Partial Molar Excess Gibbs Energy Research Articles

Excess properties, spectral analyses, and CO2 capture performance of N-methyldiethanolamine + polyethylene glycol 300 binary system

Density (ρ) and viscosity (η) data of polyethylene glycol 300 (PEG300) + N-methyldiethanolamine (MDEA) binary system at T = (298.15–318.15) K with a step of 5 K were measured at P = 1005 hPa. After that, the experimental ρ and η values were correlated and predicted by several semi-empirical models. Meanwhile, the Jouyban-Acree model presented a better fitting for the density, and the McAllister four-body equation presented a better fitting for the kinematic viscosity. Based on the ρ and η values, excess molar volume (VmE), partial molar volume (V1¯ and V2¯), viscosity deviation (Δη), and excess Gibbs energy of activation of viscous flow (ΔG∗E) of PEG300 (1) + MDEA (2) binary system were systematically calculated and analyzed. These excess properties showed the predominance of intermolecular self-conjugation in PEG300 (1) + MDEA (2) binary system, and it was further demonstrated by various spectral characterizations. Importantly, the PEG300 + MDEA aqueous system was used for 5 CO2 absorption (room temperature)-desorption (371.15 K) cycles at a CO2 flow rate of 200 mL/min, with the average CO2 capture performance of 0.65 mol CO2/mol MDEA of per cycle, demonstrating excellent absorption capability, and remained stable throughout the entire cycle.

On using excess Gibbs energy as an indicator of hydrophobicity in the flotation process

It has been shown that the partial molar excess Gibbs energy (G̅ex) can be used as an indicator of hydrophobicity and hence contributes to explaining the behaviour of collectors in the recovery of minerals by flotation. This is because hydrophobicity of a mineral particle on which a collector is adsorbed is related to the fact that the alkyl chain associated with the collector behaves in the same way as any hydrocarbon would in a non-ideal mixture with water. Such mixtures are quantified thermodynamically by determining the activity coefficient of the hydrocarbon moiety of the collector and hence its G̅ex in the mixture. The present paper is aimed at extending the above concepts in two different ways. Firstly, an investigation is made of the relationship between G̅ex and contact angle and/or recovery for systems such as ionic liquids and aminothiophenols. Secondly, on the basis of the observation that increases in G̅ex are indicative of increases in the hydrophobicity of the mineral particle-collector aggregate, a study was undertaken to examine, respectively, the effects of the presence of electrolytes or alcohols in the system, of pH and changing concentrations of the collector, on G̅ex of the collector alkyl group and hence its hydrophobicity. In the first instance, the relationship between G̅ex and contact angle and recovery is sustained. With respect to the latter, the absence of any correlation between G̅ex and recoveries supported the proposition that the major effect of electrolytes and added alcohols is rather on particle – bubble attachment. Similarly, it is also indicated that since the change in G̅ex is minimal when collector concentration or pulp temperature is increased these changes do not significantly affect the hydrophobicity of the collector-mineral particle and hence also the recovery in a microflotation.

Physicochemical characterization and activity coefficients at infinite dilution of molecular compound in poly(ethylene glycol)dimethyl ether and the eutectic mixture composed of poly(ethylene glycol) with cyclic carbonate

This work is focused on determining the effectiveness of using hitherto unexplored extractants in separation processes. It is proposed to use poly(ethylene glycol) and the eutectic mixture composed of poly(ethylene glycol) with cyclic carbonate as separating agents in desulphurization of model fuel (heptane/thiophene) and alkanes from aromatic hydrocarbons (heptane/toluene) processes. The selected glycol was poly(ethylene glycol)dimethyl ether with an average molecular weight of M = 250 g·mol−1 (abbreviated as PEG250DME). The second component of the mixture was ethylene cyclic carbonate (abbreviated as EC). These components create a non-crystallizing mixture at a temperature below T = 203 K in the range of 25–40% ethylene carbonate, thus a mixture with the following composition 30% of EC and 70% of PEG250DME (wEC = 0.331) was investigated. For this purpose, the extensive research on the infinite dilution activity coefficients for 45 molecular compounds including alkanes, alkenes, alkynes, aromatic hydrocarbons, alcohols, water, ethers, pyridine, thiophene, acetone, acetonitrile, and 1-nitropropane in both PEG250DME and {[PEG250DME] + [EC], wEC = 0.331} were determined. The experiment was performed at a temperature range from T = (308.15 to 338.15) K with an increment of 10 K using gas–liquid chromatography (GLC). Based on the experimental data, the infinite dilution capacity and selectivity of the PEG250DME and DES: {[PEG250DME] + [EC], wEC = 0.331} are presented to evaluate the effectiveness of using them as an extractant in the separation of aliphatic from aromatic hydrocarbons and sulfur compounds from alkanes. Obtained selectivity and capacity values for different separation processes are compared with the literature data for other separating agents presented in the available literature reports. From the temperature - dependence of the infinite dilution activity coefficient, the partial molar excess Gibbs energy, ΔG1E,∞, enthalpy ΔH1E,∞ and entropy term TrefΔS1E,∞ at infinite dilution were calculated and discussed. Additionally, the liquid density and dynamic viscosity of pure PEG250DME and it’s eutectic mixture with EC as a function of temperature were determined. Both of the physicochemical parameters are important from a technological point of view.

