Densities and viscosities of the binary mixtures of 1-ethyl-3- methylimidazolium bis(trifluoromethylsulfonyl)imide with N -methyl-2-pyrrolidone or ethanol at T = (293.15 to 323.15) K

Article abstract of DOI:10.1021/je200922s

Figure Persented: The densities and viscosities of 1-ethyl-3- methylimidazolium bis(trifluoromethylsulfonyl)imide ([EMIM][NTf₂]) + N-methyl-2-pyrrolidone (NMP) and [EMIM][NTf₂] + ethanol mixtures were investigated over the mole fraction range from (0.1 to 0.9) and at temperatures from (293.15 to 323.15) K at intervals of 5 K. The densities can be well-represented by the quadratic equation, and the viscosities can be represented in the form of the Vogel equation. The excess molar volumes (V ^E) and viscosity deviations (Δη) were calculated, and the results were fitted to the Redlich-Kister equation using a multiparametric nonlinear regression method. The estimated parameters of the Redlich-Kister equation and standard deviation were also presented. The results showed that the densities and viscosities were dependent strongly on NMP or ethanol content. Comparatively, the viscosity deviation Δ η was more sensitive to temperature than the excess molar volume V^E.

Full text of DOI:10.1021/je200922s

Article
pubs.acs.org/jced
Densities and Viscosities of the Binary Mixtures of 1-Ethyl-
-methylimidazolium Bis(trifluoromethylsulfonyl)imide with
N-Methyl-2-pyrrolidone or Ethanol at T = (293.15 to 323.15) K
3
Hongwei Yao,†,‡ Shuheng Zhang, Jieli Wang, Qing Zhou, Haifeng Dong,
and Xiangping Zhang*
†,‡
†,§
†
†
,†
†Beijing Key Laboratory of Ionic Liquids Clean Process, State Key Laboratory of Multiphase Complex System, Institute of Process
Engineering, Chinese Academy of Sciences, Beijing 100190, China
‡
College of Chemistry and Chemical Engineering, Graduate University of Chinese Academy of Sciences, Beijing 100049, P. R. China
§College of Chemical Engineering and Technology, Beijing University of Chemical Technology, Beijing 100029, China
ABSTRACT: The densities and viscosities of 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([EMIM][NTf ])
2
+
N-methyl-2-pyrrolidone (NMP) and [EMIM][NTf ] + ethanol mixtures were investigated over the mole fraction range from
2
(
0.1 to 0.9) and at temperatures from (293.15 to 323.15) K at intervals of 5 K. The densities can be well-represented by the
E
quadratic equation, and the viscosities can be represented in the form of the Vogel equation. The excess molar volumes (V ) and
viscosity deviations (Δη) were calculated, and the results were fitted to the Redlich−Kister equation using a multiparametric
nonlinear regression method. The estimated parameters of the Redlich−Kister equation and standard deviation were also
presented. The results showed that the densities and viscosities were dependent strongly on NMP or ethanol content.
E
Comparatively, the viscosity deviation Δη was more sensitive to temperature than the excess molar volume V .
9
,10
1
. INTRODUCTION
reported several times in literature. The experimental density
values of [EMIM][NTf ] (at p = 0.101 MPa) were reported by
Ionic liquids (ILs) have attracted considerable attention be-
cause of their unique physical and chemical properties, includ-
ing nonvolatility, thermal stability, and reusability. Particularly,
ILs have controlled miscibility, which results in many pos-
sible combinations of cations and anions and allows a large
2
11
12
Safarov et al. Its viscosities were reported by Van-Oanh et al.,
and its osmotic coefficients and vapor pressures were reported by
Calvar et al. In these articles, density and viscosity data of the
mixtures of [EMIM][NTf ] with organic solvents have not yet
1
,2
13
3
,4
2
5
variety of interactions and applications. Due to an increasing
been mentioned.
importance of ILs in many fields of technology, a large number
of publications dealing with the thermophysical properties of
these low-temperature molten salts can be found in the
In this work, the densities and viscosities of mixtures consist-
ing of [EMIM][NTf ] + N-methyl-2-pyrrolidone (NMP) and
EMIM][NTf ] + ethanol as a function of composition from
2
[
6
7,8
2
literature. Recently lots of research show that the contents
mixed with ILs will affect the physicochemical and thermo-
physical properties of ILs evidently. To study the molecular
interactions between the various components of the mixtures
and also to understand engineering applications concerning
heat transfer, mass transfer, and fluid flow, it is important to
study the experimental data of densities and viscosities of binary
mixtures of ILs systematically.
