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Excess molar properties of ternary system (ethanol + water + 1,3-dimethylimidazolium methylsulphate) and its binary mixtures at several temperatures
J. Chem. Thermodynamics 40 (2008) 1208–1216
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Excess molar properties of ternary system (ethanol + water + 1,3-dimethylimidazolium methylsulphate) and its binary mixtures at several temperatures Elena Gómez, Begoña González, Noelia Calvar, Ángeles Domínguez * Chemical Engineering Department, University of Vigo, 36310 Vigo, Pontevedra, Spain
a r t i c l e
i n f o
Article history: Received 25 January 2008 Received in revised form 3 April 2008 Accepted 12 April 2008 Available online 18 April 2008 Keywords: Viscosity Density 1,3-Dimethylimidazolium methylsulphate Ternary systems Binary systems
a b s t r a c t The density, dynamic viscosity, and refractive index of the ternary system (ethanol + water + 1,3-dimethylimidazolium methylsulphate) at T = 298.15 K and of its binary systems 1,3-dimethylimidazolium methylsulphate with ethanol and with water at several temperatures T = (298.15, 313.15, and 328.15) K and at 0.1 MPa have been measured over the whole composition range. From these physical properties, excess molar volumes, viscosity deviations, refractive index deviations, and excess free energy of activation for the binary systems at the above mentioned temperatures, were calculated and fitted to the Redlich–Kister equation to determine the fitting parameters and the root-mean-square deviations. For the ternary system, the excess properties were calculated and fitted to Cibulka, Singh et al., and Nagata and Sakura equations. The ternary excess properties were predicted from binary contributions using geometrical solution models. Ó 2008 Elsevier Ltd. All rights reserved.
1. Introduction Room temperature ionic liquids or ionic liquids (RTILs or ILs) are a class of organic salts that are comprised entirely of ions and are liquids at conditions around room temperature in their pure state. In recent years, the properties of ILs have attracted considerable attention [1–11]. In addition, their perceived status as ‘‘designer”, alternative ‘‘green” solvents has contributed to this interest. Despite their interest and importance, the physicochemical properties of ILs and the detailed knowledge of the thermodynamic behaviour of the mixtures of ILs with molecular solvents have not been studied systematically. In this context, a systematic investigation of the thermodynamic and thermophysical properties of ILs and their mixtures is an important issue. This work is a continuation of our research group’s investigation of the thermodynamic properties of ionic liquids [12–16]. In this paper, we show at atmospheric pressure experimental density and dynamic viscosity data over the whole composition range for {x1 ethanol + x2 water + (1 x1 x2) [MMIM][MeSO4]} at T = 298.15 K and its binary systems {x1 ethanol + 1 x1 [MMIM][MeSO4]} and {x1 water + (1 x1) [MMIM][MeSO4]}. These properties were measured at T = (298.15, 313.15, and 328.15) K in order to observe the evolution of the studied properties with the increase of * Corresponding author. Tel.: +34 986812422; fax: +34 986812380. E-mail address: [email protected] (Á. Domínguez). 0021-9614/$ - see front matter Ó 2008 Elsevier Ltd. All rights reserved. doi:10.1016/j.jct.2008.04.006
the temperature. The results were used to calculate excess molar volumes, viscosity deviations and excess free energies of activation of viscous flow. Refractive indices were measured from T = 298.15 K over the whole composition range for {x1 ethanol + x2 water + (1 x1 x2) [MMIM][MeSO4]}, {x1 ethanol + (1 x1) [MMIM][MeSO4]} and {x1 water + (1 x1) [MMIM][MeSO4]}. The results were used to calculate refractive index deviations. The treatment of experimental ternary data was carried out in two ways: (i) correlation using empirical equations [17–19], and (ii) prediction using geometrical models that assume that interactions in a ternary mixture depend on the interactions in binary systems [20–26]. 2. Experimental 2.1. Chemicals Ethanol was supplied by Merck. The component was degassed ultrasonically, and dried over molecular sieves 4 108 (Type 4Å), that were supplied by Aldrich, and kept in inert argon with a maximum content in water of 2 106 by mass fraction. The mass fraction purity was >0.998 for ethanol. Water was doubly distilled and deionised. The ionic liquid used in this work was synthesised in our laboratory, following the published procedure [27]. To assure its purity, a NMR was made and compared with Pereiro et al. [27]; no differences were found. To reduce the water content to negligible values (lower
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E. Gómez et al. / J. Chem. Thermodynamics 40 (2008) 1208–1216 TABLE 1 Comparison of experimental density, q, and viscosity, g, with literature data for pure components at T = 298.15 K Component
[MMIM] [MeSO4]
T/K
298.15
q/(g cm3)
g/(mPa s)
Experimental
Literature
1.32912
1.32725a 1.3290b 1.328c 1.33059d 1.31657a 1.32009d 1.30606a 1.31121d
Experimental
Literature
77.7
72.91a
41.68
39.21a
25.21
20.37a
313.15
1.31856
328.15
1.30813
Ethanol
298.15 313.15 328.15
0.78546 0.77200 0.75855
0.7854e 0.77207f 0.75861f
1.082 0.827 0.641
1.082e 0.826f 0.641f
Water
298.15 313.15 328.15
0.99720 0.99221 0.98569
0.9971g 0.99222h 0.98570i
0.890 0.653 0.504
0.890g 0.6530h 0.5042i
a b c d e f g h i
Pereiro et al. [27]. Domanska et al. [28]. Kato et al. [29]. Golden et al. [30]. Nikam et al. [31]. González et al. [32]. Kapadi et al. [33]. Grande et al. [34]. Krishnaiah et al. [35].
than 0.03% determined using a 756 Karl Fisher coulometer) vacuum (2 101Pa) and moderate temperature (343.15 K) were applied to the IL for several days, always immediately prior to their use. The IL was kept in bottles with inert gas. Table 1 shows a comparison between experimental and literature data of pure components at T = (298.15, 313.15, and 328.15) K. Compared to literature, the density value for pure [MMIM][MeSO4] is higher than those reported by Pereiro et al. [27], Domanska et al. [28] and Kato et al. [29] and lower than the one reported by Goldon et al. [30]. These discrepancies can be due to the effect of temperature or to the presence of some traces of water or impurities in our mixtures or in their mixtures. These impurities can have dramatic effects on the density and viscosity values as was established from the studies of Seddon and co-workers [11]. 2.2. Apparatus and procedure Samples were prepared by syringing known amounts of the pure liquids into stoppered bottles, in an inert-atmosphere glove box, using a Mettler AX-205 Delta Range balance with a precision of ±105 g, covering the whole composition range of the mixture. A glove box was used because the ionic liquid is sensitive to moisture. Good mixing was ensured by magnetic stirring. All samples were prepared immediately prior to performing density, refractive index or viscosity measurements to avoid variations in composition due to evaporation of solvent or pickup of water by the hygroscopic IL. Kinematic viscosities were determined using an automatic viscosimeter Lauda PVS1 with four Ubbelhode capillary microviscosimeters of 0.4 103 m, 0.53 103 m, 0.70 103 m, and 1.26 103 m diameter (the uncertainty in experimental measurement is ±0.0001, ±0.003, ±0.03, and ±0.2 mPa s respectively). Gravity fall is the principle of measurement on which this viscosimeter is based. The capillary is maintained in a D20KP LAUDA thermostat with a resolution of 0.01 K. The capillaries are calibrated and credited by the company. The equipment has a control unit PVS1 (Pro-
cessor Viscosity System) that is a PC-controlled instrument for the precise measurement of fall time, using standardized glass capillaries, with an uncertainty of 0.01 s. In order to verify the calibration, the viscosity of the pure liquids was compared with literature data (table 1). The density of the pure liquids and mixtures were measured using an Anton Paar DSA-5000 digital vibrating tube densimeter. The repeatability and the uncertainty in experimental measurement have been found to be lower than (±2 106 and ±2.6 105) g cm3. The DSA 5000 automatically corrects the influence of viscosity on the measured density. To measure refractive indices, an automatic refractometer Abbemat-HP Dr. Kernchen with a resolution of ±106 and an uncertainty in the experimental measurements of ±4 105 was used. 3. Results and discussion Dynamic viscosity, density, excess molar volume, viscosity deviation, and excess free energy of activation for the ternary system
TABLE 2 Density, q, refractive index, nD, dynamic viscosity, g, excess molar volumes, VE, deviations in the refractive index, DnD, viscosity deviations, D g and excess free energy of activation, DG*E, for {x1 water + (1 x1) [MMIM][MeSO4]} x1
q/ (g cm3)
nD
0.0000 0.0497 0.1475 0.2128 0.3086 0.3869 0.4947 0.5959 0.6947 0.7966 0.8962 0.9485 1.0000
1.32912 1.32699 1.32281 1.31954 1.31375 1.30771 1.29697 1.28277 1.26217 1.22682 1.16206 1.10041 0.99720
1.48296 1.48187 1.47986 1.47824 1.47536 1.47252 1.46739 1.46071 1.45105 1.43485 1.40572 1.37848 1.33251
0.0000 0.0497 0.1475 0.2128 0.3086 0.3869 0.4947 0.5959 0.6947 0.7966 0.8962 0.9485 1.0000
1.31856 1.31644 1.31231 1.30903 1.30327 1.29725 1.28656 1.27239 1.25191 1.21682 1.15298 1.09264 0.99221
0.0000 0.0497 0.1475 0.2128 0.3086 0.3869 0.4947 0.5959 0.6947 0.7966 0.8962 0.9485 1.0000
1.30813 1.30609 1.30196 1.29864 1.29281 1.28689 1.27622 1.26204 1.24095 1.20664 1.14343 1.08403 0.98569
DnD
Dg/ (mPa s)
DG*E/ (J mol1)
0.0000 0.0064 0.0191 0.0273 0.0388 0.0478 0.0589 0.0674 0.0726 0.0717 0.0576 0.0382 0.0000
0.000 5.788 12.858 16.467 18.800 20.439 20.177 18.065 14.753 10.599 5.945 3.104 0.000
0.0 378.8 1152.6 1618.9 2316.7 2747.1 3276.8 3660.9 3863.3 3684.0 2697.0 1653.8 0.0
T = 313.15 K 41.68 0.000 37.51 0.019 30.44 0.012 25.86 0.030 20.76 0.056 16.93 0.062 12.41 0.070 9.041 0.067 6.368 0.050 4.027 0.017 2.069 0.086 1.261 0.099 0.653 0.000
0.000 2.128 5.188 7.088 8.257 8.871 8.970 8.188 6.807 4.972 2.843 1.504 0.000
0.0 426.7 1243.4 1713.4 2429.9 2926.2 3481.9 3870.1 4050.7 3841.6 2828.8 1745.8 0.0
T = 328.15 K 25.21 0.000 23.95 0.013 19.85 0.011 17.11 0.021 13.79 0.036 10.50 0.044 8.521 0.047 6.336 0.036 4.518 0.019 2.917 0.058 1.548 0.121 0.990 0.122 0.504 0.000
