Article pubs.acs.org/jced
Density and Viscosity Measurements for Binary Mixtures of 1‑Ethyl-3-methylimidazolium Tetrafluoroborate ([Emim][BF4]) with Dimethylacetamide, Dimethylformamide, and Dimethyl Sulfoxide Xian-Heng Fan,† Yan-Ping Chen,‡ and Chie-Shaan Su*,† †
Department of Chemical Engineering and Biotechnology, National Taipei University of Technology, Taipei, Taiwan Department of Chemical Engineering, National Taiwan University, Taipei, Taiwan
‡
S Supporting Information *
ABSTRACT: The density and viscosity data of three binary liquid mixtures containing the ionic liquid (IL) 1-ethyl-3methylimidazolium tetrafluoroborate and organic solvents, dimethylacetamide (DMAC), dimethylformamide (DMF), and dimethyl sulfoxide (DMSO) were obtained under atmospheric pressure, at temperatures of 303.15 to 333.15 K over the entire composition range. A vibrating-tube digital density meter and a capillary viscometer were used for density and viscosity measurements, respectively. Excess molar volumes (VE) and viscosity deviations (Δη) for the binary mixture system were calculated from the experimental data and were satisfactorily fitted with the Redlich−Kister equation. Adding DMAC, DMF, and DMSO led to negative values of VE and Δη. This finding revealed that the packing of the constituents was more efficient, and the anion−cation interaction of IL was decreased in the binary liquid mixtures. The sequences of VE and Δη for the three binary liquid mixtures in this study are also discussed using intermolecular interactions.
1. INTRODUCTION Ionic liquids (ILs) are a unique class of ionic compounds with a low melting temperature and several desirable features such as low volatility, low flammability, and large capacity for dissolving organic and inorganic substances. The physical and chemical properties of ILs can be manipulated efficiently by choosing appropriate anions and cations. ILs have a wide range of applications in several fields such as chemistry, electrochemistry, pharmaceutical industry, and chemical engineering.1−7 Because most applications of ILs occur in a mixture, the measurements of chemical and physical properties of mixtures containing ILs are crucial and have been studied widely.8−11 In addition, molecular interactions between IL and a polar solvent in a binary mixture have been discussed widely in the literature. For example, Govinda et al. explored and compared the role of the ion effect on the thermo physical properties of two families of ILs with a polar solvent.12 Attri et al. examined the temperature effect on the molecular interactions between ammonium ILs and N,N-dimethylformamide.13 Kavitha et al. interpreted the behavior of excess properties of a binary mixture containing IL based on intermolecular interactions and structural effects between like and unlike molecules uponmixing.14 Khan et al. systematically examined the interactions between water and alkyl methylimidazolium chloride based on activity coefficients.15 Torrecilla et al. investigated the effect of the relative humidity of air on the water content, density, apparent molar volume, dynamic viscosity, and surface tension of IL.16 © 2016 American Chemical Society
In process design and development, density and viscosity play major roles regarding heat transfer, mass transfer, and fluid flow. Density and viscosity data are necessary for developing industrial processes and understanding intermolecular interactions. We previously measured and compared density and viscosity data for the binary mixture of 1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim][BF4]) and organic solvents.17,18 Despite interest in ILs, knowledge of the density and viscosity behavior is limited, particularly for the mixture of ILs with organic molecular liquids. Therefore, in this study, the density and viscosity data for binary mixtures containing the IL 1-ethyl3-methylimidazolium tetrafluoroborate ([Emim][BF4]) and organic molecular liquids, dimethylacetamide (DMAC), dimethylformamide (DMF), and dimethyl sulfoxide (DMSO), are reported, and the molecular interaction between the IL and the organic molecular liquids is compared and discussed. The experimental densities and viscosities of the three binary mixtures [Emim][BF4] + DMAC, [Emim][BF4] + DMF, and [Emim][BF4] + DMSO were measured over the entire composition range at temperatures from 303.15 to 333.15 K and under atmospheric pressure. The values of excess molar volumes and viscosity deviations were also calculated and correlated with the Redlich−Kister equation. [Emim][BF4] is an economical IL Received: September 3, 2015 Accepted: December 22, 2015 Published: January 7, 2016 920
DOI: 10.1021/acs.jced.5b00753 J. Chem. Eng. Data 2016, 61, 920−927
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Table 1. Information and Specification of Chemical Samples name
formula
CAS no.
