM][Cl], were determined by gas–liquid chromatography at temperatures range of (313.15–363.15) K. The gas-liquid partition coefficients,KLwere calculated for all solutes. The densities of [HMIM][Cl] were measured at the temperature range from 313.15 K to 363.15 K. The values of the partial molar excess enthalpies at infinite dilution H-iE,∞ were derived fromthe temperature dependence of the γi∞values. The entropies TrefS-iE,∞ and Gibbs energies G-iE,∞ of organic solutes in [HMIM][Cl] at a reference temperatureTref = 298.15 K were also calculated from the γi∞ values. The Hildebrand’s solubility parameters of the IL [HMIM][Cl] were also determined by the regular solution theory (RST) combined with Flory ‘‘combinatorial’’ equation. The values of selectivity and capacity for n-hexane (i)/benzene (j), cyclohexane (i)/benzene (j) were calculated from γi∞ and compared to literature values for [HMIM]-based or [Cl]-based ILs for the same separation problems.

The use of ionic liquids for separation of binary hydrocarbons mixtures based on gamma infinity data measurements

Abstract The effect of interactions between 64 organic solvents and water on the interfacial and bulk properties at infinite dilution of two ionic liquids (ILs) namely N-triethyl-N-octylammonium bis(fluorosulfonyl)imide, [N2,2,2,8][FSI] and 1-butyl-3-methylpyrrolidynium bis(fluorosulfonyl)imide, [BMPyr][FSI] were determined via measurement of activity coefficients γ 13 ∞ at infinite dilution using the gas-liquid chromatography technique. Measurements were undertaken at six temperatures, in 10 K intervals, in the range of (318.15 to 368.15) K. The solutes studied included both non-polar and polar compounds, as alkanes, alkenes, and alkynes, as well as aromatic hydrocarbons, alcohols, water, ethers, ketones, pyridine, thiophene, esters, acetonitrile and 1-nitropropane. The gas-liquid partition coefficients, K L at infinite dilution, and the fundamental thermodynamic functions, partial molar excess Gibbs energy, enthalpy and entropy at infinite dilution were calculated from the experimental data measurements. The values of selectivity and capacity for four important in petrochemical technology separations, viz. hexane/hex-1-ene, hexane/benzene, cyclohexane/cyclohexene, and cyclohexane/benzene were calculated from γ 13 ∞ values and compared to literature data for ammonium ILs with different cations and anions and for ILs with [BMPyr]− cation and different anions. The results from the study indicate that [N2,2,2,8][FSI] reveals not satisfied selectivity values in comparison with [BMPyr][FSI] and literature values for all four of the separation cases studied.

Thermodynamics and activity coefficients at infinite dilution for organic solutes in the ionic liquid 1-butyl-1-methylpyrrolidinium dicyanamide

The activity coefficients at infinite dilution, γ13∞, for 46 solutes, including alkanes, cycloalkanes, alkenes, alkynes, aromatic hydrocarbons, alcohols, thiophene, ethers, ketones, esters, aldehyde, acetonitrile, pyridine and 1-nitropropane in the ionic liquid (IL) 1-butyl-1-methylpyrrolidynium dicyanamide, [BMPYR][DCA] were determined by gas-liquid chromatography at five temperatures in range of (313.15–373.15) K at pressure, p = 101 kPa. The thermodynamic functions at infinite dilution as partial molar excess Gibbs free energy, ΔG1E,∞, enthalpy ΔH1E,∞, and entropy term TrefΔS1E,∞ and the gas-liquid partition coefficients, KL at infinite dilution were calculated from the experimental γ13∞ values obtained over the temperature range. The values of selectivity and capacity for few separation problems as n-heptane/benzene, n-heptane/thiophene, n-heptane/1-heptyne, and ethylbenzene/styrene at T = 323.15 K were calculated from γ13∞ and compared to literature values for [DCA]-based ionic liquids and [BMPYR]-based ILs. In comparison with the former measured [BMPYR][TCM], or [BMPYR][SCN] ILs, the [DCA]-based IL presents high selectivities for the separation of aromatic hydrocarbons from aliphatic hydrocarbons, and especially for the extraction of thiophene, or pyridine from n-heptane with slightly lower capacity than those for [BMPYR][TCM], or [BMPYR][SCN]. New data shows that [BMPYR][DCA] IL may be proposed as an alternative solvent for the separation of aliphatic from aromatic hydrocarbons.