0.000 0.031 1.718 2.839 3.792 5.154 4.468 4.152 3.528 2.614 1.521 0.786 0.000
0.0 561.8 1410.4 1900.2 2598.9 2877.9 3667.1 4063.6 4222.9 3991.9 2953.3 1913.4 0.0
g/ (mPa s)
VE / (cm3 mol1)
T = 298.15 K 77.7 0.000 68.1 0.016 53.6 0.019 44.93 0.044 35.23 0.076 27.57 0.087 19.55 0.103 13.88 0.109 9.599 0.098 5.928 0.035 2.925 0.042 1.745 0.070 0.890 0.000
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{x1 ethanol + x2 water + (1 x1 x2) [MMIM][MeSO4]} at T = 298.15 K and its binary systems {x1 ethanol + (1 x1) [MMIM][MeSO4]} and {x1 water + (1 x1) [MMIM][MeSO4]} at T = (298.15, 313.15, and 328.15) K, and refractive indices at T = 298.15 K for all studied system are reported in tables 2–4. The excess molar volumes, viscosity deviations, and refractive index deviations were calculated from experimental values as follows: VE ¼
N X
xi M i ðq1 q1 i Þ;
ð1Þ
i¼1
Dg ¼ g
N X
xi gi ;
ð2Þ
i
DnD ¼ nD
N X
xi nD;i ;
ð3Þ
i
where q and qi are the density of the mixture and the density of the pure components, respectively; xi represents the mole fraction of the i component; g and gi are the dynamic viscosity of the mixture
TABLE 3 Density, q, refractive index, nD, dynamic viscosity, g, excess molar volumes, VE, deviations in the refractive index, DnD, viscosity deviations, Dg, and excess free energy of activation, DG*E, for {x1 ethanol + (1 x1) [MMIM][MeSO4]} x1
q/ (g cm3)
nD
0.0000 0.0669 0.1228 0.2212 0.2944 0.3984 0.5000 0.5926 0.6921 0.7970 0.8957 0.9450 1.0000
1.32912 1.31647 1.30519 1.28246 1.26318 1.23122 1.19280 1.15085 1.09430 1.01810 0.92316 0.86426 0.78546
1.48296 1.48028 1.47773 1.47336 1.46936 1.46252 1.45421 1.44554 1.43248 1.41494 1.39329 1.37874 1.36023
0.0000 0.0669 0.1228 0.2212 0.2944 0.3984 0.5000 0.5926 0.6921 0.7970 0.8957 0.9450 1.0000
1.31856 1.30589 1.29459 1.27177 1.25246 1.22040 1.18188 1.13974 1.08298 1.00641 0.91098 0.85176 0.77200
0.0000 0.0669 0.1228 0.2212 0.2944 0.3984 0.5000 0.5926 0.6921 0.7970 0.8957 0.9450 1.0000
1.30813 1.29553 1.28420 1.26138 1.24197 1.20957 1.17112 1.12874 1.07175 0.99472 0.89870 0.83906 0.75855
E
Dg/ (mPa s)
DG / (J mol1)
0.000 10.548 16.726 23.816 25.617 26.946 26.580 23.532 18.984 13.132 6.980 3.696 0.000
0.0 204.9 380.2 659.9 919.7 1126.5 1095.7 1139.6 1106.1 967.0 654.2 457.3 0.0
T = 313.15 K 41.68 0.000 34.42 0.204 29.38 0.393 22.80 0.663 17.97 0.860 12.87 1.093 8.823 1.216 6.258 1.316 4.309 1.280 2.649 1.133 1.603 0.787 1.225 0.521 0.827 0.000
0.000 4.522 7.278 9.841 11.675 12.532 12.427 11.210 9.096 6.470 3.482 1.848 0.000
0.0 240.4 440.2 849.0 1016.5 1249.8 1327.7 1380.4 1404.3 1157.4 778.2 526.9 0.0
T = 328.15 K 25.21 0.000 21.43 0.240 18.72 0.451 15.07 0.762 12.28 0.977 9.141 1.220 6.461 1.387 4.727 1.496 3.246 1.472 2.077 1.310 1.265 0.921 0.961 0.613 0.641 0.000
0.000 2.139 3.476 4.705 5.700 6.281 6.465 5.923 4.961 3.552 1.938 1.030 0.000
0.0 283.1 516.5 977.0 1191.1 1470.6 1564.5 1640.9 1590.7 1370.9 926.3 618.1 0.0
g/ (mPa s)
V / (cm3 mol1)
*E
T = 298.15 K 77.7 0.000 62.1 0.179 51.6 0.348 36.97 0.589 29.56 0.760 20.26 0.966 12.83 1.062 8.784 1.148 5.706 1.104 3.513 0.965 2.096 0.652 1.602 0.420 1.082 0.000
DnD
0.0000 0.0055 0.0098 0.0176 0.0225 0.0285 0.0326 0.0353 0.0345 0.0298 0.0203 0.0118 0.0000
and the pure components, respectively, and nD and nD,i are the refractive index of the mixture and the refractive index of the pure components, respectively. The excess Gibbs free energies of activation of viscous flow were obtained from the following equation: " DGE ¼ RT lnðgVÞ
N X
# xi lnðgi V i Þ ;
ð4Þ
i¼1
where R is the universal constant of gases, T is the absolute temperature, Vi is the molar volume of component i, V is the molar volume of the mixture, xi represents the mole fraction of the component i and g, gi are the dynamic viscosity of the mixture and the pure component, respectively. The binary deviations at several temperatures were fitted to a Redlich–Kister [36] type equation: DQ 12 ¼ x1 x2
M X
Bp ðx1 x2 Þp ;
ð5Þ
p¼0
where DQ12 is the excess property, x1 and x2 are the mole fraction of component 1 and 2, respectively, Bp is the fitting parameter and M is the degree of the polynomic expansion. The fitting parameters are given in table 5 together with the root-mean-square deviations, r r¼
(n , )1=2 dat X ðzexp zcalc Þ2 ndat ;
ð6Þ
i
where zexp, zcalc, and ndat, are the values of the experimental and calculated property and the number of experimental data, respectively. Figure 1 shows the fitted curve of excess molar volume values of systems {x1 water + (1 x1) [MMIM][MeSO4]} and {x1 ethanol + (1 x1) [MMIM][MeSO4]}. The excess molar volumes are negative over the entire composition range for x1 ethanol with (1 x1) [MMIM][MeSO4] mixture presenting a minimum in a mole composition of 0.6 for the three studied temperatures. It is remarkable that in the work of Goldon et al. [30] the excess molar volumes presented for the binary system {x1 methanol + (1 x1) [MMIM][MeSO4]} are also negative over the whole composition range, presenting a minimum at x1 0.65. Comparing the two systems (with ethanol and with methanol), we can observe that when the chain of carbon increases the minimum of VE is less negative. For the water, a sinusoidal curve was observed with the VE (minimum) 0.109, 0.067 and 0.04 cm3 mol1 at x1 0.6 for T = (298.15, 313.15, and 328.15) K, respectively and a maximum at x1 0.95 with a value of 0.07, 0.099, and 0.122 for T = (298.15, 313.15, and 328.15) K, respectively and at low mole fraction of water the VE show positive values for the three studied temperatures. This behaviour can be explained because hydrogen bonding is certainly more T-dependent (becoming negligible at high temperatures) than Coulombic interactions. This result agrees with the work of Rebelo et al. [37]. We can observe that when we increase the temperature the deviations of the excess molar volume are more negative for the case of the binary system containing ethanol and less negative for the other binary system. In figure 1, the experimental data of Pereiro et al. [38] and Domanska et al. [28] are also shown too and it is seen that good agreement exists between our data and those published. In figure 2, we can observe the variation of viscosity deviations with the composition and with the temperature. The sign is negative over the whole composition range and approach to minimum at 0.4 mole fraction for both systems. The viscosity deviations decrease as the temperature increases and this behaviour is similar for both systems.
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TABLE 4 Density, q, refractive index, nD, dynamic viscosity, g, excess molar volumes, VE, deviations of refractive index, DnD, viscosity deviations, Dg and excess free energies of activation of viscous flow, DG*E, for the ternary system {x1 ethanol + x2 water + (1 x1 x2) [MMIM][MeSO4]} at T = 298.15 K x1
x2
q/(g cm3)
nD
g/(mPa s)
VE/(cm3 mol1)
DnD
Dg mPa s
DG*E/(J mol1)
0.0567 0.1168 0.1877 0.0674 0.1409 0.2203 0.3053 0.3959 0.6047 0.0395 0.1015 0.1629 0.2319 0.3106 0.5094 0.0859 0.1736 0.2646 0.3603 0.4561 0.5579 0.1180 0.2333 0.3421 0.4400 0.5500 0.7386 0.8266 0.0987 0.1993 0.2974 0.3982 0.4936 0.5968 0.6995 0.0984 0.1977 0.2977 0.4003 0.4999 0.6032 0.7142 0.1018 0.2074 0.3097 0.4116
0.9117 0.8536 0.7851 0.8724 0.8036 0.7294 0.6498 0.5651 0.3697 0.9469 0.8858 0.8252 0.7572 0.6797 0.4837 0.8132 0.7351 0.6542 0.5691 0.4839 0.3933 0.7046 0.6125 0.5256 0.4474 0.3595 0.2088 0.1385 0.5532 0.4914 0.4312 0.3694 0.3108 0.2475 0.1844 0.3754 0.3341 0.2925 0.2497 0.2083 0.1652 0.1190 0.1512 0.1334 0.1162 0.0990
1.04795 1.02304 0.99517 1.08892 1.05623 1.02107 0.98536 0.95067 0.88294 1.01567 0.99373 0.97221 0.94804 0.92259 0.87025 1.12902 1.08808 1.04602 1.00379 0.96451 0.92582 1.17378 1.12169 1.07136 1.02633 0.97677 0.89473 0.85786 1.24598 1.20769 1.16748 1.12289 1.07751 1.02579 0.97002 1.27805 1.24733 1.21246 1.17178 1.12715 1.07411 1.00889 1.29771 1.27113 1.24115 1.20604
1.36927 1.37265 1.37432 1.38837 1.38872 1.38736 1.38487 1.38179 1.37434 1.35275 1.35907 1.36307 1.36540 1.36652 1.36644 1.40706 1.40412 1.39976 1.39462 1.38933 1.38377 1.42814 1.42101 1.41318 1.40571 1.39703 1.38184 1.37463 1.45376 1.44719 1.43994 1.43140 1.42247 1.41190 1.40033 1.46636 1.46062 1.45368 1.44555 1.43624 1.42503 1.41078 1.47397 1.46879 1.46277 1.45547
1.857 2.306 2.547 2.493 2.793 2.903 2.790 2.620 2.050 1.476 2.008 2.345 2.430 2.401 2.023 3.449 3.548 3.378 3.080 2.789 2.433 4.992 5.161 4.150 3.565 2.981 2.056 1.706 10.82 8.770 7.164 5.798 4.661 3.677 2.827 19.42 14.81 11.29 8.498 6.438 4.767 3.381 33.76 24.62 17.87 12.80
0.304 0.595 0.862 0.347 0.684 0.908 1.039 1.101 1.030 0.180 0.520 0.772 0.939 1.041 1.064 0.445 0.774 0.973 1.076 1.113 1.080 0.527 0.862 1.024 1.080 1.067 0.860 0.684 0.494 0.761 0.956 1.075 1.107 1.108 0.980 0.422 0.695 0.908 1.048 1.128 1.108 1.008 0.157 0.454 0.707 0.9057
0.030 0.032 0.033 0.045 0.044 0.041 0.037 0.032 0.021 0.017 0.022 0.024 0.025 0.024 0.019 0.057 0.053 0.048 0.041 0.035 0.028 0.066 0.059 0.051 0.044 0.036 0.021 0.014 0.066 0.063 0.058 0.053 0.047 0.039 0.031 0.052 0.052 0.051 0.049 0.046 0.041 0.033 0.026 0.031 0.035 0.038
1.470 0.878 0.468 3.039 2.389 1.900 1.608 1.345 0.918 0.465 0.122 0.514 0.661 0.702 0.502 5.215 4.388 3.804 3.308 2.805 2.316 9.553 7.626 6.976 6.065 4.970 3.016 2.023 16.846 15.931 14.643 13.037 11.360 9.299 7.120 21.927 22.098 21.157 19.370 16.980 14.036 10.464 24.559 26.975 27.199 25.774
1859.7 2407.1 2657.9 2489.4 2763.9 2851.2 2738.1 2558.6 1858.9 1312.9 2105.4 2510.6 2610.6 2578.5 2070.7 3051.7 3112.3 2983.2 2745.2 2485.4 2129.1 3321.7 3451.5 2962.8 2636.3 2250.7 1432.7 1020.4 3484.7 3203.4 2937.2 2656.4 2347.6 2012.1 1614.6 2761.5 2590.4 2416.7 2220.5 2021.6 1780.1 1463.9 1194.9 1328.6 1412.8 1448.7
3.1. Correlation of physical properties The VE, DnD, Dg, and DG*E values calculated from equations (1) to (4) for the ternary system were correlated using the equations proposed by Cibulka [17], Singh et al. [18], and Nagata and Sakura [19]. The following expressions were used: Cibulka equation: Q E123 ¼ Q E12 þ Q E13 þ Q E23 þ x1 x2 x3 ðA þ Bx1 þ Cx2 Þ;
ð7Þ
Singh et al. equation: Q E123 ¼ Q E12 þ Q E13 þ Q E23 þ Ax1 x2 x3 þ Bx1 ðx2 x3 Þ þ Cx21 ðx2 x3 Þ2 ; ð8Þ where A, B and C are fitting parameters. Nagata and Sakura equation: Q E123 ¼ Q E12 þ Q E13 þ Q E23 þ x1 x2 x3 A; where A is the fitting parameter.