[Emim][BF4] DMAC DMF DMSO
C6H11BF4N2 C4H9NO C3H7NO C2H6SO
143314-16-3 127-19-5 68-12-2 67-68-5
supplier Sigma-Aldrich Sigma-Aldrich Sigma-Aldrich Sigma-Aldrich
Co. Co. Co. Co.
product number
lot number
purity (%)
analytical method
711721 271012 227056 34943
STBD4510 V STBC4524 V STBC5593 V SZBD003AV
min. 98.0 99.98 99.98 100.0
HNMR GC GC GC
Table 2. Density (ρ) and Viscosity (η) Data of [Emim][BF4], DMAC, DMF, and DMSO at Temperatures from 303.15 to 333.15 K and 101 kPaa ρ (g cm−3) temp. (K)
exp.
lit.
dev. (%)
exp.
lit.
dev. (%)
[Emim][BF4]
303.15 313.15 323.15 333.15 303.15 313.15 323.15 333.15 303.15 313.15 323.15 333.15 303.15 313.15 323.15 333.15
1.27279 1.26522 1.25771 1.25028 0.93169 0.92244 0.91317 0.90386 0.93923 0.92964 0.92002 0.91033 1.09041 1.08037 1.07033 1.06029
1.2893026 1.2819026 1.2745026 1.2670026 0.9315827 0.9223327 0.9130527 0.9037427 0.9390027 0.9294227 0.9197927 0.9101027 1.0907319 1.0806919 1.0706619 1.0606319
1.28 1.30 1.32 1.32 0.01 0.01 0.01 0.01 0.02 0.02 0.02 0.02 0.03 0.03 0.03 0.03
28.002 20.411 15.348 12.076 0.862
27.08326 20.00826 15.35026 12.10326 0.87728
3.39 2.01 0.01 0.22 1.73
0.744 0.667 0.600 0.541 1.784 1.498 1.270 1.095
0.76629 0.68429 0.61729 0.55929 1.78630 1.50630 1.27830 1.10430
2.96 2.55 2.83 3.33 0.11 0.53 0.63 0.82
DMAC
DMF
DMSO
a
η (mPa·s)
component
Standard uncertainties are u(T) = 0.01 K, u(P) = 1 kPa. Relative standard uncertainties are ur(ρ) = 0.2%, ur(η) = 0.6%.