(
293.15 to 323.15) K were studied. The excess molar volume
E
V and the viscosity deviation Δη of these binary systems were
obtained and fitted to the Redlich−Kister equation. The influ-
ences of NMP or ethanol content and temperature on the
physical properties were analyzed.
Received: October 13, 2011
Accepted: January 9, 2012
Published: February 14, 2012
1
-Ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)-
imide ([EMIM][NTf ]), as an IL with low viscosity, has been
2
©
2012 American Chemical Society
875
dx.doi.org/10.1021/je200922s | J. Chem. Eng.Data 2012, 57, 875−881

Journal of Chemical & Engineering Data
Article
Table 1. Comparison of Measured Densities ρ and
Viscosities η of the [EMIM][NTf ], NMP, and Ethanol with
2
Literature Values
ρ/g·cm−
3
η/mPa·s
T/K
exp.
lit.
EMIM][NTf ]
exp.
lit.
[
2
1
1
1
1
1
1
6
1
6
6
7
2
93.15
98.15
03.15
1.523284
1.518251
1.513232
1.52337
.52353
1.51834
.51845
40.24
33.36
28.10
40.1
16
1
38.6
2
3
1
7
1.51341
28.7
1
7
6
2
7.1
1
1
1
1
1
6
1
6
6
6
3
08.15
13.15
1.508204
1.503162
1.50839
1.50333
23.93
20.66
3
21.1
19.4
16
1
.50338
3
18.15
23.15
1.498194
1.493330
1.49839
1.49341
17.98
15.80
7
Figure 1. Excess molar volumes of the [EMIM][NTf ] (1) + NMP
3
15.7
2
1
6
(2) system at various temperatures: ■, 293.15 K; ○, 298.15 K; ▲,
1
4.9
3
03.15 K; ▽, 308.15 K; ▼, 313.15 K; ◇, 318.15 K and ◆, 323.15 K.
NMP
1
7
2
93.15
98.15
1.032313
1.027962
1.0304
1.0259
1.811
1.667
1
7
18
2
1.656
1
1
8
9
1
.02872
.02832
1
2
0
1
.0286
2
1
1
.02759
1
1
1
1
1
7
303.15
308.15
313.15
318.15
323.15
1.023521
1.019060
1.014607
1.010141
1.005677
1.0217
1.0159
1.0120
1.0082
1.0030
1.543
1.437
1.343
1.258
1.184
7
7
7
7
18
18
1.322
1.175
Ethanol
2
2
2
2
3
2
22
23
22
293.15
298.15
303.15
308.15
313.15
0.789831
0.785535
0.781220
0.776875
0.772480
0.7900
.7893
0.7857
1.189
1.095
1.003
0.9140
0.8450
1.2097
1.1802
1.0990
0
2
4
24
0
.78500
1.105
2
2
2
2
22
23
22
0.7809
0.9971
1.0191
0.9083
3
0
.7807
2
0.7780
Figure 2. Excess molar volumes of the [EMIM][NTf ] (1) + ethanol
2
2
4
4
24
0
.77631
0.921
(3) system at various temperatures: ■, 293.15 K; ○, 298.15 K; ▲,
2
2
22
23
303.15 K; ▽, 308.15 K; ▼, 313.15 K;
◇, 318.15 K and ◆, 323.15 K.
0.7733
0.8280
0.8424
2
3
0
.7725
2
24
3
3
18.15
23.15
0.768042
0.762564
0.76744
0.7650
0.7040
0.771
H O (50 mL) and was added into [EMIM][Br] (1 mol). The
mixture was stirred for at least 24 h at room temperature, and
2
2
3
23
0.7636
0.7081
crude [EMIM][NTf ] was synthesized. Then the crude
2
2. EXPERIMENTAL SECTION
[EMIM][NTf ] was extracted in dichloromethane (50 mL)
2
and cooled below 278 K. The dichloromethane solution was
washed with cooled ultrapure water (30 mL) five times until the
aqueous solution did not form any precipitate with 0.1 mol·L−
Materials. NMP (>99 % pure), ethanol (>99.8 % pure),
Li[NTf ], and ethyl bromide were purchased from Sinopharm
2
1
Chemical Reagent Beijing Co., Ltd., China. 1-Methylimidazole
(
99 %) was supplied by Johnson Matthey Company, and these
AgNO solution. The solvent dichloromethane was removed by
3
regents were used without further purification.