ð9Þ
The Q Eij is the contribution to the excess property of the constituent binary mixtures evaluated by the Redlich–Kister equation [36]: Q Eij ¼ xi xj
M X
Bp ðxi xj Þp ;
ð10Þ
p¼0
where xi is the mole fraction of component i and Bp are adjustable parameters. The parameters Bp and the root-mean-square deviations for the excess properties of the two binary mixtures containing ionic liquid involved in the ternary system are presented in this paper and are listed in table 5 as indicated previously. The properties of the binary mixture (ethanol + water) were determined in our laboratory, and its fitting Redlich–Kister parameters were published in a previous work [14]. The fitting parameters of the correlation equations and root-mean-square deviations are given in table 6. As can be observed in this table, for all the studied properties the better fitting is given by Cibulka, where the correlated values are in good agreement with the experimental data. In figures 3 to 5, the
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TABLE 5 Fitting parameters and root-mean-square deviation, r, for binary mixtures {x1 ethanol + (1 x1) [MMIM][MEtSO4]} and {x1 water + (1 x1) [MMIM][MEtSO4]} at T = (298.15, 313.15, 328.15) K
V /(cm mol ) DnD Dg/(mPa s) DG*E/(J mol1)
B0 = 0.406 B0 = 0.2384 B0 = 80.229 B0 = 13222.8
Water (1) + [MMIM][MESO4] (2) T = 298.15 K B1 = 0.297 B2 = 0.353 B1 = 0.1722 B2 = 0.1185 B1 = 24.357 B2 = 7.456 B1 = 8521.7 B2 = 7806.8
VE/(cm3 mol1) Dg/(mPa s) DG*E/(J mol1)
B0 = 0.271 B0 = 35.594 B0 = 14055.7
B1 = 0.151 B1 = 9.209 B1 = 8879.8
VE/(cm3 mol1) Dg/(mPa s) DG*E/(J mol1)
B0 = 0.168 B0 = 18.610 B0 = 14590.3
B1 = 0.052 B1 = 6.728 B1 = 9605.3
V /(cm mol ) DnD Dg/(mPa s) DG*E/(J mol1)
B0 = 4.319 B0 = 0.1313 B0 = 104.79 B0 = 4588.7
Ethanol (1) + [MMIM][MESO4] (2) T = 298.15 K B1 = 1.813 B2 = 0.907 B1 = 0.0679 B2 = 0.0341 B1 = 39.362 B2 = 9.703 B1 = 358.6 B2 = 730.1
VE/(cm3 mol1) Dg/(mPa s) DG*E/(J mol1)
B0 = 4.945 B0 = 49.556 B0 = 5349.1
B1 = 2.106 B1 = 14.219 B1 = 1838.7
VE/(cm3 mol1) Dg/(mPa s) DG*E/(J mol1)
B0 = 5.598 B0 = 25.666 B0 = 6334.5
B1 = 2.514 B1 = 3.712 B1 = 1795.8
E
3
E
3
1
1
B3 = 0.970 B3 = 0.2053 B3 = 8.293 B3 = 7047.9
B4 = 2.316 B4 = 0.1853 B4 = 28.96 B4 = 1946.1
r = 0.004 r = 0.006 r = 0.144 r = 11.19
T = 313.15 K B2 = 0.210 B2 = 0.155 B2 = 6829.8
B3 = 1.166 B3 = 1.544 B3 = 7070.7
B4 = 2.412 B4 = 3.009 B4 = 4224.6
r = 0.004 r = 0.082 r = 10.34
T = 328.15 K B2 = 0.261 B2 = 2.804 B2 = 7105.6
B3 = 1.253 B3 = 18.351 B3 = 5372.8
B4 = 1.835 B4 = 10.887 B4 = 7273.7
r = 0.008 r = 0.179 r = 56.08
B3 = 0.967 B3 = 0.0075 B3 = 27.215 B3 = 3895.3
B4 = 0.296 B4 = 0.0107 B4 = 12.494 B4 = 1332.2
r = 0.008 r = 0.0001 r = 0.207 r = 24.11
T = 313.15 K B2 = 0.790 B2 = 6.755 B2 = 3276.8
B3 = 1.742 B3 = 8.539 B3 = 546.6
B4 = 1.53 B4 = 18.751 B4 = 4089.3
r = 0.011 r = 0.109 r = 15.59
T = 328.15 K B2 = 1.201 B2 = 5.363 B2 = 2447.8
B3 = 1.976 B3 = 5.903 B3 = 2031.5
B4 = 1.796 B4 = 10.733 B4 = 1700.9
r = 0.012 r = 0.060 r = 11.95
b
a
-0.3
V E / (cm -3 .mol -1)
V E / (cm -3 .mol -1)
0.1
0.0
0.0
-0.6
-0.9
-1.2
-0.1 -1.5
-1.8
-0.2 0.0
0.5
1.0
x1
0.0
0.5
1.0
x1
FIGURE 1. Experimental excess molar volume, VE, and calculated values from the Redlich–Kister equation (—) plotted against mole fraction at T = 298.15 K (d), T = 313.15 K (j) and T = 328.15 K (N), for the binary mixtures: (a) {x1 water +(1 x1) [MMIM][MeSO4]}, Domanska et al. data (M) and (b) {x1 ethanol + (1 x1) [MMIM][MeSO4]}, Pereiro et al. data ( ).
isolines of the excess properties VE, DnD, and Dg calculated from Cibulka, are shown. 3.2. Prediction of physical properties Several empirical methods have been proposed to estimate ternary excess properties from experimental results of the constituent binary systems. These methods are of great interest, since as the
number of components in the mixture increases, the determination of its properties becomes more laborious. The predictive methods can be divided into symmetric and asymmetric, depending on whether the assumption of the three binary mixtures contributing equally to the ternary mixture magnitude is accepted or not. Asymmetry is usually understood to be caused by the strongly polar or associative behaviour of any of the compounds in the mixture. In these cases, different geometric
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E. Gómez et al. / J. Chem. Thermodynamics 40 (2008) 1208–1216
a
b
0
0
-5
-5
Δη / (mPa·s)
Δη / (mPa·s)
-10
-10
-15
-15
-20
-20
-25
-25 0.0
0.2
0.6
0.4
0.8
1.0
-30 0.0
0.2
0.4
0.6
0.8
1.0
x1
x1
FIGURE 2. Experimental dynamic viscosity deviations, Dg, and calculated values from the Redlich–Kister equation (—) plotted against mole fraction at T = 298.15 K (), T = 313.15 K (j) and T = 328.15 K (N), for the binary mixtures: (a) {x1 water + (1 x1) [MMIM][MeSO4]} and (b) {x1 ethanol + (1 x1) [MMIM][MeSO4]}.
Kohler [23]:
TABLE 6 Fitting parameters and root-mean-square deviations for empirical equations VE/(cm3 mol1)
A B C r
DnD
Dg/(mPa s)
DG*E/(J mol1)
ðx2 þ x3 Þ2 Q E 23 ðx2 ; x3 Þ:
{x1 ethanol + x2 water + (1 x1 x2) [MMIM][MeSO4]} Cibulka equation (7) 8.185 6.2471 55.242 20,302 7.845 0.3722 148.355 47,357 11.690 0.7189 142.535 13,386 0.031 0.0013 0.410 113
A B C r
1.376 0.106 0.067 0.036
Singh et al. equation (8) 0.1299 47.958 0.0114 0.982 0.0189 2.424 0.0013 0.496
A r
1.220 0.038
Nagata and Sakura equation (9) 0.1415 48.589 0.0018 0.511
7992 32 73 162 8082 162
ð11Þ
in which Q Eij or Q Eijk is the excess property, the equation of Rastogi et al. [21]: E Q E123 ¼ 0:5½ðx1 þ x2 ÞQ E 12 ðx1 ; x2 Þ þ ðx1 þ x3 ÞQ 13 ðx1 ; x3 Þþ
ðx2 þ
x3 ÞQ E 23 ðx2 ; x3 Þ;
ð14Þ
The following models are asymmetrical, so we alternatively consider each component of the ternary mixture as the asymmetric component, Toop [24]:
criteria are applied to match each point of ternary composition with the contributing binary compositions. To predict the excess properties (VE, DnD, Dg, and DG*E), we have used symmetric [20–23] and asymmetric [24–26] geometrical solution models. In this work, we applied the symmetric equations of Radojkovic et al. [20]: Q E123 ¼ Q E12 ðx1 ; x2 Þ þ Q E13 ðx1 ; x3 Þ þ Q E23 ðx2 ; x3 Þ
2 E Q E123 ¼ ½ðx1 þ x2 Þ2 Q E 12 ðx1 ; x2 Þ þ ðx1 þ x3 Þ Q 13 ðx1 ; x3 Þ þ
ð12Þ
Jacob and Fitzer [22]: h h ii E x2 x1 x3 Q E123 ¼ 4 ð2x1 þxx31Þð2x Q E 12 ðx1 ; x2 Þ þ ð2x1 þx2 Þð2x3 þx2 Þ Q 13 ðx1 ; x3 Þ þ 2 þx3 Þ h h ii ; E x3 4 ð2x2 þxx12Þð2x Q ðx ; x Þ 23 2 3 þx Þ 3 1 ð13Þ
x2 x3 Q E123 ¼ ðx ; x Þ þ Q E Q E 12 1 13 ðx1 ; x3 Þþ 2 1 x1 1 x1 i 1 x1 Þ2 Q E 23 ðx2 ; x3 Þ
ð15Þ
Tsao and Smith [25]: x2 x3 Q E123 ¼ Q E Q E 12 ðx1 ; x2 Þ þ 13 ðx1 ; x3 Þþ 1 x1 1 x1 i 1 x1 ÞQ E 23 ðx2 ; x3 Þ
ð16Þ
Scarchard et al. [26]: Q E123 ¼
x2 x3 E E Q E Q ðx ; x Þ þ ðx ; x Þ þ Q ðx ; x Þ 12 1 13 1 23 2 2 3 3 1 x1 1 x1 ð17Þ E
where the arguments of Q ðxi ; xj Þ are xi ¼ xi =ðxi þ xj Þ and xj ¼ xj =ðxi þ xj Þ. Table 7 lists the root-mean-square deviations of fitting for each dependent variable and equation. 4. Conclusions In this work, the dynamic viscosity and density data over the whole composition range for {x1 ethanol + x2 water + (1 x1 x2) [MMIM][MeSO4]} at T = 298.15 K and its binary systems {x1 ethanol + (1 x1) [MMIM][MeSO4]} and {x1 water + (1 x1) [BMIM][MeSO4]} at temperatures of (298.15, 313.15, and 328.15) K have been determined. The refractive indices at T = 298.15 K for all systems have been obtained as well. Excess molar volumes, viscosity deviations, and excess Gibbs free energies of activation were calculated and fitted to the Redlich–Kister equation to test the quality of the experimental values.