the vials were closed with screw caps to ensure a secure seal and prevent humidity buildup. The prepared samples were mixed using a vortexer and degassed in an ultrasonic water bath. The freshly prepared mixture samples were used immediately to protect them from atmospheric moisture. The mass of each compound in the vials and the accuracy of the balance were considered, and the standard uncertainty of mole fraction (x) was evaluated to be less than 0.0001. Density (ρ) measurements were performed using a vibratingtube digital density meter (Anton Parr DMA 5000M) at temperatures (T) ranging from 303.15 to 333.15 K and under atmospheric pressure. Before performing the measurements, the density meter was calibrated with ultrapure water and dry air. This apparatus corrects the viscosity influence automatically. The standard uncertainty of the reported temperature is 0.01 K. The repeatability of the density measurements is 0.000005 g·cm−3. By considering the purity of the samples, the relative standard uncertainty for the reported density is 0.2%. The reported density data were averaged from at least three runs. Viscosity (η) was measured using a viscosity-measuring equipment (PMT Tamson Co., TV2000AKV) under the same conditions as those under which density measurements were conducted. Four Cannon-Fenske routine viscometer tubes (size numbers of 25, 50, 75, and 150) were used, and the corresponding kinematic viscosity measurement ranges were 0.4−2 cSt, 0.8−4 cSt, 1.6−8 cSt, and 7−35 cSt, respectively. A thermostatic water bath was used to control the temperature of the viscometer tubes within ±0.01 K. The kinematic viscosity of a sample was determined by measuring the time taken for the sample to travel along a defined length of the capillary. The dynamic viscosities were then calculated from these data and the corresponding densities of the mixtures under the same
that is commonly used in the chemical industry. DMAC and DMF are Class 2 solvents, and DMSO is a Class 3 solvent, according to the International Conference on Harmonisation of Technical Requirements for Registration of Pharmaceuticals for Human Use Q3C guideline. These solvents are safe and acceptable for practical use in the pharmaceutical industry. For these three binary mixtures, only the density data of [Emim][BF4] + DMSO have been reported.19,20 Density data of the binary mixtures for [Emim][BF4] + DMAC and [Emim][BF4] + DMF, and viscosity data of the binary mixtures for [Emim][BF4] + DMAC, [Emim][BF4] + DMF, and [Emim][BF4] + DMSO have not been presented in the literature.
2. EXPERIMENTAL SECTION Materials. The IL [Emim][BF4] (purity, >98%) was purchased from Sigma-Aldrich Co. DMAC, DMF, and DMSO (minimum purity, 99.9%) were also purchased from SigmaAldrich Co. All chemicals were used without further purification. Detailed information on the chemicals used is listed in Table 1. All chemicals used were dried over a 3 Å molecular sieve for more than 7 days before use and were stored in an electronic dry cabinet. The water content of [Emim][BF4] and the solvents were measured through Karl Fischer titration (Metrohm Ltd., 851 Titrando). The water contents of [Emim][BF4], DMAC, DMF, and DMSO were 287, 336, 282, and 382 ppm, respectively. Density and Viscosity Measurements. The IL + organic solvent binary mixture samples were prepared in 20 mL glass vials by weighing the materials on an analytical balance (Shimadzu Corp., AUW220D; precision = 0.00001 g). The glass vials were dried overnight in an oven before use. Each liquid mixture was prepared under atmospheric pressure, and 921
DOI: 10.1021/acs.jced.5b00753 J. Chem. Eng. Data 2016, 61, 920−927
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Figure 1. Density (ρ) data for the binary mixtures of (a) [Emim][BF4] (1) + DMAC (2), (b) [Emim][BF4] (1) + DMF (2), and (c) [Emim][BF4] (1) + DMSO (2) at different approximated mole fractions of [Emim][BF4]: ★, 1.0; ▽, 0.9; ▼, 0.8; △, 0.7; ▲, 0.6; ◊, 0.5; ◆, 0.4; □, 0.3; ■, 0.2; and ○, 0.1; ●, 0.0.
Figure 2. Viscosity (η) data for the binary mixtures of (a) [Emim][BF4] (1) + DMAC (2), (b) [Emim][BF4] (1) + DMF (2), and (c) [Emim][BF4] (1) + DMSO (2) at different approximated mole fractions of [Emim][BF4]: ★, 1.0; ▽, 0.9; ▼, 0.8; △, 0.7; ▲, 0.6; ◊, 0.5; ◆, 0.4; □, 0.3; ■, 0.2; and ○, 0.1; ●, 0.0.