rotary evaporation, and the [EMIM][NTf ] was dried under high
2
Synthesis of IL. [EMIM][NTf ] was prepared according to
2
vacuum at (323 to 333) K for at least 6 h.
the following method. First, 1-ethyl-3-methylimidazolium bro-
mide was synthesized by dropping ethyl bromide (1.3 mol) into
Characterizations of IL. [EMIM][NTf ] was identified by
2
1
H NMR, spectra IR, elemental analysis, and water content
1
3
-methylimidazole (1 mol) at 283 K and mixing for 6 h under
03 K. Then ethyl acetate was added into the mixture and was
1
analysis. The H NMR spectra were recorded on an ARX600
NMR spectrometer (Bruker) at 600 MHz with dimethyl
sulfoxide (DMSO) as solvent and tetramethylsilane (TMS) as
an internal standard. IR studies were conducted with a Nicolet
removed by a separating funnel, and this step was repeated five
times. The remaining ethyl acetate was removed by rotary
evaporation, and the solution was dried under high vacuum at
3
80 FTIR spectrometer (Thermo Nicolet). Elemental analysis
3
23 K for at least 24 h to get 1-ethyl-3-methylimidazolium
bromide ([EMIM]Br) at very high purity (99 %). Second,
EMIM][NTf ] was prepared by metathesis reactions from the
was conducted with a Vario EL elemental analyzer (Elementar).
Water content analysis was determined by moisture analysis
instrument (787 KF Titrino).
[
2
corresponding bromide. [Li][NTf ] (1 mol) was dissolved in
2
8
76
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Journal of Chemical & Engineering Data
Article
E
Table 2. Experimental Densities ρ, Viscosities η, Excess Molar Volume V , and Viscosity Deviation Δη for Binary Mixtures of
[
EMIM][NTf ] (1) + NMP (2) and [EMIM][NTf ] (1) + Ethanol (3) from T = (293.15 to 323.15) K as a Function of Molar
2
2
Fraction x1
T/K
x1
293.15
298.15
303.15
308.15
313.15
318.15
323.15
[
EMIM][NTf ] (1) + NMP (2)
2
ρ/g·cm−
3
0
0
0
0
0
0
0
0
0
.9002
.7980
.6917
.5893
.4930
.3950
.2957
.1979
.0978
1.502241
1.478942
1.451444
1.420549
1.386312
1.344491
1.292831
1.228992
1.144094
1.497092
1.473784
1.446291
1.415415
1.381192
1.339439
1.287871
1.224194
1.139450
1.491961
1.468635
1.441151
1.410270
1.376090
1.334421
1.282914
1.219334
1.134720
1.486834
1.463482
1.436014
1.405147
1.371001
1.329382
1.277971
1.214471
1.130026
1.481674
1.458282
1.430827
1.399964
1.365875
1.324284
1.272990
1.209604
1.125305
1.476540
1.453092
1.425651
1.394812
1.360772
1.319235
1.267997
1.204731
1.120611
1.471411
1.448032
1.420575
1.389731
1.355621
1.314121
1.262960
1.199830
1.115906
η/mPa·s
0
0
0
0
0
0
0
0
0
.9002
.7980
.6917
.5893
.4930
.3950
.2957
.1979
.0978
34.93
29.72
24.72
20.06
15.84
12.04
8.637
5.561
3.344
28.70
24.70
20.87
17.07
13.60
10.45
7.604
4.943
3.026
24.29
21.05
17.85
14.70
11.82
9.159
6.749
4.457
2.754
20.83
18.24
15.44
12.81
10.37
8.092
6.033
4.028
18.12
15.76
13.44
11.26
9.174
7.190
5.430