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E. Gómez et al. / J. Chem. Thermodynamics 40 (2008) 1208–1216
MMIMMeSO 0.0
4
1.0
0.1
0.9
0.2 -0 .2
0.8
0.3 -0 .
4
0.7
0.4 -0 .6
0.6
0.5
0.5 .8 -0
0.6
0.4 0 -1.
0.7
0.3 -1.1
0.8
0.2 0 -1.
0.9
8 -0.
1.0
H 2O
6 -0. .4 -0
0.1 0.0
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
EtOH
FIGURE 3. Isolines for excess molar volumes, V E123 , from the Cibulka equation (7) for the ternary system {x1 ethanol + x2 water + 1(1 x1 x2) [MMIM][MeSO4]}.
MMIMMeSO4 0.0
1.0
0.01
0.1
0.9
0.02
0.2
0.8
0.0 3
0.3
0.7 0.0 4
0.4
0.6
0.0 5
0.5
0.5
0.0 6
0.6 0.7
0.4 0.0 7
0.3
0.8
0.2 0.03
0.9
0.02 0.01
1.0
H 2O
0.0
0.1 0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
EtOH
FIGURE 4. Isolines for the changes of refractive index, DnD123, from the Cibulka equation (7) for the ternary system {x1 ethanol + x2 water + 1(1 x1 x2) [MMIM][MeSO4]}.
The ternary system has been correlated used Cibulka, Singh et al., and Nagata and Sakura equations. All the correlative models are capable of representing the behaviour of the ternary mixture with a higher or lesser degree of accuracy. In the correlation, the Cibulka equation gives the smaller deviations for all the studied excess properties. The prediction of the ternary system has been done using symmetric and asymmetric geometrical solution models. Deviations obtained with the empirical equations to predict the excess prop-
erties are rather high. This fact can be due to the importance of the ternary contribution term to the quantity studied. Of the geometrical solution models used to predict the excess properties, the best for prediction of the VE was the that by Radojkovic et al.; for the DnD and Dg the best was by Kohler and for DG*E was that of Jacob and Fitzner. In general, the symmetric equations give better predictive results, specially those of Radojkovic, Jacob and Fitzner, and Kohler. The predictions of the asymmetric equations of Tsao and Smith and Scatchard erred significantly.
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E. Gómez et al. / J. Chem. Thermodynamics 40 (2008) 1208–1216
MMIMMeSO 0.0
4
1.0
0.1
0.9
0.2
0.8
0.3
0.7
0.4
0.6
0.5
0.5
-24
0.6
0.4
-20 0.7
0.3
-16 -12
0.8
0.2
-8 0.9
-4
0.1
1.0
H 2O
0.0
0.0 0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
EtOH
FIGURE 5. Isolines for the deviation of dynamic viscosity, Dg123, from the Cibulka equation (7) for the ternary system {x1 ethanol + x2 water + 1(1 x1 x2) [MMIM][MeSO4]}.
TABLE 7 Root-mean-square deviations of predictions of excess molar volumes, refractive index deviations, viscosity deviations and excess free energies of activation of viscous flow for {x1 ethanol + x2 water + (1 x1-x2) [MMIM][MeSO4]} at T = 298.15 K
Radojkovic Rastogi Jacob and Fitzner Kohler Toopa Toopb Toopc Tsao and Smitha Tsao and Smithb Tsao and Smithc Scatcharda Scatchardb Scatchardc a b c
V E123 /(cm3 mol1)
DnD
Dg/(mPa s1)
1 DGE 123 /(J mol )
0.054 0.313 0.076 0.060 0.151 0.122 0.123 0.153 0.210 0.224 0.154 0.621 0.440
0.004 0.013 0.008 0.003 0.005 0.009 0.0012 0.010 0.007 0.014 0.031 0.012 0.014
1.110 3.696 1.562 0.940 2.169 1.819 3.588 3.822 4.355 3.544 8.415 12.656 3.554
980 1519 943 1138 1276 796 1337 1410 799 1473 2089 976 1739
Ethanol is the asymmetric component. Water is the asymmetric component. [MMIM][MeSO4] is the asymmetric component.
Acknowledgements The authors are grateful to the Ministerio de Ciencia y Tecnología of Spain (Project CTQ2004-00454) and Xunta de Galicia (Project PGIDIT05PXIC38303PN) for financial support.
References [1] [2] [3] [4]
T. Welton, Chem. Rev. 99 (1999) 2071–2083. J.D. Holbrey, K.R. Seddon, Clean Prod. Process. 1 (1999) 223. J.F. Brennecke, E.J. Maggin, Alche. J. 47 (2001) 2384–2389. J.L. Anthony, E.J. Maggin, J.F. Brennecke, J. Phys. Chem. B 106 (2002) 7315– 7320. [5] U. Domanska, E. Bogel-Lukasik, R. Bogel-Lusakic, J. Phys. Chem. B 107 (2003) 1858–1863. [6] P. Wasserscheid, T. Welton (Eds.), Ionic Liquids in Synthesis, Wiley–VCH, Weinheim, 2003. [7] J.G. Huddleston, A.E. Visser, W.H. Reichert, H.D. Willauer, G.A. Broker, R.D. Rogers, Green Chem. 3 (2001) 156–164.
[8] K.N. Marsh, J.A. Boxall, R. Lichtenthaler, Fluid Phase Equilibr. 219 (2004) 93–98. [9] C.P. Fredlake, J.M. Crosthwaite, D.G. Hert, S.N.V.K. Aki, J.F. Brennecke, J. Chem. Eng. Data 49 (2004) 954–964. [10] G.J. Kabo, A.V. Blokhin, Y.U. Poulechka, A.G. Kabo, M.P. Shymanovich, J.W. Magge, J. Chem. Eng. Data 49 (2004) 453–461. [11] K.R. Seddon, A. Stark, M-J.M.-J. Torres, in: M. Abraham, L. Moens (Eds.), Clean Solvents: Alternative Media for Chemical Reactions and Processing, ACS Symposium Series, vol. 819, American Chemical Society, Washington, DC, 2002, pp. 34–40. [12] N. Calvar, B. Gonzalez, A. Dominguez, J. Tojo, J. Solution Chem. 35 (2006) 1217– 1225. [13] E. Gomez, B. Gonzalez, N. Calvar, E. Tojo, A. Domínguez, J. Chem. Eng. Data 51 (2006) 2096–2102. [14] N. Calvar, E. Gomez, B. Gonzalez, A. Dominguez, J. Chem. Eng. Data 52 (2007) 2529–2535. [15] E. Gomez, N. Calvar, I. Dominguez, A. Dominguez, Phys. Chem. Liquids 44 (2006) 409–417. [16] E. Gomez, B. Gonzalez, A. Domínguez, E. Tojo, J. Tojo, J. Chem. Eng. Data 51 (2006) 696–701. [17] I. Cibulka, Coll. Czech. Commun. 47 (1982) 1414–1419. [18] P. Singh, R. Nigam, S. Sharma, S. Aggarwal, Fluid Phase Equilibr. 18 (1984) 333–344. [19] M. Nagata, J. Sakura, J. Chem. Soc. Faraday Trans. I 83 (1987) 2449–2457.
1216
E. Gómez et al. / J. Chem. Thermodynamics 40 (2008) 1208–1216
[20] N. Radojkovic, A. Tasic, D. Grozdanic, B. Djordjevic, M. Malic, J. Chem. Thermodyn. 9 (1977) 349–352. [21] R.P. Rastogi, J. Nath, S.S. Das, J. Chem. Eng. Data 22 (1977) 249–252. [22] K.T. Jacob, K. Fitzner, Thermochim. Acta 18 (1977) 197–206. [23] F. Kohler, Monatsh. Chem. 91 (1960) 738–740. [24] G.W. Toop, Trans. TMS-AIME 223 (1965) 850–855. [25] C.C. Tsao, J.M. Smith, Chem. Eng. Prog. Symp. Ser. 49 (1953) 107–117. [26] G. Scatchard, L.B. Ticknor, J.R. Goates, E.R. McCartney, J. Am. Chem. Soc. 74 (1952) 3721–3724. [27] A.B. Pereiro, P. Verdía, E. Tojo, A. Rodríguez, J. Chem. Eng. Data 52 (2007) 377– 380. [28] U. Domanska, A. Pobudkowska, A. Wisniewska, J. Solution Chem. 35 (2006) 311–334. [29] R. Kato, J. Gmehling, Fluid Phase Equilibr. 226 (2004) 37–44. [30] A. Goldon, K. Dabrowska, T. Hofman, J. Chem. Eng. Data 52 (2007) 1830–1837. [31] P. Nikam, M. Jadhav, M.J. Hassan, J. Chem. Eng. Data 40 (1995) 931–934.
[32] E.J. González, L. Alonso, A. Domínguez, J. Chem. Eng. Data 51 (2006) 1446– 1452. [33] U.R. Kapadi, D.G. Hundiwale, N.B. Patil, P.R. Patil, M.K. Lande, J. Ind. Chem. Soc. 77 (2000) 319–321. [34] M.C. Grande, J. Álvarez Juliá, M. García, C.M. Marschoff, J. Chem. Thermodyn. 39 (2007) 1049–1056. [35] A. Krishnaiah, B. Gampper, D. Viswanath, J. Chem. Eng. Data 38 (1993) 401– 403. [36] O. Redlich, A.T. Kister, Ind. Eng. Chem. 40 (1948) 345–348. [37] L.P.N. Rebelo, V. Najdanovic-Visak, Z.P. Visak, M. Nunes da Ponte, J. Szydlowski, C.A. Cerdeiriña, J. Troncoso, L. Romani, J.M. Esperanca, S.S. Guedes, M.C. Sousa, Green Chem. 6 (2004) 369–381. [38] A.B. Pereiro, A. Rodríguez, J. Chem. Thermodyn. 39 (2007) 978–989.
