Ind. Eng. Chem. Res. 2006, 45, 6811-6817
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Calculation of Vapor-Liquid and Liquid-Liquid Phase Equilibria for Systems Containing Ionic Liquids Using a Lattice Model Jianyong Yang, Changjun Peng, Honglai Liu,* and Ying Hu State Key Laboratory of Chemical Engineering and Department of Chemistry, East China UniVersity of Science and Technology, Shanghai 200237, China
A lattice model developed previously is adopted to describe the vapor-liquid- and liquid-liquid-phase behavior of the systems containing ionic liquids that are treated as chainlike molecules with a chain length of r, while that of solvents is taken as 1. To take into account the impact of hydrogen bonds existing in the solutions to properties, the exchange energy in the model is expressed as a function of the temperature based on the concept of the double lattice model. It is found that this model can correlate infinite diluted activity coefficients, vapor pressures of solvents, and liquid-liquid equilibria of ionic liquid solutions successfully. Comparison between the calculated results and the experimental data shows the vigor of the model. 1. Introduction Ionic liquids (ILs) are a type of molten salts at ambient temperature, which are a new generation of solvents for catalysis and synthesis.1 ILs are usually composed of large asymmetric organic cations and inorganic or organic anions. The combinations of these ILs’ ions result in unique properties such as very small vapor pressure at room temperature that is almost nondetective, a stable liquid range of over 300 K, and selective solubilities of certain components in fluid mixtures.2,3 Compared to conventional organic solvents, these features of ILs bring more advantages for synthesis and extraction processes. Its recoverability and extremely low volatility also make it a green solvent. To use ILs as a solvent in an industrial scale, it is necessary to provide their thermodynamic properties. In particular, the vapor-liquid and liquid-liquid equilibria (VLE and LLE, respectively) data are of great importance for separation processes. The corresponding literature reports have been sharply increased recently. The binary systems of ILs mixed with water or nonaqueous solvents have been studied extensively. For the VLE, Verevkin and co-workers4,5 obtained the vapor pressures and activity coefficients of systems of [Emim][NTf2] with aldehydes and ketones and [Bmim][NTf2] with n-alcohols and benzene by experiments. Kato and co-workers6,7 studied the binary systems containing the ionic liquids [Emim][(CF3SO2)2N], [Bmim][(CF3SO2)2N], and [Mmim][(CH3)2PO4]. Heintz et al.8 reported the experimental VLE of [Me3BuN][NTf2] with different alcohols. Safarov et al.9 studied the VLE of binary mixtures containing methanol, ethanol, propanol-1, and benzene in the ionic liquid [Bmim][OctS] or [Omim][BF4]. The infinite diluted activity coefficient of IL solutions is another important property for VLE studied by many researchers.10-20 For the LLE, ILs including [Rmim][PF6]21-26 with R ) ethyl, butyl, pentyl, hexyl, heptyl, and octyl; [Rmim][BF4]21,27-30 with R ) butyl, heptyl, and octyl; and [Rmim][NTf2]24,30-33 with R ) ethyl and butyl are involved. In all cases, the corresponding experiments gave phase diagrams with an upper critical temperature (UCST) dependent on the chain length of R as well as on the alcohols or anions.3 Systematic studies of different IL solutions can also be found in Crosthwaite et al.’s work.34
Various models have been used for correlating experimental data of phase equilibria of IL systems. On excess Gibbs energy models, Wilson and UNIQUAC equations have been applied to correlate solid-liquid equilibria and VLE of ILs.35,36 However, group contribution methods are not useful because of the shortage of experimental data. A good model is nonrandom two-liquid (NRTL), which provides effective results not only for VLE but also for LLE of IL solutions.36-39 On equations of state, the Peng-Robinson equation has been used to describe the solubility of ILs in supercritical fluids.40 However, it requires the critical parameters of an IL, which are most scarce. It is still hard to extend cubic equations of state to IL systems at present. On the basis of unimolecular quantum chemical calculations of the individual molecules, COSMORS41 has appeared to be a novel method for the prediction of thermophysical properties of liquids. It can be considered as an alternative to the structure-interpolating group-contribution methods. Although the results of COSMO-RS look promising in some cases, distinct deviations from the experimental data also could be observed.3,5 Because of the similarity between LLE phase diagrams of polymer solutions and those of IL solutions, Rebelo and co-workers24,29 use a “polymer-like” GEmodel42,43 to correlate the LLE of IL solutions. The model is an empirically modified form of the Flory-Huggins lattice theory.44,45 Although the latter is well-known, it exhibits a notable discrepancy when compared with simulations. Recently, we developed a new lattice model based on statistical thermodynamic theories.46 The model shows great superiority over other lattice models in calculation of critical points, coexistence curves, and internal energies. In this work, we try to extend this model to IL systems. The context is arranged as follows: Section 2 briefly describes the model. On account of the hydrogen bonding existing in ILs solutions,47,48 we build in the double lattice concept;49-52 a temperaturedependent exchange energy is then naturally introduced. In Section 3, comparison between the results with experimental data is presented. It can be found that the model developed can describe the phase behavior of various IL systems satisfactorily. Various factors are also discussed. Finally, in Section 4, we give the concluding remarks. 2. Model Descriptions
* To whom correspondence should be addressed. E-mail: hlliu@ ecust.edu.cn. Tel. and Fax: 86-21-64252921.