3.647
2.314
15.79
13.78
11.83
9.989
8.180
6.440
4.916
3.325
2.130
13.95
12.31
10.51
8.911
7.344
5.816
4.481
3.079
1.980
2.519
E
3
−1
V /cm ·mol
0
0
0
0
0
0
0
0
0
.9002
.7980
.6917
.5893
.4930
.3950
.2957
.1979
.0978
0.3075
0.4180
0.4337
0.4052
0.3565
0.2985
0.2129
0.1205
0.0463
0.3299
0.4434
0.4599
0.4306
0.3824
0.3198
0.2293
0.1281
0.0523
0.3509
0.4681
0.4836
0.4557
0.4033
0.3332
0.2403
0.1360
0.0595
0.3700
0.4920
0.5055
0.4765
0.4210
0.3474
0.2481
0.1425
0.3927
0.5217
0.5336
0.5046
0.4429
0.3685
0.2600
0.1496
0.0663
0.4228
0.5603
0.5689
0.5359
0.4678
0.3881
0.2764
0.1589
0.0688
0.4689
0.5934
0.6024
0.5684
0.5084
0.4233
0.3035
0.1751
0.0743
0.0613
−1
3
Δη/cm ·mol
0.9002
0.7980
0.6917
0.5893
0.4930
0.3950
0.2957
0.1979
0.0978
−1.48
−2.76
−3.67
−4.40
−4.92
−4.95
−4.54
−3.86
−2.22
−1.50
−2.26
−2.72
−3.27
−3.69
−3.73
−3.44
−3.00
−1.74
−1.16
−1.69
−2.06
−2.49
−2.82
−2.87
−2.65
−2.34
−1.39
−0.855
−0.612
−1.00
−1.26
−1.47
−1.69
−1.78
−1.63
−1.52
−0.918
−0.521
−0.823
−0.995
−1.12
−1.32
−1.42
−1.29
−1.24
−0.763
−0.391
−0.538
−0.784
−0.886
−1.05
−1.14
−1.03
−1.00
−0.633
−1.15
−1.56
−1.88
−2.16
−2.23
−2.06
−1.86
−1.12
[
EMIM][NTf ] (1) + Ethanol (3)
2
ρ/g·cm−
3
0
0
0
0
0
0
0
0
0
.9041
.7982
.6966
.5955
.5014
.3992
.3000
.1971
.1008
1.506315
1.484184
1.458636
1.427558
1.391851
1.341773
1.276680
1.179411
1.038400
1.501313
1.479171
1.453693
1.422721
1.387125
1.337181
1.272192
1.175213
1.034141
1.496341
1.474280
1.448783
1.417990
1.382491
1.332393
1.267500
1.170587
1.029789
1.491394
1.469404
1.443984
1.413413
1.377681
1.327885
1.263400
1.166550
1.025121
1.486411
1.464393
1.439300
1.408572
1.372990
1.323621
1.259313
1.162510
1.021471
1.481541
1.459600
1.434533
1.404000
1.368707
1.319804
1.255227
1.159513
1.019104
1.476731
1.454973
1.429971
1.399501
1.364610
1.316241
1.252111
1.156541
1.015544
η/mPa·s
0
0
0
0
.9041
.7982
.6966
.5955
28.74
21.80
17.76
13.87
24.52
18.70
15.18
12.05
20.90
16.12
13.13
10.31
18.05
14.04
11.47
9.109
15.74
12.34
10.01
7.954
13.84
10.93
8.965
7.141
12.28
9.799
8.116
6.500
8
77
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Journal of Chemical & Engineering Data
Article
Table 2. continued
T/K
x1
293.15
298.15
303.15
308.15
313.15
318.15
323.15
η/mPa·s
0
0
0
0
0
.5014
.3992
.3000
.1971
.1008
10.65
7.429
4.600
2.780
1.612
9.232
6.479
4.150
2.350
1.478
8.100
5.697
3.728
2.160
1.250
7.177
5.055
3.157
1.900
1.120
6.199
4.404
2.640
1.645
1.101
5.603
3.945
2.459
1.412
1.001
5.195
3.656
2.317
1.307
0.9870
E
3
−1
V /cm ·mol
0.9041
0.7982
0.6966
0.5955
0.5014
0.3992
0.3000
0.1971
0.1008
−0.0436
−0.1046
−0.1822
−0.2838
−0.4165
−0.5447
−0.6815
−0.7105
−0.4613
−0.0518
−0.1142
−0.2042
−0.3207
−0.4660
−0.6056
−0.7468
−0.7889
−0.5132
−0.0629
−0.1406
−0.2299
−0.3706
−0.5266
−0.6473
−0.7945
−0.8337
−0.5602
−0.0799
−0.1713
−0.2731
−0.4427
−0.5698
−0.7211
−0.9009
−0.9311
