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Accepted Manuscript
Improvement the viscosity of imidazolium-based ionic liquid
using organic solvents for biofuels
Fuxin Yang, Xiaopo Wang, Houzhang Tan, Zhigang Liu
PII:
DOI:
Reference:
S0167-7322(17)33777-7
doi:10.1016/j.molliq.2017.10.107
MOLLIQ 8070
To appear in:
Journal of Molecular Liquids
Received date:
Revised date:
Accepted date:
20 August 2017
6 October 2017
23 October 2017
Please cite this article as: Fuxin Yang, Xiaopo Wang, Houzhang Tan, Zhigang Liu ,
Improvement the viscosity of imidazolium-based ionic liquid using organic solvents for
biofuels. The address for the corresponding author was captured as affiliation for all
authors. Please check if appropriate. Molliq(2017), doi:10.1016/j.molliq.2017.10.107
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ACCEPTED MANUSCRIPT
Improvement the viscosity of imidazolium-based ionic liquid
using organic solvents for biofuels
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Fuxin Yang, Xiaopo Wang*, Houzhang Tan, Zhigang Liu
Key Laboratory of Thermo-Fluid Science and Engineering, Ministry of Education,
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Xi’an Jiaotong University, Xi’an, Shaanxi 710049, China
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* Corresponding author: Xiaopo Wang.
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Tel: +86 (0)29-82668210; Fax: +86 (0)29-82663584; E-mail: wangxp@xjtu.edu.cn.
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Abstract
Imidazolium-based ionic liquids have been attracted enormous attention in making
biofuels from biomass. Due to the high viscosity, the organic solvent in general is
applied to improve the properties of the ionic liquids. In this work, the promising
substances of N,N-dimethylacetamide (DMA), N,N-dimethylformamide (DMF),
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dimethyl sulfoxide (DMSO) and pyridine (PYR) are selected to investigate for the
ionic liquid of 1-butyl-3-methylimidazolium chloride. The kinematic viscosity is
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measured by an Ubbelohde capillary viscometer at atmospheric pressure (0.0967 MPa)
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from 303.15 K to 353.15 K. The Vogel-Fulcher-Tammann equation is introduced to
correlate the viscosity. The experimental results are used to quantitatively analyze the
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effects on the viscosity of ionic liquid. Toward further understanding the interactions
between the ionic liquid and the organic solvents, the viscosity deviation is calculated,
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and the ideal Grunberg-Nissan equation is performed to check divergence from the
ideal. Moreover, Fourier transform infrared spectroscopy (FTIR) is used to study the
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structure of the sample.
Keywords: 1-butyl-3-methylimidazolium chloride; organic solvent; kinematic
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viscosity; FTIR
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1 Introduction
Ionic liquids (ILs) are considered as the green alternatives for the conventional
solvents [1]. Recently, due to their specific properties, ILs have received enormous
attention and are widely investigated in industrial applications, especially in
renewable energy by making biofuels from biomass [2, 3]. ILs can satisfy the target
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properties, e.g. high thermal stability, low vapor pressure and low volatility, large
liquidus range, and excellent solubility of organic substances, by the introduction of
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functional groups, or simple re-arrangement and combination of the available organic
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or inorganic cations and organic anions [4, 5]. There characteristics make the ILs
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more designable and diverse [1].
Rogers et al., as a pioneer, firstly reported that ILs are good solvents for biomass
especially
the
acetate-/chloride-based
imidazolium
ILs
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dissolution,
(1-alkyl-3-methylimidazolium acetate/chloride, [Cnmim][Ac]/[Cnmim][Cl], where n is
the number of carbon in alkyl chain) [6]. However, the viscosity of [Cnmim][Cl] is
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high in general and that will hinder the dissolution processes. Prausnitz et al. proposed
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to use organic solvents to improve the viscosity of the ILs [7]. And more studies are
then focusing on the use of ILs with organic solvents to make biofuels [8-10].
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However, little attention has been given to quantitatively study the improvement on
the thermophysical properties, especially the viscosity of ILs by using organic
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solvents. Heinze et al. tailored 18 organic co-solvents for minimizing the effects of
high viscosities and for homogeneous derivatization of cellulose, one of the major
components in the biomass, and it is suggested that suitable co-solvents should
possess appropriate solvatochromic parameters [11]. In the studied 18 solvents, four
of them, N,N-dimethylacetamide (DMA), N,N-dimethylformamide (DMF), dimethyl
sulfoxide (DMSO) and pyridine (PYR), show promising to facilitate the miscibility of
IL/cellulose for making biofuels.