Because of strong static interaction, IL molecules in the solution most probably take the form of ionic pairs.39 On the
10.1021/ie060515k CCC: $33.50 © 2006 American Chemical Society Published on Web 08/29/2006
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other hand, because the molecule is generally large, it is reasonable to treat it as a chain. We then adopt a simple cubic lattice containing Nr sites with a coordination number z ) 6. The lattice is filled with N1 small solvent molecules, each of which occupies one site, and N2 IL molecules with a chain length of r, which is a relative size to the solvents; consequently, Nr ) N1 + rN2. Only the nearest-neighbor interactions are considered. Similar to polymer solutions,46 the Helmholtz energy of mixing can be expressed as
β∆mixA ) Nr
[
]
φ2 θ1 q2 θ2 z ln φ2 + φ1q1 ln + φ2 ln + r 2 φ1 r φ2 z z φ φ (/kT) - φ12φ22(/kT)2 2 1 2 4 z 2 2 2 φ φ (φ + φ22)(/kT)3 12 1 2 1 1 + φ1[exp(/kT) - 1] r-1+λ (1) φ2 ln r 1 + φ1φ2[exp(/kT) - 1]
φ1 ln φ1 +
(
)
where β ) 1/kT, k ()1.381 × 10-23 J K-1) is the Boltzmann constant, and T is the absolute temperature; ) 11 + 22 212 is the exchange energy between solvents 1 and monomers 2, and ij is the attractive energy of the i-j pair; φi and θi are the volume fraction and surface fraction of component i, respectively, which can be calculated by
φi )
Niri N1 + N2r
θi ) Niqi/(N1q1 + N2q2)
The activity of solvent 1, a1, is then derived as
( ) ( )
∆mixµ1 ∂∆mixA/NrkT ) NrkT ∂N1
ln a1 )
) ln φ1 + φ2 1 -
[
(r - 1)(r - 2) (0.1321r + 0.5918) r2
z φ φ 2(4φ12φ2 - φ13 + 2φ23 - 3φ1φ22)(/kT)3 12 1 2 r-1+λ 2 1 φ2 ( exp(/kT) - 1) r 1 + φ1(exp(/kT) - 1) φ2 - φ1 (7) 1 + φ1φ2( exp(/kT) - 1)
[
where 1 and 2 are the energy parameters.
]
The infinite diluted activity coefficient of solvent 1, γ∞1 , can be calculated by
ln γ∞1 ) lim ln x1f0
) ln
a1 x1
[
1 1 z + 1 - + ln r r 2
(
)
3
(
q2 1r
3
)]
(2) (3)
Because of the nondetective vapor pressure of IL, the VLE has the following expression,
1 2+ r
+
2+
pφ1 ) p/1φ/1a1 (4)
(6)
(9)
where p and p/1 are the vapor pressures of the solution and pure solvent, respectively, and φ1 and φ•1 are the fugacity coefficients of the equilibrium vapor phase of the solution and the pure solvent, respectively. When the system pressure is not high, the fugacity coefficients can be ignored;8,9 eq 9 can be simplified as
p ) p/1a1
(5)
This proposed model can accurately describe coexistence curves, especially the critical temperature and critical composition compared with computer simulation data. Detailed descriptions can be found in the previous papers.46,53 It has been revealed that there are hydrogen bonding interactions in IL solutions when IL molecules have the elements such as N, O, and F, etc.47,48 It is well-known that a simple lattice model cannot be used directly for the systems containing oriented specific interactions beyond van der Waals between segments. Therefore, we adopt the concept of double lattice of Hu and co-workers49-52 to account for the hydrogen bonds, which naturally introduces a temperature dependence of the exchange energy as follows,
/k ) 1/k + 2/k2T
]
+ 1 r z (8) 2 kT
λ in eq 1 is a parameter characterizing the long-range correlations between monomers in the same chain beyond the close contact pairs calculated by
λ)
1 + r
θ1 q2φ2 z q ln + θ2 - φ2 + (φ - θ1) + 2 1 φ1 rφ1 1 z 2 z φ (/kT) - φ1φ22(2φ2 - φ1)(/kT)2 2 2 4
where qi is a surface area parameter defined as
zqi ) ri(z - 2) + 2
T,V,N2
(10)
Coexistence curves of liquid-liquid equilibrium can be obtained by chemical-potential equalities, (β) (R) (β) µ(R) 1 ) µ1 , µ2 ) µ2
Spinodal and critical point are obtained by
(
)
∂2∆mixA/NrkT ∂φ12
) 0,
T,V
(
(11)
)
∂3∆mixA/NrkT ∂φ13
) 0 (12)
T,V
3. Results and Discussion 3.1. Vapor-Liquid Equilibria. Four binary systems for VLE are adopted as examples. They are systems of [Bmim][NTf2] with methanol or ethanol,5 [Me3BuN][NTf2] with propanol,8 and [Bmim] [OctS] with benzene.9 Three parameters are used in the model, which are adjusted to fit simultaneously the experimental infinite diluted activity coefficients and vapor