Thermodynamics and selectivity of separation based on activity coefficients at infinite dilution of various solutes in ionic liquid [HMMIM][BF4

Abstract The activity coefficients at infinite dilution ( γ i ∞ ), gas–liquid partition coefficients ( K L ) of organic solutes (n-alkanes, alkenes, alkyl benzenes, acetonitrile, acetone, tetrahydrofuran, ethyl acetate, chloromethanes, alcohols and 1,4-dioxane) in the ionic liquid 1-Hexyl-2,3-dimethylimidazolium tetrafluoroborate ([HMMIM][BF4]) have been measured using the gas–liquid chromatographic method (GLC) at five temperatures: 313.15 K, 323.15 K, 333.15 K, 343.15 K, 353.15 K. The density of [HMMIM][BF4], as a function of temperature, was determined in atmosphere. The values of the partial molar excess enthalpies at infinite dilution ( H ‾ i E , ∞ ) were derived from the temperature dependence of the In γ i ∞ values. The entropies ( T ref S ‾ i E , ∞ ) and Gibbs energies ( G ‾ i E , ∞ ) of organic solutes in [HMMIM][BF4] at a reference temperature T r ef = 298.15 K were calculated from the γ i ∞ values. The Hildebrand’s solubility parameters of the IL [HMMIM][BF4] were determined by the regular solution theory (RST) combined with Flory ‘‘combinatorial’’ equation. Selectivity ( S ij ∞ ) and capacity ( k j ∞ ) at infinite dilution at 323.15 K have been determined for n-hexane ( i )/benzene (j), cyclohexane ( i )/benzene (j). The results were analyzed in comparison to literature data for alkylimidazolium ionic liquids (ILs) with [ BF 4 ] - . The interaction between the IL and the individual solutes can be disclosed by the linear free energy relationship (LFER) analysis.

Thermodynamic study of molecular interaction-selectivity in separation processes based on limiting activity coefficients

Abstract The effect of interactions between organic solvents and water on the interfacial and bulk properties of N-ethyl-N-methylmorpholinium dicyanamide, [EMMor][DCA] were discussed on the base of the limiting activity coefficients γ 13 ∞ values. The experimental γ 13 ∞ values were determined by gas–liquid chromatography at temperatures from (298.15 to 368.15) K for 61 assorted solutes—among them, alkanes (linear, branched, or cyclic), alkenes, alkynes, aromatic hydrocarbons, alcohols, water, thiophene, tetrahydrofuran, 1,4-dioxane, ethers, acetone, ketones, acetonitrile, pyridine, and 1-nitropropane. The partial molar excess Gibbs free energy Δ G 1 E, ∞ , the partial molar excess enthalpy Δ H 1 E, ∞ , and entropy at reference temperature T ref Δ S 1 E, ∞ at infinite dilution were calculated from the experimental γ 13 ∞ values obtained over this temperature range. The gas–liquid partition coefficient K L was calculated for each solute and discussed in light of the Abraham solvation parameter model. The density and viscosity of the [EMMor][DCA] as a function of temperature were also measured. The selectivity and capacity for six separation problems were calculated from γ 13 ∞ and compared to literature values for selected ionic liquids. These separation problems are central to the petroleum and organic chemistry industry. The data presented here shows that [EMMor][DCA] reveals large selectivity equal 140, 273, 538, 73.1, 87.5 and 10.2 in heptane/benzene, heptane/thiophene, heptane/ethanol, hexane/ethyl acetate, ethyl-tert-butyl ether, ETBE/ethanol and THF/water separation problems at T = 328.15 K. The capacities were 0.22, 0.42, 0.83, 0.17 and 2.97 for benzene, thiophene, ethanol, ethyl acetate, and water at the same temperature.

