Partial Molar Excess Enthalpies Research Articles

Measurements of activity coefficients at infinite dilution of organic solutes and water in 1-propyl-1-methylpiperidinium bis{(trifluoromethyl)sulfonyl}imide ionic liquid using g.l.c.

Activity coefficients at infinite dilution ( γ 13 ∞ ) of 38 different solutes (including alkanes, cyclohydrocarbons, alkenes, alkynes, benzene, alkylbenzenes, alcohols, water, thiophene, THF, MTBE, ethers, acetone, and n-ketones) in the ionic liquid 1-propyl-1-methylpiperidinium bis{(trifluoromethyl)sulfonyl}imide have been determined by using the g.l.c. method and have been reported over the temperature range from (308.15 to 358.15) K. The partial molar excess enthalpies of mixing at infinite dilution have been determined based on temperature dependence of γ 13 ∞ and discussed in terms of the intermolecular interactions. Selectivity and capacity at infinite dilution has been also calculated for chosen separation processes in systems ( n-hexane + benzene) and (cyclohexane + benzene) to evaluate if the studied ionic liquid is capable to be a good entrainer for these processes, e.g. in the liquid–liquid extraction. The results obtained are much better than many other ionic liquids with bis{(trifluoromethyl)sulfonyl}imide-based anion. However, the results are worse than for the thiocyanate-based ionic liquids.

Activity coefficients and partial molar excess enthalpies at infinite dilution for four esters in water

Infinite dilution activity coefficients ( γ 1 ∞ ) of four esters, namely dimethyl carbonate, diethyl carbonate, vinyl acetate, and methyl methacrylate in water were measured at several temperatures in the range from 273 K to 333 K. The inert gas stripping technique, and for methyl methacrylate also the headspace analysis with solid-phase microextraction sampling, was employed for the purpose. Infinite dilution partial molar excess enthalpies ( H ¯ 1 E , ∞ ) of these aqueous solutes were further measured at several temperatures in the range from 288 K to 318 K using isothermal flow mixing microcalorimetry which allowed reliable derivation of respective heat capacities ( C ¯ p , 1 E , ∞ ). For each ester, the data measured in this work together with those reported previously in the literature were correlated with a suitable model equation providing adequate simultaneous description of the equilibrium measurements and the calorimetric information. As a result, a recommended thermodynamically consistent temperature dependence of γ 1 ∞ of superior accuracy was established. Analogous recommendations were derived also for the temperature dependence of the Henry's law constants ( K H). In addition, literature data on mutual solubilities of esters and water were employed to calculate the γ 1 ∞ values which in turn were compared with the recommended γ 1 ∞ ( T ) dependences.

Activity Coefficients at Infinite Dilution Measurements for Organic Solutes and Water in the Ionic Liquid 1-(3-Hydroxypropyl)pyridinium Trifluorotris(perfluoroethyl)phosphate

The activity coefficients at infinite dilution, gamma(13)(infinity), for 37 solutes, alkanes, alkenes, alkynes, cycloalkanes, aromatic hydrocarbons, alcohols, thiophene, ethers, ketones, and water, in the ionic liquid 1-(3-hydroxypropyl)pyridinium trifluorotris(perfluoroethyl)phosphate [N-C(3)OHPY][FAP] were determined by gas-liquid chromatography at the temperatures from 308.15 to 358.15 K. The partial molar excess enthalpies at infinite dilution values DeltaH(1)(E,infinity) were calculated from the experimental gamma(13)(infinity) values obtained over the temperature range. The selectivities for aliphatics/aromatics hydrocarbons separation problem were calculated from the gamma(13)(infinity) values and compared to the literature values for other ionic liquids, N-methylpyrrolidone (NMP) and sulfolane. It was found that the investigated [N-C(3)OHPY][FAP] ionic liquid shows much higher selectivity and capacity at infinite dilution than the generally used organic solvents such as NMP, sulfolane, and other ionic liquids.

Activity Coefficients at Infinite Dilution Measurements for Organic Solutes and Water in the Ionic Liquid 1-Butyl-3-methyl-pyridinium Trifluoromethanesulfonate

The activity coefficients at infinite dilution, γ13∞, for 37 solutes: alkanes, alkenes, alkynes, cycloalkanes, aromatic hydrocarbons, alcohols, thiophene, ethers, ketones, and water in the ionic liquid 1-butyl-3-methyl-pyridinium trifluoromethanesulfonate [1,3bmPY][CF3SO3] were determined by gas−liquid chromatography at the temperatures from (308.15 to 358.15) K. The partial molar excess enthalpies at infinite dilution values ΔH1E,∞ were calculated from the experimental γ13∞ values obtained over the temperature range. The selectivities for the aliphatic/aromatic hydrocarbon separation problem were calculated from γ13∞ and compared to the literature values for other ionic liquids, N-methylpyrrolidone and sulfolane.