JCT 08-43
Contents lists available at ScienceDirect
J. Chem. Thermodynamics journal homepage: www.elsevier.com/locate/jct
Excess molar properties of ternary system (ethanol + water + 1,3-dimethylimidazolium methylsulphate) and its binary mixtures at several temperatures Elena Gómez, Begoña González, Noelia Calvar, Ángeles Domínguez * Chemical Engineering Department, University of Vigo, 36310 Vigo, Pontevedra, Spain
a r t i c l e
i n f o
Article history: Received 25 January 2008 Received in revised form 3 April 2008 Accepted 12 April 2008 Available online 18 April 2008 Keywords: Viscosity Density 1,3-Dimethylimidazolium methylsulphate Ternary systems Binary systems
a b s t r a c t The density, dynamic viscosity, and refractive index of the ternary system (ethanol + water + 1,3-dimethylimidazolium methylsulphate) at T = 298.15 K and of its binary systems 1,3-dimethylimidazolium methylsulphate with ethanol and with water at several temperatures T = (298.15, 313.15, and 328.15) K and at 0.1 MPa have been measured over the whole composition range. From these physical properties, excess molar volumes, viscosity deviations, refractive index deviations, and excess free energy of activation for the binary systems at the above mentioned temperatures, were calculated and fitted to the Redlich–Kister equation to determine the fitting parameters and the root-mean-square deviations. For the ternary system, the excess properties were calculated and fitted to Cibulka, Singh et al., and Nagata and Sakura equations. The ternary excess properties were predicted from binary contributions using geometrical solution models. Ó 2008 Elsevier Ltd. All rights reserved.
1. Introduction Room temperature ionic liquids or ionic liquids (RTILs or ILs) are a class of organic salts that are comprised entirely of ions and are liquids at conditions around room temperature in their pure state. In recent years, the properties of ILs have attracted considerable attention [1–11]. In addition, their perceived status as ‘‘designer”, alternative ‘‘green” solvents has contributed to this interest. Despite their interest and importance, the physicochemical properties of ILs and the detailed knowledge of the thermodynamic behaviour of the mixtures of ILs with molecular solvents have not been studied systematically. In this context, a systematic investigation of the thermodynamic and thermophysical properties of ILs and their mixtures is an important issue. This work is a continuation of our research group’s investigation of the thermodynamic properties of ionic liquids [12–16]. In this paper, we show at atmospheric pressure experimental density and dynamic viscosity data over the whole composition range for {x1 ethanol + x2 water + (1 x1 x2) [MMIM][MeSO4]} at T = 298.15 K and its binary systems {x1 ethanol + 1 x1 [MMIM][MeSO4]} and {x1 water + (1 x1) [MMIM][MeSO4]}. These properties were measured at T = (298.15, 313.15, and 328.15) K in order to observe the evolution of the studied properties with the increase of * Corresponding author. Tel.: +34 986812422; fax: +34 986812380. E-mail address: [email protected] (Á. Domínguez). 0021-9614/$ - see front matter Ó 2008 Elsevier Ltd. All rights reserved. doi:10.1016/j.jct.2008.04.006
the temperature. The results were used to calculate excess molar volumes, viscosity deviations and excess free energies of activation of viscous flow. Refractive indices were measured from T = 298.15 K over the whole composition range for {x1 ethanol + x2 water + (1 x1 x2) [MMIM][MeSO4]}, {x1 ethanol + (1 x1) [MMIM][MeSO4]} and {x1 water + (1 x1) [MMIM][MeSO4]}. The results were used to calculate refractive index deviations. The treatment of experimental ternary data was carried out in two ways: (i) correlation using empirical equations [17–19], and (ii) prediction using geometrical models that assume that interactions in a ternary mixture depend on the interactions in binary systems [20–26]. 2. Experimental 2.1. Chemicals Ethanol was supplied by Merck. The component was degassed ultrasonically, and dried over molecular sieves 4 108 (Type 4Å), that were supplied by Aldrich, and kept in inert argon with a maximum content in water of 2 106 by mass fraction. The mass fraction purity was >0.998 for ethanol. Water was doubly distilled and deionised. The ionic liquid used in this work was synthesised in our laboratory, following the published procedure [27]. To assure its purity, a NMR was made and compared with Pereiro et al. [27]; no differences were found. To reduce the water content to negligible values (lower
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E. Gómez et al. / J. Chem. Thermodynamics 40 (2008) 1208–1216 TABLE 1 Comparison of experimental density, q, and viscosity, g, with literature data for pure components at T = 298.15 K Component
[MMIM] [MeSO4]
T/K
298.15
q/(g cm3)
g/(mPa s)
Experimental
Literature
1.32912
1.32725a 1.3290b 1.328c 1.33059d 1.31657a 1.32009d 1.30606a 1.31121d
Experimental
Literature
77.7
72.91a
41.68
39.21a
25.21
20.37a
313.15
1.31856
328.15
1.30813
Ethanol
298.15 313.15 328.15
0.78546 0.77200 0.75855
0.7854e 0.77207f 0.75861f
1.082 0.827 0.641
1.082e 0.826f 0.641f
Water
298.15 313.15 328.15
0.99720 0.99221 0.98569
0.9971g 0.99222h 0.98570i
0.890 0.653 0.504
0.890g 0.6530h 0.5042i
a b c d e f g h i
Pereiro et al. [27]. Domanska et al. [28]. Kato et al. [29]. Golden et al. [30]. Nikam et al. [31]. González et al. [32]. Kapadi et al. [33]. Grande et al. [34]. Krishnaiah et al. [35].
than 0.03% determined using a 756 Karl Fisher coulometer) vacuum (2 101Pa) and moderate temperature (343.15 K) were applied to the IL for several days, always immediately prior to their use. The IL was kept in bottles with inert gas. Table 1 shows a comparison between experimental and literature data of pure components at T = (298.15, 313.15, and 328.15) K. Compared to literature, the density value for pure [MMIM][MeSO4] is higher than those reported by Pereiro et al. [27], Domanska et al. [28] and Kato et al. [29] and lower than the one reported by Goldon et al. [30]. These discrepancies can be due to the effect of temperature or to the presence of some traces of water or impurities in our mixtures or in their mixtures. These impurities can have dramatic effects on the density and viscosity values as was established from the studies of Seddon and co-workers [11]. 2.2. Apparatus and procedure Samples were prepared by syringing known amounts of the pure liquids into stoppered bottles, in an inert-atmosphere glove box, using a Mettler AX-205 Delta Range balance with a precision of ±105 g, covering the whole composition range of the mixture. A glove box was used because the ionic liquid is sensitive to moisture. Good mixing was ensured by magnetic stirring. All samples were prepared immediately prior to performing density, refractive index or viscosity measurements to avoid variations in composition due to evaporation of solvent or pickup of water by the hygroscopic IL. Kinematic viscosities were determined using an automatic viscosimeter Lauda PVS1 with four Ubbelhode capillary microviscosimeters of 0.4 103 m, 0.53 103 m, 0.70 103 m, and 1.26 103 m diameter (the uncertainty in experimental measurement is ±0.0001, ±0.003, ±0.03, and ±0.2 mPa s respectively). Gravity fall is the principle of measurement on which this viscosimeter is based. The capillary is maintained in a D20KP LAUDA thermostat with a resolution of 0.01 K. The capillaries are calibrated and credited by the company. The equipment has a control unit PVS1 (Pro-
cessor Viscosity System) that is a PC-controlled instrument for the precise measurement of fall time, using standardized glass capillaries, with an uncertainty of 0.01 s. In order to verify the calibration, the viscosity of the pure liquids was compared with literature data (table 1). The density of the pure liquids and mixtures were measured using an Anton Paar DSA-5000 digital vibrating tube densimeter. The repeatability and the uncertainty in experimental measurement have been found to be lower than (±2 106 and ±2.6 105) g cm3. The DSA 5000 automatically corrects the influence of viscosity on the measured density. To measure refractive indices, an automatic refractometer Abbemat-HP Dr. Kernchen with a resolution of ±106 and an uncertainty in the experimental measurements of ±4 105 was used. 3. Results and discussion Dynamic viscosity, density, excess molar volume, viscosity deviation, and excess free energy of activation for the ternary system
TABLE 2 Density, q, refractive index, nD, dynamic viscosity, g, excess molar volumes, VE, deviations in the refractive index, DnD, viscosity deviations, D g and excess free energy of activation, DG*E, for {x1 water + (1 x1) [MMIM][MeSO4]} x1
q/ (g cm3)
nD
0.0000 0.0497 0.1475 0.2128 0.3086 0.3869 0.4947 0.5959 0.6947 0.7966 0.8962 0.9485 1.0000
1.32912 1.32699 1.32281 1.31954 1.31375 1.30771 1.29697 1.28277 1.26217 1.22682 1.16206 1.10041 0.99720
1.48296 1.48187 1.47986 1.47824 1.47536 1.47252 1.46739 1.46071 1.45105 1.43485 1.40572 1.37848 1.33251
0.0000 0.0497 0.1475 0.2128 0.3086 0.3869 0.4947 0.5959 0.6947 0.7966 0.8962 0.9485 1.0000
1.31856 1.31644 1.31231 1.30903 1.30327 1.29725 1.28656 1.27239 1.25191 1.21682 1.15298 1.09264 0.99221
0.0000 0.0497 0.1475 0.2128 0.3086 0.3869 0.4947 0.5959 0.6947 0.7966 0.8962 0.9485 1.0000
1.30813 1.30609 1.30196 1.29864 1.29281 1.28689 1.27622 1.26204 1.24095 1.20664 1.14343 1.08403 0.98569
DnD
Dg/ (mPa s)
DG*E/ (J mol1)
0.0000 0.0064 0.0191 0.0273 0.0388 0.0478 0.0589 0.0674 0.0726 0.0717 0.0576 0.0382 0.0000
0.000 5.788 12.858 16.467 18.800 20.439 20.177 18.065 14.753 10.599 5.945 3.104 0.000
0.0 378.8 1152.6 1618.9 2316.7 2747.1 3276.8 3660.9 3863.3 3684.0 2697.0 1653.8 0.0
T = 313.15 K 41.68 0.000 37.51 0.019 30.44 0.012 25.86 0.030 20.76 0.056 16.93 0.062 12.41 0.070 9.041 0.067 6.368 0.050 4.027 0.017 2.069 0.086 1.261 0.099 0.653 0.000
0.000 2.128 5.188 7.088 8.257 8.871 8.970 8.188 6.807 4.972 2.843 1.504 0.000
0.0 426.7 1243.4 1713.4 2429.9 2926.2 3481.9 3870.1 4050.7 3841.6 2828.8 1745.8 0.0
T = 328.15 K 25.21 0.000 23.95 0.013 19.85 0.011 17.11 0.021 13.79 0.036 10.50 0.044 8.521 0.047 6.336 0.036 4.518 0.019 2.917 0.058 1.548 0.121 0.990 0.122 0.504 0.000
0.000 0.031 1.718 2.839 3.792 5.154 4.468 4.152 3.528 2.614 1.521 0.786 0.000