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In this work, four organic solvents (i.e. DMA, DMF, DMSO and PYR) are selected to
study for improving the viscosity of 1-butyl-3-methylimidazolium chloride
([C4mim][Cl]). The viscosities of pure IL and pure solvents are determined as well as
the binary mixtures of IL with solvents at atmospheric pressure (0.0967 MPa) from
303.15 K to 353.15 K. The effect of organic solvents on the viscosity of IL is
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quantitatively analyzed and discussed. Moreover, Fourier transform infrared
spectroscopy (FTIR) is performed to get an insight into the micro-structure of the
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binary mixture aiming to further understand the relationship between the properties
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and the structures.
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2 Experimental section
2.1 Materials
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The details of the studied substances in this work are given in Table 1. The organic
solvents of DMA, DMF, DMSO and PYR were received from Sigma-Aldrich (St
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Louis, MO). The initial mass fraction purities of the solvents were more than 0.98,
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and all of them were used without further purification. The studied IL of [C4mim][Cl]
was synthesized by the Center for Green Chemistry and Catalysis (CGCC), Lanzhou
Institute of Chemical Physics, Chinese Academy of Sciences (CAS). The IL was
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purified before the use.
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2.2 Sample purification and preparation procedure
The impurities would affect the measured thermophysical properties, especially the
viscosity. In order to alleviate the effects, 3A molecular sieves (from Sigma-Aldrich,
St Louis, MO) were performed to the IL for purification, especially for removing the
moisture. Before the use, acetone and methanol were applied to clean the sieves and
eliminate the impurities. The sieves were then put into a furnace set at 473.15 K to dry
for overnight. The IL with the well-prepared sieves was stable in a vacuum oven at
353.15 K for more than 24 hours with a pressure of 2.0 ± 0.1 kPa. The water contents
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in the samples were determined by a Karl Fischer moisture titrator (Coulometric
titration, MKC-710B, Kyoto Electronics Manufacturing Co., Ltd.) before and after the
experimental measurement, and the value of the water content in the sample detected
was less than 0.3 wt. %. More procedure details are presented in the previous
publications [12, 13].
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The binary samples of IL with organic solvents were prepared by gravity using the
analytical balances (ME204 and AB204-N, Mettler-Toledo) with the uncertainty of
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0.0001 g.
2.3 Viscosity measurements
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The kinematic viscosities of the pure substances and the binary mixtures were
determined by an Ubbelohde capillary viscometer (9721-R50, 9721-R56, 9721-R62,
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9721-R71, 9721-R77 and 9721-R83) purchased from Cannon Instrument Company
(State College, PA, USA). Before the experiment, the capillary viscometer was
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cleaned by acetone/methanol, and the viscometer constant was calibrated using the
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viscosity standards obtained from Cannon Instrument Company. When the viscometer
was filled with the solution studied, it was soaked in an oil bath controlled by a
thermostat (LAUDA ECO Silver, Germany) with an uncertainty of 0.01 K. The efflux
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time of the sample through the capillary was recorded by an electronic stopwatch with
an uncertainty of 0.01 s. The kinematic viscosities were calculated by the
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multiplication of the efflux time with the viscometer constant. During the
measurement, the viscosity was determined in triplicate and, the average was received.
Considering the impurities of the sample, the mixture preparation and measurement
procedure, the relative expanded uncertainty of the viscosity in this work is specified
as less than 0.08 with the confidence level of 0.95.
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2.4 FTIR measurements
The Bruker Vertex 70 with the detector of DTGS & LN MCT was applied to obtain
the infrared spectra. The wave number accuracy was 0.01 cm-1. The Vertex 70 was
equipped with optical components to cover the entire spectral ranges from 350-8000
cm-1, and the spectral resolution was specialized to a non-apodized resolution of less
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than 0.16 cm-1 that is sufficient even for gaseous samples at normal pressure, since the
typical natural line width is more than 0.2 cm-1. From the acquired spectra, the
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baseline correction was applied [14].
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3.1 Experimental viscosity data
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3 Results and discussions
The experimental viscosities of pure IL and the binary mixtures measured at
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atmospheric pressure from 303.15 K to 353.15 K are tabulated in Tables 2-5. The
Vogel-Fulcher-Tammann (VFT) equation characterizing the glass forming liquids is
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applied to correlate the viscosity data using the following equation:
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(1)
where ν (mm2·s-1) is the kinematic viscosity; T (K) is the temperature; A
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(mm2·s-1·K-0.5), k (K), and T0 (K) are the fitted parameters determined from the
measured viscosities. The measured fluid is considered to exist as an equilibrium
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glass where the mass transporting motions are frozen [15]. The empirical parameter of
T0 (K) is defined as the ―ideal glass transition temperature‖, a temperature that should
be lower than the experimental glass transition temperature, and it cannot reach in a
finite time scale experiment [13, 15].
The average absolute relative deviation (AARD) between the measured viscosity and
the calculated value using the VFT equation is determined by the following equation:
∑
|
|
(2)
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where N is the number of experimental points, ηexp and ηcal are the experimental and
calculated data, respectively.