Activity Coefficients at Infinite Dilution Measurements for Organic Solutes and Water in the Ionic Liquid 1-Hexyl-3-methylimidazolium Thiocyanate

Activity coefficients at infinite dilution (γ ∞ 13 ) for 34 solutes: alkanes, alkenes, alkynes, cycloalkanes, aromatic hydrocarbons, alcohols, thiophene, ethers, acetone, and water in the ionic liquid 1-hexyl-3-methylimidazolium thiocyanate ([hmim][SCN]) were determined by gas—liquid chromatography over temperature range from (298.15 to 368.15) K. The partial molar excess enthalpies at infinite dilution values (ΔH E,∞ i ) were calculated from the experimental γ ∞ 13 values, obtained over the temperature range. The selectivities for aliphatic/aromatic hydrocarbon separation problems were calculated from the γ ∞ 13 and compared to the literature values for other ionic liquids with a thiocyanate-based anion or a -C≡N group in an anion or a cation, N-methyl-2-pyrrolidinone (NMP) and sulfolane.

Temperature Dependence of Limiting Activity Coefficients, Henry’s Law Constants, and Related Infinite Dilution Properties of Branched Pentanols in Water. Measurement, Critical Compilation, Correlation, and Recommended Data

Limiting activity coefficients (γ1∞) of six branched pentanols (2-pentanol, 3-pentanol, 2-methyl-1-butanol, 3-methyl-1-butanol, 2-methyl-2-butanol, and 3-methyl-2-butanol) in water were measured at several temperatures covering the range from the melting to the normal boiling point of water. Five experimental techniques, namely, inert gas stripping, headspace analysis in two variants, the classical and the relative, Rayleigh distillation, and the method of circulation still, were employed for the purpose. A comprehensive review is further presented of experimental data on the limiting activity coefficients, γ1∞, infinite dilution partial molar excess enthalpies (H1E,∞), and heat capacities (Cp,1E,∞) of these aqueous solutes. Since H1E,∞ data for 2-methyl-1-butanol in water are lacking in the literature, they were also determined in this work. For each pentanol isomer, the compiled data were critically evaluated and together with the data measured in this work correlated with a suitable model equation p...

Activity coefficients at infinite dilution of organic solutes in the ionic liquid 1-ethyl-3-methylimidazolium tetracyanoborate [EMIM][TCB] using gas–liquid chromatography

The activity coefficients at infinite dilution, γ i ∞ , for both polar and non-polar solutes in the ionic liquid 1-ethyl-3-methylimidazolium tetracyanoborate [EMIM][TCB] have been determined by gas–liquid chromatography at the temperatures from (303 to 343) K. The partial molar excess enthalpies at infinite dilution H i E, ∞ of the solutes in the ionic liquid were also calculated from the temperature dependence of the γ i ∞ values. The selectivity for the hexane/benzene and cyclohexane/benzene separation problems was calculated from experimental infinite dilution activity coefficient values and compared to the other ionic liquids, taken from the recent literature.

Activity Coefficients at Infinite Dilution of Alkanes, Alkenes, and Alkyl Benzenes in Glycerol Using Gas−Liquid Chromatography

The activity coefficients at infinite dilution, γi∞, for 16 organic solutes, alkanes, alkenes, and alkyl benzenes in glycerol, have been measured by the gas−liquid chromatographic method at five temperatures from (303.15 to 343.15) K. The overall uncertainty was estimated to be about 5 %. The partial molar excess enthalpies at infinite dilution, HiE,∞, of the solutes in glycerol were also derived from the temperature dependence of the γi∞ values.

Effect of anion species on infinite dilution activity coefficients of epoxides in imidazolium-based ionic liquids

The infinite dilution activity coefficients of 1,2-epoxypropane, 1,2-epoxybutane, 2-methyl-1,2-epoxypropane and 1,2-epoxyhexane in the ionic liquids with 1-butyl-3-methylimidazolium cation ([bmim]), [bmim][BF 4] and [bmim][PF 6] were measured by gas–liquid chromatograph (GC) from (325.2–363.4) K and atmospheric pressure. The ionic liquids were used as stationary phases in GC. The experimental data of the activity coefficients were determined from the extrapolations to zero of the gas flow rate on GC. The activity coefficients of the all epoxides in [bmim][PF 6] are smaller than those in [bmim][BF 4]. The partial molar excess enthalpies and entropies at infinite dilution for the epoxides in the ionic liquids were obtained from the experimental data of the activity coefficients. The enthalpies for the epoxides in [bmim][PF 6] are negative. The values of entropies in [bmim][PF 6] are lower than those in [bmim][BF 4]. It can be explained that the interactions of the epoxides with [bmim][PF 6] are larger than those with [bmim][BF 4].