0.0 561.8 1410.4 1900.2 2598.9 2877.9 3667.1 4063.6 4222.9 3991.9 2953.3 1913.4 0.0
g/ (mPa s)
VE / (cm3 mol1)
T = 298.15 K 77.7 0.000 68.1 0.016 53.6 0.019 44.93 0.044 35.23 0.076 27.57 0.087 19.55 0.103 13.88 0.109 9.599 0.098 5.928 0.035 2.925 0.042 1.745 0.070 0.890 0.000
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{x1 ethanol + x2 water + (1 x1 x2) [MMIM][MeSO4]} at T = 298.15 K and its binary systems {x1 ethanol + (1 x1) [MMIM][MeSO4]} and {x1 water + (1 x1) [MMIM][MeSO4]} at T = (298.15, 313.15, and 328.15) K, and refractive indices at T = 298.15 K for all studied system are reported in tables 2–4. The excess molar volumes, viscosity deviations, and refractive index deviations were calculated from experimental values as follows: VE ¼
N X
xi M i ðq1 q1 i Þ;
ð1Þ
i¼1
Dg ¼ g
N X
xi gi ;
ð2Þ
i
DnD ¼ nD
N X
xi nD;i ;
ð3Þ
i
where q and qi are the density of the mixture and the density of the pure components, respectively; xi represents the mole fraction of the i component; g and gi are the dynamic viscosity of the mixture
TABLE 3 Density, q, refractive index, nD, dynamic viscosity, g, excess molar volumes, VE, deviations in the refractive index, DnD, viscosity deviations, Dg, and excess free energy of activation, DG*E, for {x1 ethanol + (1 x1) [MMIM][MeSO4]} x1
q/ (g cm3)
nD
0.0000 0.0669 0.1228 0.2212 0.2944 0.3984 0.5000 0.5926 0.6921 0.7970 0.8957 0.9450 1.0000
1.32912 1.31647 1.30519 1.28246 1.26318 1.23122 1.19280 1.15085 1.09430 1.01810 0.92316 0.86426 0.78546
1.48296 1.48028 1.47773 1.47336 1.46936 1.46252 1.45421 1.44554 1.43248 1.41494 1.39329 1.37874 1.36023
0.0000 0.0669 0.1228 0.2212 0.2944 0.3984 0.5000 0.5926 0.6921 0.7970 0.8957 0.9450 1.0000
1.31856 1.30589 1.29459 1.27177 1.25246 1.22040 1.18188 1.13974 1.08298 1.00641 0.91098 0.85176 0.77200
0.0000 0.0669 0.1228 0.2212 0.2944 0.3984 0.5000 0.5926 0.6921 0.7970 0.8957 0.9450 1.0000
1.30813 1.29553 1.28420 1.26138 1.24197 1.20957 1.17112 1.12874 1.07175 0.99472 0.89870 0.83906 0.75855
E
Dg/ (mPa s)
DG / (J mol1)
0.000 10.548 16.726 23.816 25.617 26.946 26.580 23.532 18.984 13.132 6.980 3.696 0.000
0.0 204.9 380.2 659.9 919.7 1126.5 1095.7 1139.6 1106.1 967.0 654.2 457.3 0.0
T = 313.15 K 41.68 0.000 34.42 0.204 29.38 0.393 22.80 0.663 17.97 0.860 12.87 1.093 8.823 1.216 6.258 1.316 4.309 1.280 2.649 1.133 1.603 0.787 1.225 0.521 0.827 0.000
0.000 4.522 7.278 9.841 11.675 12.532 12.427 11.210 9.096 6.470 3.482 1.848 0.000
0.0 240.4 440.2 849.0 1016.5 1249.8 1327.7 1380.4 1404.3 1157.4 778.2 526.9 0.0
T = 328.15 K 25.21 0.000 21.43 0.240 18.72 0.451 15.07 0.762 12.28 0.977 9.141 1.220 6.461 1.387 4.727 1.496 3.246 1.472 2.077 1.310 1.265 0.921 0.961 0.613 0.641 0.000
0.000 2.139 3.476 4.705 5.700 6.281 6.465 5.923 4.961 3.552 1.938 1.030 0.000
0.0 283.1 516.5 977.0 1191.1 1470.6 1564.5 1640.9 1590.7 1370.9 926.3 618.1 0.0
g/ (mPa s)
V / (cm3 mol1)
*E
T = 298.15 K 77.7 0.000 62.1 0.179 51.6 0.348 36.97 0.589 29.56 0.760 20.26 0.966 12.83 1.062 8.784 1.148 5.706 1.104 3.513 0.965 2.096 0.652 1.602 0.420 1.082 0.000
DnD
0.0000 0.0055 0.0098 0.0176 0.0225 0.0285 0.0326 0.0353 0.0345 0.0298 0.0203 0.0118 0.0000
and the pure components, respectively, and nD and nD,i are the refractive index of the mixture and the refractive index of the pure components, respectively. The excess Gibbs free energies of activation of viscous flow were obtained from the following equation: " DGE ¼ RT lnðgVÞ
N X
# xi lnðgi V i Þ ;
ð4Þ
i¼1
where R is the universal constant of gases, T is the absolute temperature, Vi is the molar volume of component i, V is the molar volume of the mixture, xi represents the mole fraction of the component i and g, gi are the dynamic viscosity of the mixture and the pure component, respectively. The binary deviations at several temperatures were fitted to a Redlich–Kister [36] type equation: DQ 12 ¼ x1 x2
M X
Bp ðx1 x2 Þp ;
ð5Þ
p¼0
where DQ12 is the excess property, x1 and x2 are the mole fraction of component 1 and 2, respectively, Bp is the fitting parameter and M is the degree of the polynomic expansion. The fitting parameters are given in table 5 together with the root-mean-square deviations, r r¼
(n , )1=2 dat X ðzexp zcalc Þ2 ndat ;
ð6Þ
i
where zexp, zcalc, and ndat, are the values of the experimental and calculated property and the number of experimental data, respectively. Figure 1 shows the fitted curve of excess molar volume values of systems {x1 water + (1 x1) [MMIM][MeSO4]} and {x1 ethanol + (1 x1) [MMIM][MeSO4]}. The excess molar volumes are negative over the entire composition range for x1 ethanol with (1 x1) [MMIM][MeSO4] mixture presenting a minimum in a mole composition of 0.6 for the three studied temperatures. It is remarkable that in the work of Goldon et al. [30] the excess molar volumes presented for the binary system {x1 methanol + (1 x1) [MMIM][MeSO4]} are also negative over the whole composition range, presenting a minimum at x1 0.65. Comparing the two systems (with ethanol and with methanol), we can observe that when the chain of carbon increases the minimum of VE is less negative. For the water, a sinusoidal curve was observed with the VE (minimum) 0.109, 0.067 and 0.04 cm3 mol1 at x1 0.6 for T = (298.15, 313.15, and 328.15) K, respectively and a maximum at x1 0.95 with a value of 0.07, 0.099, and 0.122 for T = (298.15, 313.15, and 328.15) K, respectively and at low mole fraction of water the VE show positive values for the three studied temperatures. This behaviour can be explained because hydrogen bonding is certainly more T-dependent (becoming negligible at high temperatures) than Coulombic interactions. This result agrees with the work of Rebelo et al. [37]. We can observe that when we increase the temperature the deviations of the excess molar volume are more negative for the case of the binary system containing ethanol and less negative for the other binary system. In figure 1, the experimental data of Pereiro et al. [38] and Domanska et al. [28] are also shown too and it is seen that good agreement exists between our data and those published. In figure 2, we can observe the variation of viscosity deviations with the composition and with the temperature. The sign is negative over the whole composition range and approach to minimum at 0.4 mole fraction for both systems. The viscosity deviations decrease as the temperature increases and this behaviour is similar for both systems.
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TABLE 4 Density, q, refractive index, nD, dynamic viscosity, g, excess molar volumes, VE, deviations of refractive index, DnD, viscosity deviations, Dg and excess free energies of activation of viscous flow, DG*E, for the ternary system {x1 ethanol + x2 water + (1 x1 x2) [MMIM][MeSO4]} at T = 298.15 K x1
x2
q/(g cm3)
nD
g/(mPa s)
VE/(cm3 mol1)
DnD
Dg mPa s
DG*E/(J mol1)
0.0567 0.1168 0.1877 0.0674 0.1409 0.2203 0.3053 0.3959 0.6047 0.0395 0.1015 0.1629 0.2319 0.3106 0.5094 0.0859 0.1736 0.2646 0.3603 0.4561 0.5579 0.1180 0.2333 0.3421 0.4400 0.5500 0.7386 0.8266 0.0987 0.1993 0.2974 0.3982 0.4936 0.5968 0.6995 0.0984 0.1977 0.2977 0.4003 0.4999 0.6032 0.7142 0.1018 0.2074 0.3097 0.4116
0.9117 0.8536 0.7851 0.8724 0.8036 0.7294 0.6498 0.5651 0.3697 0.9469 0.8858 0.8252 0.7572 0.6797 0.4837 0.8132 0.7351 0.6542 0.5691 0.4839 0.3933 0.7046 0.6125 0.5256 0.4474 0.3595 0.2088 0.1385 0.5532 0.4914 0.4312 0.3694 0.3108 0.2475 0.1844 0.3754 0.3341 0.2925 0.2497 0.2083 0.1652 0.1190 0.1512 0.1334 0.1162 0.0990
1.04795 1.02304 0.99517 1.08892 1.05623 1.02107 0.98536 0.95067 0.88294 1.01567 0.99373 0.97221 0.94804 0.92259 0.87025 1.12902 1.08808 1.04602 1.00379 0.96451 0.92582 1.17378 1.12169 1.07136 1.02633 0.97677 0.89473 0.85786 1.24598 1.20769 1.16748 1.12289 1.07751 1.02579 0.97002 1.27805 1.24733 1.21246 1.17178 1.12715 1.07411 1.00889 1.29771 1.27113 1.24115 1.20604
1.36927 1.37265 1.37432 1.38837 1.38872 1.38736 1.38487 1.38179 1.37434 1.35275 1.35907 1.36307 1.36540 1.36652 1.36644 1.40706 1.40412 1.39976 1.39462 1.38933 1.38377 1.42814 1.42101 1.41318 1.40571 1.39703 1.38184 1.37463 1.45376 1.44719 1.43994 1.43140 1.42247 1.41190 1.40033 1.46636 1.46062 1.45368 1.44555 1.43624 1.42503 1.41078 1.47397 1.46879 1.46277 1.45547
1.857 2.306 2.547 2.493 2.793 2.903 2.790 2.620 2.050 1.476 2.008 2.345 2.430 2.401 2.023 3.449 3.548 3.378 3.080 2.789 2.433 4.992 5.161 4.150 3.565 2.981 2.056 1.706 10.82 8.770 7.164 5.798 4.661 3.677 2.827 19.42 14.81 11.29 8.498 6.438 4.767 3.381 33.76 24.62 17.87 12.80
0.304 0.595 0.862 0.347 0.684 0.908 1.039 1.101 1.030 0.180 0.520 0.772 0.939 1.041 1.064 0.445 0.774 0.973 1.076 1.113 1.080 0.527 0.862 1.024 1.080 1.067 0.860 0.684 0.494 0.761 0.956 1.075 1.107 1.108 0.980 0.422 0.695 0.908 1.048 1.128 1.108 1.008 0.157 0.454 0.707 0.9057
0.030 0.032 0.033 0.045 0.044 0.041 0.037 0.032 0.021 0.017 0.022 0.024 0.025 0.024 0.019 0.057 0.053 0.048 0.041 0.035 0.028 0.066 0.059 0.051 0.044 0.036 0.021 0.014 0.066 0.063 0.058 0.053 0.047 0.039 0.031 0.052 0.052 0.051 0.049 0.046 0.041 0.033 0.026 0.031 0.035 0.038
1.470 0.878 0.468 3.039 2.389 1.900 1.608 1.345 0.918 0.465 0.122 0.514 0.661 0.702 0.502 5.215 4.388 3.804 3.308 2.805 2.316 9.553 7.626 6.976 6.065 4.970 3.016 2.023 16.846 15.931 14.643 13.037 11.360 9.299 7.120 21.927 22.098 21.157 19.370 16.980 14.036 10.464 24.559 26.975 27.199 25.774
1859.7 2407.1 2657.9 2489.4 2763.9 2851.2 2738.1 2558.6 1858.9 1312.9 2105.4 2510.6 2610.6 2578.5 2070.7 3051.7 3112.3 2983.2 2745.2 2485.4 2129.1 3321.7 3451.5 2962.8 2636.3 2250.7 1432.7 1020.4 3484.7 3203.4 2937.2 2656.4 2347.6 2012.1 1614.6 2761.5 2590.4 2416.7 2220.5 2021.6 1780.1 1463.9 1194.9 1328.6 1412.8 1448.7
3.1. Correlation of physical properties The VE, DnD, Dg, and DG*E values calculated from equations (1) to (4) for the ternary system were correlated using the equations proposed by Cibulka [17], Singh et al. [18], and Nagata and Sakura [19]. The following expressions were used: Cibulka equation: Q E123 ¼ Q E12 þ Q E13 þ Q E23 þ x1 x2 x3 ðA þ Bx1 þ Cx2 Þ;
ð7Þ
Singh et al. equation: Q E123 ¼ Q E12 þ Q E13 þ Q E23 þ Ax1 x2 x3 þ Bx1 ðx2 x3 Þ þ Cx21 ðx2 x3 Þ2 ; ð8Þ where A, B and C are fitting parameters. Nagata and Sakura equation: Q E123 ¼ Q E12 þ Q E13 þ Q E23 þ x1 x2 x3 A; where A is the fitting parameter.