Ind. Eng. Chem. Res., Vol. 45, No. 20, 2006 6813 Table 1. Model Parameters for VLE of Different Systems systems
r
1/k (K)
2/k2 (K2)
[Bmim][NTf2]/methanol [Bmim][NTf2]/ethanol [Me3BuN][NTf2]/propanol [Bmim][OctS]/benzene
5.5 5.3 3.1 6.3
-205.4 -437.1 -135.1 -39.4
81 790.6 169 451.0 91 182.9 51 954.4
pressures. Table 1 lists the model parameters. The comparison between the calculated results and the experimental data for infinite diluted activity coefficients is shown in Figure 1. We can see that this model can reproduce the infinite diluted activity coefficients satisfactorily. Figures 2-5 show the VLE of different systems. The coincidence of the results calculated by the model with the experimental data can be observed. With the theory-based double lattice model, only three model parameters are needed to predict the VLE properties of IL solutions in a certain range of temperature, while the NRTL model used in the literature needs different parameters for different temperatures. 3.2. Liquid-Liquid Equilibria. In the cases of LLE, the chain length r and the energy parameters are obtained by correlation with the experimental data. Figure 6 shows the liquid-liquid equilibria for the solutions of [Rnmim][PF6] and butan-1-ol.25 Rn stands for an alkyl group with n carbon atoms. x2 is the mole fraction of IL. As n increases, we can see from Figure 6 that the coexistence curve moves to a lower temperature. This means that a longer alkyl chain length or a more organic ingredient in IL molecules enhances the solubility of IL in alcohols. The model adjustable parameter values are listed
Figure 3. Vapor-liquid equilibria of system containing x1 {ethanol} + (1 - x1){[Bmim][NTf2]}. Experimental data:5 T ) 298.15 K (squares); T ) 303.15 K (triangles); T ) 308.15 K (diamonds); T ) 313.15 K (crosses). Solid line: this work.
Figure 4. Vapor-liquid equilibria of system containing x1 {propanol} + (1 - x1){[Me3BuN][NTf2]}. Experimental data:8 T ) 298.15 K (squares); T ) 303.15 K (triangles); T ) 308.15 K (diamonds); T ) 313.15 K (crosses). Solid lines: this work.
Figure 1. Infinite dilution activity coefficients of different systems. Experimental data: [Me3BuN][NTf2] with propanol (diamonds);8 [Emim][NTf2] with propan-1-ol (solid circles);12 [Bmim][NTf2] with ethanol5 (crosses); [Bmim][OctS] with benzene9 (triangles); [Bmim][NTf2] with methanol5 (squares). Solid lines: this work. Figure 5. Vapor-liquid equilibria of system containing x1 {benzene} + (1 - x1){[Bmim][OctS]}. Experimental data:9 T ) 298.15 K (squares); T ) 303.15 K (triangles); T ) 308.15 K (diamonds); T ) 313.15 K (crosses). Solid lines: this work.
Figure 2. Vapor-liquid equilibria of system containing x1 {methanol} + (1 - x1){[Bmim][NTf2]}. Experimental data:5 T ) 298.15 K (squares); T ) 303.15 K (triangles); T ) 308.15 K (diamonds); T ) 313.15 K (crosses). Solid lines: this work.
in Table 2. As shown in this table, r and 2 increase with increasing chain length of Rn, while 1 decreases with n increasing and is negative, too. With these values, the results calculated by our model fit the experimental data very well. Figure 7 shows the liquid-liquid coexistence curves of mixtures of [Emim][NTf2] in different alcohols.32 w2 is the weight fraction. Here, Rn represents the alkyl group in the alcohol molecules. Different from the previous case, the miscibility of IL in alcohols is weakened with increasing n, as shown in Figure 7. Table 3 lists the adjustable parameters in the model. From Figure 7, it can be seen that the model can reproduce the experimental data pretty well. Additionally, we
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Figure 6. Liquid-liquid-phase equilibria for x2{[Rnmim][PF6]} + (1 x2){butan-1-ol}. Experimental data:25 Rn ) butyl (diamonds); Rn ) pentyl (bars); Rn ) hexyl (triangles); Rn ) heptyl (crosses); Rn ) octyl (squares). Solid lines: this work.
Figure 8. Liquid-liquid-phase equilibria for x2{[Emim][PF6]} + (1 x2){propanol}. Experimental data:26 propan-1-ol (diamonds); propan-2ol(triangles). Solid lines: this work + dotted lines: boiling point of propanol.