−0.0939
−0.1850
−0.3359
−0.4855
−0.6308
−0.8251
−1.0138
−1.0336
−0.6952
−0.1153
−0.2223
−0.3801
−0.5571
−0.7359
−0.9750
−1.1271
−1.2267
−0.9082
−0.1382
−0.2875
−0.4662
−0.6619
−0.8966
−1.1963
−1.3873
−1.4875
−1.1033
−0.5860
3
−1
Δη/cm ·mol
0.9041
0.7982
0.6966
0.5955
0.5014
0.3992
0.3000
0.1971
0.1008
−7.76
−10.6
−10.6
−10.6
−10.1
−9.35
−8.31
−6.10
−3.51
−5.75
−8.15
−8.39
−8.26
−8.04
−7.50
−6.63
−5.10
−2.87
−4.60
−6.51
−6.75
−6.83
−6.49
−6.12
−5.40
−4.18
−2.48
−3.67
−3.02
−4.32
−4.64
−4.69
−4.58
−4.35
−4.15
−3.10
−1.74
−2.49
−3.58
−3.79
−3.87
−3.79
−3.69
−3.47
−2.75
−1.50
−2.07
−2.95
−3.10
−3.19
−3.08
−3.07
−2.92
−2.37
−1.24
−5.25
−5.48
−5.51
−5.28
−5.05
−4.66
−3.55
−2.11
E
Table 3. Parameters of the Quadratic Equation and AADs
Table 4. Parameters of the Redlich−Kister Equation for V
of [EMIM][NTf ] (1) + NMP (2) and [EMIM][NTf ] (1) +
for the Density Correlation of [EMIM][NTf ] (1) + NMP
2
2
2
(
2) and EMIM][NTf ] (1) + Ethanol (3) from T = (293.15
Ethanol (3)
2
to 323.15) K as a Function of Molar Fraction x1
T/K
A0
A1
A2
A3
σ
3
7
4
x1
A0
10 A
1
10 A
2
10 ADD
[EMIM][NTf ] (1) + NMP (2)
2
[
EMIM][NTf ] (1) + NMP (2)
293.15
298.15
303.15
308.15
313.15
318.15
323.15
1.441
1.537
1.614
1.682
1.775
1.878
2.015
1.118
1.159
1.246
1.313
1.397
1.497
1.435
0.7503
0.8069
0.8976
0.9643
1.038
1.105
1.228
1.233
1.311
1.381
1.521
2.022
0.003383
0.004732
0.005844
0.006223
0.007304
0.007130
0.01053
2
1
0
0
0
0
0
0
0
0
0
0
.0000
.9002
.7980
.6917
.5893
.4930
.3950
.2957
.1979
.0978
.0000
1.865
1.804
1.790
1.758
1.727
1.675
1.615
1.556
1.489
1.412
1.263
−1.315
−1.0330
−1.088
5.105
0.09048
0.9095
0.5000
−1.114
−1.114
−2.776
−3.052
−2.800
−0.8524
−3.210
20.00
0.05786
0.2314
0.1811
0.0996
0.0996
0.1169
0.1143
0.06886
0.1091
0.1589
−1.0610
−1.0610
−0.9537
−0.8407
−0.8068
−0.7999
−0.8879
−0.6912
1.167
1.298
[EMIM][NTf ] (1) + Ethanol (3)
2
293.15
298.15
303.15
308.15
313.15
318.15
323.15
−1.673
−1.863
−2.055
−2.331
−2.611
−2.963
−3.612
3.003
3.276
3.285
3.653
3.991
4.328
5.374
−2.124
−2.338
−2.444
−2.647
−3.140
−4.247
−5.216
0.02745
0.1324
0.4752
0.1587
0.5747
1.988
0.01613
0.01745
0.01677
0.02694
0.02089
0.01390
0.01241
[
EMIM][NTf ] (1) + Ethanol (3)
2
1.0000
0.9041
0.7982
0.6966
0.5955
0.5014
0.3992
0.3000
0.1971
0.1008
0.0000
1.865
1.859
1.867
1.867
1.790
1.892
2.067
1.967
2.050
1.960
0.7537
−1.315
−1.398
−1.607
−1.792
−1.510
−2.423
−3.936
−3.737
−4.960
−5.300
1.048
5.143
6.657
10.24
13.57
9.319
24.47
49.94
47.22
67.95
73.60
−31.55
0.2733
0.2050
0.5197
0.1993
0.4329
0.9736
0.9239
1.218
2.099
1H NMR (600 MHz, DMSO): δ 1.432 (t, 3H), 3.360 (s, 3H),
4.210 (q, 2H), 7.673 (s, 1H), 7.755 (s, 1H), 9.103 (s, 1H); IR
(neat) 3160, 3121, 1352, 1194, 1139, 1057, 617, 571. Elemental
analysis: C (24.48 wt %), H (2.81 wt %), N (10.71 wt %), S
(16.33 wt %), O (16.41 wt %); the content of water <100 ppm.
