The Viscosity and Density of Ionic Liquid + Tetraglyme Mixtures and the Effect of Tetraglyme on CO2 Solubility

Article abstract of DOI:10.1021/acs.jced.6b00596

We show that the addition of tetraglyme (TG), which is a low viscosity liquid with relatively low vapor pressure, is effective in reducing the viscosity of ionic liquids (ILs). In particular, we measure the viscosities of mixtures of 18 ionic liquids with tetraglyme at temperatures between 278.15 and 323.15 K, with a focus on mixtures that are primarily ionic liquid. Thirteen of the ionic liquids contain aprotic heterocyclic anions (AHA ILs) paired with tetra-alkylphosphonium and imidazolium cations, which we have developed for cofluid vapor compression refrigeration and postcombustion CO₂ capture applications. Three bis(trifluoromethylsulfonyl)amide ([Tf₂N]^-) ionic liquids are included for comparison, as well as trihexyltetradecylphosphonium acetate and trihexyltetradecylphosphonium dicyanamide ([P₆₆₆₁₄][acetate] and [P₆₆₆₁₄][DCA]). In addition, we present the densities of trihexyltetradecylphosphonium 1,2,3-triazolide ([P₆₆₆₁₄][3-Triz]) + tetraglyme mixtures at temperatures between 283.15 and 353.15 K. Finally, we show that the solubility of CO₂ in mixtures of [P₆₆₆₁₄][3-Triz] + 30 mol % tetraglyme and trihexyltetradecylphosphonium 1,2,4-triazolide ([P₆₆₆₁₄][4-Triz]) + 30 mol % tetraglyme at 313.15, 333.5, and 353.6 K and pressures to 34 bar can be represented reasonably well by a mole fraction weighted sum of the solubilities (on a mole ratio basis) in the two pure components. (Figure Presented).

Full text of DOI:10.1021/acs.jced.6b00596

Article
pubs.acs.org/jced
The Viscosity and Density of Ionic Liquid + Tetraglyme Mixtures and
the Effect of Tetraglyme on CO2 Solubility
Joseph J. Fillion, Joshua Edward Bennett, and Joan F. Brennecke*
Department of Chemical and Biomolecular Engineering, University of Notre Dame, Notre Dame, Indiana 46556, United States
S
* Supporting Information
ABSTRACT: We show that the addition of tetraglyme (TG), which is a low viscosity liquid
with relatively low vapor pressure, is effective in reducing the viscosity of ionic liquids (ILs). In
particular, we measure the viscosities of mixtures of 18 ionic liquids with tetraglyme at
temperatures between 278.15 and 323.15 K, with a focus on mixtures that are primarily ionic
liquid. Thirteen of the ionic liquids contain aprotic heterocyclic anions (AHA ILs) paired
with tetra-alkylphosphonium and imidazolium cations, which we have developed for cofluid
vapor compression refrigeration and postcombustion CO2 capture applications. Three
bis(trifluoromethylsulfonyl)amide ([Tf2N]−) ionic liquids are included for comparison, as well
as trihexyltetradecylphosphonium acetate and trihexyltetradecylphosphonium dicyanamide
([P66614][acetate] and [P66614][DCA]). In addition, we present the densities of trihexylte-
tradecylphosphonium 1,2,3-triazolide ([P66614][3-Triz]) + tetraglyme mixtures at temperatures
between 283.15 and 353.15 K. Finally, we show that the solubility of CO2 in mixtures of [P66614][3-Triz] + 30 mol % tetraglyme and
trihexyltetradecylphosphonium 1,2,4-triazolide ([P66614][4-Triz]) + 30 mol % tetraglyme at 313.15, 333.5, and 353.6 K and
pressures to 34 bar can be represented reasonably well by a mole fraction weighted sum of the solubilities (on a mole ratio basis)
in the two pure components.
resistances so that we could determine the kinetics of CO2
reacting with amino acid and AHA-based ILs. In this case, the
ILs were very dilute in the tetraglyme, and associated viscosity
measurements were focused on these dilute solutions in that
study.33 Nonetheless, tetraglyme is a very good choice as a
diluent for ILs because it has low vapor pressure34 and low
viscosity.35,36
1. INTRODUCTION
The viscosities of many ILs (salts with melting points below
373.15 K)1 are quite high, leading to poor mass transfer and
increased pumping costs if they were to be used in flow
processes. One way to reduce the viscosity is judicious choice of
cations, anions, and substituents, which is a major reason for the
popularity of ILs containing the bis(trifluoromethylsulfonyl)-
amide ([Tf2N]−) anion.2−4 For cofluid vapor compression
refrigeration and postcombustion CO2 capture applications,
we have developed ILs containing aprotic heterocyclic anions
(AHAs).5−8 Unfortunately, some of the AHA ILs have
relatively high viscosities, especially at low temperatures.2
Therefore, here we consider the use of a low viscosity additive
or diluent as a way to lower the viscosity.
Many research groups have measured properties of ILs mixed
with solvents such as water,9−24 ethanol,12,13,25 diethyl ether,12
acetone,12,25 methanol,25,26 1-methylimidazole,10 toluene,10,24,25
1,4-dimethylbenzene,10 1,2-dimethoxyethane,10 ethanenitrile,10
2-propenenitrile,10 trimethylethanenitrile,10 hexane,12,25,27 ben-
zene,25,27 phenol,27 anisole,27 acetophenone,27 benzoic acid,24,27
methylbenzoate,27 benzaldehyde,27 1-chlorohexane,27 1-hexa-
nol,25,27−29 1-propanol,25,28,29 1-butanol,25,28,29 1-octanol,16,23,28
butyl ethyl ether,27 cyclohexane,25,27 2-hexanone,27 hexanoic
acid,27 methyl pentanoate,27 and 1,4-butanediol.27 Some of the
solvents used were chosen because they are completely miscible
with the ILs, whereas others were chosen because they are
not and might be candidates for separation using the IL in a
liquid−liquid extraction system.12,24,27,30−32 Tetraglyme is not a
common additive for ionic liquids. Our group has previously
used it to reduce viscosity and eliminate mass transfer
A common way to correlate viscosity data as a function of
temperature is the Vogel−Fulcher−Tamman equation,37−39
⎛
⎜
⎝
⎞
⎟
⎠
B
μ = μ exp
o
T − T
(1)
o
where μo, B, and T0 are the fitting parameters. T0 should be
close to the glass transition temperature,40−43 but here it is used
as an adjustable parameter. A discussion of the origin and
theoretical basis of the Vogel−Fulcher−Tamman (VFT)
equation can be found elsewhere.44,45 The modified Vogel−
Fulcher−Tamman equation adds a factor of T0.5 in order to
try to fit experimental data better.15 Subsequently, the Litovitz46
and other equations47 have been proposed by different
researchers.48,49
In addition, there are multiple ways to represent the viscosity
of a mixture of two liquids. Arrhenius50 proposed an equation
based on the logarithm of the viscosity, which is
log(μ ) = x1 log μ1 + x2 log μ2
(2)
m
Received: July 6, 2016
Accepted: January 9, 2017
© XXXX American Chemical Society
A
DOI: 10.1021/acs.jced.6b00596
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Table 1. Structure of the Family of Cations and Anions Investigated in This Study. Bracket Denotes It Is Not a Family of Ions,
But the Specific One Used in This Study
where x1 and x2 are the mole fractions of the two liquids, μ1 and
μ2 are the viscosities of the two pure liquids, and μm is the
viscosity of the mixture. This equation is entirely predictive
and does not always adequately represent experimental data.
Therefore, Grunberg and Nissan51 added an additional term
containing an adjustable parameter, which leads to
properties. Unfortunately, adjustments can improve some
properties while worsening others. For instance, cations with
long alkyl chains, such as [P66614]+, suppress melting points but
are relatively viscous.2 Reducing the size of the cation tends to
reduce the viscosity, but could lead to the appearance of a
melting point. Previously, we have shown2 that the tri-
ethyloctylphosphonium ([P2228]+) cation is a good compromise
for many AHA anions. As mentioned above, AHA ILs with the
[4-NO2pyra]− and [3-Triz]− anions are of particular interest for
cofluid vapor compression refrigeration applications. Unfortu-
nately, the melting point of [P2228][3-Triz] is above room
temperature2 because of easy stacking of the anion, so longer alkyl
chains are required. Moreover, the viscosities of [P66614][3-Triz]
and [P2228][4-NO2pyra] (as well as [P66614][4-NO2pyra]) are
higher than desired, so tetraglyme is investigated as an additive
to reduce the viscosity. The data were fit with the empirical
equations described above in order to estimate how much
tetraglyme would be required to achieve a particular viscosity.
A variety of IL + tetraglyme mixtures are investigated to establish
trends in the data. The effect of tetraglyme on mixture density
and the solubility of CO2 in the mixtures is also of interest.
log(μ ) = x1 log μ1 + x2 log μ2 + x1x2G
(3)
m
where G is a constant for a particular binary mixture.
Alternatively, G can be assumed to be a slight function of tem-
perature.18 Katti and Chaudhri52 incorporated the molar volume
into the equation
W
RT
visc
log(μ Vm) = x1 log(μ V) + x2 log(μ V ) + x1x2
1
2
2
m
1
(4)
where wvisc is the interaction parameter for the activation of flow.
Redlich−Kister46 and other groups53−56 have proposed addi-
tional correlations for the viscosity of mixtures of two liquids.
As mentioned above, the cations and anions of an IL can be
adjusted in numerous ways in order to obtain desired physical
B
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Therefore, we present detailed measurements of density for the
[P66614][3-Triz] + tetraglyme system and CO2 solubility measure-
ments for [P66614][3-Triz] + tetraglyme and [P66614][4-Triz] +
tetraglyme.
[P66614][acetate], [hmim][Tf2N], [P66614][3-Triz], [P44412][3-Triz],
[P2228][4-NO2pyra], [P2228][4-NO2imid], [P2228][2-CH3,
5-NO2imid], [P2224][2-CH3,5-NO2imid], [mm(butene)im]
[4-NO2pyra], [pmmim][4-NO2pyra], [P66614][BrBnim] and
[P66614][4-Triz].2,57 [P66614][DCA] was ordered from Sigma-
Aldrich (95% purity) and dried under vacuum prior to mea-
surements.
2. EXPERIMENTAL SECTION
Materials. Table 1 and Table 2 show the structure, name,
abbreviation, and purity of the ILs used in this work. The materials
and synthesis have been reported previously for [P66614][Tf2N],
The synthesis of [hmmim][Tf2N] involves a two-step
procedure. The first step of mixing dimethylimidazole
(Sigma-Aldrich, 98% purity) with 1-bromohexane (Acros
Organics, 98% purity) takes place in toluene (Sigma-Aldrich,
99.8% purity) at about 273 K for 1 to 2 days. This is the same
alkylation procedure used in our previous work.2 When the
stirring is stopped, the mixture separates into two liquid phases.