Table 2. Model Parameters for [Rnmim][PF6] + Butan-1-ol Systems Rn
r
1/k (K)
2/k2 (K2)
butyl pentyl hexyl heptyl octyl
5.0 5.2 5.6 6.2 6.4
-10.2 -66.5 -91.5 -122.8 -144.3
78 495.9 91 494.9 91 905.2 94 847.4 97 444.4
Table 3. Model Parameters for [Emim][NTf2] (2) + Rn -1-ol Systems Rn
r
1/k (K)
2/k2 (K2)
propan butan pentan
4.7 4.5 4.3
-87.3 -122.2 -258.1
70 147.3 92 413.3 148 167.5
use the model parameters of [Emim][NTf2]/propan-1-ol to calculate the infinite diluted activity coefficients, which are shown in Figure 1. Compared with Krummen et al.’s experimental data,12 our calculated results are a little lower. It also reveals, to a certain extent, that our model parameters are universal for both VLE and LLE. In other words, we can use the information obtained from one type of equilibrium properties to predict another. Of course, more experimental data is required to test if this is valid for other systems. Figure 8 presents the phase diagrams for [Emim][PF6] in different structural propanols.26 The upper dotted lines represent the boiling temperatures of these two alcohols, above which the systems will exhibit a vapor-liquid-liquid equilibria. In our model, r ) 4.9 is adopted for the two systems. The energy parameters are 1/k ) -54.3 K and 2/k2 ) 98 780.4 K2 for propan-1-ol system; and 1/k ) -55.4 K and 2/k2 ) 96 098.6 K2 for propan-2-ol system. As shown in Figure 8, it is observed
Figure 7. Liquid-liquid-phase equilibria for x2{[Emim][NTf2]} + (1 x2){Rn -1-ol}. Experimental data:32 Rn ) propan (squares); Rn ) butan (triangles); Rn ) pentan (diamonds). Solid lines: this work.
Figure 9. Liquid-liquid-phase equilibria for x2{IL} + (1 - x2){butanol}. Experimental data: [Bmim][PF6]25 (diamonds); [Bmim][NTf2]31 (triangles). Solid lines: this work.
Figure 10. Liquid-liquid-phase equilibria for x2{[Bmim][BF4]} + (1 x2){water}. Experimental data:29 squares; solid line: this work.
that the IL affinity for the alcohols is propan-2-ol > propan1-ol. The reason is that the ability of propan-2-ol to accept a hydrogen bond is stronger than that of propan-1-ol.54 We can see that the description by the model is satisfactory. The predicted UCSTs are 392 and 385 K for propan-1-ol and propan1-ol systems, respectively. Figure 9 shows the effect of the anions in IL molecules on the phase behavior.25,31 It is found that the IL containing NTf2 is more soluble in alcohols. According to Crosthwite et al.’s work,34 the alcohol affinity is (CN)2N > CF3SO3 > (CF3SO2)2N(NTf2) > BF4 > PF6. As for the model of this work, r ) 5.5, 1/k ) -405.8 K, and 2/k2 ) 165 078.1 K2 for [Bmim][NTf2] are adopted, and the parameters for [Bmim][PF6] are the same as in Figure 6. Again, the agreement between the experiment data and the calculated results is found.
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The last case is the phase diagram for the aqueous solutions of [Bmim][BF4],29 as shown in Figure 10. Similarly, an UCST ()277.7 K) is exhibited, which is lower than that of [Bmim][BF4]/ alcohol systems. For example, the value of UCST is 337 K for [Bmim][BF4]/butanol system.34 Except a slight deviation between calculated values and experimental data in the waterrich phase, we can see that the calculated results are satisfactory with the parameters of r ) 7.5, 1/k ) -54.6 K, and 2/k2 ) 50 111.8 K2. 4. Conclusions The phase behavior of ionic systems is still subject to debate.55 Recent accurate simulation56 revealed that the ionic solutions exhibit an Ising-type phase behavior similar to that of polymer systems. It implies that the anions and cations are possibly coupled at low temperature due to the strong Coulombic forces.57-59 Yan and de Pablo60 have testified by computer simulation that these closely coupled pairs aggregate easily into clusters. In such clusters, the long-range forces are screened and the ionic solution behaved like a common fluid. That’s the reason that we try to adopt a lattice model developed previously to describe the phase behavior of IL solutions. It is found that the model can correlate infinite diluted activity coefficients and experimental data of VLE and LLE for IL solutions satisfactorily when combined with a double lattice concept. This work also proves that the lattice models can simulate the phase behavior of IL systems properly. For both VLE and LLE, the correlated energy parameter 1 is negative, which stands for the miscibility of IL in solvents, while the positive 2 brings about the phase separation at low temperature. From Tables 1-3, we can see that the value of r is not exactly equal to the ratio of the molar volumes of two components but is close to it. For example, r ) 5.3 in [Bmim][NTf2]/ethanol mixture, while the ratio of the