Impurity peaks were not observed in the H NMR spectra,
and the chemical shift of other peaks corresponded to the
structure of the [EMIM][NTf ]. The water content of the
1
1.479
3.123
1.606
2
8
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Journal of Chemical & Engineering Data
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Table 5. Parameters of the Vogel Equation and AADs for the
Viscosity Correlation of [EMIM][NTf ] (1) + NMP (2) and
2
[
3
EMIM][NTf ] (1) + Ethanol (3) from T = (293.15 to
23.15) K as a Function of Molar Fraction x1
2
2
x1
A0
A1
A2
10 ADD
[
EMIM][NTf ] (1) + NMP (2)
2
1.0000
0.9002
0.7980
0.6917
0.5893
0.4930
0.3950
0.2957
0.1979
0.0978
0.0000
−0.9712
−0.2337
−0.6813
−1.404
−1.175
−1.333
−1.811
−1.708
−1.821
−1.821
−1.943
559.1
358.2
442.4
607.1
519.7
532.1
632.0
566.1
525.3
525.3
378.9
−173.3
−198.5
−184.5
−161.5
−168.6
−163.2
−146.1
−146.6
−144.6
−144.6
−143.8
1.020
6.455
5.439
0.9059
0.5143
0.2921
0.3903
0.09564
0.9186
0.9186
0.07073
Figure 3. Viscosity deviations of the [EMIM][NTf ] (1) + NMP (2)
2
[
EMIM][NTf ] (1) + Ethanol (3)
system at various temperatures: ■, 293.15 K; ○, 298.15 K; ▲, 303.15 K;
▽, 308.15 K; ▼, 313.15 K; ◇, 318.15 K and ◆, 323.15 K.
2
1.0000
0.9041
0.7982
0.6966
0.5955
0.5014
0.3992
0.3000
0.1971
0.1008
0.0000
−0.9712
−1.985
−1.558
−0.9650
−1.340
−1.598
−2.616
−13.76
−17.54
−0.6863
−51.39
559.1
842.3
664.9
445.4
494.9
522.0
743.9
8959
−173.3
−135.6
−149.9
−177.2
−168.6
−161.5
−132.2
292.4
1.020
3.877
2.053
3.552
5.721
5.692
3.480
8.172
3.199
2.870
0.3311
13005
43.70
150243
407.7
−256.0
2621
Table 6. Parameters of the Redlich−Kister Equation for Δη
of [EMIM][NTf ] (1) + NMP (2) and [EMIM][NTf ] (1) +
2
2
Ethanol (3)
T/K
A0
A1
A2
A3
σ
[
EMIM][NTf ] (1) + NMP (2)
2
2
2
3
3
3
3
3
93.15
98.15
03.15
08.15
13.15
18.15
23.15
−19.31
−14.23
−10.86
−8.317
−6.583
−6.574
−4.052
6.167
5.696
4.636
4.079
2.875
2.894
2.153
−2.757
−5.627
−4.690
−3.405
−3.134
−3.156
−2.195
−0.9268
−5.595
−4.107
−2.580
−0.8774
−0.9059
−0.2525
0.04798
0.06333
0.05433
0.05351
0.03492
0.03336
0.03514
Figure 4. Viscosity deviations of the [EMIM][NTf ] (1) + ethanol (3)
2
system at various temperatures: ■, 293.15 K; ○, 298.15 K; ▲, 303.15 K;
▽
, 308.15 K; ▼, 313.15 K; ◇, 318.15 K and ◆, 323.15 K.
the absolute room pressure was approximately 101 kPa at that
−3
time. The precision of measurement was ± 0.000001 g·cm , and
−3
[
EMIM][NTf ] (1) + Ethanol (3)
2
the accuracy of density measurements was ± 0.000005 g·cm ,
which was calibrated with ultrapure water and dry air. The same
data point of the same sample with one injection into the
apparatus was measured three times, and the average of the
data was calculated as the final density.