The investigation of the infinite dilution activity coefficients for molecular compounds in 1-(3-hydroxypropyl)-3-methyl-imidazolium thiocyanate

Measurements of infinite dilution activity coefficients of 46 organic solutes including alkanes, alkenes, alkynes, aromatic hydrocarbons, alcohols, ethers, ketones, pyridine, thiophene, acetonitrile, and 1-nitropropane in ionic liquids (IL), 1-(3-hydroxypropyl)-3-methyl-imidazolium thiocyanate (abbreviated as [C1C3OHIM][SCN]) are reported in the temperature range from T = (318.15 to 358.15) K. Based on the experimental data, the infinite dilution capacity and selectivity of the studied IL are presented to evaluate the effectiveness of using it as an extractant in the separation of aliphatic from aromatic hydrocarbons and sulfur compounds from alkanes. Obtained selectivity and capacity values for different separation processes are compared with the literature data for other ionic liquids. From the temperature – dependence of the infinite dilution activity coefficient, the partial molar excess Gibbs energy, ΔG1E,∞, enthalpyΔH1E,∞ and entropy term TrefΔS1E,∞ at infinite dilution were calculated and discussed.

Derivations of Partial Molar Excess Gibbs Energy of Mixing Expressions for Common Thermodynamic Models

Derivations of Partial Molar Excess Gibbs Energy of Mixing Expressions for Common Thermodynamic Models

Investigating the use of excess Gibbs energy to predict the hydrophobicity of a mineral treated with a collector

The paper sets out to determine whether there is any evidence to support the hypothesis that the hydrophobicity of a mineral particle treated with a collector may be strongly related to the fact that the alkyl chain associated with the collector adsorbed on a mineral particle behaves in the same way as any hydrocarbon would behave in an aqueous medium. Such a mixture is classified as a non-ideal mixture which is a concept widely used in chemical engineering in the study of many separation processes. Non-ideal mixtures are quantified by determining the activity coefficient of the hydrocarbon and hence its partial molar excess Gibbs energy in the mixture. In the absence of a turbulent environment hydrophobicity of a mineral particle is responsible for flotation recovery in, for example, a microflotation cell. It is also indicated by a contact angle measurement. Using data from published literature of the behaviour of collectors with different alkyl chain lengths the paper has demonstrated that there is a strong linear relationship between partial molar excess Gibbs energy of the alkyl moiety of the collector and the flotation recovery and the contact angle for, inter alia, a xanthate-galena and an amine-quartz system. These relationships seem to provide good evidence that the extent to which a collector will enhance recovery of a mineral is strongly related to the partial molar excess Gibbs energy of the alkyl chain or, in other words, the extent to which the alkyl group associated with the mineral particle represents a significant contribution to the force driving a particle from the aqueous(water) phase to the gas (bubble) phase.

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 solubility of clotrimazole and some thermodynamic aspects of dissolution in different solvents

Equilibrium solubility of clotrimazole, an important antimycotic drug, was measured between (293.15–313.15) K in four pharmaceutically relevant solvents including buffer pH 2.0, buffer pH 7.4, hexane and 1-octanol. The experimental solubility results were correlated by modified Apelblat and van’t Hoff equations. The compound melting temperature and enthalpy were determined. The activity coefficients at infinite dilution of clotrimazole in each solvent were calculated from experimental data on solubility and thermophysical properties. Substitution aqueous solvents for organic ones leads to lower activity coefficients and higher solubility of the drug. The limiting partial molar excess enthalpies, entropies and Gibbs energies of clotrimazole were evaluated.