More toluene is added, and the toluene-rich phase is decanted.
This process is repeated to remove residual alkyl halide. NMR
confirms the purity of the [hmmim][Br] product. The second
step involves dissolving [hmmim][Br] in water, adding lithium
bis(trifluoromethylsulfonyl)imide (3M, trace impurities) and
stirring overnight. The [hmmim][Tf2N] product is not miscible
with water so it forms a separate liquid phase. The water
containing the LiBr byproduct is removed by decanting. More
water is added and decanted until LiBr is no longer present, as
determined by testing the aqueous phase with AgNO3 solution
and observing no precipitate. [hmmim][Tf2N] is dried on a
vacuum line to remove the remaining water, and then the purity
is determined with NMR spectroscopy. The NMR spectrum for
this IL is shown in the Supporting Information.
Table 2. Materials Used, Including Full Name and
Abbreviation for All Ionic Liquids Investigated
purity
(mass %)
carbon dioxide, Praxair, CAS no.
124-38-9
CO2
99.995
a
2,5,8,11,14-pentaoxapentadecane,
Sigma-Aldrich, CAS no. 143-24-8
tetraglyme, tetraethylene glycol
dimethyl ether
99
a
trihexyl(tetradecyl)phosphonium
4-nitro imidazolide
[P66614][4-NO2imid]
[P66614][4,5-CNimid]
[P66614][Tf2N]
98
b
trihexyl(tetradecyl)phosphonium
99
b
4,5-dicyano imidazolide
trihexyl(tetradecyl)phosphonium
99
bis(trifluoromethylsulfonyl)imi-
b
de
trihexyl(tetradecyl)phosphonium
2-methyl-5-nitro imidazolide
[P66614][2-CH3,5-NO2imid]
[P66614][DCA]
99
95
99
b
trihexyl(tetradecyl)phosphonium
a
dicyanamide, Sigma-Aldrich
1-hexyl-3-methylimidazolium
[hmim][Tf2N]
bis(trifluoromethylsulfonyl)imi-
b
Prior to preparation of any mixtures, the water content of
the IL was measured using a Brinkman 831 Karl Fischer
coulometer. If the water content was high (above weight
fraction of 0.0005), the IL was dried further under vacuum
(∼0.013 Pa at 323 K). Tetraethylene glycol dimethyl ether
(Sigma-Aldrich, 99% purity, IUPAC name 2,5,8,11,14-pentaox-
apentadecane), also known as tetraglyme, was used without
drying unless it was above 0.0005 weight fraction. Each mixture
was made in a glovebox under nitrogen to prevent absorption
of water from the atmosphere and then stirred for about an
hour. The mixture was examined to ensure it was completely
mixed and that only one phase existed. If two phase are present,
no measurements are taken for that overall composition. Prior
to any measurements, the water content of the mixture is
measured to make sure it is below 0.0005 weight fraction.
Viscosity. The viscosity of each mixture was measured with
an ATS viscoanalyzer under a flow of dry nitrogen. A parallel
plate spindle with 30 mm diameter was used, and the gap was
set at 0.300 mm. The stress was varied from 0.1 to 25 Pa.
The instrument requires 0.3−0.4 mL of sample. The estimated
uncertainty is 6%. The lower limit of the viscosity apparatus is
50 mPa·s. Between 50 and 100 mPa·s the viscosity tends to
be overestimated. Above 150 mPa·s, the apparatus tends to
de
trihexyl(tetradecyl)phosphonium
6-bromo-benzimidazolide
[P66614][BrBnim]
[P66614][Acetate]
[hmmim][Tf2N]
99
99
97
b
trihexyl(tetradecyl)phosphonium
b
acetate
1-hexyl-2-methyl-3-methylimidazo-
lium bis(trifluoromethylsulfonyl)
b
imide
trihexyl(tetradecyl)phosphonium
[P66614][4-Triz]
[P66614][3-Triz]
99
99
99
97
95
99
98
95
97
b
1,2,4 triazolide
trihexyl(tetradecyl)phosphonium
b
1,2,3 triazolide
tributyl(dodecyl)phosphonium 1,2,3 [P44412][3-Triz]
b
triazolide
octyltriethylphosphonium 4-nitro
[P2228][4-NO2pyra]
[P2228][4-NO2imid]
b
pyrazolide
octyltriethylphosphonium 4-nitro
b
imidazolide
octyltriethylphosphonium 2-methyl- [P2228][2-CH3,5-NO2imid]
b
5-nitro imidazolide
1-butene-2-methyl-3-methylimida-
[mm(butene)im][4-NO2pyra]
b
zolium 4-nitro pyrazolide
butyltriethylphosphonium 2-methyl- [P2224][2-CH3,5-NO2imid]
b
5-nitro imidazolide
1-propyl-2-methyl-3-methylimidazo- [pmmim][4-NO2pyra]
b
lium 4-nitro pyrazolide
a
b
Used without further purification. Synthesized in house.
a
Table 3a. Viscosity of [P66614][4-NO2imid] Mixed with Tetraglyme at 0.1 MPa and Various Compositions and Temperatures
μ/mPa·s
IL mole
fraction
water content before/after
T/K =
278.15
T/K =
283.15
T/K =
288.15
T/K =
293.15
T/K =
298.15
T/K =
303.15
T/K =
308.15
T/K =
313.15
T/K =
318.15
T/K =
323.15
(weight fraction ×102)
12
0.0173/0.1055
0.0233/0.0597
0.0302/0.0488
3376
1503
443
2222
1036
324
1497
726
1036
522
735
384
135
3.4
533
290
107
2.99
396
222
85
298
173
70
230
138
57
180
111
0.811
0.596
059
240
180
5.91
5.06
4.37
3.84
2.77
2.44
2.24
2.02
a
Standard uncertainties u are u(T) = 0.1 K and u(p) = 0.005 MPa, and relative standard uncertainty ur is ur(μ) = 0.06 for new values reported here.
C
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a
Table 3b. Viscosity of [P66614][4,5-CNimid] Mixed with Tetraglyme at 0.1 MPa and Various Compositions and Temperatures
μ/mPa·s
IL mole
fraction
water content before/after
T/K =
278.15
T/K =
283.15
T/K =
288.15
T/K =
293.15
T/K =
298.15
T/K =
303.15
T/K =
308.15
T/K =
313.15
T/K =
318.15
T/K =
323.15
(weight fraction ×102)
12
0.0151/0.0764
0.0258/0.0430
0.0285/0.0496
2489
1051
389
1628
723
1092
507
754
365
158
535
269
122
391
203
97
291
156
77
220
123
63
171
98
135
79
0.799
0.599
283
209
a
Standard uncertainties u are u(T) = 0.1 K and u(p) = 0.005 MPa, and relative standard uncertainty ur is ur(μ) = 0.06 for new values reported here.
a
Table 3c. Viscosity of [P66614][Tf2N] Mixed with Tetraglyme at 0.1 MPa and Various Compositions and Temperatures
μ/mPa·s
IL mole
fraction
water content before/after
T/K =
278.15
T/K =
283.15
T/K =
288.15
T/K =
293.15
T/K =
298.15
T/K =
303.15
T/K =
313.15
T/K =
323.15
(weight fraction ×102)
12
0.0061/0.0169
0.0259/0.1078
0.0322/0.0458
0.0300/0.0824
0.0226/0.0863
1210
589
281
111
64
841
414
207
85
594
299
157
67
430
221
121
54
318
168
96
241
130
77
145
83
92
60
0.809
0.634
0.441
0.336
52
51
a
Standard uncertainties u are u(T) = 0.1 K and u(p) = 0.005 MPa, and relative standard uncertainty ur is ur(μ) = 0.06 for new values reported here.
a
Table 3d. Viscosity of [P66614][2-CH3,5-NO2imid] Mixed with Tetraglyme at 0.1 MPa and Various Compositions and Temperatures
μ/mPa·s
IL mole
fraction
water content before/after
T/K =
278.15
T/K =
283.15
T/K =
288.15
T/K =
293.15
T/K =
298.15
T/K =
303.15
T/K =
308.15
T/K =
313.15
T/K =
318.15
T/K =
323.15
(weight fraction ×102)
12
0.0193/0.1286
0.0215/0.0725
0.0310/0.0692
5887
2535
595
3730
1685
425
2421
1140
308
1619
791
1114
563
786
411
134
569
306
106
420
232
85
317
179
69
244
141
57
0.849
0.601
228
173
a
Standard uncertainties u are u(T) = 0.1 K and u(p) = 0.005 MPa, and relative standard uncertainty ur is ur(μ) = 0.06 for new values reported here.
a
Table 3e. Viscosity of [P66614][DCA] Mixed with Tetraglyme at 0.1 MPa and Various Compositions and Temperatures
μ/mPa·s
IL mole
fraction
water content before/after
T/K =
278.15
T/K =
283.15
T/K =
288.15
T/K =
293.15
T/K =
298.15
T/K =
303.15
T/K =
308.15
T/K =
313.15
T/K =
318.15
T/K =
323.15
(weight fraction ×102)
158
1646.8
1750
1130
708
1144.9
1210
794
816.36
842
566
370
258
95
592.93
603
413
275
195
75
438.57
442
308
209
151
61
329.68
331
251.71
253
182
128
96
195.00
196
143
103
78
153.15
155
115
83
121.78
124
93
1
0.0068/0.0501
0.0122/0.0519
0.0171/0.0487
0.0156/0.0414
0.0225/0.0651
0.0207/0.1263
0.901
0.797
0.701
0.499
0.348
234
508
162
69
479
348
119
64
54
160
122
73
57
a
Standard uncertainties u are u(T) = 0.1 K and u(p) = 0.005 MPa, and relative standard uncertainty ur is ur(μ) = 0.06 for new values reported here.
underestimate the viscosity by about 3%. The viscosity of the
mixtures were measured from 278.15 to 323.15 K in 5 K
increments. The viscosity of [P66614][DCA] matches previously
published data within the experimental uncertainty.58 A com-
parison of the pure IL viscosities with literature data was
provided in a previous paper.2 The viscosity of pure tetraglyme
was taken from the literature.59 The viscosity of the mixture of
[hmim][Tf2N] with tetraglyme follows the same trend as
observed for this mixture previously at higher temperatures.60
Density. The density of mixtures of [P66614][3-Triz] and
tetraglyme was measured with an oscillating u-tube Anton Paar
4500 densitometer. The instrument requires about 1.7 mL of
sample. Even though the densitometer has a reported uncertainty
of 0.00005 g cm−3, we estimate that based on the purity of
[P66614][3-Triz] the uncertainty in the density measurements is
0.002 g cm−3 with a repeatability (for the same sample of IL) of
0.0001 g cm−3. The densities of the particular batches of pure
[P66614][3-Triz] and tetraglyme used to make the mixtures were
Table 3f. Viscosity of [hmim][Tf2N] Mixed with Tetraglyme
at 0.1 MPa and Various Compositions and Temperatures.
a
The Data Are Consistent with Higher Temperature Mixture
Data Published Elsewhere60
μ/mPa·s
IL mole
fraction
water content before/after
T/K =
278.15
T/K =
283.15
T/K =
288.15
T/K =
293.15
(weight fraction ×102)
12
0.0031/0.0134
0.0053/0.0220
0.0208/0.0429
0.0169/0.0292
0.0148/0.0304
0.0250/0.0272
0.0142/0.0624
203
204
171
130
109
78
150
151
126
97
113
115
96
87
89
74
57
1
0.901
0.810
0.724
0.587
0.456
74
81
63
60
50
a
Standard uncertainties u are u(T) = 0.1 K and u(p) = 0.005 MPa, and
relative standard uncertainty ur is ur(μ) = 0.06 for new values reported
here.