Activity coefficients at infinite dilution and physicochemical properties for organic solutes and water in the ionic liquid trihexyl-tetradecyl-phosphonium tricyanomethanide

The activity coefficients at infinite dilution, γ13∞ and gas-liquid partition coefficients, KL for 62 solutes: alkanes, alkenes, alkynes, cycloalkanes, aromatic hydrocarbons, alcohols, thiophene, ethers, ketones, esters, butanal, nitrogen compounds and water in the ionic liquid trihexyl-tetradecyl-phosphonium tricyanamide were determined by gas-liquid chromatography at the temperatures from 328.15 K to 368.15 K. The partial molar excess Gibbs energies ΔG1E,∞, enthalpies ΔH1E,∞ and entropies ΔS1E,∞ at infinite dilution were calculated from the experimental γ13∞ values obtained over the temperature range. The selectivities and capacities at infinite dilution for water/butan-1-ol separation problem were calculated from the γ13∞ and compared to the literature values for other ionic liquids. High selectivity was obtained in comparison to other ionic liquids. Butanol is considered as possible biofuel. This alcohol is produced by fermentation and it must be separated from the aqueous fermentation broth. The values of KL were used to determine the linear free energy relationship (LFER) system constants as a function of temperature. The density of the investigated ionic liquid was also measured at temperatures from 298.15 K to 368.15 K.

Separation of binary mixtures hexane/hex-1-ene, cyclohexane/cyclohexene and ethylbenzene/styrene based on gamma infinity data measurements

Abstract The activity coefficients γ 13 ∞ at infinite dilution for 64 solutes were determined in the 1-(3-hydroxypropyl)-3-methylimidazolium dicyanamide, [N-C3OHMIM][DCA] and 58 solutes in (3-hydroxypropyl)-1-methylmorpholinium dicyanamide, [N-C3OHMMor][DCA] using the gas-liquid chromatography technique. Measurements were undertaken at six temperatures, in 10 K intervals, in the range of (298.15–368.15) K. The solutes studied included both non-polar and polar compounds, as alkanes, alkenes, and alkynes, as well as aromatic hydrocarbons, alcohols, water, ethers, ketones, acetonitrile, pyridine, 1-nitropropane, thiophene, and esters. Density, ρ, measurements for a range of temperatures (298.15–368.15) K for the synthesized, new ionic liquids (ILs) were also undertaken at pressure, p = 101 kPa. The gas-liquid partition coefficients, K L at infinite dilution, and the fundamental thermodynamic functions, partial molar excess Gibbs energy, enthalpy and entropy at infinite dilution were calculated from the experimental data measurements. The values of selectivity and capacity for three separation cases, viz. hexane/hex-1-ene, cyclohexane/cyclohexene, and ethylbenzene/styrene were calculated from γ 13 ∞ values and compared to literature for imidazolium-based, morfolinium-based, or dicyanamide-based, ILs. The results from the study indicate that [N-C3OHMIM][DCA] has large selectivity values for all three of the separation cases studied and that [N-C3OHMMor][DCA] has the largest selectivity ever noted for cyclohexane/cyclohexene, and ethylbenzene/styrene separation processes.

Separation of water/butan-1-ol mixtures based on limiting activity coefficients with phosphonium-based ionic liquid

In the present work the limiting activity coefficients (γ13∞) for 64 solutes, including polar and non-polar solutes as alkanes, alkenes and alkynes as well as aromatic hydrocarbons, alcohols, water, ethers, ketones, acetonitrile, pyridine, 1-nitropropane, thiophene, and esters in the tributyltetradecylphosphonium dodecylbenzenesulfonate, [P14,4,4,4][DBS] were determined by gas-liquid chromatography at six temperatures in range of (318.15–368.15) K. Density, ρ as a function of temperature, T for chosen ionic liquid, [P14,4,4,4][DBS] at pressure p=101kPa was measured. The gas-liquid partition coefficients, KL at infinite dilution and the fundamental thermodynamic functions, the limiting partial molar excess Gibbs energy, enthalpy and entropy were calculated. The values of selectivity and capacity for water/butan-1-ol separation problem were calculated from γ13∞ and compared to literature values for phosphonium-based or other selected ionic liquids for the same separation problem. The Abraham solvation parameter model was also presented for all solutes. On the bases of the results the intermolecular interactions of the chosen IL and solutes were discussed. The data presented here shows that [P14,4,4,4][DBS] reveals the best ever measured selectivity and capacity for the for water/butan-1-ol separation.

