Article pubs.acs.org/jced
Viscosimetric Study of Binary Mixtures Containing Pyridinium-Based Ionic Liquids and Alkanols Mónica García-Mardones, Ignacio Gascón, M. Carmen López, Félix M. Royo, and Carlos Lafuente* Departamento de Química Física, Facultad de Ciencias, Universidad de Zaragoza, 50009 Zaragoza, Spain ABSTRACT: In this contribution we have determined densities and kinematic viscosities at atmospheric pressure and four temperatures, T = (293.15, 303.15, 313.15 and 323.15) K for six binary systems formed by three pyridinium-based ionic liquids (1-butylpyridinium tetrafluoroborate, 1-butyl-3-methylpyridinium tetrafluoroborate, or 1-butyl-4-methylpyridinium tetrafluoroborate) and two alkanols (methanol or ethanol). Kinematic viscosities were fitted using a four-body McAllister equation. From experimental densities and kinematic viscosities, absolute viscosities and viscosity deviations were calculated. The viscosity deviations for all systems are negative over the entire composition and temperature ranges. This behavior can be justified by the weakening of the interactions in the pure components during the mixing process.
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INTRODUCTION Interest in ionic liquids (ILs) has increased over the past few years in both industry and academia. This relevance is mainly due to the fact that they are considered substitutes for volatile organic compounds that cause environmental pollution. Their interesting physical and chemical properties, such as low vapor pressures, good solvent behavior, a wide electrochemical window, and chemical stability at high temperatures opens the possibility of using them as substitutes for classical industrial solvents, most of which are volatile organic compounds.1 Consequently the knowledge of ILs physical properties can provide valuable information to design compounds with suitable applications.2−4 However, these room temperature salts have also some disadvantages, e.g., the high viscosity of ionic liquids in comparison with other organic solvents has been considered as one of main drawbacks of these fluids in some applications. In this sense, the use of a combination of ionic liquids with molecular solvents leads to mixtures with low viscosity that are still useful for a variety of applications, so an exhaustive study of binary mixtures would be advantageous.5,6 There are few references in the literature reporting the viscosity behavior of mixtures formed by pyridinium-based ionic liquids and common solvents. Heintz et al.7 presented viscosities for 1-butyl-4-methylpyridinium tetrafluoroborate + methanol, and these authors showed that viscosities decrease when methanol is added to the ionic liquid, due to the weakening of the attractive Coulombic interactions. Gonzalez et al.5 reported viscosity values for 1-ethyl-3methylpyridinium ethylsulfate with ethanol or water, and from viscosity values they calculated the corresponding viscosity deviations, which were negative for both systems, and their values were higher in absolute value for the mixture containing ethanol instead of water. Nageshwar et al.8 investigated the viscosity behavior of binary mixtures formed © 2012 American Chemical Society