The fitted parameters for VFT equation with the AARD are summarized in Table 6.
The total AARD is 0.35%; obviously, the calculated values agree well with the
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measured viscosities, and no significant divergences are observed.
3.2 Effect of organic solvent on improving the viscosity of IL
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Figures 1-4 depict the viscosity of IL with the organic solvents at atmospheric
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pressure as a function of mole fraction. The viscosity of pure IL at 303.15 K and
atmospheric pressure is 6040.34 mm2·s-1, while the corresponding value of water is
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0.811 mm2·s-1 [16]. It is shown that IL is three orders of magnitude more viscous than
water. In Figures 1-4, when the mole fraction of DMA is 0.096 (corresponds to 0.05
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in mass), at 303.15 K, the viscosity of pure IL decreases from 6040.34 mm2·s-1 to
3084.23 mm2·s-1; when the mole fraction of DMA is 0.184 (corresponds to 0.10 in
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mass), the viscosity of pure IL decreases from 6040.34 mm2·s-1 to 1447.06 mm2·s-1;
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when the mole fraction of DMA is 0.336 (corresponds to 0.20 in mass ), the viscosity
of pure IL decreases from 6040.34 mm2·s-1 to 319.25 mm2·s-1, indicating that a little
volume of solvent added would significantly improve the viscosity of pure IL. Similar
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behaviors are observed for the other solvents of DMF, DMSO and PYR with pure IL.
Moreover, when the mole fraction of solvent is more than 0.400 (corresponds to
in mass), the viscosity of pure IL would be not improved tremendously. Figure
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∼0.23
5 presents the viscosities of [C4mim][Cl] with organic solvents of DMA, DMF,
DMSO and PYR at 303.15 K and atmospheric pressure. Clearly, it is observed that
the solvents of DMF and DMSO have the largest and smallest effects on the viscosity
of pure IL, respectively.
Toward better understanding the effect of organic solvent on the viscosity of pure IL,
the viscosity deviation is introduced:
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∑
(3)
where ∆ν is viscosity deviation; νm is the kinematic viscosity of the binary mixture; xi
and νi are the mole fraction and the corresponding kinematic viscosity of pure
component i, respectively.
Figures 6-9 give the viscosity deviations of [C4mim][Cl] with solvents at atmospheric
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pressure. All of the binary mixtures show the negative values at the studied mole
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fraction and temperature, and the absolute values of the deviations increase with the
decrease of the temperature. Moreover, the curves are asymmetric and the minimum
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values occur at IL-rich ranges. Figure 10 presents the viscosity deviations of
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[C4mim][Cl] with solvents of DMA, DMF, DMSO and PYR at 303.15 K and
atmospheric pressure. In the four binary mixtures, the system of IL with DMF shows
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the largest negative deviations, while the system of IL with DMSO exhibits the
smallest negative deviations. The viscosity of the fluid substance is generally
determined by how the molecules constitute the samples, and the minimum values can
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be construed by the interactions between the pure IL and the organic solvents,
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especially the hydrogen-bonding interactions [12].
Moreover, the viscosity of the binary mixture can be obtained by the viscosity of pure
(4)
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∑
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component using the ideal Grunberg-Nissan equation,
where νm is the kinematic viscosity of binary system, xi and νi are the mole fraction
and the corresponding kinematic viscosity of component i, respectively.
The ideal Grunberg-Nissan equation applied here is to check the deviations between
the realistic systems and the ideal binary mixtures. Figures 11-14 show the relative
deviations for the viscosities of [C4mim][Cl] with solvents from the ideal mixtures. It
is not surprising that the ideal equation fails to correlate the viscosities of the binary
mixtures. The AARD for IL with DMA is 9.46%, for DMF is 12.35%, for DMSO is
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19.39%, for PYR is 14.10%. It seems that the system of IL with DMSO performs the
large divergence from the ideal.
3.3 FTIR studies
The infrared spectra are presented in Figures 15-16 with the ranges from 2600-3800
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cm-1 and 1100-1800 cm-1, and the mole fractions of DMA, DMF, DMSO and PYR in
these binary mixtures are 0.336, 0.374, 0.359 and 0.356 (corresponds to 0.20 mass
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fraction of organic solvents), respectively. Due to the hygroscopic characteristic of
pure IL, the O-H stretching bands, mainly originated from the absorbed water are
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observed at ∼3400 cm-1 and ∼1636 cm-1 in FTIR spectra of pure IL and the binary
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mixtures [14]. At ∼3400 cm-1, the pure IL possesses the highest value of the
absorbance, while the binary mixture of IL with PYR has the lowest value. At ∼1636
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cm-1, the mixture of IL with DMF displays a blue shift of ∼26 cm-1 (a shift to ∼1662
cm-1) in the peak position of the O-H bending vibration, indicating the strengthening
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of the hydrogen-bonding [14, 17].