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a
Table 3g. Viscosity of [P66614][BrBnIm] Mixed with Tetraglyme at 0.1 MPa and Various Compositions and Temperatures
μ/mPa·s
IL mole
fraction
water content before/after
T/K =
278.15
T/K =
283.15
T/K =
288.15
T/K =
293.15
T/K =
298.15
T/K =
303.15
T/K =
308.15
T/K =
313.15
T/K =
318.15
T/K =
323.15
(weight fraction ×102)
157
4346
4760
2780
2190
1360
597
1903
1910
1190
972
631
301
164
62
1319
1270
813
675
449
222
125
936
872
572
481
326
167
98
491
441
304
261
185
101
63
278
246
177
155
114
66
1
0.0071/0.1897
0.0322/0.1791
0.0291/0.1351
0.0382/0.1366
0.0414/0.0897
0.0255/0.1771
0.0414/0.1571
7870
4400
3390
2070
954
2960
1780
1440
913
420
220
80
613
413
351
243
129
77
325
230
199
143
81
0.898
0.862
0.782
0.654
0.522
0.362
426
304
51
138
103
a
Standard uncertainties u are u(T) = 0.1 K and u(p) = 0.005 MPa, and relative standard uncertainty ur is ur(μ) = 0.06 for new values reported here.
a
Table 3h. Viscosity of [P66614][Acetate] Mixed with Tetraglyme at 0.1 MPa and Various Compositions and Temperatures
μ/mPa·s
IL mole
fraction
water content before/after
T/K =
278.15
T/K =
283.15
T/K =
288.15
T/K =
293.15
T/K =
298.15
T/K =
303.15
T/K =
308.15
T/K =
313.15
T/K =
318.15
T/K =
323.15
(weight fraction ×102)
12
0.0705/0.3100
0.0729/0.1361
0.0658/0.1500
0.0671/0.1326
0.0681/0.1478
0.0659/0.2437
1820
1160
651
1200
789
462
291
191
121
814
549
332
215
145
92
566
392
244
162
111
73
406
287
184
125
88
298
216
142
99
224
166
112
79
172
130
89
135
103
73
107
84
0.897
0.793
0.701
0.600
0.501
60
401
64
53
257
70
57
176
58
a
Standard uncertainties u are u(T) = 0.1 K and u(p) = 0.005 MPa, and relative standard uncertainty ur is ur(μ) = 0.06 for new values reported here.
a
Table 3i. Viscosity of [hmmim][Tf2N] Mixed with Tetraglyme at 0.1 MPa and Various Compositions and Temperatures
μ/mPa·s
IL mole
fraction
water content before/after
T/K =
278.15
T/K =
283.15
T/K =
288.15
T/K =
293.15
T/K =
298.15
T/K =
303.15
T/K =
308.15
T/K =
323.15
(weight fraction ×102)
1
0.0011/0.0170
0.0189/0.0198
0.0175/0.0266
0.0204/0.0421
0.0250/0.0418
0.0285/0.0556
0.0349/0.0703
485
370
251
161
109
70
335
258
177
116
81
236
184
129
86
172
135
96
129
103
74
99
80
58
78
64
63
52
0.898
0.795
0.694
0.601
0.501
0.401
66
51
61
53
48
a
Standard uncertainties u are u(T) = 0.1 K and u(p) = 0.005 MPa, and relative standard uncertainty ur is ur(μ) = 0.06 for new values reported here.
a
Table 3j. Viscosity of [P66614][4-Triz] Mixed with Tetraglyme at 0.1 MPa and Various Compositions and Temperatures
μ/mPa·s
IL mole
fraction
water content before/after
T/K =
278.15
T/K =
283.15
T/K =
288.15
T/K =
293.15
T/K =
298.15
T/K =
303.15
T/K =
308.15
T/K =
313.15
T/K =
318.15
T/K =
323.15
(weight fraction ×102)
157
3338
2980
2150
1400
1010
691
1390
1320
994
679
508
360
272
167
111
66
1024
918
706
491
374
269
208
128
88
664
654
512
364
281
205
162
101
70
367
354
289
212
169
126
104
66
224
209
176
133
109
83
1
0.0091/0.0830
0.0245/0.2750
0.0170/0.1139
0.0134/0.1600
0.0145/0.1181
0.0330/0.1586
0.0346/0.1823
0.0340/0.2183
0.0346/0.2328
4640
3290
2080
1470
989
1960
1440
961
708
493
366
220
145
85
477
382
275
217
160
129
81
269
223
166
135
102
86
0.954
0.874
0.804
0.751
0.694
0.610
0.516
0.418
709
504
71
415
299
54
259
191
57
163
110
53
a
Standard uncertainties u are u(T) = 0.1 K and u(p) = 0.005 MPa, and relative expanded standard ur is ur(μ) = 0.06 for new values reported here.
measured here in order to obtain as accurate values as possible
with which to calculate the excess molar volumes of the mixtures.
CO2 Solubility. The measurement of CO2 solubility is done
using a custom built high pressure and temperature apparatus
(HPTA). Five mL of sample is required, which is mixed with a
PPI DYNA/MAG mixer that runs continuously, breaking the
gas/liquid interface, and rotates at 2500 rpm. The HPTA uses
a DKN 600 mechanical convention oven that controls the
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Article
temperature between 313.15 and 353.15 K with an uncertainty
of 0.15 K. The HPTA has a pressure range from vacuum
(Welch Chem Star 1400N vacuum pump capable of 0.013 Pa)
to 5.0 MPa. Once the system is evacuated and the temper-
ature is equilibrated, a small amount of CO2 (Praxair, 99.995%
purity) is transferred from a reservoir to the sample cell.
Equilibrium is determined by steady pressure and temperature
in both the reservoir and the sample cell. From the pressure
and temperature of CO2, the molar density is calculated with
the Span Wagner equation of state (EOS).61 This assumes that
the vapor phase in both the reservoir and the sample cell is
pure CO2, which is reasonable since the vapor pressure of
the IL and the TG (tetraglyme) are both extremely small. The
molar density times the volume gives the moles of CO2 present
in each of the vessels, both before and after addition of CO2 to
the sample cell. The amount of moles of CO2 in the liquid is
simply the total moles added from the reservoir minus the
moles of vapor CO2 in the sample cell. From this, the mole
ratio and mole fraction can be determined based on the amount
of liquid sample used. The volume expansion of the liquid can
be measured based on the increase in height of the liquid when
exposed to CO2. The overall standard uncertainty for the
measurements is u(xCO2) = 0.02. However, this overstates the
uncertainty at lower pressures. For mole fractions of CO2 less
than 0.1, the standard uncertainty is closer to u(xCO2) = 0.01.
The solubility of CO2 was measured in pure [P66614][4-Triz]
using a Hiden Intelligent Gravimetric Analyzer. The details of
these measurements are provided elsewhere.11
Table 3l. Viscosity of [P44412][3-Triz] Mixed with
Tetraglyme at 0.1 MPa and Various Compositions and
a
Temperatures
μ/mPa·s
water
content
before/
after
(Weight
fraction
×102)
IL
mole
T/K = T/K = T/K = T/K = T/K = T/K =
278.15 283.15 288.15 293.15 298.15 303.15
fraction
12
0.0220/
0.0420
2660
1980
1230
907
671
361
226
131
73
1660
1260
809
608
458
256
165
98
1060
824
549
419
320
186
124
75
706
557
383
297
231
139
95
484
389
276
218
171
107
74
343
280
203
164
130
84
0.938 0.0300/
0.2600
0.877 0.0280/
0.2145
0.845 0.0236/
0.3170
0.786 0.0226/
0.1946
0.695 0.0202/
0.1597
0.605 0.0330/
0.1860
59
0.505 0.0272/
0.2168
59
0.404 0.0280/
0.2960
57
a
Standard uncertainties u are u(T) = 0.1 K and u(p) = 0.005 MPa, and
relative standard uncertainty ur is ur(μ) = 0.06 for new values reported
here.
3. RESULT AND DISCUSSION
As expected, the viscosities of all 18 ILs decrease with
increasing temperature and increasing tetraglyme composition.
The IL/tetraglyme binary mixture viscosity data was fit using
eq 3, obtaining different values of the empirical parameter,
G, for each temperature (Table 4). Note that if G = 0, this
reduces to eq 2, which is entirely predictive, as long as one has the
pure component viscosities, and indicates that the logarithm of
the viscosity is a linear function of composition (in mole fraction).
The motivation of this study was the addition of small amounts
of tetraglyme to the ILs in order to reduce their viscosities to
values that could be more easily handled in flow equipment.