by a pyridinium-based ionic liquid and water, methanol, or dichloromethane and observed that the drop in viscosity in the close vicinity of the pure ionic liquid is more prominent in polar solvents like water. Mokhtarani et al.9 studied the viscosities of mixtures constituted by 1-butylpyridinium tetrafluoroborate or 1-octylpyridinium tetrafluoroborate and water, and the calculated viscosity deviations for both systems were negative and similar, although the viscosity of the two ionic liquids involved is very different. Now with the aim to enlarge and complete this useful information, we present a study of the densities and viscosities of the binary mixtures formed by a pyridinium-based ionic liquid (1-butylpyridinium tetrafluoroborate [bpy][BF4], 1-butyl-3-methylpyridinium tetrafluoroborate [b3mpy][BF4], or 1-butyl-4-methylpyridinium tetrafluoroborate [b4mpy][BF4]) and one of these two short chain alcohols (methanol or ethanol), at atmospheric pressure and four temperatures, T = (293.15, 303.15, 313.15 and 323.15) K over the whole composition range, although the system [bpy][BF4] + ethanol showed a miscibility gap at T = 293.15 K and was not characterized at this temperature. The volumetric behavior of these binary systems has been analyzed by our research group in previous papers. 10,11 From experimental values reported here, absolute viscosities and viscosity deviations have been calculated and correlated to get useful information about the phenomena that take place in the mixture. Furthermore, the results of three systems have been compared to analyze the influence of the methyl group in the cation, and we discuss how the lack of this group in [bpy][BF4] affects to the behavior of these mixtures. Finally, there are two previous references of viscosities of [bpy][BF4], [b3mpy][BF4], Received: July 5, 2012 Accepted: October 17, 2012 Published: October 31, 2012 3549
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Journal of Chemical & Engineering Data
Article
by SH Calibration service GmbH and dry air. The final estimated uncertainty of density measurements is ± 0.1 kg·m−3. Kinematic viscosities, ν, were measured using a set of Ubbelohde viscosimeters with a Schott-Geräte automatic measuring unit model AVS-440. The temperature was kept constant within ± 0.01 K by means of Shott-Geräte CT 1150/2 thermostat. Kinetic energy corrections were applied to the experimental data. The estimated uncertainty of kinematic viscosity measurements, expressed as percentage, is ± 1 %. Finally, from density and kinematic viscosity the absolute viscosity, η, can be obtained, η = ρ·ν, and the estimated uncertainty in the calculated absolute viscosity is ± 1 %. The mixtures were prepared by filling glass vials with the liquids and weighing using a Sartorius semimicro balance CP225-D with the precision of ± 1 × 10−5 g. The estimated uncertainty in the mole fraction is ± 1 × 10−4. Vials are closed with screw caps, to ensure a secure seal and prevent alcohol evaporation. All of the binary systems were prepared immediately prior to measurements to avoid variations in composition due to evaporation of solvent or pick up of water by the ionic liquid.