High selective water/butan-1-ol separation on investigation of limiting activity coefficients with [P8,8,8,8][NTf2] ionic liquid

The limiting activity coefficients (γ13∞) for 65 solutes, including polar and non-polar solutes as alkanes, alkenes and alkynes as well as aromatic hydrocarbons, alcohols, ethers, ketones, acetonitrile, pyridine, 1-nitropropane, thiophene, esters and water in the tetraoctylphosphonium bis{(trifluomethyl)sulfonyl}imide ionic liquid (IL), [P8,8,8,8][NTf2] were determined by gas-liquid chromatography at six temperatures in range of (318.15–368.15) K. The synthesis and DSC data are presented for this IL. Density, ρ and viscosity, η as a function of temperature, T in a range of (298.15–398.15) K for [P8,8,8,8][NTf2] were measured at pressure p = 101 kPa. The gas-liquid partition coefficients, KL at infinite dilution and the thermodynamic functions, the limiting partial molar excess Gibbs energy, enthalpy and entropy were calculated. The values of selectivity and capacity for water/butan-1-ol separation problem were calculated from γ13∞ and compared to literature values for phosphonium-based or other selected ionic liquids for the same separation problem. The Abraham solvation parameter model was also presented for all solutes. On the basis of the results, the intermolecular interactions of the chosen IL and solutes were discussed. The data presented here show that [P8,8,8,8][NTf2] reveals very large selectivity for the water/butan-1-ol separation.

Determination of gas–liquid partition coefficients of several organic solutes in trihexyl(tetradecyl)phosphonium bromide using capillary gas chromatography columns

In this paper, we report gas-liquid partition constants for thirty-five volatile organic solutes in the room temperature ionic liquid trihexyl(tetradecyl)phosphonium bromide measured by gas-liquid chromatography using capillary columns. The relative contribution of gas-liquid partition and interfacial adsorption to retention was evaluated through the use of columns with different the phase ratio. Four capillary columns with exactly known phase ratios were constructed and employed to measure the solute retention factors at four temperatures between 313.15 and 343.15K. The partition coefficients were calculated from the slopes of the linear regression between solute retention factors and the reciprocal of phase ratio at a given temperature according to the gas-liquid chromatographic theory. Gas-liquid interfacial adsorption was detected for a few solutes and it has been considered for the calculations of partition coefficient. Reliable solute's infinite dilution activity coefficients can be obtained when retention data are determined by a unique partitioning mechanism. The partial molar excess enthalpies at infinite dilution have been estimated from the dependence of experimental values of solute activity coefficients with the column temperature. A thorough discussion of the uncertainties of the experimental measurements and the main advantages of the use of capillary columns to acquire the aforementioned relevant thermodynamic information was performed.

Separation of binary mixtures hexane/hex-1-ene, cyclohexane/cyclohexene and ethylbenzene/styrene based on limiting activity coefficients

The measurements of a limiting activity coefficients, γ13∞ at infinite dilution for 63 solutes including wide spectra of alkanes, alkenes and alkynes as well as aromatic hydrocarbons, alcohols, water, ethers, ketones, acetonitrile, pyridine, 1-nitropropane, thiophene, and esters in the 1-(3-hydroxypropyl)pyridinium dicyanamide, [N-C3OHPY][DCA], determined by gas-liquid chromatography at temperature range of (298.15–368.15)K are developed. The synthesis and thermochemical characteristic of the ionic liquid (IL) is described. The density and viscosity of the IL was measured as a function of temperature in a range of (298.15–368.15) K. The comparison of γ13∞ for selected solutes in ionic liquids (ILs) with [N-C3OHPY]+ cation and [TCM]−, [DCA]−, [TCB]− and [SCN]−-anions at one temperature, T=328.15K is shown. The gas-liquid partition coefficients, KL at infinite dilution and the limiting fundamental thermodynamic functions, the partial molar excess Gibbs energy, enthalpy and entropy were calculated for all solutes. The values of selectivity and capacity for three separation problems hexane/hex-1-ene, cyclohexane/cyclohexene and methylbenzene/styrene were calculated from γ13∞ and compared to literature values for [N-C3OHPY]-based or [DCA]-based ILs for the same separation problems. The data presented here shows that [N-C3OHPY][DCA] reveals large selectivity 2.34, 2.79 and 2.27 in three of discussed separation problems. However, the comparison to the measured earlier [DCA]-based ILs shows the low capacity for the hex-1-ene and cyclohexene. The Abraham solvation parameter model was also presented for all solutes. On the bases of the results the intermolecular interactions of the chosen IL and solutes was discussed.