The densities and viscosities of [Emim][BF4] + DMAC, [Emim][BF4] + DMF, and [Emim][BF4] + DMSO measured at temperatures ranging from 303.15 to 333.15 K are shown in Figures 1 and 2, with the detailed data listed in Tables 3 and 4. All mixtures were miscible over the entire range of compositions. In all of the mixtures, the density and viscosity values increased with the concentration of [Emim][BF4]. This result was expected because [Emim][BF4] is considerably dense and viscous compared with organic solvents. For a fixed composition, density decreases linearly with temperature. According to Kavitha et al.,14 density and viscosity values are relatively sensitive to the ionic size, temperature, and mixture composition. The density and viscosity values of IL mixtures mainly depend on the packaging and size and shape of ions as well as ion−ion interactions. With a higher temperature and lower IL composition, the packing of ions in mixture becomes less efficient, resulting in low density and viscosity values. In addition, at the same temperature and with the same composition, the mixture densities and viscosities of [Emim][BF4] + DMSO were higher than those of [Emim][BF4] + DMAC and [Emim][BF4] + DMF because DMSO is more dense and viscous compared with DMAC and DMF. To further understand the interactions between IL and an organic solvent, the excess molar volume (VE) and viscosity
conditions. The reported dynamic viscosities are the averaged values for at least three runs. The relative standard uncertainty of the viscosity measurements was defined as the ratio of the standard deviation and average viscosity value and was evaluated to be less than 0.6% in this study.
3. RESULTS AND DISCUSSION The densities and viscosities of pure [Emim][BF4], DMAC, DMF, and DMSO measured in this study at temperatures from 303.15 to 333.15 K and under atmospheric pressure are listed in Table 2, against data from previous studies for a comparison. Table 2 lists the deviations between measured pure fluid properties and data from past studies. The density and viscosity values for these pure fluids were in agreement with the literature data. In addition, a complete comparison of densities and viscosities for pure [Emim][BF4] at 303.15, 313.15, 323.15, and 333.15 K is presented in the Supporting Information (Tables S1 and S2). The variance in the density and viscosity measurements of pure [Emim][BF4] might be attributed to the effect of trace impurity such as water content in IL. Table S3 and Figure S1 present a comparison of the measured density of [Emim][BF4] + DMSO mixture with the literature data.19,20 The trend of our density data for measured mixtures was also in agreement with the literature data. 922
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Table 3. Density (ρ) Data for the Binary Systems of IL (1) + Solvent (2) at T = 303.15−323.15 K and 101 kPaa
Table 4. Viscosity (η) Data for the Binary Systems of IL (1) + Solvent (2) at T = 303.15−323.15 K and 101 kPaa
ρ/g·cm−3 x1 0.0000 0.1006 0.1999 0.3004 0.4000 0.4995 0.6011 0.7005 0.8002 0.9004 1.0000 0.0000 0.1001 0.2003 0.3000 0.3996 0.4995 0.6013 0.7006 0.7984 0.8984 1.0000 0.0000 0.0998 0.2004 0.2998 0.3998 0.5004 0.6000 0.7004 0.7993 0.8999 1.0000
T/K = 303.15
T/K = 313.15
T/K = 323.15