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The bands discovered at the ranges of 2800-3200 cm-1 are contributed to the C-H
stretching vibrations and overtones of aromatic ring [14, 18]. In these studied ranges,
a red shift is observed for the binary mixture of IL with PYR at ∼3145 cm-1 and the
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peak is shifted to 3139 cm-1 that is assigned to the anti-symmetric stretching vibration
of C4-H [14, 18, 19]. The shift detected indicates that C4-H in the IL and the solvent
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of PYR may form the weakest hydrogen-bonding. The hydrogen-bonding formations
of C-H originated from IL with the other solvents of DMA, DMF and DMSO do not
show significant distinction [20]. In addition, due to the zero value of the solvent
acidity, the four solvents lack the ability to act as hydrogen-bond donor and that is
less likely to disrupt the interactions between the Cl- ion and the imidazolium protons
[13, 21]. Remsing et al. employed the NMR to illustrate the solvation and aggregation
of IL in DMSO and, suggested that the interactions between the Cl- ion and the
imidazolium cation seem to be strengthened in the presence of the solvent of DMSO
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[21]. The more factors influencing the viscosity of the mixture may be the
ion-dipole/dipole–dipole interactions between the solvents and the IL as well as the
amount of free volume in the solution [22-24].
Moreover, there are several studies indicating that organic solvents with high
dielectric constant will be more likely to reduce the electrostatic attraction between
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ions of the IL and consequently reduce the viscosity distinctly [22]. It is noted that, at
298.15 K, the dielectric constant for DMA is 38.25 [25], for DMF is 36.71 [22], for
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DMSO is 46.2 [26], for PYR is 12.04 [27]. Nevertheless, DMSO possesses the largest
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dielectric constant among the studied solvents, however, DMSO does not have the
largest effect on the viscosity of IL and that is contradictory with the prediction only
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from the dielectric constant.
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4 Conclusions
IL of [C4mim][Cl] has received enormous attention and is widely studied in
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renewable energy by making biofuels from biomass. The high viscosity of
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[C4mim][Cl] would impede the process of decomposing the biomass, and the organic
solvents of DMA, DMF, DMSO and PYR are introduced to perfect the viscosity of
the pure IL. The viscosities for the pure substances as well as the binary mixtures of
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IL with organic solvents are determined at atmospheric pressure from 303.15 K to
353.15K using an Ubbelohde capillary viscometer. It is shown that a little volume of
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solvent added would significantly reduce the viscosity of pure IL, and the solvent of
DMF has the largest effects on the viscosity of pure IL. The viscosity deviations of
[C4mim][Cl] with solvents exhibit the negative values at the studied mole fraction and
temperature. The absolute values of the deviations increase with the decrease of the
temperature. The red shift detected by FTIR indicates that C4-H in the IL and the
solvent of PYR may form the weakest hydrogen-bonding. And the hydrogen-bonding
formations of C-H originated from IL with the other solvents of DMA, DMF and
DMSO do not show significant distinction.
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Acknowledgements