ð9Þ
The Q Eij is the contribution to the excess property of the constituent binary mixtures evaluated by the Redlich–Kister equation [36]: Q Eij ¼ xi xj
M X
Bp ðxi xj Þp ;
ð10Þ
p¼0
where xi is the mole fraction of component i and Bp are adjustable parameters. The parameters Bp and the root-mean-square deviations for the excess properties of the two binary mixtures containing ionic liquid involved in the ternary system are presented in this paper and are listed in table 5 as indicated previously. The properties of the binary mixture (ethanol + water) were determined in our laboratory, and its fitting Redlich–Kister parameters were published in a previous work [14]. The fitting parameters of the correlation equations and root-mean-square deviations are given in table 6. As can be observed in this table, for all the studied properties the better fitting is given by Cibulka, where the correlated values are in good agreement with the experimental data. In figures 3 to 5, the
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E. Gómez et al. / J. Chem. Thermodynamics 40 (2008) 1208–1216
TABLE 5 Fitting parameters and root-mean-square deviation, r, for binary mixtures {x1 ethanol + (1 x1) [MMIM][MEtSO4]} and {x1 water + (1 x1) [MMIM][MEtSO4]} at T = (298.15, 313.15, 328.15) K
V /(cm mol ) DnD Dg/(mPa s) DG*E/(J mol1)
B0 = 0.406 B0 = 0.2384 B0 = 80.229 B0 = 13222.8
Water (1) + [MMIM][MESO4] (2) T = 298.15 K B1 = 0.297 B2 = 0.353 B1 = 0.1722 B2 = 0.1185 B1 = 24.357 B2 = 7.456 B1 = 8521.7 B2 = 7806.8
VE/(cm3 mol1) Dg/(mPa s) DG*E/(J mol1)
B0 = 0.271 B0 = 35.594 B0 = 14055.7
B1 = 0.151 B1 = 9.209 B1 = 8879.8
VE/(cm3 mol1) Dg/(mPa s) DG*E/(J mol1)
B0 = 0.168 B0 = 18.610 B0 = 14590.3
B1 = 0.052 B1 = 6.728 B1 = 9605.3
V /(cm mol ) DnD Dg/(mPa s) DG*E/(J mol1)
B0 = 4.319 B0 = 0.1313 B0 = 104.79 B0 = 4588.7
Ethanol (1) + [MMIM][MESO4] (2) T = 298.15 K B1 = 1.813 B2 = 0.907 B1 = 0.0679 B2 = 0.0341 B1 = 39.362 B2 = 9.703 B1 = 358.6 B2 = 730.1
VE/(cm3 mol1) Dg/(mPa s) DG*E/(J mol1)
B0 = 4.945 B0 = 49.556 B0 = 5349.1
B1 = 2.106 B1 = 14.219 B1 = 1838.7
VE/(cm3 mol1) Dg/(mPa s) DG*E/(J mol1)
B0 = 5.598 B0 = 25.666 B0 = 6334.5
B1 = 2.514 B1 = 3.712 B1 = 1795.8
E
3
E
3
1
1
B3 = 0.970 B3 = 0.2053 B3 = 8.293 B3 = 7047.9
B4 = 2.316 B4 = 0.1853 B4 = 28.96 B4 = 1946.1
r = 0.004 r = 0.006 r = 0.144 r = 11.19
T = 313.15 K B2 = 0.210 B2 = 0.155 B2 = 6829.8
B3 = 1.166 B3 = 1.544 B3 = 7070.7
B4 = 2.412 B4 = 3.009 B4 = 4224.6
r = 0.004 r = 0.082 r = 10.34
T = 328.15 K B2 = 0.261 B2 = 2.804 B2 = 7105.6
B3 = 1.253 B3 = 18.351 B3 = 5372.8
B4 = 1.835 B4 = 10.887 B4 = 7273.7
r = 0.008 r = 0.179 r = 56.08
B3 = 0.967 B3 = 0.0075 B3 = 27.215 B3 = 3895.3
B4 = 0.296 B4 = 0.0107 B4 = 12.494 B4 = 1332.2
r = 0.008 r = 0.0001 r = 0.207 r = 24.11
T = 313.15 K B2 = 0.790 B2 = 6.755 B2 = 3276.8
B3 = 1.742 B3 = 8.539 B3 = 546.6
B4 = 1.53 B4 = 18.751 B4 = 4089.3
r = 0.011 r = 0.109 r = 15.59
T = 328.15 K B2 = 1.201 B2 = 5.363 B2 = 2447.8
B3 = 1.976 B3 = 5.903 B3 = 2031.5
B4 = 1.796 B4 = 10.733 B4 = 1700.9
r = 0.012 r = 0.060 r = 11.95
b
a
-0.3
V E / (cm -3 .mol -1)
V E / (cm -3 .mol -1)
0.1
0.0
0.0
-0.6
-0.9
-1.2
-0.1 -1.5
-1.8
-0.2 0.0
0.5
1.0
x1
0.0
0.5
1.0
x1
FIGURE 1. Experimental excess molar volume, VE, and calculated values from the Redlich–Kister equation (—) plotted against mole fraction at T = 298.15 K (d), T = 313.15 K (j) and T = 328.15 K (N), for the binary mixtures: (a) {x1 water +(1 x1) [MMIM][MeSO4]}, Domanska et al. data (M) and (b) {x1 ethanol + (1 x1) [MMIM][MeSO4]}, Pereiro et al. data ( ).
isolines of the excess properties VE, DnD, and Dg calculated from Cibulka, are shown. 3.2. Prediction of physical properties Several empirical methods have been proposed to estimate ternary excess properties from experimental results of the constituent binary systems. These methods are of great interest, since as the
number of components in the mixture increases, the determination of its properties becomes more laborious. The predictive methods can be divided into symmetric and asymmetric, depending on whether the assumption of the three binary mixtures contributing equally to the ternary mixture magnitude is accepted or not. Asymmetry is usually understood to be caused by the strongly polar or associative behaviour of any of the compounds in the mixture. In these cases, different geometric
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E. Gómez et al. / J. Chem. Thermodynamics 40 (2008) 1208–1216
a
b
0
0
-5
-5
Δη / (mPa·s)
Δη / (mPa·s)
-10
-10
-15
-15
-20
-20
-25
-25 0.0
0.2
0.6
0.4
0.8
1.0
-30 0.0
0.2
0.4
0.6
0.8
1.0
x1
x1
FIGURE 2. Experimental dynamic viscosity deviations, Dg, and calculated values from the Redlich–Kister equation (—) plotted against mole fraction at T = 298.15 K (), T = 313.15 K (j) and T = 328.15 K (N), for the binary mixtures: (a) {x1 water + (1 x1) [MMIM][MeSO4]} and (b) {x1 ethanol + (1 x1) [MMIM][MeSO4]}.
Kohler [23]:
TABLE 6 Fitting parameters and root-mean-square deviations for empirical equations VE/(cm3 mol1)
A B C r
DnD
Dg/(mPa s)
DG*E/(J mol1)
ðx2 þ x3 Þ2 Q E 23 ðx2 ; x3 Þ:
{x1 ethanol + x2 water + (1 x1 x2) [MMIM][MeSO4]} Cibulka equation (7) 8.185 6.2471 55.242 20,302 7.845 0.3722 148.355 47,357 11.690 0.7189 142.535 13,386 0.031 0.0013 0.410 113
A B C r
1.376 0.106 0.067 0.036
Singh et al. equation (8) 0.1299 47.958 0.0114 0.982 0.0189 2.424 0.0013 0.496
A r
1.220 0.038
Nagata and Sakura equation (9) 0.1415 48.589 0.0018 0.511
7992 32 73 162 8082 162
ð11Þ
in which Q Eij or Q Eijk is the excess property, the equation of Rastogi et al. [21]: E Q E123 ¼ 0:5½ðx1 þ x2 ÞQ E 12 ðx1 ; x2 Þ þ ðx1 þ x3 ÞQ 13 ðx1 ; x3 Þþ
ðx2 þ
x3 ÞQ E 23 ðx2 ; x3 Þ;
ð14Þ
The following models are asymmetrical, so we alternatively consider each component of the ternary mixture as the asymmetric component, Toop [24]:
criteria are applied to match each point of ternary composition with the contributing binary compositions. To predict the excess properties (VE, DnD, Dg, and DG*E), we have used symmetric [20–23] and asymmetric [24–26] geometrical solution models. In this work, we applied the symmetric equations of Radojkovic et al. [20]: Q E123 ¼ Q E12 ðx1 ; x2 Þ þ Q E13 ðx1 ; x3 Þ þ Q E23 ðx2 ; x3 Þ
2 E Q E123 ¼ ½ðx1 þ x2 Þ2 Q E 12 ðx1 ; x2 Þ þ ðx1 þ x3 Þ Q 13 ðx1 ; x3 Þ þ
ð12Þ
Jacob and Fitzer [22]: h h ii E x2 x1 x3 Q E123 ¼ 4 ð2x1 þxx31Þð2x Q E 12 ðx1 ; x2 Þ þ ð2x1 þx2 Þð2x3 þx2 Þ Q 13 ðx1 ; x3 Þ þ 2 þx3 Þ h h ii ; E x3 4 ð2x2 þxx12Þð2x Q ðx ; x Þ 23 2 3 þx Þ 3 1 ð13Þ
x2 x3 Q E123 ¼ ðx ; x Þ þ Q E Q E 12 1 13 ðx1 ; x3 Þþ 2 1 x1 1 x1 i 1 x1 Þ2 Q E 23 ðx2 ; x3 Þ
ð15Þ
Tsao and Smith [25]: x2 x3 Q E123 ¼ Q E Q E 12 ðx1 ; x2 Þ þ 13 ðx1 ; x3 Þþ 1 x1 1 x1 i 1 x1 ÞQ E 23 ðx2 ; x3 Þ
ð16Þ
Scarchard et al. [26]: Q E123 ¼
x2 x3 E E Q E Q ðx ; x Þ þ ðx ; x Þ þ Q ðx ; x Þ 12 1 13 1 23 2 2 3 3 1 x1 1 x1 ð17Þ E
where the arguments of Q ðxi ; xj Þ are xi ¼ xi =ðxi þ xj Þ and xj ¼ xj =ðxi þ xj Þ. Table 7 lists the root-mean-square deviations of fitting for each dependent variable and equation. 4. Conclusions In this work, the dynamic viscosity and density data over the whole composition range for {x1 ethanol + x2 water + (1 x1 x2) [MMIM][MeSO4]} at T = 298.15 K and its binary systems {x1 ethanol + (1 x1) [MMIM][MeSO4]} and {x1 water + (1 x1) [BMIM][MeSO4]} at temperatures of (298.15, 313.15, and 328.15) K have been determined. The refractive indices at T = 298.15 K for all systems have been obtained as well. Excess molar volumes, viscosity deviations, and excess Gibbs free energies of activation were calculated and fitted to the Redlich–Kister equation to test the quality of the experimental values.