Gas–liquid chromatography measurements of activity coefficients at infinite dilution of various organic solutes and water in tri- iso-butylmethylphosphonium tosylate ionic liquid

Activity coefficients at infinite dilution ( γ 13 ∞ ) of 33 different solutes (including alkanes, cycloalkanes, alkenes, alkynes, benzene, alkylbenzenes, water, alcohols, MTBE, thiophene and THF) in the ionic liquid tri- iso-butylmethylphosphonium tosylate have been determined by using the GLC method and have been reported over the temperature range (298.15 to 368.15) K. The partial molar excess enthalpies of mixing at infinite dilution have been determined based on temperature dependence of γ 13 ∞ . Selectivity and capacity at infinite dilution has been also calculated for exemplary separation processes in systems n-hexane/benzene and n-hexane/thiophene, to evaluate if the studied ionic liquid is capable to be a good entrainer for these processes, e.g. in the liquid–liquid extraction. The obtained results are promising however the ionic liquid studied shows a lower selectivity than some of imidazolium-based ionic liquids. To our best knowledge, the results indicate that tri- iso-butylmethylphosphonium tosylate is the best for the separation problem of aliphatic hydrocarbons from aromatic hydrocarbons among all of the studied quaternary phosphonium-based ionic liquids.

Excess molar enthalpies of dibromomethane with acetonitrile, furan and acetophenone at 303.15K

Abstract Excess molar enthalpies HE at 303.15 K using a microcalorimeter have been determined for binary liquid mixtures of dibromomethane (DBM) with acetonitrile, furan and acetophenone over the entire composition range. The excess molar enthalpies values are endothermic for DBM + acetonitrile, and +furan but they are exothermic for the system DBM + acetophenone. The observed values are fitted with the Redlich–Kister equation by means of the least squares method. The excess partial molar enthalpies of the components H m , 1 E and H m , 2 E have also been evaluated with the help of HE values. The results indicate the existence of specific interactions between all these components.

Activity Coefficients at Infinite Dilution of Organic Solutes in 1-Ethyl-3-methylimidazolium Tris(pentafluoroethyl)trifluorophosphate [EMIM][FAP] Using Gas−Liquid Chromatography

The activity coefficients at infinite dilution, γi∞, for both polar and nonpolar solutes in the ionic liquid 1-ethyl-3-methylimidazolium tris(pentafluoroethyl)trifluorophosphate ([EMIM][FAP]) have been determined by gas−liquid chromatography using the ionic liquid as the stationary phase. The measurements were carried out in the temperature range of (313 to 364) K. The partial molar excess enthalpies at infinite dilution HiE,∞ of the solutes in the ionic liquid were also derived from the temperature dependence of the γi∞ values.

Activity Coefficients at Infinite Dilution of Polar Solutes in 1-(2-Hydroxyethyl)-3-methylimidazolium Tetrafluoroborate Using Gas−Liquid Chromatography

Activity coefficients at infinite dilution of methanol, ethanol, 1-propanol, 1-butanol, 1-pentanol, 2-propanol, 2-methyl-1-propanol, 2-butanol, 3-methyl-1-butanol, acetonitrile, ethyl acetate, acetone, tetrahydrofuran, 1,4-dioxane, dichloromethane, and trichloromethane in 1-(2-hydroxyethyl)-3-methylimidazolium tetrafluoroborate have been determined using gas−liquid chromatography over a temperature range of (303.15 to 363.15) K with the ionic liquid as the stationary phase. The partial molar excess enthalpies at infinite dilution were also determined for the solutes from the temperature dependence of the experimental activity values.

Activity coefficients at infinite dilution of organic solutes in the ionic liquid 1-octyl-3-methylimidazolium hexafluorophosphate using gas–liquid chromatography at T = (313.15, 323.15, and 333.15) K

Activity coefficients at infinite dilution were determined for 24 solutes: n-alkanes, alk-1-enes, alk-1-ynes, cycloalkanes, alkylbenzenes and alcohols in the ionic liquid 1-octyl-3-methylimidazolium hexafluorophosphate, [OMIM][PF 6], by gas–liquid chromatography at three different temperatures T = (313.15, 323.15, and 333.15) K. The partial molar excess enthalpy values at infinite dilution were calculated from the experimental data over the same temperature range. Capacities and selectivities at infinite dilution for the systems hexane/benzene and methanol/benzene were determined from the experimental data and compared to the literature values for other ionic liquids, as well as for industrial molecular solvents. The influence of the cation and anion of the ionic liquid on the activity coefficient is discussed, as well as the usefulness of [OMIM][PF 6] in separating organic liquids.