The work is supported by the National Natural Science Foundation of China (No.
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51606147) and the Fundamental Research Funds for the Central Universities.
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Tables
Table 1 Descriptions of the substances studied in this work
Initial
Substance
Abbreviation
CAS No.
Source
Mass
Purification
Fraction
Method
Purity
1-butyl-3-methylimidazolium
171058-17-6
Academy
of
≥0.98
drying
≥0.98
none
≥0.99
none
≥0.99
none
≥0.998
none
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chloride
[C4mim][Cl]
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Chinese
Sciences
Sigma -
DMA
127-19-5
N,N-dimethylformamide
DMF
68-12-2
dimethyl sulfoxide
DMSO
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N,N-dimethylacetamide
pyridine
PYR
110-86-1
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67-68-5
12
Aldrich
Sigma Aldrich
Sigma Aldrich
Sigma Aldrich
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Table 2 Experimental viscosities of [C4mim][Cl] with organic solvent of DMA
x [C4mim][Cl] + (1 - x) DMA, ν / mm2·s-1
x
0.816
0.538
0.428
0.332
0.177
0.000
303.15 6040.34 3084.23 1447.06 319.25
97.82
37.18
16.06
4.25
0.96
308.15 3462.71 1871.65
920.26
223.38
74.00
29.67
13.51
3.77
0.90
313.15 2093.88 1185.26
607.13
160.51
57.00
24.14
11.45
3.39
0.85
318.15 1313.74
772.92
412.71
119.49
44.88
20.02
9.88
3.07
0.81
323.15
867.13
524.35
288.52
90.34
36.20
328.15
581.85
366.56
208.36
70.02
29.58
333.15
403.71
261.73
154.78
55.15
338.15
288.01
192.15
116.78
44.31
343.15
210.90
143.45
90.10
35.96
348.15
157.76
110.09
70.51
353.15
120.81
85.46
56.36
8.54
2.79
0.76
14.22
7.49
2.55
0.73
24.40
12.21
6.60
2.35
0.69
20.45
10.57
5.87
2.17
0.66
17.32
9.23
5.26
2.01
0.63
29.68
14.82
8.13
4.74
1.86
0.61
12.80
7.22
4.29
1.74
0.58
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16.77
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0.904
24.79
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1.000
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0.664
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T/K
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Table 3 Experimental viscosities of [C4mim][Cl] with organic solvent of DMF
x [C4mim][Cl] + (1 - x) DMF, ν / mm2·s-1
x
0.626
0.493
0.385
0.295
0.151
0.000
303.15 6040.34 2267.47 954.72
191.40
56.42
21.42
9.51
4.76
0.82
308.15 3462.71 1435.49 629.94
139.77
45.80
17.73
8.29
4.36
0.77
313.15 2093.88
976.64
429.63
104.02
35.94
14.92
7.24
4.01
0.74
318.15 1313.74
669.13
301.89
79.45
29.03
12.69
6.36
3.68
0.70
323.15
867.13
469.22
217.84
61.83
23.86
10.90
5.65
3.39
0.67
328.15
581.85
338.59
160.47
49.05
19.91
9.49
5.04
3.14
0.64
333.15
403.71
249.20
119.96
39.42
16.82
8.33
4.55
2.93
0.62
338.15
288.01
187.87
92.38
32.20
14.36
7.30
4.11
2.74
0.59
343.15
210.90
142.59
72.60
26.75
12.40
6.50
3.75
2.56
0.57
348.15
157.76
111.29
57.95
22.36
10.79
5.83
3.42
2.41
0.55
353.15
120.81
88.15
46.34
5.24
3.14
2.27
0.53
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0.887
19.10
AC
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1.000
14
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0.790
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T/K
9.47
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Table 4 Experimental viscosities of [C4mim][Cl] with organic solvent of DMSO
x [C4mim][Cl] + (1 - x) DMSO, ν / mm2·s-1
x
0.801
0.510
0.401
0.309
0.161
0.000
303.15 6040.34 3300.50 1754.67 461.34
153.99
59.71
26.31
8.43
1.65
308.15 3462.71 1973.13 1092.08 310.92
112.47
43.81
20.60
6.67
1.53
313.15 2093.88 1238.20
710.07
218.97
83.25
35.51
16.82
5.32
1.42
318.15 1313.74
806.48
474.09
157.65
63.33
27.52
14.03
4.68
1.31
323.15
867.13
541.53
328.72
116.32
49.01
328.15
581.85
377.12
234.00
88.39
39.03
333.15
403.71
268.10
170.64
67.89
338.15
288.01
194.87
127.82
343.15
210.90
145.70
348.15
157.76
353.15
120.81
11.81
4.29
1.22
18.52
10.07