or [b4mpy][BF4] with methanol at several temperatures,7,8 and we have include the corresponding comparison when possible.
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EXPERIMENTAL SECTION Methanol and ethanol were obtained from Aldrich with purities >0.998 and >0.995 in mass, respectively, and the ILs used (1butylpyridinium tetrafluoroborate, 1-butyl-3-methylpyridinium tetrafluoroborate, and 1-butyl-4-methylpyridinium tetrafluoroborate) were obtained from IoLiTec with purities >0.99 in mass. To decrease the water content as much as possible, the ILs were dried for 24 h under vacuum of about 0.05 kPa while stirring and stored before use in a desiccator. The water content of ILs was less than 100 ppm as determined by Karl Fischer titration using an automatic titrator Crison KF 1S-2B. The properties of the pure compounds, density and absolute viscosity, at working temperatures and comparison with literature values7−9,12−18 are gathered in Table 1. Table 1. Densities, ρ, and Absolute Viscosities, η, of the Pure Compounds at Pressure p = 0.1 MPa and at Several Temperatures and Comparison with Literature Dataa ρ/kg·m3 T/K 293.15 303.15 313.15 323.15 293.15 303.15 313.15 323.15 293.15 303.15 313.15 323.15 293.15 303.15 313.15 323.15 293.15 303.15 313.15 323.15
exptl.
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η/mPa·s lit.
exptl.
1-Butylpyridinium tetrafluoroborate 1217.11 1216.9b 220.54 1210.83 1210.0b 119.52 1203.72 1203.2b 71.110 1196.68 1196.4b 45.593 1-Butyl-3-methylpyridinium tetrafluoroborate 1185.66 1188.6c 246.62 1178.86 1181.7c 129.91 1172.11 1174.9c 76.457 1165.37 1165.48d 48.176 1-Butyl-4-methylpyridinium tetrafluoroborate 1185.92 284.62 1179.12 144.68 1172.12 1171.94f 85.530 1165.52 1165.40f 52.530 Methanol 791.24 791.29h 0.5833 781.81 781.808i 0.5070 772.29 772.6h 0.4438 762.63 763.7h 0.3873 Ethanol 789.48 789.37h 1.1800 781.30 781.15j 0.9810 772.57 772.1h 0.8220 763.65 763.6h 0.6939
RESULTS AND DISCUSSION Experimental kinematic viscosities and densities for the binary mixtures at work temperatures are given in Table 2. The system [bpy][BF4] + ethanol showed miscibility problems at T = 293.15 K, and it was not measured. The kinematic viscosities have been plotted in Figures 1 and 2. There are several equations that have been used to correlate viscosity data of mixtures containing ionic liquids,8,9,19−23 we have employed the McAllister equation, and for the systems whose components have similar size, the corresponding three-body equation is suitable. However, in our case, differences in size between ionic liquids and alcohols are higher, and the three-body model may not always be realistic. Therefore, a four-body McAllister equation with three parameters has been used to correlate the experimental kinematic viscosities
lit. 223.06b 122.99b 70.29b 45.12b 246e 132e 78e 48e
138.10g 80.85f 50.22f
ln ν = x14 ln ν1 + 4x13x 2 ln ν1112 + 6x12x 2 2 ln ν1122 + 4x1x 2 3 ln ν2221 + x 2 4 ln ν2 − ln[x1 + x 2M 2 /M1]
0.586h 0.510h 0.447h 0.383f
+ 4x13x 2 ln[(3 + M 2 /M1)/4] + 6x12 x 2 2 ln[(1 + M 2 /M1)/2] + 4x1 x 2 3 ln[(1 + 3M 2 /M1)/4]x 2 4 ln[M 2 /M1]
h
1.190 0.987k 0.828h 0.697h
(1)