293.15
298.15
303.15
308.15
313.15
318.15
323.15
−40.02
−31.86
−25.93
−21.25
−18.42
−15.29
−12.58
−9.742
−7.148
−6.088
−3.438
−1.595
0.4988
0.2466
−34.97
−26.20
−21.11
−17.70
−13.57
−12.00
−10.51
−34.08
−22.32
−15.20
−13.14
−12.29
−10.49
−9.515
0.1117
0.04089
0.05258
0.03779
0.05180
0.03605
0.04904
Viscosity. Viscosities of the mixtures of [EMIM][NTf ] +
2
NMP and [EMIM][NTf ] + ethanol were measured by a
2
viscosity meter (Anton Paar AMVn, Anton Paar Co., Austria)
based on the approved and acknowledged falling ball principle
according to DIN 53015 and ISO 12058. The reproducibility
product [EMIM][NTf ] was determined to be below 200 ppm.
The purity of the IL was >99 %.
2
<
2 %, repeatability <0.1 %, and calibration were carried out
using ultrapure water or viscosity standard oils (no. H117,
Anton Paar Co., Austria). The temperature range of this study
was from (293.15 to 323.15) K, at 5 K intervals, the precision of
which was ± 0.01 K (the temperature accuracy is controlled by
a built-in precise Peltier thermostat), and the absolute room
pressure was approximate 101 kPa at that time.
Density. The densities of the mixtures of [EMIM][NTf ] +
2
NMP and [EMIM][NTf ] + ethanol were measured by a den-
sity meter (Anton Paar DMA 5000, Anton Paar Co., Austria).
The temperature of this study was between (293.15 and
23.15) K, at 5 K intervals, the precision of which was ± 0.001 K
the temperature accuracy is controlled traceably to national
standards by two integrated Pt 100 platinum thermometers), and
2
3
(
The mixtures of [EMIM][NTf ] + NMP and [EMIM]-
2
[NTf ] + ethanol were prepared using a JA2003 electronic
2
8
79
dx.doi.org/10.1021/je200922s | J. Chem. Eng.Data 2012, 57, 875−881

Journal of Chemical & Engineering Data
Article
digital balance accurate to within ± 0.1 mg. The uncertainty in
the mole fraction of the mixtures was estimated to less than
accommodation. For the investigated systems, NMP is a cyclic
organic molecule that interacted with [EMIM][NTf ] as a
2
±
0.0001. The uncertainty of excess molar volumes was esti-
molecule with a molecule. However ethanol is a chain-shaped
molecule that can be dispersed into IL easily. The coefficients
and the standard deviation (σ) are presented in Table 4.
Experimentally measured viscosities of the binary mixtures of
3
−1
mated better than ± 0.02 cm ·mol . All molar quantities are
based on the International Union of Pure and Applied
Chemistry (IUPAC) relative atomic mass table.
[
EMIM][NTf ] + NMP and [EMIM][NTf ] + ethanol are
2
2
3. RESULTS AND DISCUSSION
listed in Table 2. The values of pure [EMIM][NTf ], NMP,
2
and ethanol are also in very good agreement with the values
recently published literature data (Table 1), which means the
experimental values are reliable.
The experimental density values for pure [EMIM][NTf ], NMP,
2
and ethanol in this work are in very good agreement with the
values recently published literature data (Table 1), which illus-
trates that the measured methods are dependable. Experimen-
The measured data of viscosities could be fitted and
14
regressed by the Vogel equations as follows:
tally measured densities of the mixture of [EMIM][NTf ] (1) +
2
NMP (2) and [EMIM][NTf ] (1) + ethanol (3) at (293.15,
2
⎡
⎤
⎥
A1
2
98.15, 303.15, 308.15, 313.15, 318.15, and 323.15) K through-
η/mPa·s = exp⎢A +
0
out the whole mole fraction range are listed in Table 2. The
measured data of densities could be fitted and regressed by the
quadratic equations as follows:
⎣
T/K + A ⎦
2
(6)
(2)
n
14
1
ADD = ∑ |η
− ηi,calcd|
i,exptl
−
3
2
n
ρ/g·cm =A + A (T/K) + A (T/K)
(1)
i=1
0
1
2
n
the values of A
, A , A , and ADD of the two systems are listed
0 1 2
ADD = 1
|ρi,exptl − ρi,calcd
|
in Table 5. The viscosity deviation can be calculated with eq 7:
∑
n
(2)
i=1
Δη = η − (x η + x η )
1
1 2 2
(7)
where ρ stands for the densities, A , A , and A are the
0
1
2
where η is the viscosity of the mixture and η and η are those
1 2
of pure component 1 and pure component 2, respectively.