Therefore, the emphasis in fitting the data was placed on the
mixtures with small amounts of added tetraglyme. In addition,
we chose to use the same number of data points to fit the
G values at each temperature. Therefore, some of the lower
viscosity data points (higher tetraglyme concentrations) were
Viscosity. Each of the 18 ILs was mixed with tetraglyme
and the viscosities measured as a function of temperature and
composition. The results are shown in Tables 3a−3r. The water
content of the samples was measured both before and after the
viscosity measurements and these values are shown in the
tables. Despite efforts to exclude water vapor, all of the samples
increase somewhat in water content over the course of the mea-
surements. Also shown in the tables are previously published
measurements of the viscosities of the pure ILs, when
available.2,57,58 All of the pure IL viscosities match previously
published values within experimental uncertainties except
[P2228][4-NO2pyra]. The sample of [P2228][4-NO2pyra] used
here was part of a 2 L bulk synthesis that was of lower purity
(97%) than the sample used in a previous publication,2 which
can account for the 20% higher viscosity reported here.
a
Table 3k. Viscosity of [P66614][3-Triz] Mixed with Tetraglyme at 0.1 MPa and Various Compositions and Temperatures
μ/mPa·s
IL mole
fraction
water content before/after
T/K =
278.15
T/K =
283.15
T/K =
288.15
T/K =
293.15
T/K =
298.15
T/K =
303.15
T/K =
308.15
T/K =
313.15
T/K =
318.15
T/K =
323.15
(weight fraction ×102)
157
1221
1300
803
707
469
306
201
132
595
611
400
358
250
172
118
80
433
438
294
266
190
134
93
321
321
221
201
147
106
74
186
185
133
123
93
115
116
86
12
0.0294/0.1516
0.0313/0.2263
0.0172/0.1473
0.0205/0.1400
0.0168/0.1210
0.0230/0.2400
0.0244/0.1505
0.0250/0.2200
1970
1180
1030
665
420
271
173
53
878
562
497
339
226
152
102
242
170
156
116
85
145
106
99
0.917
0.878
0.793
0.690
0.602
0.499
0.300
81
76
63
69
57
62
51
65
53
a
Standard uncertainties u are u(T) = 0.1 K and u(p) = 0.005 MPa, and relative standard uncertainty ur is ur(μ) = 0.06 for new values reported here.
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a
Table 3m. Viscosity of [P2228][4-NO2pyra] Mixed with Tetraglyme at 0.1 MPa and Various Compositions and Temperatures
μ/mPa·s
IL mole
fraction
water content before/after
T/K =
278.15
T/K =
283.15
T/K =
288.15
T/K =
293.15
T/K =
298.15
T/K =
303.15
T/K =
308.15
T/K =
313.15
T/K =
318.15
T/K =
323.15
(weight fraction ×102)
12
0.0380/0.1525
0.0080/0.0872
0.0192/0.0742
0.0180/0.1062
0.0152/0.1039
0.0169/0.1110
0.0181/0.0869
0.0215/0.0904
1100
1340
1010
693
395
229
129
78
716
868
666
471
277
166
97
480
578
452
327
199
123
74
333
398
317
234
147
94
238
282
229
172
112
73
175
207
170
130
87
133
155
130
101
69
103
119
101
80
81
94
80
64
65
75
65
52
1
0.949
0.898
0.801
0.700
0.596
0.497
55
58
59
60
a
Standard uncertainties u are u(T) = 0.1 K and u(p) = 0.005 MPa, and relative standard uncertainty ur is ur(μ) = 0.06 for new values reported here.
a
Table 3n. Viscosity of [P2228][4-NO2imid] Mixed with Tetraglyme at 0.1 MPa and Various Compositions and Temperatures
μ/mPa·s
IL mole
fraction
water content before/after
T/K =
278.15
T/K =
283.15
T/K =
288.15
T/K =
293.15
T/K =
298.15
T/K =
303.15
T/K =
308.15
T/K =
313.15
T/K =
318.15
T/K =
323.15
(weight fraction ×102)
12
0.0104/0.1600
0.0075/0.1058
0.0377/0.1291
0.0305/0.1769
0.0281/0.1581
0.0326/0.2385
0.0357/0.2562
1220
1270
700
385
210
125
77
804
838
481
274
153
93
547
569
337
198
114
72
382
398
243
148
87
276
286
180
113
69
204
212
137
88
155
160
107
70
120
124
85
95
98
69
76
78
56
1
0.900
0.800
0.699
0.599
0.499
57
55
56
60
a
Standard uncertainties u are u(T) = 0.1 K and u(p) = 0.005 MPa, and relative standard uncertainty ur is ur(μ) = 0.06 for new values reported here.
Table 3o. Viscosity of [P2228][2-CH3,5-NO2imid] Mixed with Tetraglyme at 0.1 MPa and Various Compositions and
a
Temperatures
μ/mPa·s
IL mole
fraction
water content before/after
T/K =
278.15
T/K =
283.15
T/K =
288.15
T/K =
293.15
T/K =
298.15
T/K =
303.15
T/K =
308.15
T/K =
313.15
T/K =
318.15
T/K =
323.15
(weight fraction ×102)
12
0.0084/0.1628
0.0149/0.1880
0.0457/0.2299
0.0372/0.1897
0.0307/0.1429
0.0280/0.1539
0.0313/0.1332
0.0297/0.1502
0.0320/0.1503
0.0335/0.1900
3720
3660
2730
1990
1470
651
2280
2240
1700
1270
955
1440
1410
1090
829
636
311
187
107
66
940
920
722
559
438
223
137
81
637
623
495
390
310
166
103
64
446
435
350
280
227
126
80
321
313
255
206
170
98
237
231
189
155
130
78
179
174
145
120
101
62
138
135
113
95
1
0.964
0.933
0.885
0.767
0.700
0.601
0.500
0.402
81
446
375
262
64
51
200
145
50
113
86
51
62
a
Standard uncertainties u are u(T) = 0.1 K and u(p) = 0.005 MPa, and relative standard uncertainty ur is ur(μ) = 0.06 for new values reported here.
Table 3p. Viscosity of [mm(butene)im][4-NO2pyra] Mixed with Tetraglyme at 0.1 MPa and Various Compositions and
a
Temperatures
μ/mPa·s
IL mole
fraction
water content before/after
T/K =
278.15
T/K =
283.15
T/K =
288.15
T/K =
293.15
T/K =
298.15
T/K =
303.15
T/K =
308.15
T/K =
313.15
T/K =
318.15
T/K =
323.15
(weight fraction ×102)
12
0.1073/0.1717
0.0768/0.3045
0.0750/0.2522
0.0713/0.2234
0.0724/0.1838
0.1171/0.3747
0.0781/0.4037
0.0690/0.3300
6650
4300
2810
1280
622
3260
2200
1510
737
385
176
97
1720
1210
864
447
249
121
70
973
706
525
288
169
87
590
439
338
195
121
65
380
289
228
138
89
255
204
161
101
69
179
140
117
77
131
104
89
99
81
70
0.952
0.900
0.801
0.701
0.601
0.500
0.400
60
53
267
139
53
70
51
a
Standard uncertainties u are u(T) = 0.1 K and u(p) = 0.005 MPa, and relative standard uncertainty ur is ur(μ) = 0.06 for new values reported here.
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Table 3q. Viscosity of [P2224][2-CH3,5-NO2imid] Mixed with Tetraglyme at 0.1 MPa and Various Compositions and
a
Temperatures
μ/mPa·s
IL mole
fraction
water content before/after
T/K =
278.15
T/K =
283.15
T/K =
288.15
T/K =
293.15
T/K =
298.15
T/K =
303.15
T/K =
308.15
T/K =
313.15
T/K =
318.15
T/K =
323.15
(weight fraction ×102)
12
0.0292/0.1871
0.0497/0.2417
0.0388/0.1875
0.0437/0.2207
0.0510/0.3567
0.0499/0.3198
0.0409/0.3416
2180
1540
972
516
258
134
74
1350
975
631
350
183
99
858
634
421
243
134
74
569
428
291
175
100
57
391
299
208
130
76
277
215
153
99
202
159
116
77
150
121
90
115
94
90
74
57
0.952
0.898
0.799
0.701
0.599
0.499
71
62
60
57
a
Standard uncertainties u are u(T) = 0.1 K and u(p) = 0.005 MPa, and relative standard uncertainty ur is ur(μ) = 0.06 for new values reported here.
a
Table 3r. Viscosity of [pmmim][4-NO2pyra] Mixed with Tetraglyme at 0.1 MPa and Various Compositions and Temperatures
μ/mPa·s
IL mole
fraction
water content before/after
T/K =
278.15
T/K =
283.15
T/K =
288.15
T/K =
293.15
T/K =
298.15
T/K =
303.15
T/K =
308.15
T/K =
313.15
T/K =
318.15
T/K =
323.15
(weight fraction ×102)
12
0.0390/0.2128
0.1110/0.3000
0.1120/0.3012
0.0854/0.3091
0.0324/0.2263
0.0758/0.3245
0.0661/0.2276
0.0617/0.2696
9610
5420
3220
1300
546
4500
2660
1670
743
338
167
88
2270
1400
929
449
218
115
64
1240
798
552
287
149
83
722
487
350
194
106
62
447
314
234
137
79
294
213
163
100
61
200
150
118
76
143
111
90
106
84
0.950
0.900
0.799
0.698
0.601
0.501
0.400
70
59
252
125
65
a
Standard uncertainties u are u(T) = 0.1 K and u(p) = 0.005 MPa, and relative standard uncertainty ur is ur(μ) = 0.06 for new values reported here.
Table 4. Value G, from eq 3, of Various IL + Tetraglyme Mixtures As a Function of Temperature. The ILs Are Ordered from
Highest to Lowest Values of G at 278.15 K
G
T/K =
278.15
T/K =
283.15
T/K =
288.15
T/K =
293.15
T/K =
298.15
T/K =
303.15
T/K =
308.15
T/K =
313.15
T/K =
318.15
[P66614][4-NO2imid]
[P66614][4,5-CNimid]
[P66614][Tf2N]
1.02
1.00
1.01
0.99
1.00
0.98
0.98
0.96
0.86
0.76
0.73
0.93
0.95
0.94
0.95
0.91
0.93
0.93
0.95
0.93
0.75
0.75
0.95
0.90
0.88
[P66614][2-CH3,5-NO2imid]
[P66614][DCA]
0.78
0.78
0.78
0.76
0.73
0.77
0.72
0.74
0.72
0.75
0.74
0.76
0.75
0.74
[hmim][Tf2N]
0.73
0.65
0.61
[P66614][BrBnIm]
0.73
0.70
0.70
0.71
0.63
0.71
0.64
[P66614][Acetate]
0.61
0.60
0.61
[hmmim][Tf2N]
0.57
0.53
0.50
[P66614][4-Triz]
0.49
0.52
0.55
0.58
0.53
0.61
0.56
0.65
0.60
[P66614][3-Triz]
0.42
0.46
0.50
[P44412][3-Triz]
−0.12
−0.31
−0.32
−0.64
−0.68
−0.76
−1.40
−0.06
−0.25
−0.28
−0.56
−0.54
−0.68
−1.20
0.01
0.06
[P2228][4-NO2pyra]
[P2228][4-NO2imid]
[P2228][2-CH3,5-NO2imid]
[mm(butene)im][4-NO2pyra]
[P2224][2-CH3,5-NO2imid]
[pmmim][4-NO2pyra]
−0.19
−0.23
−0.49
−0.41
−0.60
−1.01
−0.12
−0.19
−0.43
−0.30
−0.53
−0.84
−0.68
not used in the data fitting. Also please note that the viscosities
of the pure ILs and the IL/tetraglyme mixtures were measured
in a viscometer whose uncertainty increases greatly for vis-
cosities less than 50 mPa·s. Therefore, measurements are only
reported for mixtures with viscosities greater than 50 mPa·s.