where ν refers to the kinematic viscosity of the mixture, ν1 and ν2 are the kinematic viscosities of components 1 and 2, M1 and M2 are their corresponding molar masses, and ν1112, ν1122, and ν2221 are the adjustable parameters of the equation. The estimated parameters of the four-body McAllister equations are shown in Table 3 together with the corresponding average absolute deviations, AAD, between experimental and correlated values
a
Standard uncertainty u is u(T) = 0.01 K, and the combined expanded uncertainties Uc are Uc(ρ) = 0.1 kg·m−3, Uc(η) = 1 % with 0.95 level of confidence (k ≈ 2). bReference 9. cReference 12. dReference 13. e Reference 14. fReference 7. gReference 8. hReference 15. iReference 16. jReference 17. kReference 18.
Densities, ρ, of the samples required to calculate absolute viscosities from kinematic viscosities were determined with an Anton Paar DSA 5000 vibrating tube densimeter and sound analyzer, automatically thermostatted within ± 0.001 K. By measuring the damping of the oscillation of the U-tube caused by the viscosity of the filled-in sample, the DSA 5000 automatically corrects the viscosity related errors in the density. The calibration was carried out with ultrapure water supplied
AAD(%) =
n νi ,exp − νi ,cal 1 × 100 ∑ νi ,exp n i=1
(2)
where n is the number of experimental data. The overall average absolute deviation is 1.23 %, with the deviations at lower temperatures being slightly higher. Taking into account the enormous differences in viscosity of mixing compounds, we can conclude that the four-body McAllister 3550
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3551
0.0481 0.0975 0.1973 0.3001 0.4013 0.4969 0.5985 0.6972 0.7942 0.8427 0.8978 0.9689
1.0279 1.4490 2.7171 4.4529 7.0253 11.979 19.800 33.599 59.225 78.011 109.56 170.56
1.0760 1.5545 2.7872 4.6206 7.4047 11.940 19.984 32.583 53.178 72.020 96.281 129.91
0.0478 0.0959 0.1952 0.2938 0.3916 0.4921 0.5949 0.6989 0.7972 0.8478 0.8978 0.9471
0.0482 0.0945 0.1932 0.2702 0.3959 0.4954 0.5999 0.6990 0.7963 0.8477 0.8984 0.9461
ν /mm ·s
x1
2 −1
876.92 937.91 1017.57 1067.85 1101.07 1123.81 1142.18 1156.20 1167.41 1172.30 1177.37 1183.27
878.25 940.74 1026.08 1080.36 1117.45 1145.14 1166.53 1183.41 1196.34 1202.15 1207.40 1212.30
ρ/kg·m
−3
0.9014 1.3590 2.7648 4.7550 7.7353 13.462 22.615 38.847 69.140 91.452 128.99 201.82
0.9450 1.4615 2.8599 4.9919 8.2744 13.673 23.312 38.559 63.619 86.579 116.25 157.49
η/mPa·s
T = 293.15/K
−11.516 −23.213 −46.361 −69.663 −91.581 −109.375 −125.219 −133.270 −126.843 −116.463 −92.479 −37.146
0.8989 1.2658 2.2102 3.5304 5.6084 8.7711 14.033 22.179 34.011 44.925 57.203 73.878
−10.152 −20.216 −40.659 −60.215 −78.444 −95.151 −108.124 −115.752 −112.314 −100.483 −81.806 −51.417
0.8949 1.2159 2.2036 3.4406 5.6353 9.0438 14.488 23.139 35.299 45.943 62.765 92.996
1.4216 1.9612 3.1737 4.3710 7.1274 10.325 15.713 23.633 35.834 44.775 58.349 73.676
ν /mm ·s
Δη/mPa·s
2 −1
η/mPa·s
Δη/mPa·s
ν /mm ·s
2 −1
ρ/kg·m
−3
0.6767 0.9770 1.8836 3.2000 5.1365 8.0139 12.172 19.350 28.956 36.151 46.940 66.072
1.0809 1.4865 2.4828 3.4910 5.8030 8.3920 12.914 19.027 28.221 34.854 44.410 54.768
0.6406 0.9508 1.7657 2.9105 4.7309 7.4187 11.816 18.296 27.258 35.270 43.913 55.279
η/mPa·s
T = 313.15/K