Activity coefficients at infinite dilution for various organic solutes in the ionic liquid 1-(2-hydroxyethyl)-3-methylimidazolium hexafluorophosphate

Activity coefficients at infinite dilution (γi∞) for a variety of polar and non-polar organic solutes (alkanes, cycloalkanes, alkenes, alkyl benzenes, alcohols, 1,4-dioxane, acetone, acetonitrile, tetrahydrofuran, chloroform and dichloromethane) in the ionic liquid (IL) 1-(2-hydroxyethyl)-3-methylimidazolium hexafluorophosphate ([C2OHmim][PF6]) have been determined by gas-liquid chromatography using the IL as the stationary phase. The measurements were conducted over the temperature range of 303–353 K. The partial molar excess Gibbs energies (ΔGiE,∞), enthalpies (ΔHiE,∞) and entropies (ΔSiE,∞) at infinite dilution of the 29 solutes in the IL have been calculated from the experimental γi∞ values obtained over the temperature range. The selectivity sij∞ and capacity kj∞ at T = 323.15 K for aliphatic/aromatic hydrocarbons and aliphatic/alcohol separation problems were calculated from the γi∞ and compared to the reported literature data for other [C2OHmim] based ILs.

Separation of (water/butan-1-ol) binary systems based on activity coefficients at infinite dilution with phosphonium ionic liquid

Gas-liquid chromatography (GLC) was used to examine the types of interactions among the volatile organic solvents (VOS) and (trihexyltetradecylphosphonium-bis-(2,4,4-trimethylpentyl)-phosphinate, [P14, 6, 6, 6] [(C8H17)2 PO2)], a phosphonium based ionic liquid. Activity coefficients at infinite dilution (γ13∞) was determined for 26 solutes, including alkanes, alkenes, cycloalkanes, cycloalkenes, ketones, alcohols, aromatic hydrocarbons, tetrahydrofuran, acetonitrile, thiophene and water at different temperatures i.e. 313.15, 323.15, 333.15 and 343.15 K. The γ13∞ data was obtained with the use of packed column with a mass fraction loading of the ionic liquid from 0.28 to 0.35 in the stationary phase. The temperature dependent data of γ13∞ was used to compute the partial molar excess enthalpies ΔH1E,∞, entropies ΔS1E,∞ and Gibbs energies ΔG1E,∞ at infinite dilution for the solutes. The capacities kj∞and selectivities (Sij∞), at infinite dilution for the selected extraction problems were also computed from γ13∞ and compared with values from literature. Examination of activity coefficients at infinite dilution gives a better understanding regarding the interactions among the ionic liquid and investigated compounds.

Evaluation of Experimental Studies in the U-Rich Region of the U-Pu Phase Diagram

Upon the re-examination of two experimental studies, additional thermophysical data pertaining to the uranium-rich portion of the uranium-plutonium binary phase diagram have been elucidated. The first study involved the analysis of solidification cooling curves following the processing of U-Pu alloys. Two phase transitions (liquidus and bcc) were evaluated and the results agreed very well with the established boundaries. The second study was actually performed over sixty years ago but still warrants recognition due to the paucity of thermodynamic data on the U-Pu system to date. From the investigation, the activity coefficients of plutonium in liquid uranium from 1813 K to 2042 K were derived assuming Henry’s law from which the partial molar excess Gibbs energy change of plutonium was obtained: \( \Delta \bar{G}^{\text{ex}} = R*T*\ln \gamma^{\text{o}}_{\text{Pu}} = - \;76694 + 39.2*T\left( {{\text{J}}/{\text{mol}}} \right). \)

Ammonium ionic liquids in extraction of bio-butan-1-ol from water phase using activity coefficients at infinite dilution

The activity coefficients at infinite dilution (γ13∞) for 64 solutes including water in two new ammonium-based ionic liquids (ILs), the dimethyldodecylphenoxyethylammonium bis{(trifluoromethyl)sulfonyl}imide, [N1,1,12,2OPh][NTf2] and dimethyldodecylphenoxyethylammonium dicyanamide, [N1,1,12,2OPh][DCA] were determined by gas-liquid chromatography at six temperatures in range of (318.15–368.15) K and (328.15–378.15) K for [N1,1,12,2OPh][NTf2] and [N1,1,12,2OPh][DCA], respectively. 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 ammonium-based or other selected ionic liquids for the same separation problem. On the bases of the results, the intermolecular interactions of the chosen ILs and solutes were discussed. The data presented here shows that [N1,1,12,2OPh][NTf2] reveals attractive selectivity with low capacity and [N1,1,12,2OPh][DCA] shows attractive capacity with low selectivity in the water/butan-1-ol separation.

New ionic liquid [P4,4,4,4][NTf2] in bio-butanol extraction on investigation of limiting activity coefficients

The limiting activity coefficients (γ13∞) for 65 solutes and water in the tetrabutylphosphonium bis{(trifluomethyl)sulfonyl}imide ionic liquid (IL), [P4,4,4,4][NTf2] were determined by gas-liquid chromatography at six temperatures in range of (358.15–408.15) K. The DSC data are presented for new, synthesized by us [P4,4,4,4][NTf2]. 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. On the bases of the results the intermolecular interactions of the chosen IL and solutes was discussed. The data presented here shows that [P4,4,4,4][NTf2] reveals second large ever published selectivity for the water/butan-1-ol separation.