The pure tetraglyme viscosities are taken from the literature.59
This means that fit G values are not reported for all temper-
atures. For instance, for [P66614][3-Triz], the highest temper-
ature for which a G value is reported is 303.15 K, where the
lowest mole fraction of [P66614][3-Triz] is 0.499. The G values
are given for temperatures between 278.15 and 303.15 K,
always using the IL compositions between 0.499 and pure IL.
The G values were determined based on reducing the percent
error between experimental data and the fit. It is not recom-
mended to use eq 3 with the G values in Table 4 for com-
positions between pure tetraglyme and lowest mole fraction of
IL measured because the mixture may not be single phase in
that region.
H
DOI: 10.1021/acs.jced.6b00596
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Journal of Chemical & Engineering Data
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Figure 2. Value of G (eq 3) at 278.15 K as a function of IL molecular
weight (MW).
Figure 3. Value of G (eq 3) at 278.15 K as a function of log(ΔMW/
1000)/ρ, where ΔMW is MWIL − MWTG and ρ is the density of the
IL at 293.15 K.
Figure 1. (a) Viscosities of [pmmim][4-NO2pyra] + tetraglyme
mixtures as a function of temperature at the following [pmmim]
[4-NO2pyra] mole fractions: 1.000, blue circle; 0.950, red square;
0.900, yellow triangel; 0.799, blue X; 0.698, purple asterisk; 0.601,
green diamond; 0.501, open square; and 0.000, red dash. (b) Vis-
cosities of [pmmim][4-NO2pyra] + tetraglyme mixtures as a function
of composition at 278.15 K, purple asterisk; 283.15 K, blue circle;
288.15 K, green diamond; 293.15 K, yellow triangle; and 298.15 K, red
square. The lines are the fits to eq 3, with the G values for the fits given
in Table 4.
Table 6. Slope and Intercept of the Linear Correlation
Shown in Figure 3 for 278.15 K, as Well As the Equivalent
Correlations at Other Temperatures
T/K
slope
intercept
278.15
283.15
288.15
293.15
2.36
2.15
1.96
1.84
1.77
1.65
1.57
1.53
As an example, Figure 1a shows the viscosity of [pmmim]
[4-NO2pyra] + tetraglyme mixtures as a function of temperature.
The solid lines are the VFT fits, with both the pure IL2 and the
mixtures with tetraglyme showing a slight curvature. Figure 1b
shows the same data, plotted as a function of composition at
various temperatures. The G values are fit to the data at constant
temperature and various composition. The G values for
[pmmim][4-NO2pyra] + tetraglyme are negative, which is obvious
from Figure 1b, where the mixture viscosities are values are less
than a straight line between the two pure component viscosities.
Table 5. Properties of Various Ionic Liquids, Including the Molecular Weight, G Value for Mixing with Tetraglyme at 278.15 K,
the Density at 293.15 K, the Viscosity at 278.15 K, and the Slope and Intercept of the Lines Shown in Figure 1
MW
G at 278.15 K
ρ/g cm−3 at 293.15 K
μ/mPa·s at 278.15 K
slope
intercept
[P66614][4-NO2imid]
[P66614][4,5-CNimid]
[P66614][Tf2N]
595.9
600.9
764
1.02
1.00
0.9432
0.9232
1.0692
0.9422
0.90258
1.3782
1.02057
0.8892
1.364
0.90457
0.9012
0.9152
1.0342
1.0322
1.0322
1.1842
1.0682
1.1862
33762
24892
12102
58872
1750
204
−0.0026
−0.0018
−0.0055
−0.0009
−0.0011
−0.0127
0.0009
1.74
1.51
0.95
2.47
[P66614][2-CH3,5-NO2imid]
[P66614][DCA]
610.0
549.9
447.4
683.9
542.9
461.4
551.9
551.9
439.7
343.5
345.5
357.5
263.3
301.4
251.3
0.78
1.04
0.76
1.06
[hmim][Tf2N]
0.73
4.27
[P66614][BrBnIm]
0.73
7870
18202
485
0.45
[P66614][Acetate]
0.61
0.0019
0.06
[hmmim][Tf2N]
0.57
−0.0068
0.0063
2.46
[P66614][4-Triz]
0.49
4640
19702
26602
1340
12202
37202
66502
21802
96102
−1.25
−1.54
−3.58
−3.78
−2.73
−4.54
−7.63
−5.02
−11.35
[P66614][3-Triz]
0.42
0.0071
[P44412][3-Triz]
−0.12
−0.31
−0.32
−0.64
−0.68
−0.76
−1.40
0.0124
[P2228][4-NO2pyra]
[P2228][4-NO2imid]
[P2228][2-CH3,5-NO2imid]
[mm(butene)im][4-NO2pyra]
[P2224][2-CH3,5-NO2imid]
[pmmim][4-NO2pyra]
0.0125
0.0087
0.0140
0.0250
0.0153
0.0358
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a
Table 7. Density of [P66614][3-Triz] Mixed with Tetraglyme at 0.1 MPa and Various Compositions and Temperatures
ρ/g cm−3
IL mole
fraction
water content
T/K =
283.15
T/K =
288.15
T/K =
293.15
T/K =
295.15
T/K =
298.15
T/K =
303.15
T/K =
308.15
T/K =
313.15
(weight fraction ×102)
1
0.0090
0.0203
0.0234
0.0193
0.0204
0.0301
0.0312
0.0182
0.0244
0.0307
0.0192
0.0171
0.0180
0.0126
0.9066
0.9128
0.9166
0.9206
0.9268
0.9348
0.9448
0.9528
0.9565
0.9620
0.9035
0.9097
0.9134
0.9174
0.9235
0.9315
0.9412
0.9491
0.9528
0.9581
1.0008
1.0037
1.0096
1.0156
0.9005
0.9066
0.9103
0.9141
0.9203
0.9281
0.9377
0.9454
0.9492
0.9543
0.9964
0.9992
1.0051
1.0110
0.8993
0.9053
0.9090
0.9129
0.9190
0.9268
0.9363
0.9440
0.9477
0.9528
0.9946
0.9975
1.0033
1.0092
0.8975
0.9035
0.9071
0.9110
0.9170
0.9248
0.9342
0.9417
0.9455
0.8945
0.9004
0.9040
0.9078
0.9138
0.9214
0.9307
0.9381
0.8915
0.8973
0.9009
0.9047
0.9106
0.9180
0.9272
0.9345
0.8885
0.8943
0.8978
0.9016
0.9075
0.9147
0.9237
0.9309
0.850
0.775
0.700
0.600
0.500
0.399
0.330
0.300
0.263
0.050
0.040
0.019
0
1.0082
1.0142
1.0203
1.0006
1.0064
ρ/g cm−3
0.9961
1.0018
0.9916
0.9972
0.9871
0.9926
IL mole
fraction
water content
T/K =
318.15
T/K =
323.15
T/K =
328.15
T/K =
333.15
0.8767
T/K =
338.15
T/K =
343.15
T/K =
348.15
T/K =
353.15
(weight fraction ×102)
1
0.0090
0.0203
0.0234
0.0193
0.0204
0.0301
0.0312
0.0182
0.0180
0.0126
0.8855
0.8826
0.8796
0.8738
0.8708
0.8679
0.8650
0.850
0.775
0.700
0.600
0.500
0.399
0.330
0.019
0
0.8913
0.8948
0.8984
0.9043
0.9114
0.9202
0.9274
0.9826
0.9880
0.8882
0.8917
0.8953
0.9011
0.9080
0.9168
0.9238
0.9781
0.9834
0.8852
0.8886
0.8922
0.8978
0.9047
0.9133
0.9202
0.9736
0.9788
0.8822
0.8855
0.8890
0.8946
0.9014
0.9098
0.9167
0.9691
0.9742
0.8792
0.8824
0.8859
0.8914
0.8981
0.9064
0.9131
0.9646
0.9696
0.8762
0.8794
0.8828
0.8882
0.8947
0.9029
0.9095
0.9601
0.9650
0.8731
0.8763
0.8797
0.8850
0.8914
0.8995
0.9060
0.9556
0.9604
0.8701
0.8733
0.8765
0.8818
0.8881
0.8960
0.9024
0.9511
0.9558
a
Standard uncertainties u are u(T) = 0.01 K, u(p) = 0.005 MPa, and u(ρ) = 0.002 g cm−3.
temperature. All of the negative G values increase with increasing
temperature. ILs with positive G values do not show any clear
trend with temperature. The slopes and intercepts of linear fits
of the G values as a function of temperature can be found in
Table 5 (G = slope × T(K) + intercept).
The G values are positive for all the [P66614]+ ILs. By contrast,
the G values are negative for all the shorter chain tetra-
alkylphosphonium ILs. The [Pnnnm][2-CH3,5-NO2imid] ILs
provide an excellent comparison. The G values for [P66614
]
[2-CH3,5-NO2imid], [P2228][2-CH3,5-NO2imid], and [P2224
]
[2-CH3,5-NO2imid] are 0.8, −0.64, and −0.76 at 273.15 K,
respectively. The G values for the imidazolium ILs are more
varied, with the [Tf2N]− ILs having positive G values but the
mixtures of tetraglyme with imidazolium AHA ILs being less
viscous than the “ideal” mixing model (eq 2). Some under-
standing can be drawn from recent molecular simulation results
for [hmim][Tf2N] + tetraglyme mixtures.60 The simulations
show that the tetraglyme effectively breaks up the interactions
between the cation and the anion, with the oxygen atoms of
the tetraglyme interacting with the acidic hydrogens of the
imidazolium cation. The positive G values for this system can be
interpreted as the cation being a larger specie since it is
associated with tetraglyme. If one assumes that tetraglyme can
also weaken cation−anion interactions for tetra-alkylphospho-
nium cations, then one can envision screening of the cation short
chains from the anion, but the longer alkyl chains extending out
and the viscosity being dominated by van der Waals interactions
between these long alkyl chains. This effect would be dominant
for the largest cations (positive G values for [P66614]+) but less
Figure 4. Excess molar volume of [P66614][3-Triz] mixed with
tetraglyme at various compositions and at 293.15 K, blue circle;
313.15 K, red square; 333.15 K, green diamond; and 353.15 K, yellow
triangle.
The viscosities of all 18 ILs mixed with tetraglyme are
roughly linear functions of composition on a logarithmic scale
for viscosity (i.e., G = 0). Some of the IL + tetraglyme mixtures
are a bit more viscous (G > 0) and some are less viscous (G < 0).