[Emim][BF4] (1) + DMAC (2) 0.93169 0.92244 0.91317 0.99372 0.98495 0.97620 1.04360 1.03512 1.02667 1.08657 1.07832 1.07012 1.12337 1.11529 1.10728 1.15556 1.14763 1.13977 1.18469 1.17687 1.16912 1.20930 1.20156 1.19389 1.23300 1.22533 1.21774 1.25414 1.24652 1.23899 1.27279 1.26522 1.25771 [Emim][BF4] (1) + DMF (2) 0.93923 0.92964 0.92002 1.00921 1.00023 0.99124 1.06297 1.05433 1.04573 1.10605 1.09767 1.08935 1.14194 1.13378 1.12567 1.17212 1.16412 1.15618 1.19842 1.19054 1.18274 1.22057 1.21279 1.20510 1.23945 1.23174 1.22412 1.25679 1.24915 1.24160 1.27279 1.26522 1.25771 [Emim][BF4] (1) + DMSO (2) 1.09041 1.08037 1.07033 1.13109 1.12180 1.11254 1.16217 1.15333 1.14454 1.18625 1.17773 1.16927 1.20585 1.19757 1.18935 1.22207 1.21397 1.20594 1.23558 1.22763 1.21974 1.24729 1.23946 1.23170 1.25728 1.24955 1.24189 1.26637 1.25871 1.25113 1.27279 1.26522 1.25771
η/mPa·s x1
T/K = 333.15 0.90386 0.96746 1.01825 1.06195 1.09932 1.13196 1.16144 1.18631 1.21023 1.23152 1.25028
0.0000 0.1006 0.1999 0.3004 0.4000 0.4995 0.6011 0.7005 0.8002 0.9004 1.0000
0.91033 0.98226 1.03715 1.08107 1.11762 1.14831 1.17501 1.19747 1.21659 1.23412 1.25028
0.0000 0.1001 0.2003 0.3000 0.3996 0.4995 0.6013 0.7006 0.7984 0.8984 1.0000
1.06029 1.10332 1.13580 1.16085 1.18119 1.19798 1.21194 1.22402 1.23431 1.24365 1.25028
0.0000 0.0998 0.2004 0.2998 0.3998 0.5004 0.6000 0.7004 0.7993 0.8999 1.0000
T/K = 303.15
T/K = 313.15
T/K = 323.15
[Emim][BF4] (1) + DMAC (2) 0.862 0.758 0.673 1.549 1.328 1.154 2.499 2.092 1.790 3.833 3.147 2.638 5.678 4.493 3.690 7.831 6.172 4.982 10.620 8.231 6.555 13.989 10.652 8.356 18.054 13.592 10.446 22.753 16.856 12.804 28.002 20.411 15.348 [Emim][BF4] (1) + DMF (2) 0.744 0.667 0.600 1.305 1.144 1.010 2.114 1.806 1.567 3.214 2.689 2.293 4.720 3.867 3.226 6.703 5.397 4.475 9.335 7.351 5.935 12.545 9.741 7.735 16.522 12.531 9.796 21.608 16.029 12.290 28.002 20.411 15.348 [Emim][BF4] (1) + DMSO (2) 1.784 1.498 1.270 2.928 2.385 1.996 4.395 3.515 2.893 6.249 4.936 3.971 8.523 6.575 5.296 11.132 8.463 6.667 14.076 10.585 8.202 17.261 12.878 9.905 20.758 15.250 11.623 24.387 17.834 13.544 28.002 20.411 15.348
T/K = 333.15 0.602 1.029 1.563 2.252 3.115 4.122 5.375 6.912 8.309 10.087 12.076 0.541 0.899 1.387 1.993 2.775 3.744 4.930 6.291 7.829 9.722 12.076 1.095 1.710 2.438 3.294 4.335 5.382 6.571 7.868 9.178 10.645 12.076
a
Standard uncertainties are u(T) = 0.01 K, u(P) = 1 kPa, u(x1) = 0.0001. Relative standard uncertainties are ur(ρ) = 0.2%.
a
deviation (Δη) for the binary mixtures were calculated using the following equations:
and are shown in the Supporting Information (Figure S2). The excess molar volumes obtained for the [Emim][BF4] + DMSO system were in qualitative agreement with those obtained by Iulian and Ciocirlan19 but differed substantially from those obtained by Bhagour et al. at 303.15 K.20 This difference might be due to the effect of trace impurity in IL, particularly for the excess property.21−24 This substantial variance in the excess molar volume was also observed for the [Bmim][BF4] + N-methyl-2-pyrrolidone system by Qi and Wang25 and Kavitha et al.14 Regarding the use of the experimental density and viscosity data, the calculated results of VE and Δη are shown in Figures 3 and 4, respectively. The VE values for the three binary mixtures considered in this study were all negative and exhibited a minimum value at the mole fraction of [Emim][BF4] between 0.3 and 0.4. After mixing [Emim][BF4] and an organic solvent, the interactions between anions and solvent molecules and between cations and solvent molecules were generated. The ionic interactions for [Emim][BF4] weakened considerably
Standard uncertainties are u(T) = 0.01 K, u(P) = 1 kPa, u(x1) = 0.0001. Relative standard uncertainties are ur(η) = 0.6%.