quadratic fitting regression parameters with the least-squares
method, and ADD is the average absolute deviation between
the experimental results and the calculated values by eq 2.
Figures 3 and 4 display the dependence of Δη on the
temperature of the [EMIM][NTf ] (1) + NMP (2) system and
2
The parameters of eq 1 and ADDs of the [EMIM][NTf2]
the [EMIM][NTf ] (1) + ethanol (3) system, respectively. It
2
(
1) + NMP (2) system and [EMIM][NTf ] (1) + NMP (3)
2
can be observed that Δη values of the two systems are all
negative over the measured composition range. Values of Δη in
Figure 3 were negative with a minimum around 40 mol % of
system at various temperatures were calculated and shown in
Table 3. The experimental data of the two systems fitted the
eq 2 very well.
[
EMIM][NTf ] for all temperatures. A minimum of Δη is
2
The density values of the binary mixtures were used to
reached with the mole fraction of this IL near to 0.7 in Figure 4.
It can be concluded that both the temperature and the content
of solvent in IL will affect the viscosities very much.
E
calculate the excess molar volume, V , as
x M + x M
x1M
x2M
2
E
1
1
2
2
1
V =
−
−
The calculated values of Δη were correlated with a Redlich−
ρ
ρ1
ρ2
15
(
(
3)
4)
Kister relation (eqs 4 and 5). The coefficients and the
standard deviation (σ) are presented in Table 6.
m
i
Y = x1x2
∑
A (x − x )
i 1 2
4
. CONCLUSION
New experimental data of density and viscosity for the systems
of [EMIM][NTf ] (1) + NMP (2) and [EMIM][NTf ] (1) +
i=0
2
1/2
2
2
σ(Y) = [
∑
(Ycal − Y ) /(n − m)]
exp
(5)
ethanol (3) were measured over the whole range of
compositions from (293.15 to 323.15) K. The excess molar
E
where V is the excess molar volume of the mixture and M and
1
E
volume V and viscosity deviations Δη were correlated using
M are the molar masses; x and x are the mole fractions of the
2
1
2
the Redlich−Kister polynomial equation. Estimated coefficients
and standard error values are also presented. The results show
that the NMP or ethanol content has a stronger effect on the
physical properties and excess thermodynamic properties of ILs
for the binary systems. The volumetric and transport properties
of the ILs can be significantly varied by adding organic solvents
or changing the temperature to meet the needs of industrial
requirement.
component 1 and component 2; ρ and ρ are the densities
1
2
of component 1 and component 2, respectively. A Redlich−
1
5
Kister relation was used to correlate the excess volume data
(
eqs 4 and 5).
Figures 1 and 2 display the dependence of VE on the
[
EMIM][NTf ] (1) + NMP (2) and the [EMIM][NTf ] (1) +
2
2
ethanol (3) mixtures at various temperatures, respectively. In
Figure 1, the V values are positive and become more positive
E
with increasing temperature. It shows a sharp change at around
E
AUTHOR INFORMATION
Corresponding Author
*Tel.: +86-10-82627080 E-mail address: xpzhang@home.ipe.ac.
cn (X. P. Zhang).
25 mol % NMP. On the contrary, the V values in Figure 2 are
■
negative and become more negative as temperature increases,
E
with the maxima lying nearly at x ≈ 0.25. It is known that V is
1
the result of several opposing effects. Interactions between like
molecules lead to increased V values, while negative contribu-
tions to V arise from interactions between unlike molecules,
E
Funding
E
The authors sincerely appreciate the National Basic Research
Program of China (973 Program) (No. 2009CB13219901), the
or structural effects as changes in free volume, or interstitial
8
80
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Journal of Chemical & Engineering Data
Article
Key Program of National Natural Science Foundation of China
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