Table 4 shows that the highest to lowest G values at 278.15 K are
[P66614][4-NO2imid], [P66614][4,5-CNimid] < [P66614][Tf2N] <
[P66614][2-CH3,5-NO2imid], [P66614][DCA], [hmim][Tf2N],
[P66614][BrBnIm] < [P66614][acetate] < [hmmim][Tf2N]
<[P66614][4-Triz], [P66614][3-Triz]<[P44412][3-Triz] < [P2228][4-
NO2pyra], [P2228][4-NO2imid] < [P2228][2-CH3,5-NO2imid],
[mm(butene)im][4-NO2pyra] < [P2224][2-CH3,5-NO2imid] <
[pmmim][4-NO2pyra], with the G value of [P44412][3-Triz]
being near 0. Table 4 and Figure S1 (in the Supporting
Information) shows how the G values change with increasing
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DOI: 10.1021/acs.jced.6b00596
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Table 8. Solubility of CO2 (Mole Fraction) In Tetraglyme, [P66614][3-Triz], and [P66614][4-Triz] at 313.15, 333.15, and
a
353.15 K
tetraglyme (TG)
[P66614][3-Triz]
[P66614][4-Triz]
T/K
P/MPa
xCO2
T/K
P/MPa
xCO2
T/K
P/MPa
xCO2
313.15
0.305
0.344
0.726
0.735
1.130
1.269
1.612
1.771
2.190
2.238
2.775
3.210
0.433
0.979
1.512
2.106
2.730
3.365
0.06
0.08
0.15
0.16
0.22
0.25
0.29
0.32
0.37
0.38
0.44
0.48
0.08
0.15
0.22
0.28
0.34
0.40
312.25
0.055
0.123
0.260
0.576
0.846
1.275
1.718
2.036
2.768
3.377
0.11
0.15
0.20
0.28
0.34
0.41
0.45
0.49
0.56
0.60
313.15
0.005
0.015
0.031
0.061
0.123
0.243
0.369
0.504
0.695
1.003
1.509
0.16
0.25
0.31
0.35
0.40
0.44
0.47
0.48
0.51
0.53
0.57
333.3
333.15
0.086
0.230
0.412
0.640
0.974
1.371
1.908
2.326
3.134
0.07
0.12
0.17
0.24
0.30
0.34
0.40
0.46
0.52
333.15
0.006
0.016
0.031
0.061
0.094
0.121
0.243
0.502
0.696
1.008
1.516
0.10
0.17
0.22
0.28
0.31
0.33
0.38
0.44
0.47
0.50
0.54
353.6
0.449
0.931
1.419
1.908
2.548
3.093
0.05
0.10
0.15
0.20
0.25
0.30
353.3
0.132
0.375
0.749
1.404
2.120
2.827
3.358
0.06
0.12
0.18
0.27
0.36
0.42
0.47
a
Standard uncertainties u are u(T) = 0.15 K, u(p) = 0.001 MPa, and u(xCO2) = 0.02 for tetraglyme and [P66614][3-Triz] data. Standard uncertainty u
is u(T) = 0.01 K and relative standard uncertainties ur are ur(p) = 0.00025 and ur(xCO2) = 0.0015 for the [P66614][4-Triz] data.
important for short chains (e.g., [P2224]+), where the reduced
cation−anion interactions dominate and yield a negative G value.
The explanation for the negative G values for the imidazolium
AHA ILs is not obvious. Other researchers55 have suggested that
diluents can both act to solvate the ions, reducing electrostatic
forces between the ions (as has been discussed above), and by
increasing free volume. While we anticipate that excess molar
volumes for all of the IL + tetraglyme mixtures will be small
(see next section), it is possible that is not the case for the
imidazolium AHA systems, for which no mixture density data are
yet available.
In an effort to develop a correlation so that one might be
able to “predict” the viscosity of mixtures of other ILs with
tetraglyme, we start with the observation that G is dependent
on the molecular weight, as shown in Figure 2. Moreover,
Table 5 shows the G values at 278.15 K, the viscosities at
278.15 K, and the densities at 293.15 K of the IL + tetraglyme
mixtures, as well as the molecular weight of the IL. The molec-
ular weight of tetraglyme is 222.28 g/mol and the density of
pure tetraglyme at 293.15 K is 1.011 g cm−3. Figure 3 shows a
linear fit of G versus log(ΔMW × 10−3) ρ−1 at 278.15 K. ΔMW
is the difference between the molecular weight of the IL and
tetraglyme and the 10−3 term is simply a scaling factor. The
density was included to account for the much higher densities
of the imidazolium [Tf2N]− ILs. The graphs of G versus
log(ΔMW × 10−3)ρ−1 are relatively linear at temperatures
between 278.15 and 293.15 K and the slopes and intercepts are
reported in Table 6. The density used at all four temperatures is
the density of the IL at 293.15 K. This is because the pure IL
density changes very little over this temperature range. Since
the slopes and intercepts shown in Table 6 vary systematically
with temperature, they can be further fit as linear functions of
temperature to yield eq 5, which gives an entirely empirical
estimate of the viscosity of IL + tetraglyme mixtures. Obviously,
the molecular weight of the IL must be greater than the
molecular weight of tetraglyme and the correlation was fit for
temperatures from just 278.15 to 293.15 K. Moreover, a limited
number of imidazolium and tetra-alkylphosphonium ILs were
used in the development of this correlation.
G = (−0.0350T(K) + 12.08) × log(ΔMW/1000)
/ρ(293.15K) + (−0.0160T(K) + 6.20)
(5)
Nonetheless, eq 5 gives an equation for G, allowing one to
estimate the viscosity of other ILs mixed with tetraglyme. Of
course, eq 5 should be used with great caution, as a very rough
estimate of mixture viscosity.
Density. Previously it has been shown that the excess molar
volumes of [hmim][Tf2N] + tetraglyme mixtures are very small.60
Here we confirm this observation with one of the [P66614]+ ILs.
K
DOI: 10.1021/acs.jced.6b00596
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Table 9. Solubility of CO2 (Mole Fraction) In an Initial Mixture of 70 mol % [P66614][3-Triz] + 30 mol % Tetraglyme and in an
a
Initial Mixture of 70 mol % [P66614][4-Triz] + 30 mol % Tetraglyme at 313.15, 333.3, and 353.6 K.
[P66614][3-Triz] 0.700/TG
[P66614][4-Triz] 0.700/TG
[P66614][3-Triz] 0.700/TG
[P66614][4-Triz] 0.700/TG
T/K
313.15
P/MPa
xCO2
T/K
313.15
P/MPa
xCO2
T/K
P/MPa
xCO2
T/K
P/MPa
xCO2
0.037
0.079
0.120
0.200
0.379
0.534
0.795
1.231
1.625
2.005
2.353
2.682
0.04
0.06
0.09
0.15
0.20
0.24
0.30
0.38
0.41
0.45
0.49
0.52
0.007
0.030
0.049
0.072
0.092
0.136
0.200
0.288
0.411
0.558
0.716
0.920
1.120
1.372
1.702
2.063
2.533
3.031
0.008
0.018
0.036
0.055
0.077
0.094
0.137
0.203
0.289
0.13
0.20
0.24
0.26
0.29
0.31
0.33
0.36
0.38
0.40
0.42
0.45
0.47
0.49
0.52
0.55
0.58
0.61
0.06
0.10
0.14
0.17
0.20
0.21
0.24
0.27
0.30
2.003
2.360
2.747
0.38
0.41
0.45
0.423
0.568
0.727
0.923
1.131
1.389
1.715
2.064
2.540
3.008
0.016
0.036
0.059
0.088
0.115
0.145
0.206
0.293
0.427
0.571
0.731
0.920
1.138
1.393
1.708
2.065
2.535
3.004
0.33
0.35
0.38
0.41
0.43
0.45
0.47
0.50
0.53
0.56
0.05
0.09
0.12
0.15
0.18
0.19
0.22
0.24
0.28
0.30
0.33
0.35
0.37
0.40
0.42
0.44
0.47
0.49
353.6
0.072
0.128
0.211
0.389
0.551
0.806
1.244
1.491
0.05
0.06
0.08
0.12
0.15
0.18
0.24
0.28
353.6
333.3
0.040
0.082
0.123
0.200
0.383
0.538
0.800
1.258
1.639
0.05
0.06
0.08
0.12
0.16
0.20
0.25
0.31
0.34
333.3
a
Standard uncertainties u are u(T) = 0.15 K, u(p) = 0.001 MPa, and u(xCO2) = 0.02.
Figure 5. Solubility of CO2 in tetraglyme at 313.15 K, blue circle;
333.3 K, yellow triangle; and 353.6 K, red square.
Figure 7. Solubility of CO2 in [P66614][4-Triz] at 313.15 K, blue circle;
and 333.15 K, yellow triangle.
Specifically, we have measured the density of [P66614][3-Triz]
mixed with tetraglyme, and the results are shown in Table 7.
There is a two phase region between IL mole fractions of
roughly 0.072 and 0.263. The phase separation kinetics are
sluggish so there is some uncertainty in these liquid−liquid
phase split composition estimates. Mole fractions near the two-
phase region were measured only at low temperatures because
there is some indication of lower critical solution temperature
behavior. Tetraglyme is more dense than [P66614][3-Triz] and
all of the mixtures have densities between the two pure
components. The excess molar volumes were calculated at each
temperature and mole fraction, and these values are shown in
tabular form in the Supporting Information. The excess molar
Figure 6. Solubility of CO2 in [P66614][3-Triz] at 312.25 K, blue circle;
333.15 K, yellow triangle; and 353.3 K, red square.
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volumes are all positive, as shown in Figure 4. The greatest
excess molar volume value is near a mole fraction of 0.5 of
[P66614][3-Triz] and the values tend to decrease with increasing
temperature. All of the excess molar volumes are quite small,
less than 0.8 cm3 mol−1, consistent with the previously reported
values for [hmim][Tf2N] + TG mixtures.60 These small values
are within the experimental uncertainty of the density mea-
surements, when taking the sample purities into account.
Therefore, no other IL + tetraglyme excess molar volume
measurements were undertaken. This is also why the curves in
Figure 4 do not fit the data perfectly.