molar volumes of [Bmim][NTf2] and ethanol at 298.15 K is ∼4.9. The reason lies in the coarse-grained nature and also in the simplifications inherent in the model. Nevertheless, we still observe an increase of ∼0.2 in r with the addition of a CH2 group in IL (solvent) molecules, which brings a potential advantage for the predictive ability of the model. Acknowledgment The authors are grateful to Prof. S. J. Zhang for advice about the structure of IL molecules. This work was supported by the National Natural Science Foundation of China (Nos. 20236010, 20476025), the Doctoral Research Foundation sponsored by the Ministry of Education of China (Project No. 20050251004), Shanghai Municipal Science and Technology Commission of China (No. 05DJ14002), and E-institute of Shanghai High Institution Grid (No. 200303). Nomenclature A ) Helmholtz function (J) Nr ) number of total sites N ) number of molecules T ) temperature (K) k ) Boltzmann constant (J K-1) z ) coordination number r ) chain length q ) surface area parameter
p ) vapor pressure (Pa) w ) weight fraction x ) mole fraction n ) number of carbon atoms in alkyl group V ) volume (m3) a ) activity λ ) parameter characterizing the long-range correlations ) exchange energy (J) 1, 2 ) energy parameter (J, J2) ij ) interaction energy of i-j pair (J) φ ) volume fraction or fugacity coefficient θ ) surface fraction µ ) chemical potential (J) γ ) activity coefficient Literature Cited (1) Wong, H.; Han, S.; Livingston, A. G. The Effect of Ionic Liquids on Product Yield and Catalyst Stability. Chem. Eng. Sci. 2006, 61, 1338. (2) Marsh, K. N.; Boxall, J. A.; Lichtenthaler, R. Room-Temperature Ionic Liquids and Their MixturessA Review. Fluid Phase Equilib. 2004, 219, 93. (3) Heintz, A. Recent Developments in Thermodynamics and Thermophysics of Nonaqueous Mixtures Containing Ionic Liquids. A Review. J. Chem. Thermodyn. 2005, 37, 525. (4) Verevkin, S. P.; Vasiltsova1, T. V.; Bich, E.; Heintz, A. Thermodynamic Properties of Mixtures Containing ionic Liquids Activity Coefficients of Aldehydes and Ketones in 1-Methyl-3-ethyl-imidazolium Bis(trifluoromethyl-sulfonyl) imide Using the Transpiration Method. Fluid Phase Equilib. 2004, 218, 165. (5) Verevkin, S. P.; Safarov, J. b; Bich, E.; Hassel, E.; Heintz, A. Thermodynamic Properties of Mixtures Containing Ionic Liquids Vapor Pressures and Activity Coefficients of n-Alcohols and Benzene in Binary Mixtures with 1-Methyl-3-butyl-imidazolium Bis(trifluoromethyl-sulfonyl) imide. Fluid Phase Equilib. 2005, 236, 222. (6) Kato, R.; Krummen, M.; Gmehling, J. Measurement and Correlation of Vapor-Liquid Equilibria and Excess Enthalpies of Binary Systems Containing Ionic Liquids and Hydrocarbons. Fluid Phase Equilib. 2004, 224, 47. (7) Kato, R.; Gmehling, J. Measurement and Correlation of VaporLiquid Equilibria of Binary Systems Containing the Ionic Liquids [Emim][(CF3SO2)2N], [Bmim][(CF3SO2)2N], [Mmim][(CH3)2PO4] and Oxygenated Organic Compounds Respectively Water. Fluid Phase Equilib. 2005, 231, 38. (8) Heintz, A.; Vasiltsova, T. V.; Safarov, J.; Bich, E.; Verevkin, S. P. Thermodynamic Properties of Mixtures Containing Ionic Liquids. 9. Activity Coefficients at Infinite Dilution of Hydrocarbons, Alcohols, Esters, and Aldehydes in Trimethyl-butylammonium Bis(trifluoromethylsulfonyl) imide Using Gas-liquid Chromatography and Static Method. J. Chem. Eng. Data 2006, 51, 648. (9) Safarov, J.; Verevkin, S. P.; Bich, E.; Heintz, A. Vapor Pressures and Activity Coefficients of n-Alcohols and Benzene in Binary Mixtures with 1-Methyl-3-Butylimidazolium Octyl Sulfate and 1-Methyl-3-octylimidazolium Tetrafluoroborate. J. Chem. Eng. Data 2006, 51, 518. (10) Heintz, A.; Kulikov, D. V.; Verevkin, S. P. Thermodynamic Properties of Mixtures Containing Ionic Liquids. 1. Activity Coefficients at Infinite Dilution of Alkanes, Alkenes, and Alkylbenzenes in 4-Methyln-butylpyridinium Tetrafluoroborate Using Gas-Liquid Chromatography. J. Chem. Eng. Data 2001, 46, 1526. (11) Heintz, A.; Kulikov, D. V.; Verevkin, S. P. Thermodynamic Properties of Mixtures Containing Ionic Liquids. Activity Coefficients at Infinite Dilution of Polar Solutes in 4-Methyl-N-butyl-pyridinium Tetrafluoroborate Using Gas-Liquid Chromatography. J. Chem. Thermodyn. 2002, 34, 1341. (12) Krummen, M.; Wasserscheid, P.; Gmehling, J. Measurement of Activity Coefficients at Infinite Dilution in Ionic Liquids Using the Dilutor Technique. J. Chem. Eng. Data 2002, 47, 1411. (13) David, W.; Letcher, T. M.; Ramjugernath, D.; Raal, J. D. Activity Coefficients of Hydrocarbon Solutes at Infinite Dilution in the Ionic Liquid, 1-Methyl-3-octyl-imidazolium Chloride from Gas-Liquid Chromatography. J. Chem. Thermodyn. 2003, 35, 1335.