V E = [x1M1 + (1 − x1)M 2]/ρm − [x1M1/ρ1 + (1 − x1)M 2 /ρ2 ]
Δη = ηm − x1η1 − (1 − x1)η2
(1) (2)
where x, M, η, and ρ are the mole fraction, molecular weight, viscosity, and density, respectively. Subscripts 1, 2, and m indicate the pure fluid property of IL ([Emim][BF4]), that of organic solvents (DMAC, DMF, and DMSO), and the property of the binary mixtures, respectively. The excess properties were defined as the difference between the actual property of mixtures and that of an ideal mixture under the same condition. The calculated excess molar volume and viscosity deviation values are listed in Tables S4 and S5, respectively. The excess molar volumes obtained in this study for [Emim][BF4] + DMSO were also compared against the literature results,19,20 923
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Figure 3. Excess molar volume (VE) for the binary mixtures of (a) [Emim][BF4] (1) + DMAC (2), (b) [Emim][BF4] (1) + DMF (2), and (c) [Emim][BF4] (1) + DMSO (2) at different temperatures: ●, 303.15 K; ■, 313.15 K; ◆, 323.15 K; ▲, 333.15 K; −, Redlich−Kister correlations.
Figure 4. Viscosity deviations (Δη) for the binary mixtures of (a) [Emim][BF4] (1) + DMAC (2), (b) [Emim][BF4] (1) + DMF (2), and (c) [Emim][BF4] (1) + DMSO (2) at different temperatures: ●, 303.15 K; ■, 313.15 K; ◆, 323.15 K; ▲, 333.15 K; −, Redlich−Kister correlations.
compared with those for the pure fluid. An organic solvent molecule can be inserted into the space formed by the departure of an anion or cation. Therefore, the total volume of the mixture decreases, and the packing of constituents is more efficient. In addition, the negative deviation of VEdependedon the organic solvent (Figure 3). At the same temperature and with the same composition, the sequence of VE is |VE[Emim][BF4]+DMAC| > |VE[Emim][BF4]+DMF| > |VE[Emim][BF4]+DMSO|. This could be attributed to the p−pi conjugation in DMAC and DMF molecules, and this conjugation is more pronounced in DMAC. The Δη values in the examined systems were also negative and exhibited a minimum value at the mole fraction of [Emim][BF4] between 0.5 and 0.6. Δη was strongly influenced by the intermolecular interactions. With stronger intermolecular interactions such as anion−cation interactions in pure IL, the movement of molecule from one equilibrium position to the next is strongly interfered by the adjacent molecules, resulting in a higher viscosity value. By adding an organic solvent into the IL, the anion−cation interactions in the IL weakened considerably, and the viscosity value decreased dramatically. To further compare the VE and Δη values for binary mixture containing [Emim][BF4] or [Bmim][BF4] with an organic solvent, the density and viscosity data of [Bmim][BF4] + DMAC and [Bmim][BF4] + DMF reported in our previous study were used.17,18 Figure 5 shows a comparison of VE and Δη between [Emim][BF4] + DMAC and [Bmim][BF4] + DMAC,