CO2 Solubility. The solubility of CO2 in tetraglyme,
[P66614][3-Triz], [P66614][4-Triz], a mixture of 70 mol %
[P66614][3-Triz] + 30 mol % tetraglyme, and 70 mol %
[P66614][4-Triz] + 30 mol % tetraglyme was measured at
313.15, 333.3, and 353.6 K. The solubility data, expressed as
mole fractions, are shown in Tables 8 and 9 and Figures 5−9,
the IL + tetraglyme mixtures is between that of the pure IL and
pure tetraglyme. As expected, the CO2 uptake by the mixtures of
[P66614][4-Triz] + tetraglyme is higher than [P66614][3-Triz] +
tetraglyme because [P66614][4-Triz] has a larger magnitude of
enthalpy of reaction with CO2 than [P66614][3-Triz]. As shown
in the Supporting Information, the solubility of CO2 in the IL +
tetraglyme mixtures can be represented reasonably well by the
following equation:
Zmixture = xILZIL(T, P) + xTGZTG(T, P)
(6)
where Zmixture, ZIL, and ZTG are the solubility of CO2 in the
mixture, the pure IL, and pure tetraglyme, respectively,
expressed as a mole ratio (i.e., moles of CO2/(moles IL +
moles TG), moles of CO2/mols of IL and moles of CO2/mols
of TG). xIL and xTG are the mole fractions of IL and tetra-
glyme in the initial IL + tetraglyme mixture. This indicates
that tetraglyme does not affect the chemical CO2 uptake by
the IL.
CONCLUSIONS
■
Although ionic liquids with aprotic heterocyclic anions (AHA
ILs) show promise for postcombustion and precombustion CO2
capture applications, as well as in cofluid vapor-compression
refrigeration systems, their relatively high viscosities (i.e., higher
than the equivalent [Tf2N]− ILs) present a challenge for mass
and momentum transfer. Here we show that tetraglyme, which
has a relatively low vapor pressure at temperatures of interest for
these applications, is an effective additive in reducing viscosity.
Tetraglyme is most effective in reducing viscosity for short alkyl
chain tetra-alkylphosphonium AHA ILs. Only at very high
tetraglyme compositions for some of the ILs whose cations have
very long alkyl chains (i.e., [P66614]+) are any liquid−liquid phase
splits observed. Excess molar volumes were determined for
one [P66614][AHA] + tetraglyme mixture and the values were
very small. Therefore, it is anticipated that the density of IL +
tetraglyme mixtures can be estimated assuming an ideal solution.
Moreover, the solubility of CO2 in two [P66614][AHA] +
tetraglyme mixtures suggests that it can be safely estimated from
the solubility of CO2 in the two pure liquids.
Figure 8. Solubility of CO2 in [P66614][3-Triz] mixed with 30% mole
fraction of tetraglyme at 313.15 K, blue circle; 333.3 K, yellow triangle;
and 353.6 K, red square.
ASSOCIATED CONTENT
■
S
* Supporting Information
The Supporting Information is available free of charge on the
ACS Publications website at DOI: 10.1021/acs.jced.6b00596.
Figure 9. Solubility of CO2 in [P66614][4-Triz] mixed with 30% mole
fraction of tetraglyme at 313.15 K, blue circle; 333.3 K, yellow triangle;
and 353.6 K, red square.
Details on the NMR characterization of [hmmim]-
[Tf2N], data of excess molar volumes of [P66614][3-Triz]
+ tetraglyme mixtures and CO2 solubility data analysis
(PDF)
where the CO2 solubility increases with increasing pressure and
decreases with increasing temperature. Both [P66614][3-Triz]
and [P66614][4-Triz] can react with CO2, with reported
experimental enthalpies of reaction of −37 and −42 kJ/mol,
respectively.57 This is consistent with density functional theory
calculations that show [P66614][3-Triz] having a smaller
enthalpy of reaction with CO2 than [P66614][4-Triz]. This is
because the negative charge on the anion is more evenly spread
over the anion for [P66614][3-Triz] than [P66614][4-Triz],
which leads to [P66614][[3-Triz] being less nucleophilic than
[P66614][4-Triz]. Therefore, [P66614][3-Triz] has a lower CO2
capacity and lower enthalpy of reaction than [P66614][4-Triz].57
The solubility of CO2 in tetraglyme is significantly less because
tetraglyme does not chemically react with CO2the mech-
anism is simply physical dissolution. The solubility of CO2 in
AUTHOR INFORMATION
■
Corresponding Author
*Tel: (574) 631-5847. Fax: (574) 631-8366. E-mail: jfb@nd.edu.
ORCID
Joan F. Brennecke: 0000-0002-7935-2134
Funding
This material is based upon work supported by the Department
of Energy ARPAe under Award No. AR000019.
Notes
The authors declare no competing financial interest.
M
DOI: 10.1021/acs.jced.6b00596
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Journal of Chemical & Engineering Data
Article
(18) Carvalho, P. J.; Regueira, T.; Santos, L. M. N. B. F.; Fernandez,
J.; Coutinho, J. A. P. Effect of water on the viscosites and densites of 1-
butyl-3-methylimidazolim dicyanamide and 1-butyl-3-methylimidazo-
lium tricyanomethane at atmospheric pressure. J. Chem. Eng. Data
2010, 55, 645−652.
(19) Papaiconomou, N.; Estager, J.; Traore, Y.; Bauduin, P.; Bas, C.;
Legeai, S.; Viboud, S.; Draye, M. Synthesis, Physicochemical
Properties, and Toxicity Data of New Hydrophobic Ionic Liquids
Containing Dimethylpyridinium and Trimethylpyridinium Cations. J.
Chem. Eng. Data 2010, 55, 1971−1979.
(20) Ficke, L. E.; Novak, R. R.; Brennecke, J. F. Thermodynamic and
thermophysical properties of ionic liquid + water systems. J. Chem.
Eng. Data 2010, 55, 4946−4950.
(21) Kunze, M.; Jeong, S.; Paillard, E.; Winter, M.; Passerini, S.
Melting Behavior of Pyrrolidinium-Based Ionic Liquids and Their
Binary Mixtures. J. Phys. Chem. C 2010, 114, 12364−12369.
(22) Jarosik, A.; Krajewski, S. R.; Lewandowski, A.; Radzimski, P.
Conductivity of ionic liquids in mixtures. J. Mol. Liq. 2006, 123, 43−
50.
(23) Domanska, U.; Bogel-Lukasik, E.; Bogel-Lukasik, R. 1-Octanol/
Water Partition Coefficients of 1-Alkyl-3-methylimidazolium Chloride.
Chem. - Eur. J. 2003, 9, 3033−3041.
(24) Huddleston, J. G.; Willauer, H. D.; Swatloski, R. P.; Visser, A. E.;
Rogers, R. D. Room temperature ionic liquids as novel media for
‘clean’ liquid−liquid extraction. Chem. Commun. 1998, 1765−1766.
(25) Eike, D. M.; Brennecke, J. F.; Maginn, E. J. Predicting Infinite-
dilution Activity coefficients of organic solutes in ionic liquids. Ind.
Eng. Chem. Res. 2004, 43, 1039−1048.
(26) Liu, Z.; Wu, W.; Han, B.; Dong, Z.; Zhao, G.; Wang, J.; Jiang,
T.; Yang, G. Study on the Phase Behaviors, Viscosities, and
Thermodynamic Properties of CO2/[C4mim][PF6]/Methanol System
at Elevated Pressures. Chem. - Eur. J. 2003, 9, 3897−3903.
(27) Blanchard, L. A.; Brennecke, J. F. Recovery of Organic Products
from Ionic Liquids Using Supercritical Carbon Dioxide. Ind. Eng.
Chem. Res. 2001, 40, 287−292.
(28) Crosthwaite, J. M.; Aki, S. N. V. K.; Maginn, E. J.; Brennecke, J.
F. Liquid phase behavior of imidazolium-based ionic liquids with
alcohols. J. Phys. Chem. B 2004, 108, 5113−5119.
(29) Crosthwaite, J. M.; Muldoon, M. J.; Aki, S. N. V. K.; Maginn, E.
J.; Brennecke, J. F. Liquid phase behavior of ionic liquids with alcohols:
experimental studies and modeling. J. Phys. Chem. B 2006, 110, 9354−
9361.
(30) Chun, S.; Dzyuba, S. V.; Bartsch, R. A. Influence of Structural
Variation in Room-Temperature Ionic Liquids on the Selectivity and
Efficiency of Competitive Alkali Metal Salt Extraction by a Crown
Ether. Anal. Chem. 2001, 73 (15), 3737−3741.
(31) Dai, S.; Ju, Y. H.; Barnes, C. E. Solvent extraction of strontium
nitrate by a crown ether using room-temperature ionic liquids. J. Chem.
Soc., Dalton Trans. 1999, 1201−1202.
ACKNOWLEDGMENTS
■
We acknowledge Dr. Aruni Desilva, Dr. Mauricio Quiroz-
Guzman, and Dr. Oscar Morales-Collazo for the synthesis of
the ionic liquids, which we describe in more detail in a previous
publication.2 Dr. J. Edward Bennett measured CO2 solubility in
[P66614][4-Triz]. Joseph J. Fillion performed all of the other
measurements.
REFERENCES
■
(1) Plechkova, N. V.; Seddon, K. R. Applications of ionic liquids in
the chemical industry. Chem. Soc. Rev. 2008, 37, 123−150.
(2) Fillion, J. J.; Xia, H.; Desilva, M. A.; Quiroz-Guzman, M.;
Brennecke, J. F. Phase Transitions, Decomposition Temperatures,
Viscosities, and Densities of Phosphonium, Ammonium, and
Imidazolium Ionic Liquids with Aprotic Heterocyclic Anions. J.
Chem. Eng. Data 2016, 61, 2897−2914.
(3) Bonho
̂
te, P.; Dias, A.-P.; Armand, M.; Papageorgiou, N.;
Kalyanasundaram, K.; Gratzel, M. Hydrophobic, Highly Conductive
Ambient-Temperature Molten Salts. Inorg. Chem. 1996, 35, 1168−
1178.
̈
(4) Fredlake, C. P.; Crosthwaite, J. M.; Hert, D. G.; Aki, S. N. V. K.;
Brennecke, J. F. Thermophysical Properties of Imidazolium-Based
Ionic Liquids. J. Chem. Eng. Data 2004, 49, 954−964.
(5) Aki, S. N. V. K.; Mellein, B. R.; Saurer, E. M.; Brennecke, J. F.
High-Pressure Phase Behavior of Carbon Dioxide with Imidazolium-
Based Ionic Liquids. J. Phys. Chem. B 2004, 108, 20355−20365.
(6) Gurkan, B.; Goodrich, B. F.; Mindrup, E. M.; Ficke, L. E.; Massel,
M.; Seo, S.; Senftle, T. P.; Wu, H.; Glaser, M. F.; Shah, J. K.; Maginn,
E. J.; Brennecke, J. F.; Schneider, W. F. Molecular Design of High
Capacity, Low Viscosity, Chemically Tunable Ionic Liquids for CO2
Capture. J. Phys. Chem. Lett. 2010, 1, 3494−3499.