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(14) Kato, R.; Gmehling, J. Activity Coefficients at Infinite Dilution of Various Solutes in the Ionic Liquids [MMIM]+[CH3SO4]-, [MMIM]+[CH3OC2H4SO4]-, [MMIM]+[(CH3)2PO4]-, [C5H5NC2H5]+[(CF3SO2)2N]- and [C5H5NH]+[C2H5OC2H4OSO3]-. Fluid Phase Equilib. 2004, 226, 37. (15) Heintz, A.; Casas, L. M.; Nesterov, I. A.; Emel’yanenko, V. N.; Verevkin, S. P. Thermodynamic Properties of Mixtures Containing Ionic Liquids. 5. Activity Coefficients at Infinite Dilution of Hydrocarbons, Alcohols, Esters, and Aldehydes in 1-Methyl-3-butyl-imidazolium Bis(trifluoromethyl-sulfonyl) Imide Using Gas-Liquid Chromatography. J. Chem. Eng. Data 2005, 50, 1510. (16) Heintz, A.; Verevkin, S. P. Thermodynamic Properties of Mixtures Containing Ionic Liquids. 6. Activity Coefficients at Infinite Dilution of Hydrocarbons, Alcohols, Esters, and Aldehydes in 1-Methyl-3-octylimidazolium Tetrafluoroborate Using Gas-Liquid Chromatography. J. Chem. Eng. Data 2005, 50, 1510. (17) Kato, R.; Gmehling, J. Systems with ionic liquids: Measurement of VLE and γ∞ data and prediction of their thermodynamic behavior using original UNIFAC, mod. UNIFAC(Do) and COSMO-RS(Ol). J. Chem. Thermodyn. 2005, 37, 603. (18) Letche, T. M.; Marciniak, A.; Marciniak, M.; Domanska, U. Activity coefficients at infinite dilution measurements for organic solutes in the ionic liquid 1-hexyl-3-methyl-imidazolium bis(trifluoromethylsulfonyl)-imide using GLC at T ) (298.15, 313.15, and 333.15) K. J. Chem. Thermodyn. 2005, 37, 1327. (19) Mutelet, F.; Butet, V.; Jaubert, J. Application of Inverse Gas Chromatography and Regular Solution Theory for Characterization of Ionic Liquids. Ind. Eng. Chem. Res. 2005, 44, 4120. (20) Heintz, A.; Verevkin, S. P. Thermodynamic Properties of Mixtures Containing Ionic Liquids. 8. Activity Coefficients at Infinite Dilution of Hydrocarbons, Alcohols, Esters, and Aldehydes in 1-Hexyl-3-methylimidazolium Bis(trifluoromethylsulfonyl) Imide Using Gas-Liquid Chromatography. J. Chem. Eng. Data 2006, 51, 434. (21) Anthony, J. L.; Maginn, E. J.; Brennecke, J. F. Solution Thermodynamics of Imidazolium-based Ionic Liquids and Water. J. Phys. Chem. B 2001, 105, 10942. (22) Wong, D. S. H.; Chena, J. P.; Changa, J. M.; Choub, C. H. Phase Equilibria of Water and Ionic Liquids [emim][PF6] and [bmim][PF6]. Fluid Phase Equilib. 2002, 194-197, 1089. (23) Najdanovic-Visak, V.; Esperanca, J. M. S. S.; Rebelo, L. P. N.; da Ponte, M. N.; Guedes, H. J. R.; Seddon, K. R.; de Sousa, H. C.; Szydlowski, J. Phase Behaviour of Room Temperature Ionic Liquid Solutions: An Unusually Large Cosolvent Effect in (Water + Ethanol). Phys. Chem. Chem. Phys. 2002, 4, 1701. (24) Najdanovic-Visak, V.; Esperanca, J. M. S.; S.; Rebelo, L. P. N.; da Ponte, M. N.; Guedes, H. J. R.; Seddon, K. R.; de Sousa, H. C.; Szydlowski, J. Pressure, Isotope, and Water Co-solvent Effects in LiquidLiquid Equilibria of (Ionic Liquid + Alcohol) Systems. J. Phys. Chem. B 2003, 107, 12797. (25) Wu, C. T.; Marsh, K. N.; Deev, A. V.; Boxall, J. A. Liquid-Liquid Equilibria of Room-Temperature Ionic Liquids and Butan-1-ol. J. Chem. Eng. Data 2003, 48, 486. (26) Domanska, U.; Marciniak, A. Solubility of Ionic Liquid [emim][PF6] in Alcohols. J. Phys. Chem. B 2004, 108, 2376. (27) Wagner, M.; Stanga, O.; Schroer, W. Corresponding