1-Butylpyridinium tetrafluoroborate (1) + Methanol (2) 869.29 0.7814 −5.414 0.7444 860.54 931.43 1.1790 −10.741 1.0296 923.47 1017.92 2.2498 −21.488 1.7472 1010.59 1072.63 3.7868 −31.685 2.7319 1065.38 1109.94 6.2250 −40.886 4.2903 1102.70 1137.76 9.9794 −49.092 6.5622 1130.52 1159.20 16.267 −55.038 10.256 1152.11 1176.16 26.086 −57.596 15.648 1169.22 1189.23 40.447 −54.934 23.052 1182.46 1195.10 53.690 −47.713 29.678 1188.42 1200.46 68.670 −38.683 36.783 1193.84 1205.38 89.051 −24.170 46.112 1198.80 1-Butylpyridinium tetrafluoroborate (1) + Ethanol (2) 843.38 1.1989 −5.496 1.2945 834.98 892.42 1.7502 −10.433 1.6810 884.28 972.49 3.0864 −20.796 2.5736 964.73 1019.05 4.4543 −28.555 3.4514 1011.49 1076.24 7.6708 −40.238 5.4290 1068.89 1110.49 11.466 −48.237 7.6064 1103.28 1139.33 17.902 −54.188 11.405 1132.29 1161.67 27.454 −56.383 16.477 1154.79 1179.99 42.284 −53.087 24.054 1173.24 1188.50 53.215 −48.248 29.492 1181.82 1196.25 69.800 −37.673 37.331 1189.62 1203.06 88.636 −24.491 45.773 1196.46 1-Butyl-3-methylpyridinium tetrafluoroborate (1) + Methanol (2) 868.11 0.7769 −5.954 0.7879 858.90 929.46 1.1301 −11.994 1.0609 920.91 1009.42 2.2244 −23.814 1.8809 1001.41 1059.92 3.6468 −35.694 3.0418 1052.02 1093.38 6.1615 −46.275 4.7314 1085.61 1116.36 10.096 −54.712 7.2276 1108.79 1134.95 16.443 −61.512 10.794 1127.63 1149.14 26.590 −64.137 16.943 1142.07 1160.48 40.964 −62.315 25.101 1153.59 1165.41 53.542 −56.014 31.203 1158.59 1170.53 73.468 −43.218 40.335 1163.75 1176.47 109.41 −16.479 56.485 1169.72
ρ/kg·m
−3
T = 303.15/K
0.7001 0.9172 1.6096 2.5448 3.9474 5.6811 8.3805 12.664 17.586 21.317 26.724 36.135
1.1527 1.4115 2.0573 2.7327 4.2377 5.9420 8.5476 12.038 17.024 20.490 25.324 30.539
−3.129 −5.978 −11.919 −16.323 −22.846 −27.251 −30.074 −30.926 −28.571 −25.551 −19.559 −12.556 −3.423 −6.878 −13.558 −20.055 −25.811 −30.201 −33.766 −34.090 −31.857 −28.349 −21.748 −8.021
0.6213 0.8643 1.4362 2.2043 3.4131 5.1316 7.6798 11.555 16.520 20.707 25.098 30.604
ν /mm ·s
−3.181 −6.270 −12.472 −18.295 −23.386 −27.800 −30.667 −31.537 −29.521 −25.085 −19.975 −12.093
Δη/mPa·s
2 −1
850.00 912.45 993.31 1044.13 1077.93 1101.32 1120.38 1134.99 1146.64 1151.69 1156.91 1162.95
826.69 876.45 957.44 1004.32 1061.70 1096.06 1125.08 1147.65 1166.21 1174.82 1182.65 1189.47
852.41 916.00 1003.55 1058.43 1095.78 1123.61 1145.11 1162.18 1175.36 1181.32 1186.75 1191.71
ρ/kg·m−3
0.5951 0.8369 1.5988 2.6571 4.2550 6.2567 9.3893 14.374 20.165 24.551 30.917 42.023
0.9529 1.2371 1.9697 2.7445 4.4992 6.5128 9.6167 13.816 19.854 24.072 29.949 36.325
0.5296 0.7917 1.4413 2.3331 3.7400 5.7659 8.7942 13.429 19.417 24.462 29.785 36.471
η/mPa·s
T = 323.15/K
−2.091 −4.210 −8.217 −12.072 −15.310 −17.877 −19.600 −19.332 −18.176 −16.108 −12.375 −4.667
−1.905 −3.700 −7.399 −10.081 −13.970 −16.424 −18.012 −18.263 −16.594 −14.683 −11.082 −6.848
−2.019 −3.931 −7.770 −11.336 −14.350 −16.867 −18.486 −18.553 −17.009 −14.251 −11.188 −6.731
Δη/mPa·s
Table 2. Experimental Kinematic Viscosities, ν, Densities, ρ, Calculated Absolute Viscosities, η, and Viscosity Deviations, Δη, of the Binary Mixtures Pyridinium Ionic Liquid + Alkanol at Pressure p = 0.1 MPa and at Several Temperatures
Journal of Chemical & Engineering Data Article
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a
3552
2.0661 2.6719 4.3071 6.8447 9.2845 14.429 22.068 36.567 61.285 83.706 111.47 149.77