Thermodynamic Properties of Hyperbranched Polymer, Boltorn U3000, Using Inverse Gas Chromatography

Mass-fraction activity coefficients at infinite dilution (Omega13(infinity)) of alkanes (C5-C10), cycloalkanes (C5-C8), alkenes (C5-C8), alkynes (C5-C8), aromatic hydrocarbons (benzene, toluene, ethylbenzene, o-, m-, p-xylene, thiophene), alcohols (C1-C5), water, ethers (tetrahydrofuran (THF), methyl-tert-butylether (MTBE), diethyl-, di-n-propyl-, di-n-butyl ether), and ketones (propanone, 2-pentanone, 3-pentanone, 2-hexanone, 3-hexanone, cyclopentanone) in the hyperbranched polymer, Boltorn U3000 (B-U3000), have been determined by inverse gas chromatography (IGC) using the polymer as the stationary phase. The measurements were carried out at different temperatures between 308.15 and 348.15 K. The density and thermophysical properties of polymer were described. The specific retention volume (V(g)), the Flory-Huggins interaction parameter (chi13(infinity)), the molar enthalpy of sorption (the partial molar enthalpies of solute dissolution) (Delta(s)H), the partial molar excess enthalpy at infinite dilution of the solute and polymer (DeltaH1(E,infinity)), the partial molar Gibbs excess energy at infinite dilution (DeltaG1(E,infinity)), and the solubility parameter (delta3) were calculated.

Measurements of mass-fraction activity coefficient at infinite dilution of aliphatic and aromatic hydrocarbons, thiophene, alcohols, water, ethers, and ketones in hyperbranched polymer, Boltorn H2004, using inverse gas chromatography

Thermodynamic properties of the hyperbranched polymer, Boltorn H2004 (B-H2004), were investigated by inverse gas chromatography with 42 different solvents: n-alkanes (C 5–C 10), cycloalkanes (C 5–C 8), alkenes (C 5–C 8), alkynes (C 5–C 8), aromatic hydrocarbons (benzene, toluene, ethylbenzene, o-, m-, p-xylene, thiophene), alcohols (C 1–C 5), water, ethers (tetrahydrofuran (THF), methyl- tert-butylether (MTBE), diethyl-, di- n-propyl-, di- n-butyl ether), and ketones (acetone, 2-pentanone, 3-pentanone, 2-hexanone, 3-hexanone, cyclopentanone) at the temperatures from (308.15 to 348.15) K using the inverse gas chromatography (IGC). The density and thermophysical properties of polymer were described. The specific retention volume ( V g ), the mass-fraction activity coefficient at infinite dilution ( Ω 13 ∞ ) , the Flory–Huggins interaction parameter ( χ 13 ∞ ) , the molar enthalpy of sorption in the polymer ( Δ s H ) , the partial molar excess enthalpy at infinite dilution ( Δ H 1 E , ∞ ) , the molar enthalpy of vaporization to the ideal-gas state for the pure solutes ( Δ vap H 0 ) , the partial molar Gibbs excess energy at infinite dilution ( Δ G 1 E , ∞ ) , and the solubility parameter of the polymer ( δ 3), were calculated. The UNIFAC-FV model was used to predict the mass-fraction activity coefficient at infinite dilution for different solutes in the B-H2004 polymer.

Knudsen effusion mass spectrometric determination of mixing thermodynamic data of liquid Al–Cu–Sn alloy