3.71
1.14
31.56
15.48
8.68
3.34
1.06
53.22
25.75
13.14
7.57
3.03
1.00
97.51
42.53
21.49
11.24
6.64
2.75
0.94
111.46
75.78
34.62
17.99
9.73
5.89
2.52
0.89
86.42
60.00
15.31
8.49
5.25
2.32
0.84
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22.39
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0.894
28.55
AC
CE
PT
E
D
1.000
RI
0.641
PT
T/K
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Table 5 Experimental viscosities of [C4mim][Cl] with organic solvent of PYR
x [C4mim][Cl] + (1 - x) PYR, ν / mm2·s-1
x
0.514
0.404
0.313
0.163
0.000
303.15 6040.34 2890.50 1193.52 286.89
85.19
32.22
13.90
3.65
0.87
308.15 3462.71 1763.00
783.03
204.77
65.69
26.16
11.75
3.27
0.81
313.15 2093.88 1124.46
527.71
150.35
51.44
21.58
10.09
2.96
0.77
318.15 1313.74
742.37
365.76
112.69
40.93
18.01
8.73
2.70
0.73
323.15
867.13
503.90
260.02
85.86
33.19
328.15
581.85
352.69
189.43
67.19
27.24
333.15
403.71
253.91
141.77
53.46
338.15
288.01
186.26
108.02
43.24
343.15
210.90
139.50
84.03
35.36
348.15
157.76
107.38
66.74
353.15
120.81
83.97
53.25
15.21
7.64
2.46
0.69
13.04
6.73
2.26
0.66
22.72
11.25
6.00
2.08
0.63
19.11
9.82
5.37
1.93
0.60
16.31
8.64
4.84
1.81
0.57
29.24
14.06
7.66
4.39
1.68
0.55
12.24
6.86
3.99
1.57
0.53
SC
RI
0.803
NU
0.895
24.34
AC
CE
PT
E
D
1.000
MA
0.644
PT
T/K
16
ACCEPTED MANUSCRIPT
Table 6 The parameters for Eq. (1), and the average absolute relative deviations
A/
x IL
k/K
mm2·s-1·K-0.5
T0 / K
AARD / %
DMA
0.0016
1273.4754
199.2996
0.36
0.904
0.0012
1342.6899
190.6658
0.29
0.816
0.0017
1210.2593
191.2033
0.47
0.664
0.0041
926.0490
193.1113
0.14
0.538
0.0051
813.5700
186.9511
0.428
0.0058
726.0848
180.3756
0.16
0.332
0.0043
762.5206
0.177
0.0046
620.1818
0.000
0.0022
756.3387
0.18
161.1044
0.11
147.0163
0.12
69.2670
0.07
1273.4754
199.2996
0.36
1292.6639
185.9579
1.02
1236.1870
184.8589
0.26
970.9921
183.4635
0.18
0.0018
1117.7612
154.3118
0.91
0.0048
759.8355
166.0739
0.16
0.0036
813.5853
141.3176
0.14
0.0044
832.9803
101.5059
0.20
0.0024
716.0781
60.8402
0.07
NU
SC
RI
PT
1.000
0.887
0.0021
0.790
0.0016
0.626
0.0033
0.493
0.385
AC
0.000
CE
0.295
0.151
D
0.0016
PT
E
1.000
MA
DMF
DMSO
1.000
0.0016
1273.4754
199.2996
0.36
0.894
0.0016
1250.8558
196.0652
0.20
0.801
0.0016
1217.7369
193.2248
0.31
0.641
0.0030
991.4780
194.0905
0.26
0.510
0.0032
911.0188
188.0023
0.38
0.401
0.0096
565.9151
206.7946
0.82
0.309
0.0103
495.1423
203.8300
0.63
0.161
0.0352
128.0313
254.2650
2.04
17
ACCEPTED MANUSCRIPT
0.000
0.0015
935.0064
77.8872
0.21
0.0016
1273.4754
199.2996
0.36
0.895
0.0013
1319.6438
190.8874
0.23
0.803
0.0010
1386.0802
179.1016
0.67
0.644
0.0029
1040.3690
182.8991
0.21
0.514
0.0037
918.4818
175.4826
0.21
0.404
0.0054
755.7671
173.7058
0.08
0.313
0.0059
664.2835
167.6077
0.11
0.163
0.0041
648.4745
138.2710
0.18
0.000
0.0020
729.6678
75.3141
0.04
AC
CE
PT
E
D
MA
NU
SC
PT
1.000
RI
PYR
18
ACCEPTED MANUSCRIPT
Figures
7000
6000
5000
2
/ mm .s
-1
PT
4000
RI
3000
SC
2000
1000
1.0
0.8
0.6
NU
0
0.4
0.2
0.0
MA
x
Figure 1 Viscosities of [C4mim][Cl] with the organic solvent of DMA at atmospheric
D
pressure as a function of IL mole fraction; ■, 303.15 K; □, 308.15 K; ●, 313.15 K; ○,
PT
E
318.15 K; ▲, 323.15 K; △, 328.15 K; ▼, 333.15 K; ▽, 338.15 K; ◆, 343.15 K; ◇,
AC
CE
348.15 K; ★, 353.15 K.
19
ACCEPTED MANUSCRIPT
7000
6000
5000
2
/ mm .s
-1
4000
PT
3000
RI
2000
0
1.0
0.8
0.6
SC
1000
0.4
0.0
NU
x
0.2
MA
Figure 2 Viscosities of [C4mim][Cl] with the organic solvent of DMF at atmospheric
pressure as a function of IL mole fraction; ■, 303.15 K; □, 308.15 K; ●, 313.15 K; ○,
AC
CE
PT
E
348.15 K; ★, 353.15 K.
D
318.15 K; ▲, 323.15 K; △, 328.15 K; ▼, 333.15 K; ▽, 338.15 K; ◆, 343.15 K; ◇,
20
ACCEPTED MANUSCRIPT
7000
6000
5000
2
/ mm .s
-1
4000
PT
3000
RI
2000
0
1.0
0.8
0.6
SC
1000
0.4
0.0
NU
x
0.2
MA
Figure 3 Viscosities of [C4mim][Cl] with the organic solvent of DMSO at
atmospheric pressure as a function of IL mole fraction; ■, 303.15 K; □, 308.15 K; ●,