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.

Determination of Activity Coefficients at Infinite Dilution of Organic Solutes in the Ionic Liquid 1-(2-Hydroxyethyl)-3-methylimidazolium Nonafluoro-1-butanesulfonate Using Gas–Liquid Chromatography

Activity coefficients at infinite dilution (γi∞) for a variety of organic solutes (alkanes, cycloalkanes, alkenes, alkyl benzenes, alcohols, 1,4-dioxane, acetone, acetonitrile, tetrahydrofuran, chloroform, and dichloromethane) in the ionic liquid (IL) 1-(2-hydroxyethyl)-3-methylimidazolium nonafluoro-1-butanesulfonate ([C2OHmim][C4F9SO3]) have been determined by gas–liquid chromatography using the IL as the stationary phase. The measurements were conducted in the temperature range from 303 to 353 K. The partial molar excess Gibbs energies (ΔGiE,∞), enthalpies (ΔHiE,∞), and entropies (ΔSiE,∞) at infinite dilution of the solutes in the ionic liquid were calculated from the temperature dependence of the values of γi∞. Values of selectivity sij∞ and capacity kj∞ at T = 323.15 K for the IL [C2OHmim][C4F9SO3] were calculated for both cyclohexane/benzene and benzene/methanol binary systems. The results obtained from this work were compared with reported literature data for other [C2OHmim] based ILs.

A surface energy driven dissolution model for immiscible Cu-Fe alloy

Cu-Fe alloy processed by conventional preparation methods has serious large-scale composition segregation or spatial separation of individual Cu and Fe phases prior to solidification. For immiscible Cu-Fe alloy, a homogeneous melt is the prerequisite to obtain the subsequent uniform solidification microstructure. In this paper, the uniform metastable immiscible Cu100−xFex alloys (x=10, 20, 30, 40wt%) were prepared by arc-melting. The results indicated that with increasing melting times, the initial aggregated Fe-rich melt gradually dissolves into the bulk copper matrix and a homogeneous melt is obtained. Herein a thermodynamic model was constructed to discuss the surface energy driven melting process and the formation of uniform Cu-Fe alloy. During melting process, if the radius of detached liquid Fe-rich droplet is less than the calculated critical radius, the surface energy is high enough to compensate for the partial molar excess Gibbs energy of iron, thereby leading to the spontaneously dissolution of detached liquid Fe-rich droplet into the bulk liquid. As a result, the aggregated Fe-rich melt dissolves step by step eventually forming a homogeneous melt. After subsequent solidification, the immiscible Cu-Fe alloy exhibits homogeneous microstructure. The rapid melt quenching experiments are further performed to validate the proposal model. The results provide strong evidence and support for the surface energy driven dissolution model. The findings give us a basic understanding for the evolution of melting process in other immiscible alloys.

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 based on limiting activity coefficients data using specific ammonium-based ionic liquid and modelling of thermodynamic functions

Thermodynamic properties of quaternary ionic liquid (IL), N-benzyl-N-dimethyl-N-tetradecylammonium cinnamate, [NBz,1,1,14][Cyn] were investigated by the inverse chromatography with 65 different solvents: alkanes (C5-C10), cycloalkanes (C5-C8), alkenes (C5-C10), alkynes (C5-C8), aromatic hydrocarbons (benzene, toluene, ethylbenzene, o-, m-, p-xylene, thiophene), alcohols (C1-C5), water, ethers (diethyl-, di-n-propyl-, di-n-butylether, methyl-tert-butylether, MTBE, tetrahydrofuran, THF) and ketones (propanone, 2-pentanone, 3-pentanone, 2-hexanone, 3-hexanone, cyclopentanone) at five temperatures ranging from (328.15–368.15) K. The limiting activity coefficients, 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, water/ethanol, water/THF, water/1,4-dioxane and many others separation problems were calculated from γ13∞ and compared to literature values for selected ionic liquids. On the basis of the results, the intermolecular interactions of the chosen IL and solutes were discussed. The data presented here shows that [NBz,1,1,14][Cyn] reveals very large selectivity for the hexane/ethanol and heptane/ethanol separation. It allows expanding our knowledge about nature of the [NBz,1,1,14][Cyn], influence of polar functional groups and the structure on thermodynamical properties of [NBz,1,1,14][Cyn] and designing suitable solvent for specific extraction problem. It was shown earlier in many data that the selectivities of ammonium-based ILs in separating organic liquids are often higher than those for commonly used solvents. However, the examination has to be always done of the selectivity together with capacity for a variety of solute in entrainers to provide a picture of interactions and costs.