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MMIMMeSO 0.0
4
1.0
0.1
0.9
0.2 -0 .2
0.8
0.3 -0 .
4
0.7
0.4 -0 .6
0.6
0.5
0.5 .8 -0
0.6
0.4 0 -1.
0.7
0.3 -1.1
0.8
0.2 0 -1.
0.9
8 -0.
1.0
H 2O
6 -0. .4 -0
0.1 0.0
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
EtOH
FIGURE 3. Isolines for excess molar volumes, V E123 , from the Cibulka equation (7) for the ternary system {x1 ethanol + x2 water + 1(1 x1 x2) [MMIM][MeSO4]}.
MMIMMeSO4 0.0
1.0
0.01
0.1
0.9
0.02
0.2
0.8
0.0 3
0.3
0.7 0.0 4
0.4
0.6
0.0 5
0.5
0.5
0.0 6
0.6 0.7
0.4 0.0 7
0.3
0.8
0.2 0.03
0.9
0.02 0.01
1.0
H 2O
0.0
0.1 0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
EtOH
FIGURE 4. Isolines for the changes of refractive index, DnD123, from the Cibulka equation (7) for the ternary system {x1 ethanol + x2 water + 1(1 x1 x2) [MMIM][MeSO4]}.
The ternary system has been correlated used Cibulka, Singh et al., and Nagata and Sakura equations. All the correlative models are capable of representing the behaviour of the ternary mixture with a higher or lesser degree of accuracy. In the correlation, the Cibulka equation gives the smaller deviations for all the studied excess properties. The prediction of the ternary system has been done using symmetric and asymmetric geometrical solution models. Deviations obtained with the empirical equations to predict the excess prop-
erties are rather high. This fact can be due to the importance of the ternary contribution term to the quantity studied. Of the geometrical solution models used to predict the excess properties, the best for prediction of the VE was the that by Radojkovic et al.; for the DnD and Dg the best was by Kohler and for DG*E was that of Jacob and Fitzner. In general, the symmetric equations give better predictive results, specially those of Radojkovic, Jacob and Fitzner, and Kohler. The predictions of the asymmetric equations of Tsao and Smith and Scatchard erred significantly.
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E. Gómez et al. / J. Chem. Thermodynamics 40 (2008) 1208–1216
MMIMMeSO 0.0
4
1.0
0.1
0.9
0.2
0.8
0.3
0.7
0.4
0.6
0.5
0.5
-24
0.6
0.4
-20 0.7
0.3
-16 -12
0.8
0.2
-8 0.9
-4
0.1
1.0
H 2O
0.0
0.0 0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
EtOH
FIGURE 5. Isolines for the deviation of dynamic viscosity, Dg123, from the Cibulka equation (7) for the ternary system {x1 ethanol + x2 water + 1(1 x1 x2) [MMIM][MeSO4]}.
TABLE 7 Root-mean-square deviations of predictions of excess molar volumes, refractive index deviations, viscosity deviations and excess free energies of activation of viscous flow for {x1 ethanol + x2 water + (1 x1-x2) [MMIM][MeSO4]} at T = 298.15 K
Radojkovic Rastogi Jacob and Fitzner Kohler Toopa Toopb Toopc Tsao and Smitha Tsao and Smithb Tsao and Smithc Scatcharda Scatchardb Scatchardc a b c
V E123 /(cm3 mol1)
DnD
Dg/(mPa s1)
1 DGE 123 /(J mol )
0.054 0.313 0.076 0.060 0.151 0.122 0.123 0.153 0.210 0.224 0.154 0.621 0.440
0.004 0.013 0.008 0.003 0.005 0.009 0.0012 0.010 0.007 0.014 0.031 0.012 0.014
1.110 3.696 1.562 0.940 2.169 1.819 3.588 3.822 4.355 3.544 8.415 12.656 3.554
980 1519 943 1138 1276 796 1337 1410 799 1473 2089 976 1739
Ethanol is the asymmetric component. Water is the asymmetric component. [MMIM][MeSO4] is the asymmetric component.
Acknowledgements The authors are grateful to the Ministerio de Ciencia y Tecnología of Spain (Project CTQ2004-00454) and Xunta de Galicia (Project PGIDIT05PXIC38303PN) for financial support.
References [1] [2] [3] [4]
T. Welton, Chem. Rev. 99 (1999) 2071–2083. J.D. Holbrey, K.R. Seddon, Clean Prod. Process. 1 (1999) 223. J.F. Brennecke, E.J. Maggin, Alche. J. 47 (2001) 2384–2389. J.L. Anthony, E.J. Maggin, J.F. Brennecke, J. Phys. Chem. B 106 (2002) 7315– 7320. [5] U. Domanska, E. Bogel-Lukasik, R. Bogel-Lusakic, J. Phys. Chem. B 107 (2003) 1858–1863. [6] P. Wasserscheid, T. Welton (Eds.), Ionic Liquids in Synthesis, Wiley–VCH, Weinheim, 2003. [7] J.G. Huddleston, A.E. Visser, W.H. Reichert, H.D. Willauer, G.A. Broker, R.D. Rogers, Green Chem. 3 (2001) 156–164.
[8] K.N. Marsh, J.A. Boxall, R. Lichtenthaler, Fluid Phase Equilibr. 219 (2004) 93–98. [9] C.P. Fredlake, J.M. Crosthwaite, D.G. Hert, S.N.V.K. Aki, J.F. Brennecke, J. Chem. Eng. Data 49 (2004) 954–964. [10] G.J. Kabo, A.V. Blokhin, Y.U. Poulechka, A.G. Kabo, M.P. Shymanovich, J.W. Magge, J. Chem. Eng. Data 49 (2004) 453–461. [11] K.R. Seddon, A. Stark, M-J.M.-J. Torres, in: M. Abraham, L. Moens (Eds.), Clean Solvents: Alternative Media for Chemical Reactions and Processing, ACS Symposium Series, vol. 819, American Chemical Society, Washington, DC, 2002, pp. 34–40. [12] N. Calvar, B. Gonzalez, A. Dominguez, J. Tojo, J. Solution Chem. 35 (2006) 1217– 1225. [13] E. Gomez, B. Gonzalez, N. Calvar, E. Tojo, A. Domínguez, J. Chem. Eng. Data 51 (2006) 2096–2102. [14] N. Calvar, E. Gomez, B. Gonzalez, A. Dominguez, J. Chem. Eng. Data 52 (2007) 2529–2535. [15] E. Gomez, N. Calvar, I. Dominguez, A. Dominguez, Phys. Chem. Liquids 44 (2006) 409–417. [16] E. Gomez, B. Gonzalez, A. Domínguez, E. Tojo, J. Tojo, J. Chem. Eng. Data 51 (2006) 696–701. [17] I. Cibulka, Coll. Czech. Commun. 47 (1982) 1414–1419. [18] P. Singh, R. Nigam, S. Sharma, S. Aggarwal, Fluid Phase Equilibr. 18 (1984) 333–344. [19] M. Nagata, J. Sakura, J. Chem. Soc. Faraday Trans. I 83 (1987) 2449–2457.
1216
E. Gómez et al. / J. Chem. Thermodynamics 40 (2008) 1208–1216
[20] N. Radojkovic, A. Tasic, D. Grozdanic, B. Djordjevic, M. Malic, J. Chem. Thermodyn. 9 (1977) 349–352. [21] R.P. Rastogi, J. Nath, S.S. Das, J. Chem. Eng. Data 22 (1977) 249–252. [22] K.T. Jacob, K. Fitzner, Thermochim. Acta 18 (1977) 197–206. [23] F. Kohler, Monatsh. Chem. 91 (1960) 738–740. [24] G.W. Toop, Trans. TMS-AIME 223 (1965) 850–855. [25] C.C. Tsao, J.M. Smith, Chem. Eng. Prog. Symp. Ser. 49 (1953) 107–117. [26] G. Scatchard, L.B. Ticknor, J.R. Goates, E.R. McCartney, J. Am. Chem. Soc. 74 (1952) 3721–3724. [27] A.B. Pereiro, P. Verdía, E. Tojo, A. Rodríguez, J. Chem. Eng. Data 52 (2007) 377– 380. [28] U. Domanska, A. Pobudkowska, A. Wisniewska, J. Solution Chem. 35 (2006) 311–334. [29] R. Kato, J. Gmehling, Fluid Phase Equilibr. 226 (2004) 37–44. [30] A. Goldon, K. Dabrowska, T. Hofman, J. Chem. Eng. Data 52 (2007) 1830–1837. [31] P. Nikam, M. Jadhav, M.J. Hassan, J. Chem. Eng. Data 40 (1995) 931–934.
[32] E.J. González, L. Alonso, A. Domínguez, J. Chem. Eng. Data 51 (2006) 1446– 1452. [33] U.R. Kapadi, D.G. Hundiwale, N.B. Patil, P.R. Patil, M.K. Lande, J. Ind. Chem. Soc. 77 (2000) 319–321. [34] M.C. Grande, J. Álvarez Juliá, M. García, C.M. Marschoff, J. Chem. Thermodyn. 39 (2007) 1049–1056. [35] A. Krishnaiah, B. Gampper, D. Viswanath, J. Chem. Eng. Data 38 (1993) 401– 403. [36] O. Redlich, A.T. Kister, Ind. Eng. Chem. 40 (1948) 345–348. [37] L.P.N. Rebelo, V. Najdanovic-Visak, Z.P. Visak, M. Nunes da Ponte, J. Szydlowski, C.A. Cerdeiriña, J. Troncoso, L. Romani, J.M. Esperanca, S.S. Guedes, M.C. Sousa, Green Chem. 6 (2004) 369–381. [38] A.B. Pereiro, A. Rodríguez, J. Chem. Thermodyn. 39 (2007) 978–989.
JCT 08-43