1.0195 1.4177 2.8265 4.5663 7.5049 13.070 21.236 36.061 64.227 84.315 120.27 167.62
1.9531 2.5671 4.0829 6.3519 9.9141 19.628 25.694 39.970 72.727 97.873 131.86 176.71
0.0521 0.0964 0.1964 0.3210 0.3936 0.4941 0.5900 0.6910 0.7952 0.8500 0.8992 0.9477
0.0477 0.0958 0.2055 0.2889 0.3846 0.4866 0.5890 0.7073 0.7963 0.8459 0.8947 0.9465
0.0481 0.0952 0.1896 0.2856 0.3839 0.5297 0.5858 0.6862 0.7889 0.8418 0.8942 0.9460
852.00 900.20 972.12 1024.13 1063.87 1107.23 1120.51 1140.91 1158.26 1166.08 1173.20 1179.69
876.71 936.07 1021.53 1062.26 1095.45 1121.16 1140.60 1157.80 1168.12 1173.12 1177.58 1181.89
855.55 900.79 977.43 1041.50 1068.86 1098.93 1121.77 1141.60 1158.80 1166.81 1173.47 1179.57
1.6640 2.3109 3.9691 6.5052 10.547 21.733 28.790 45.602 84.237 114.13 154.70 208.46
0.8938 1.3271 2.8874 4.8506 8.2212 14.654 24.222 41.751 75.025 98.912 141.63 198.11
1.7677 2.4068 4.2099 7.1288 9.9238 15.856 24.755 41.745 71.017 97.669 130.81 176.66
η/mPa·s
T = 293.15/K
ρ/kg·m−3
ν /mm2·s−1 1.6750 2.1221 3.3638 5.1518 6.8187 10.350 15.003 23.196 36.835 48.647 62.496 82.893 0.8834 1.1954 2.2934 3.5971 5.7269 9.5564 15.795 25.902 41.140 51.572 69.212 91.446 1.6050 2.0655 3.1708 4.7628 7.2516 14.398 17.583 27.825 43.703 57.112 74.125 95.161
Δη/mPa·s −12.200 −22.433 −45.174 −72.836 −87.860 −106.594 −121.232 −129.031 −125.334 −112.132 −91.069 −57.116 −13.238 −26.467 −56.065 −77.791 −101.603 −124.142 −143.659 −159.731 −151.737 −141.938 −113.083 −71.316 −13.149 −25.853 −50.951 −75.625 −99.446 −129.585 −138.429 −150.075 −140.549 −125.652 −99.934 −60.851
Δη/mPa·s
ν /mm2·s−1
1.1214 1.4919 2.4175 3.7800 5.8133 11.492 14.769 22.097 34.926 44.600 55.819 69.258
0.6684 0.9386 1.9192 3.0519 4.8954 8.0824 12.999 21.706 32.342 39.547 51.295 65.289
1.1742 1.5474 2.6087 4.3011 5.8417 8.7300 12.791 19.828 29.905 37.840 46.723 59.174
η/mPa·s
T = 313.15/K ρ/kg·m−3
1-Butyl-3-methylpyridinium tetrafluoroborate (1) + Ethanol (2) 847.17 1.4190 −6.279 1.3998 838.85 892.48 1.8939 −11.516 1.7498 884.31 969.49 3.2612 −23.042 2.7132 961.48 1033.92 5.3265 −37.041 4.1913 1026.20 1061.42 7.2375 −44.490 5.5429 1053.90 1091.66 11.299 −53.386 8.0509 1084.35 1114.64 16.723 −60.327 11.550 1107.46 1134.58 26.318 −63.753 17.586 1127.48 1151.88 42.429 −61.077 26.121 1144.87 1159.93 56.427 −54.144 32.819 1152.99 1166.61 72.908 −44.007 40.287 1159.75 1172.74 97.21 −25.956 50.752 1165.95 1-Butyl-4-methylpyridinium tetrafluoroborate (1) + Methanol (2) 867.94 0.7667 −6.617 0.7783 858.74 927.56 1.1088 −13.210 1.0214 918.89 1013.48 2.3243 −27.810 1.9089 1005.40 1054.51 3.7932 −38.365 2.9159 1046.65 1087.98 6.2308 −49.725 4.5314 1080.32 1113.92 10.645 −60.017 7.3047 1106.46 1133.51 17.904 −67.521 11.542 1126.23 1150.84 29.809 −72.672 18.978 1143.72 1161.22 47.773 −67.539 28.022 1154.18 1166.24 60.145 −62.318 34.115 1159.23 1170.73 81.029 −48.470 44.078 1163.73 1175.06 107.46 −29.512 55.895 1168.07 1-Butyl-4-methylpyridinium tetrafluoroborate (1) + Ethanol (2) 843.78 1.3543 −6.539 1.3421 835.55 892.25 1.8429 −12.818 1.6875 884.10 964.56 3.0584 −25.168 2.5274 956.53 1016.72 4.8424 −37.179 3.7464 1008.96 1056.57 7.6618 −48.485 5.5413 1049.08 1100.11 15.839 −61.259 10.515 1092.88 1113.47 19.578 −65.582 13.350 1106.29 1133.97 31.553 −68.034 19.610 1126.84 1151.41 50.320 −64.025 30.522 1144.30 1159.26 66.208 −55.739 38.710 1152.16 1166.40 86.459 −43.018 48.148 1159.32 1172.89 111.61 −25.307 59.406 1165.84