States Analysis of the Critical Points in Binary Solutions of Room-Temperature Ionic Liquids. Phys. Chem. Chem. Phys. 2003, 5, 3943. (28) Wagner, M.; Stanga, O.; Schroer, W. The Liquid-liquid Coexistence of Binary Mixtures of the Room-Temperature Ionic Liquid 1-Methyl3-hexylimidazolium Tetrafluoroborate with Alcohols. Phys. Chem. Chem. Phys. 2004, 6, 4421. (29) Rebelo, L. P. N.; Najdanovic-Visak, V.; Visak, Z. P.; da Ponte, M. N.; Szydlowski, J.; Cerdeirin˜a, C. A.; Troncoso, J.; Romanı´, L.; Esperanc¸ a, J. M. S. S.; Guedesc, H. J. R.; de Sousad, H. C. A Detailed Thermodynamic Analysis of [C4mim][BF4] + Water as a Case Study to Model Ionic Liquid Aqueous Solutions. Green Chem. 2004, 6, 369. (30) Domanska, U.; Marciniak, A. Liquid-Phase Behaviour of 1-Hexyloxymethyl-3-methyl-imidazolium-based Ionic Liquids with Hydrocarbons: The Influence of Anion. J. Chem. Thermodyn. 2005, 37, 577. (31) Najdanovic-Visak, V.; Rebelo, L. P. N.; da Ponte, M. N. LiquidLiquid Behaviour of Ionic Liquid-1-Butanol-Water and High-Pressure CO2Induced Phase Changes. Green Chem. 2005, 7, 443. (32) Heintz, A.; Lehmann, J. K.; Wertz, C. Thermodynamic Properties of Mixtures Containing Ionic Liquids. 3. Liquid-Liquid Equilibria of Binary Mixtures of 1-Ethyl-3-methylimidazolium Bis(trifluoromethylsulfonyl)imide with Propan-1-ol, Butan-1-ol, and Pentan-1-ol. J. Chem. Eng. Data 2003, 48, 472. (33) Heintz, A.; Lehmann, J K.; Wertz, C.; Jacquemin J. Thermodynamic Properties of Mixtures Containing Ionic Liquids. 4. LLE of Binary Mixtures
of [C2mim][NTf2] with Propan-1-ol, Butan-1-ol, and Pentan-1-ol and [C4mim][NTf2] with Cyclohexanol and 1,2-Hexanediol Including Studies of the Influence of Small Amounts of Water. J. Chem. Eng. Data 2005, 50, 956. (34) Crosthwaite, J. M.; Aki, S. N. V. K.; Maginn, E. J.; Brennecke, J. F. Liquid-Phase Behavior of Imidazolium-based Ionic Liquids with Alcohols. J. Phys. Chem. B 2004, 108, 5113. (35) Domanska, U.; Bogel-£ukasik, E. Measurements and Correlation of the (Solid + Liquid) Equilibria of [1-Decyl-3-methylimidazolium Chloride + Alcohols (C2-C12)]. Ind. Eng. Chem. Res. 2003, 42, 6986. (36) Doker, M.; Gmehling, J. Measurement and Prediction of VaporLiquid Equilibria of Ternary Systems Containing Ionic Liquids. Fluid Phase Equilib. 2005, 227, 255. (37) Letcher, T. M.; Deenadayalu, N.; Soko, B.; Ramjugernath, D.; Naicker, P. K. Ternary Liquid-Liquid Equilibria for Mixtures of 1-Methyl3-octylimidazolium Chloride + an Alkanol + an Alkane at 298.2 K and 1 bar. J. Chem. Eng. Data 2003, 48, 904. (38) Letcher, T. M.; Reddy, P. Ternary Liquid-Liquid Equilibria for Mixtures of 1-Hexyl-3-methylimidozolium (Tetrafluoroborate or Hexafluorophosphate) + Ethanol + an Alkene at T ) 298.2K. Fluid Phase Equilib. 2004, 219, 107. (39) Shi, Q.; Zheng, F.; Li, C.; Lu, G.; Wang Z. Calculation of VaporLiquid Equilibrium for Ionic Liquid-Containing Systems with NRTL Equation. J. Chem. Ind. Eng. (China) 2005, 56, 751. (40) Shariati, A.; Peters, C. J. High-Pressure Phase Behavior of Systems with Ionic Liquids: Measurements and Modeling of the Binary System Fluoroform + 1-Ethyl-3-methylimidazolium Hexafluorophosphate. J. Supercrit. Fluids 2003, 2, 109. (41) Klamt, A.; Eckert, F. COSMO-RS: A Novel and Efficient Method for the a Priori Prediction of Thermophysical Data of Liquids. Fluid Phase Equilib. 