(7) Seo, S.; DeSilva, M. A.; Xia, H.; Brennecke, J. F. Effect of Cation
on Physical Properties and CO2 Solubility for Phosphonium-Based
Ionic Liquids with 2-Cyanopyrrolide Anions. J. Phys. Chem. B 2015,
119, 11807−11814.
(8) Wujek, S. S.; McCready, M. J.; Mozurkewich, G.; Schneider, W.
F.; Elbel, S. Experimental and Modeling Improvements to a Co-Fluid
Utilizing Ionic Liquids and Carbon Dioxide. 15th International
Refrigeration and Air Conditioning Conference, Purdue, 2014, 2501.
(9) Yang, P.; Lau, C.; Liu, X.; Lu, J. Direct Solid-Support Sample
Loading for Fast Cataluminescence Determination of Acetone in
Human Plasma. Anal. Chem. 2007, 79, 8476−8485.
(10) Seddon, K. R.; Stark, A.; Torres, M.-J. Influence of chloride,
water, and organic solvents on the physical properties of ionic liquids.
Pure Appl. Chem. 2000, 72 (12), 2275−2287.
(11) Anthony, J. L.; Maginn, E. J.; Brennecke, J. F. Solution
Thermodynamics of Imidazolium-Based Ionic Liquids and Water. J.
Phys. Chem. B 2001, 105, 10942−10949.
(12) Zhao, D.; Fei, Z.; Scopelliti, R.; Dyson, P. J. Synthesis and
Characterization of Ionic Liquids Incorporating the Nitrile Function-
ality. Inorg. Chem. 2004, 43, 2197−2205.
(32) Carda-Broch, S.; Berthod, A.; Armstrong, D. W. Solvent
properties of the 1-butyl-3-methylimidazolium hexafluorophosphate
ionic liquid. Anal. Bioanal. Chem. 2003, 375, 191−199.
(33) Gurkan, B. E.; Gohndrone, T. R.; McCready, M. J.; Brennecke,
J. F. Reaction kinetics of CO2 absorption in to phosphonium based
anion-functionalized ionic liquids. Phys. Chem. Chem. Phys. 2013, 15,
7796−7811.
(34) Aschenbrenner, O.; Supasitmongkol, S.; Taylor, M.; Styring, P.
Measurement of vapour pressures of ionic liquids and other low
vapour pressure solvents. Green Chem. 2009, 11, 1217−1221.
(35) Kodama, D.; Kanakubo, M.; Kokubo, M.; Hashimoto, S.; Nanjo,
H.; Kato, M. Density; viscosity; and solubility of carbon dioxide in
glymes. Fluid Phase Equilib. 2011, 302, 103−108.
(36) McGee, R. L.; Wallace, W. J.; Rataiczak, R. D. Densities,
Viscosities, Refractive Indices, and Molar Refractions of the Binary
System Tetraethylene Glycol Dimethyl Ether-Water at 25°C. J. Chem.
Eng. Data 1983, 28, 305−307.
(37) Fulcher, G. S. Analysis of Recent Measurements of the Viscosity
of Glasses. J. Am. Ceram. Soc. 1925, 8, 339−355.
(13) Xu, H.; Zhao, D.; Xu, P.; Liu, F.; Gao, G. Conductivity and
Viscosity of 1-Allyl-3-methyl-imidazolium Chloride + Water and +
Ethanol from 293.15 to 333.15 K. J. Chem. Eng. Data 2005, 50, 133−
135.
(14) Fu, D.; Sun, X.; Pu, J.; Zhao, S. Effect of Water Content on the
Solubility of CO2 in the Ionic Liquid [bmim][PF6]. J. Chem. Eng. Data
2006, 51, 371−375.
(15) Rodriguez, H.; Brennecke, J. F. Temperature and composition
dependence of the density and viscosity of binary mixtures of water +
Ionic liquids. J. Chem. Eng. Data 2006, 51, 2145−2155.
(16) Chapeaux, A.; Simoni, L. D.; Stadtherr, M. A.; Brennecke, J. F.
Liquid Phase Behavior of Ionic Liquids with Water and 1-Octanol and
Modeling of 1-Octanol/Water Partition Coefficients. J. Chem. Eng.
Data 2007, 52, 2462−2467.
(17) Ficke, L. E.; Rodriguez, H.; Brennecke, J. F. Heat Capacities and
Excess Enthalpies of 1-Ethyl-3-methylimidazolium-Based Ionic Liquids
and Water. J. Chem. Eng. Data 2008, 53, 2112−2119.
N
DOI: 10.1021/acs.jced.6b00596
J. Chem. Eng. Data XXXX, XXX, XXX−XXX

Journal of Chemical & Engineering Data
Article
(38) Tammann, G.; Hesse, W. Die abhangigkeit der viskositat von
(59) Kodama, D.; Kanakubo, M.; Kokubo, M.; Hashimoto, S.; Nanjo,
H.; Kato, M. Density, viscosity, and solubility of carbon dioxide in
glymes. Fluid Phase Equilib. 2011, 302, 103−108.
̈
̈
dertemperature bei unterkuhlten flussigkeiten. Z. Anorg. Allg. Chem.
̈
̈
1926, 156, 245−257.
(60) Sharma, A.; Zhang, Y.; Gohndrone, T.; Oh, S.; Brennecke, J. F.;
McCready, M. J.; Maginn, E. J. How Mixing Tetraglyme with the Ionic
Liquid 1-n-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)-
imide Changes Volumetric and Transport Properties: An Experimental
and Computational Study. Chem. Eng. Sci. 2016, 159, 43.
(61) Span, R.; Wagner, W. A New Equation of State for Carbon
Dioxide Covering the Fluid Region from the Triple-Point Temper-
ature to 1100 K at Pressures up to 800 MPa. J. Phys. Chem. Ref. Data
1996, 25, 1509−1596.
(39) Vogel, H. Das temperature-abhangigketsgesetz der viskositat
̈
̈
vonflussigkeiten. Phys. Zeit. 1921, 22, 645−646.
̈
(40) Cohen, M. H.; Turnbull, D. Molecular Transport in Liquids and
Glasses. J. Chem. Phys. 1959, 31, 1164−1169.
(41) Gibbs, J. H.; DiMarzio, E. A. Nature of the Glass Transition and
the Glassy State. J. Chem. Phys. 1958, 28, 373−383.
(42) Adam, G.; Gibbs, J. H. On the Temperature Dependence of
Cooperative Relaxation Properties in Glass-Forming Liquids. J. Chem.
Phys. 1965, 43, 139−146.
(43) Rault, J. Origin of the Vogel-Fulcher-Tammann law in glass-
forming materials: the α-β bifurcation. J. Non-Cryst. Solids 2000, 271,
177−217.
(44) Eyring, H. Viscosity, Plasticity, and Diffusion as Examples of
Absolute Reaction Rates. J. Chem. Phys. 1936, 4, 283−291.
(45) Gong, Y.-h.; Shen, C.; Lu, Y.-z.; Meng, H.; Li, C.-x. Viscosity and
density measurements for six binary mixtures of water (methanol or
ethanol) with an Ionic liquid ([bmim][DMP] or [emim][DMP] at
atmospheric pressure in the temperature range of (293.15 to 333.15)
K. J. Chem. Eng. Data 2012, 57, 33−39.
(46) Redlich, O.; Kister, A. T. Algebraic Representation of
Thermodynamic Properties and the Classification of Solutions. Ind.
Eng. Chem. 1948, 40, 345−348.
(47) Ghatee, M. H.; Zare, M.; Moosavi, F.; Zolghadr, A. R.
Temperature-Dependent Density and Viscosity of the Ionic Liquids 1-
Alkyl-3-methylimidazolium Iodides: Experiment and Molecular
Dynamics Simulation. J. Chem. Eng. Data 2010, 55, 3084−3088.
(48) Seoane, R. G.; Corderi, S.; Gomez, E.; Calvar, N.; Gonzalez, E.
J.; Macedo, E. A.; Dominguez, A. Temperature Dependence and
Structural Influence on the Thermophysical Properties of Eleven
Commercial Ionic Liquids. Ind. Eng. Chem. Res. 2012, 51, 2492−2504.
(49) Navia, P.; Troncoso, J.; Romani, L. Viscosities for Ionic Liquid
Binary Mixtures with a Common Ion. J. Solution Chem. 2008, 37, 677−
688.
(50) Arrhenius, S. Z. Phys. Chem. 1887, 1, 285.
(51) Grunberg, L.; Nissan, A. H. Mixture Law for Viscosity. Nature
1949, 164, 799−800.
(52) Katti, P. K.; Chaudhri, M. M. Viscosities of Binary Mixtures of
Benzyl Acetate with Dioxane, Aniline, and m-Cresol. J. Chem. Eng.
Data 1964, 9, 442−443.
(53) Domanska, U.; Krolikowska, M.; Walczak, K. Effect of
temperature and composition on the density, viscosity surface tension
and excess quantities of binary mixtures of 1-ethyl-3-methylimidazo-
lium tricyanomethanide with thiophene. Colloids Surf., A 2013, 436,
504−511.
(54) Comminges, C.; Barhdadi, R.; Laurent, M.; Troupel, M.
Determination of viscosity, ionic conductivity, and diffusion coeffients
in binary system: ionic liquids + molecular solvents. J. Chem. Eng. Data
2006, 51, 680−685.
(55) Lopes, J. N. C.; Gomes, M. F. C.; Husson, P.; Padua, A. A. H.;
Rebelo, L. P. N.; Sarraute, S.; Tariq, M. Polarity, Viscosity, and Ionic
Conductivity of Liquid Mixtures Containing [C4C1im][Ntf2] and a
Molecular Component. J. Phys. Chem. B 2011, 115, 6088−6099.
(56) Anouti, M.; Jacquemin, J.; Porion, P. Transport Properties
Investigation of Aqueous Protic Ionic Liquid Solutions through
Conductivity, Viscosity, and NMR Self-Diffusion Measurements. J.
Phys. Chem. B 2012, 116, 4228−4238.
(57) Seo, S.; Quiroz-Guzman, M.; DeSilva, M. A.; Lee, T. B.; Huang,
Y.; Goodrich, B. F.; Schneider, W. F.; Brennecke, J. F. Chemically
Tunable Ionic Liquids with Aprotic Heterocyclic Anion (AHA) for
CO2 Capture. J. Phys. Chem. B 2014, 118, 5740−5751.
(58) Neves, C. M. S. S.; Carvalho, P. J.; Freire, M. G.; Coutinho, J. A.
P. Thermophysical properties of pure and water-saturated tetradecyl-
trihexylphosphonium-based ionic liquids. J. Chem. Thermodyn. 2011,
43, 948−957.
O
DOI: 10.1021/acs.jced.6b00596
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