The vaporisation of a liquid Al–Cu–Sn system has been investigated at 1273–1473 K by Knudsen effusion mass spectrometry (KEMS) and the data fitted to a Redlich–Kister–Muggianu (RKM) sub-regular solution model. Thirty-one different compositions (41 samples) have been examined at eight fixed copper mole fractions, X Cu = 0.10, 0.20, 0.30, 0.333, 0.40, 0.50, 0.60 and 0.70. The ternary L-parameters, the thermodynamic activities and the thermodynamic functions of mixing have been evaluated using standard KEMS procedures. In addition, the same quantities were obtained from the measured ion intensity ratios of Al + to Cu +, Al + to Sn + and Cu + to Sn + using a mathematical regression technique. The intermediate data obtained directly are the RKM ternary L-parameters that are, as a function of temperature, as follows: L ( 0 ) = ( 14270 ± 1270 ) + ( 100.1 ± 7.6 ) T − ( 11.77 ± 0.93 ) T ln ( T ) ; L ( 1 ) = ( 145600 ± 9780 ) + ( 101.6 ± 58.7 ) T − ( 15.56 ± 7.14 ) T ln ( T ) ; L ( 2 ) = ( 76730 ± 1240 ) + ( 79.2 ± 7.4 ) T − ( 15.69 ± 0.91 ) T ln ( T ) . From the obtained ternary L-parameters the integral molar excess Gibbs energy, the excess chemical potentials, the activity coefficients and the activities have been evaluated. Using the temperature dependence of the activities, the integral and partial molar excess enthalpies and entropies can be also determined. In addition, for comparison, for some compositions, the Knudsen effusion isothermal evaporation method (IEM) and the Gibbs–Duhem ion intensity ratio method (GD-IIR) were used to determine activities and good agreement was obtained from the RKM model.

Mass-Fraction Activity Coefficients at Infinite Dilution Measurements for Organic Solutes and Water in the Hyperbranched Polymer Boltorn W3000 Using Inverse Gas Chromatography

Thermodynamic properties of hyperbranched polymer, Boltorn BW3000, were investigated by inverse chromatography with 42 different solvents: alkanes (C5−C10), cycloalkanes (C5−C8), alkenes (C5−C8), alkynes (C5−C8), aromatic hydrocarbons (benzene, toluene, ethylbenzene, o-, m-, p-xylene, thiophene), alcohols (C1−C5) and 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 the temperatures ranging from (308.15 to 348.15) K. The density and thermophysical properties of polymer were described. The specific retention volume (Vg), the mass-fraction activity coefficient at infinite dilution (Ω13∞), the Flory−Huggins parameter (χ13∞), the molar enthalpy of solute’s absorption in the polymer (ΔsH), the partial molar excess enthalpy at infinite dilution (ΔH1E,∞), the partial molar Gibbs excess energy at infinite dilution (ΔG1E,∞), and the solubility parameter of the poly...

Activity coefficients at infinite dilution measurements for organic solutes and water in the 1-hexyloxymethyl-3-methyl-imidazolium and 1,3-dihexyloxymethyl-imidazolium bis(trifluoromethylsulfonyl)-imide ionic liquids—The cation influence

The activity coefficients at infinite dilution, γ 13 ∞ for 35 solutes: alkanes, alkenes, alkynes, cycloalkanes, aromatic hydrocarbons, alcohols, thiophene, ethers, acetone and water in the ionic liquids 1-hexyloxymethyl-3-methyl-imidazolium bis(trifluoromethylsulfonyl)-imide [C 6H 13OCH 2MIM][NTf 2] and 1,3-dihexyloxymethyl-imidazolium bis(trifluoromethylsulfonyl)-imide [(C 6H 13OCH 2) 2IM][NTf 2] were determined by gas–liquid chromatography over a wide range of temperature from (298.15–368.15) K. The values of the partial molar excess enthalpies at infinite dilution, Δ H 1 E , ∞ , were calculated from the experimental γ 13 ∞ values obtained in the temperature range investigated. The selectivity for the separation of n-hexane/benzene, cyclohexane/benzene, n-hexane/thiophene, hex-1-ene/ n-hexane and hex-1-ene/benzene by the extractive distillation or solvent extraction processes were calculated from the γ 13 ∞ values and were compared to the literature values for other ionic liquids, and popular entrainers as NMP and sulfolane at temperature T = 298.15 K.

Activity coefficients at infinite dilution of organic solutes in the ionic liquid 1-ethyl-3-methylimidazolium trifluoromethanesulfonate using gas–liquid chromatography at T = (313.15, 323.15, and 333.15) K

Activity coefficients at infinite dilution were determined for 24 solutes (n-alkanes, alk-1-enes, alk-1-ynes, cycloalkanes, alkylbenzenes, and alcohols) in the ionic liquid 1-ethyl-3-methylimidazolium trifluoromethanesulfonate by gas-liquid chromatography at three different temperatures T = (313.15, 323.15, 333.15) K. The partial molar excess enthalpy values at infinite dilution were calculated from the experimental results over the same temperature range. Selectivities and capacities at infinite dilution for the hexane/benzene and methanol/benzene separation problems were calculated from experimental infinite dilution activity coefficient values. The activity coefficients, enthalpies, selectivities, and capacities are discussed and compared to literature values for other ionic liquids, as well as industrial molecular solvents.