D
313.15 K; ○, 318.15 K; ▲, 323.15 K; △, 328.15 K; ▼, 333.15 K; ▽, 338.15 K; ◆,
AC
CE
PT
E
343.15 K; ◇, 348.15 K; ★, 353.15 K.
21
ACCEPTED MANUSCRIPT
7000
6000
5000
2
/ mm .s
-1
4000
PT
3000
RI
2000
0
1.0
0.8
0.6
SC
1000
0.4
0.0
NU
x
0.2
MA
Figure 4 Viscosities of [C4mim][Cl] with the organic solvent of PYR at atmospheric
pressure as a function of IL mole fraction; ■, 303.15 K; □, 308.15 K; ●, 313.15 K; ○,
AC
CE
PT
E
348.15 K; ★, 353.15 K.
D
318.15 K; ▲, 323.15 K; △, 328.15 K; ▼, 333.15 K; ▽, 338.15 K; ◆, 343.15 K; ◇,
22
ACCEPTED MANUSCRIPT
7000
6000
5000
2
/ mm .s
-1
4000
PT
3000
RI
2000
0
1.0
0.8
0.6
SC
1000
0.4
0.0
NU
x
0.2
MA
Figure 5 Viscosities of [C4mim][Cl] with organic solvents of DMA, DMF, DMSO
and PYR at 303.15 K and atmospheric pressure as a function of IL mole fraction; ■,
AC
CE
PT
E
D
DMA; □, DMF; ●, DMSO; ○, PYR.
23
ACCEPTED MANUSCRIPT
500
0
-500
-1500
2
/ mm .s
-1
-1000
PT
-2000
RI
-2500
-3500
-4000
1.0
0.8
0.6
SC
-3000
0.4
0.0
NU
x
0.2
MA
Figure 6 Viscosity deviations of [C4mim][Cl] with solvent of DMA at atmospheric
pressure as a function of IL mole fraction; ■, 303.15 K; □, 308.15 K; ●, 313.15 K; ○,
AC
CE
PT
E
348.15 K; ★, 353.15 K.
D
318.15 K; ▲, 323.15 K; △, 328.15 K; ▼, 333.15 K; ▽, 338.15 K; ◆, 343.15 K; ◇,
24
ACCEPTED MANUSCRIPT
500
0
-500
-1500
-2000
PT
2
/ mm .s
-1
-1000
-2500
RI
-3000
-4000
-4500
1.0
0.8
0.6
SC
-3500
0.4
0.0
NU
x
0.2
MA
Figure 7 Viscosity deviations of [C4mim][Cl] with solvent of DMF at atmospheric
pressure as a function of IL mole fraction; ■, 303.15 K; □, 308.15 K; ●, 313.15 K; ○,
AC
CE
PT
E
348.15 K; ★, 353.15 K.
D
318.15 K; ▲, 323.15 K; △, 328.15 K; ▼, 333.15 K; ▽, 338.15 K; ◆, 343.15 K; ◇,
25
ACCEPTED MANUSCRIPT
500
0
-500
-1500
PT
2
/ mm .s
-1
-1000
-2000
RI
-2500
-3500
1.0
0.8
0.6
SC
-3000
0.4
0.0
NU
x
0.2
MA
Figure 8 Viscosity deviations of [C4mim][Cl] with solvent of DMSO at atmospheric
pressure as a function of IL mole fraction; ■, 303.15 K; □, 308.15 K; ●, 313.15 K; ○,
AC
CE
PT
E
348.15 K; ★, 353.15 K.
D
318.15 K; ▲, 323.15 K; △, 328.15 K; ▼, 333.15 K; ▽, 338.15 K; ◆, 343.15 K; ◇,
26
ACCEPTED MANUSCRIPT
500
0
-500
-1500
2
/ mm .s
-1
-1000
PT
-2000
RI
-2500
-3500
-4000
1.0
0.8
0.6
SC
-3000
0.4
0.0
NU
x
0.2
MA
Figure 9 Viscosity deviations of [C4mim][Cl] with solvent of PYR at atmospheric
pressure as a function of IL mole fraction; ■, 303.15 K; □, 308.15 K; ●, 313.15 K; ○,
AC
CE
PT
E
348.15 K; ★, 353.15 K.
D
318.15 K; ▲, 323.15 K; △, 328.15 K; ▼, 333.15 K; ▽, 338.15 K; ◆, 343.15 K; ◇,
27
ACCEPTED MANUSCRIPT
500
0
-500
-1000
-2000
PT
2
/ mm .s
-1
-1500
-2500
RI
-3000
-4000
-4500
1.0
0.8
0.6
SC
-3500
0.4
0.0
NU
x
0.2
MA
Figure 10 Viscosity deviations of [C4mim][Cl] with solvents of DMA, DMF, DMSO
and PYR at 303.15 K and atmospheric pressure as a function of IL mole fraction; ■,
AC
CE
PT
E
D
DMA; □, DMF; ●, DMSO; ○, PYR.