η/mPa·s
T = 303.15/K ρ/kg·m−3
−3.775 −7.394 −14.465 −21.235 −27.528 −34.200 −35.675 −36.852 −32.722 −27.529 −20.749 −11.698
−3.834 −7.656 −16.010 −21.973 −28.273 −33.764 −37.561 −38.919 −35.856 −32.871 −25.275 −15.689
−3.588 −6.566 −13.068 −20.800 −24.750 −29.463 −32.655 −33.258 −31.062 −27.271 −22.110 −13.327
Δη/mPa·s
1.1390 1.4124 2.0850 3.0298 4.3965 7.4033 9.3280 13.575 20.775 25.928 31.503 37.949
0.6883 0.8916 1.6243 2.4443 3.6972 5.7757 8.6022 13.034 19.269 22.938 28.512 35.591
1.1807 1.4690 2.2445 3.3945 4.4912 6.2448 8.8623 12.805 18.143 22.262 26.726 32.889
ν /mm2·s−1
827.17 875.80 948.48 1001.26 1041.70 1085.83 1099.32 1119.98 1137.51 1145.41 1152.61 1159.18
849.60 910.02 997.15 1038.82 1072.88 1099.31 1119.29 1136.94 1147.48 1152.56 1157.09 1161.45
830.02 875.68 953.37 1018.52 1046.35 1076.96 1100.21 1120.38 1137.90 1146.06 1152.86 1159.11
0.9421 1.2370 1.9776 3.0336 4.5798 8.0387 10.254 15.204 23.632 29.698 36.311 43.990
0.5848 0.8114 1.6197 2.5392 3.9667 6.3493 9.6284 14.819 22.111 26.437 32.991 41.337
0.9800 1.2864 2.1398 3.4574 4.6994 6.7254 9.7504 14.346 20.645 25.514 30.811 38.122
η/mPa·s
T = 323.15/K ρ/kg·m−3
Standard uncertainties u are u(T) = 0.01 K, u(x1) = 0.0001, and the combined expanded uncertainties Uc are Uc(ρ) = 0.1 kg·m−3, Uc(η) = 1 % with 0.95 level of confidence (k ≈ 2).
ν /mm2·s−1
x1
Table 2. continued
−2.245 −4.392 −8.544 −12.465 −16.014 −20.113 −20.805 −21.060 −17.955 −14.632 −10.735 −5.741
−2.290 −4.571 −9.483 −12.912 −16.475 −19.411 −21.471 −22.449 −19.798 −18.058 −14.048 −8.403
−2.188 −3.985 −7.880 −12.478 −14.684 −17.430 −18.958 −19.158 −17.807 −15.540 −12.579 −7.571
Δη/mPa·s
Journal of Chemical & Engineering Data Article
dx.doi.org/10.1021/je300557g | J. Chem. Eng. Data 2012, 57, 3549−3556
Journal of Chemical & Engineering Data
Article
Figure 1. Kinematic viscosities, ν, for 1-butylpyridynium tetrafluoroborate with methanol (a), 1-butyl-3-methylpyridynium tetrafluoroborate with methanol (b), and 1-butyl-4-methylpyridynium tetrafluoroborate with methanol (c): ■, T = 293.15 K; □, T = 303.15 K; ●, T = 313.15 K; ○, T = 323.15 K; , four-body McAllister equation.
Figure 2. Kinematic viscosities, ν, for 1-butylpyridynium tetrafluoroborate with ethanol (a), 1-butyl-3-methylpyridynium tetrafluoroborate with ethanol (b), and 1-butyl-4-methylpyridynium tetrafluoroborate with ethanol (c): ■, T = 293.15 K; □, T = 303.15 K; ●, T = 313.15 K; ○, T = 323.15 K; , four-body McAllister equation. m
equation correlates the kinematic viscosity data of this kind of mixtures with good accuracy. Viscosity deviations have been calculated from absolute viscosities as follows:
Δη = η − x1η1 − x 2η2
Δη = x1x 2 ∑ Ai (x1 − x 2)i i=0
(4)
where Ai are adjustable parameters, obtained by the leastsquares method. The values of these parameters are given in Table 3, together with the corresponding standard deviations, σ(Δη)
(3)