2000, 172, 43. (42) Rebelo, L. P. N. A Simple gE-model for Generating All Basic Types of Binary Liquid-Liquid Equilibria and Their Pressure Dependence. Thermodynamic Constraints at Critical Loci. Phys. Chem. Chem. Phys. 1999, 1, 4277. (43) de Sousa, H. C.; Rebelo, L. P. N. A Continuous Polydisperse Thermodynamic Algorithm for a Modified Flory-Huggins Model: The (Polystyrene + Nitroethane) Example. J. Polym. Sci., Part B: Polym. Phys. 2000, 38, 632. (44) Flory, P. J. Thermodynamics of High Polymer Solutions. J. Chem. Phys. 1942, 10, 51. (45) Huggins, M. L. Some Properties of Solutions of Long-Chain Compounds. J. Phys. Chem. 1942, 46, 151. (46) Yang, J. Y.; Yan, Q. L.; Liu, H. L.; Hu, Y. A Molecular Thermodynamic Model for Compressible Lattice Polymers. Polymer 2006, 47, 5187. (47) Fuller, J.; Carlin, R. T.; De Long, H. C. Structure of 1-Ethyl-3methylimidazolium Hexafluorphoshate: Model for Room-Temperature Molten Salts. J. Chem. Soc. Chem. Commun. 1994, 3, 299. (48) Fang, Y. S.; Zhou, R. Q. Room-Temperature Molten Salt as Medium for Lithium Battery. J. Power Sources 1999, 81, 891. (49) Hu, Y.; Lambert, S. M.; Soane, D. S.; Prausnitz, J. M. DoubleLattice Model for Binary Polymer Solutions. Macromolecules 1991, 24, 4356. (50) Hu, Y.; Liu, H. L.; Soane, D. S.; Prausnitz, J. M. Binary LiquidLiquid Equilibria from a Double-Lattice Model. Fluid Phase Equilib. 1991, 67, 65. (51) Hu, Y.; Ying, X. G.; Wu, D. T.; Prausnitz, J. M. Molecular Thermodynamics of Polymer Solutuions. Fluid Phase Equilib. 1993, 83, 289. (52) Hu, Y.; Liu, H. L.; Shi, Y. H. Molecular Thermodynamic Theory for Polymer Systems. I. A Closed-Packed Lattice Model. Fluid Phase Equilib. 1996, 117, 100. (53) Yang, J. Y.; Peng, C. J.; Liu, H. L.; Hu, Y.; Jian, J. W. A Generic Molecular Thermodynamic Model for Linear and Branched Polymer Solutions in a Lattice. Fluid Phase Equilib. 2006, accepted for publication. (54) Kamlet, M. J.; Doherty, R. M.; Abraham, M. H.; Marcus, Y.; Taft, R. W. Linear Solvation Energy Relationships. 46. An Improved Equation for Correlation and Prediction of Octano/Water Partition Coefficients of Organic Nonelectrolytes (Including Strong Hydrogen Bond Donor Solutes). J. Phys. Chem. 1988, 92, 5244. (55) Luijtena, E.; Fisher, M. E.; Panagiotopoulos, A. Z. The Heat Capacity of the Restricted Primitive Model Electrolyte. J. Chem. Phys. 2001, 114, 5468. (56) Orkoulas, G.; Fisher, M. E.; Panagiotopoulos, A. Z. Precise Simulation of Criticality in Asymmetric Fluids. Phys. ReV. E 2001, 63, 051507.
Ind. Eng. Chem. Res., Vol. 45, No. 20, 2006 6817 (57) Keblinski, P.; Eggebrecht, J.; Wolf, D.; Phillpot, S. R. Molecular Dynamics Study of Screening in Ionic Fluids. J. Chem. Phys. 2000, 113, 282. (58) Del Po’polo, M. G.; Voth, G. A. On the Structure and Dynamics of Ionic Liquids. J. Phys. Chem. B 2004, 108, 1744. (59) Liu, X. M.; Zhang, S. J.; Zhou, G. H.; Wu, G. W.; Yuan, X. L.; Yao, X. Q. A New Force Field for Molecular Simulation of GuanidiniumBased Ionic Liquids. J. Phys. Chem. 2006, in press.
(60) Yan, Q. L.; de Pablo, J. J. Phase Equilibria and Clustering in SizeAsymmetric Primitive Model Electrolytes. J. Chem. Phys. 2001, 114, 1727.
ReceiVed for reView April 24, 2006 ReVised manuscript receiVed July 20, 2006 Accepted July 31, 2006 IE060515K