28
ACCEPTED MANUSCRIPT
20
10
PT
5
0
RI
(exp-cal)exp
15
-10
1.0
0.8
0.6
SC
-5
0.4
0.0
NU
x
0.2
MA
Figure 11 Relative deviations for the viscosities of [C4mim][Cl] with solvent of DMA
between the measured values and calculated data using ideal Grunberg-Nissan
D
equation at atmospheric pressure as a function of IL mole fraction; ■, 303.15 K; □,
PT
E
308.15 K; ●, 313.15 K; ○, 318.15 K; ▲, 323.15 K; △, 328.15 K; ▼, 333.15 K; ▽,
AC
CE
338.15 K; ◆, 343.15 K; ◇, 348.15 K; ★, 353.15 K.
29
ACCEPTED MANUSCRIPT
55
50
45
40
35
25
20
15
PT
(exp-cal)exp
30
10
5
0
RI
-5
-15
-20
-25
1.0
0.8
0.6
SC
-10
0.4
0.0
NU
x
0.2
MA
Figure 12 Relative deviations for the viscosities of [C4mim][Cl] with solvent of DMF
between the measured values and calculated data using ideal Grunberg-Nissan
D
equation at atmospheric pressure as a function of IL mole fraction; ■, 303.15 K; □,
PT
E
308.15 K; ●, 313.15 K; ○, 318.15 K; ▲, 323.15 K; △, 328.15 K; ▼, 333.15 K; ▽,
AC
CE
338.15 K; ◆, 343.15 K; ◇, 348.15 K; ★, 353.15 K.
30
ACCEPTED MANUSCRIPT
35
30
20
PT
15
10
RI
(exp-cal)exp
25
0
-5
1.0
0.8
0.6
SC
5
0.4
0.0
NU
x
0.2
MA
Figure 13 Relative deviations for the viscosities of [C4mim][Cl] with solvent of
DMSO between the measured values and calculated data using ideal Grunberg-Nissan
D
equation at atmospheric pressure as a function of IL mole fraction; ■, 303.15 K; □,
PT
E
308.15 K; ●, 313.15 K; ○, 318.15 K; ▲, 323.15 K; △, 328.15 K; ▼, 333.15 K; ▽,
AC
CE
338.15 K; ◆, 343.15 K; ◇, 348.15 K; ★, 353.15 K.
31
ACCEPTED MANUSCRIPT
35
30
20
PT
15
10
RI
(exp-cal)exp
25
0
1.0
0.8
0.6
SC
5
0.4
0.0
NU
x
0.2
MA
Figure 14 Relative deviations for the viscosities of [C4mim][Cl] with solvent of PYR
between the measured values and calculated data using ideal Grunberg-Nissan
D
equation at atmospheric pressure as a function of IL mole fraction; ■, 303.15 K; □,
PT
E
308.15 K; ●, 313.15 K; ○, 318.15 K; ▲, 323.15 K; △, 328.15 K; ▼, 333.15 K; ▽,
AC
CE
338.15 K; ◆, 343.15 K; ◇, 348.15 K; ★, 353.15 K.
32
MA
NU
SC
RI
PT
ACCEPTED MANUSCRIPT
Figure 15 Infrared spectra of pure IL and the binary mixtures at high wavenumber
green,
IL (35.9%)-DMSO (64.1%): turquoise,
PT
E
(37.4%)-DMF (62.6%):
D
region (2600-3800 cm-1); IL: red, IL (33.6%)-DMA (66.4%): purple, IL
AC
CE
(35.6%)-PYR (64.4%): pink.
33
IL
MA
NU
SC
RI
PT
ACCEPTED MANUSCRIPT
Figure 16 Infrared spectra of pure IL and the binary mixtures at low wavenumber
green,
IL (35.9%)-DMSO (64.1%):
PT
E
(37.4%)-DMF (62.6%):
D
region (1100-1800 cm-1); IL: red, IL (33.6%)-DMA (66.4%): purple, IL
AC
CE
(35.6%)-PYR (64.4%): pink.
34
turquoise,
IL
ACCEPTED MANUSCRIPT
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CE
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36
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[26] S.A. Markarian, L.S. Gabrielyan, Dielectric relaxation
diethylsulfoxide/water mixtures, Phys. Chem. Liq., 47 (2009) 311-321.
study
of
AC
CE
PT
E
D
MA
NU
SC
RI
PT
[27] A. Chaudhari, S. Ahire, S.C. Mehrotrac, Dielectric relaxation study of
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37
ACCEPTED MANUSCRIPT
Highlights:

Imidazolium-based ionic liquids have been widely investigated in making
biofuels from biomass.

Ionic liquids generally have high viscosity that would impede the dissolution of
biomass.
The effect of organic solvents on lowering the viscosity was studied at
PT

atmospheric pressure from 303.15 K to 353.15 K.
RI
Fourier transform infrared spectroscopy was performed to understand the
CE
PT
E
D
MA
NU
SC
structures of the samples.
AC

38
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