where η represents the absolute viscosity of the mixture, xi is the mole fraction of component i, and ηi is the absolute viscosity of pure component i. Viscosity deviations are included in Table 2, and they are graphically represented in Figures 3 and 4. These viscosity deviations have been correlated with the Redlich−Kister equation
1/2 ⎛ ∑n (Δη − Δηi ,cal )2 ⎞ i ,exp i = 1 ⎟ σ(Δη) = ⎜⎜ ⎟ (n − p) ⎝ ⎠
(5)
where n is the number of experimental data and p is the number of parameters. 3553
dx.doi.org/10.1021/je300557g | J. Chem. Eng. Data 2012, 57, 3549−3556
Journal of Chemical & Engineering Data
Article
Table 3. Parameters and Deviations of the Four-Body McAllister Equation and Redlich−Kister Equation four-body McAllister T/K
ν1112/mm2·s
ν1122/mm2·s
293.15 303.15 313.15 323.15
39.854 27.143 19.129 14.067
9.275 7.518 6.337 5.297
303.15 313.15 323.15
24.493 18.689 14.087
11.28 7.326 5.541
293.15 303.15 313.15 323.15
47.767 28.432 21.454 15.165
7.691 7.489 6.014 5.203
293.15 303.15 313.15 323.15
47.072 28.201 21.391 14.966
9.842 7.910 6.881 5.828
293.15 303.15 313.15 323.15
40.211 30.018 21.996 15.257
12.651 9.888 7.612 5.970
293.15 303.15 313.15 323.15
59.159 37.981 29.444 21.619
12.882 10.792 7.858 5.014
ν2221/mm2·s
Redlich−Kister A0/mPa·s
AAD/%
A1/mPa·s
1-Butylpyridinium tetrafluoroborate (1) + Methanol (2) 8.770 1.57 −380.930 −293.978 6.122 1.34 −196.893 −139.554 4.159 1.19 −111.686 −73.167 3.123 1.12 −67.964 −40.688 1-Butylpyridinium tetrafluoroborate + Ethanol (2) 5.291 1.61 −192.095 −136.370 4.768 0.94 −108.483 −72.134 3.838 0.73 −65.768 −40.798 1-Butyl-3-methylpyridinium tetrafluoroborate (1) + Methanol (2) 8.005 1.43 −437.419 −346.114 5.691 1.99 −218.509 −160.663 5.083 0.96 −121.115 −80.858 4.245 1.14 −71.063 −41.903 1-Butyl-3-methylpyridinium tetrafluoroborate (1) + Ethanol (2) 9.854 1.62 −426.231 −331.343 7.071 1.47 −214.403 −160.566 5.400 1.31 −117.604 −75.444 4.333 1.41 −69.177 −40.528 1-Butyl-4-methylpyridinium tetrafluoroborate (1) + Methanol (2) 7.207 1.64 −505.736 −422.379 5.431 1.23 −243.578 −180.505 4.403 0.99 −136.571 −89.623 3.855 1.05 −79.047 −49.690 1-Butyl-4-methylpyridinium tetrafluoroborate (1) + Ethanol (2) 8.791 0.95 −496.265 −394.274 6.088 1.12 −237.437 −169.051 4.731 0.99 −133.257 −84.728 4.222 0.51 −78.349 −48.428
A2/mPa·s
A3/mPa·s
σ/mPa·s
−280.074 −117.353 −52.357 −24.979
−188.817 −74.627 −28.391 −11.624
0.879 0.499 0.253 0.148
−119.053 −54.498 −27.242
−77.580 −32.503 −14.391
0.555 0.250 0.101
−303.602 −136.462 −56.706 −31.031
−189.005 −83.210 −29.815 −20.524
0.980 0.521 0.218 0.203
−310.875 −139.677 −60.681 −33.150
−211.932 −87.807 −43.827 −25.994
1.093 0.473 0.346 0.208
−406.311 −149.902 −70.228 −35.594
−244.817 −84.412 −44.167 −18.348
1.394 0.635 0.379 0.217
−294.994 −108.974 −34.515 −8.130
−133.626 −41.696 0.310 15.014
0.669 0.448 0.331 0.214
Figure 3. Viscosity deviations, Δη, for 1-butylpyridynium tetrafluoroborate with methanol (a), 1-butyl-3-methylpyridynium tetrafluoroborate with methanol (b), and 1-butyl-4-methylpyridynium tetrafluoroborate with methanol (c): ■, T = 293.15 K; □, T = 303.15 K; ●, T = 313.15 K; ○, T = 323.15 K; , Redlich−Kister equation.
remarkably asymmetric with the minimum Δη values shifted toward ionic liquid rich region, xIL ≈ 0.7. When the results obtained for the ionic liquids are compared, it can be seen that the absolute Δη values follow the sequence: [bpy][BF4]