and [Emim][BF4] + DMF and [Bmim][BF4] + DMF. With a short alkyl side chain, the packing of IL with an organic solvent in the mixture is more efficient and results in a more negative behavior of the VE value for the binary mixture containing [Emim][BF4]. However, for Δη, with a long alkyl side chain, the interference of molecular movement is more evident. Thus, the viscosity of pure [Bmim][BF4] is considerably higher than that of [Emim][BF4]. By adding the organic solvent, the reduction in viscosity for the [Bmim][BF4] binary mixture system was more pronounced, resulting in a larger deviation from the ideal. In this study, the calculated excess properties (VE and Δη) were finally correlated with the IL composition at each temperature. To satisfactorily correlate the experimental excess properties with the value of coefficient of determination (r2) of higher than 0.99, a four-parameter Redlich−Kister equation was used. 3
V E = x1x 2 ∑ Ai (x1 − x 2)i i=0
(3)
3
Δη = x1x 2 ∑ Ai (x1 − x 2)i i=0
(4)
where x1 is the mole fraction of [Emim][BF4] and x2 is that of DMAC, DMF, and DMSO. Ai is the adjustable binary coefficient. For each binary mixture at a specific temperature, 924
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Figure 5. Excess molar volume (VE) and viscosity deviation (Δη) for the binary mixture of ILs with organic solvents at 303.15 K: (a) comparison of VE for [Bmim][BF4] + DMAC and [Emim][BF4] + DMAC, (b) comparison of VE for [Bmim][BF4] + DMF and [Emim][BF4] + DMF, (c) comparison of Δη for [Bmim][BF4] + DMAC and [Emim][BF4] + DMAC, and (d) comparison of Δη for [Bmim][BF4] + DMF and [Emim][BF4] + DMF: ○, [Bmim][BF4] + DMAC; ●, [Emim][BF4] + DMAC; □, [Bmim][BF4] + DMF; ■, [Emim][BF4] + DMF; −, Redlich−Kister correlations.
Table 5. Values of Parameters (Ai) and Average Relative Deviation (ARD) of the Redlich−Kister Equation for Excess Molar Volume at T = 303.15−333.15 K
a
T (K)
A0
303.15 313.15 323.15 333.15
−4.647 −4.970 −5.324 −5.708
303.15 313.15 323.15 333.15
−4.241 −4.524 −4.840 −5.187
303.15 313.15 323.15 333.15
−2.464 −2.641 −2.834 −3.044
A1
A2
[Emim][BF4] + DMAC 3.250 −2.363 3.419 −2.497 3.598 −2.661 3.782 −2.855 [Emim][BF4] + DMF 2.513 −1.842 2.666 −1.978 2.832 −2.142 3.015 −2.335 [Emim][BF4] + DMSO 1.233 −1.586 1.336 −1.682 1.447 −1.794 1.558 −1.930
Table 6. Values of Parameters (Ai) and Average Relative Deviation (ARD) of the Redlich−Kister Equation for Viscosity Deviation at T = 303.15−333.15 K
ARDa (%)
T (K)
A0
0.672 0.778 0.898 1.054
3.3 3.1 3.1 3.0
303.15 313.15 323.15 333.15
−26.374 −17.710 −12.107 −8.698
2.267 2.420 2.574 2.735
1.5 1.6 1.6 1.6
303.15 313.15 323.15 333.15
−30.615 −20.511 −14.069 −10.213
−0.846 −0.771 −0.713 −0.642
2.7 2.7 2.6 2.6
303.15 313.15 323.15 333.15
−15.117 −9.938 −6.577 −4.786
A3
ARD(%) = 100/N[|(VE,cal − VE,exp)/VE,exp|].
a
925
A1
A2
[Emim][BF4] + DMAC −4.742 1.096 −2.295 1.458 −0.990 0.802 0.232 0.142 [Emim][BF4] + DMF −9.351 −2.082 5.005 −1.157 −2.677 −0.519 −1.774 −0.979 [Emim][BF4] + DMSO 3.067 1.946 2.192 0.725 1.321 0.498 0.764 0.126
A3
ARDa (%)
2.048 1.571 0.505 −1.938
0.5 0.5 0.2 2.0
−0.846 −1.412 −0.953 −1.354
0.1 0.3 0.4 0.4
0.660 −0.026 0.990 0.430
0.8 0.8 2.4 2.3
ARD(%) = 100/N[|(ηE,cal − ηE,exp)/ηE,exp|]. DOI: 10.1021/acs.jced.5b00753 J. Chem. Eng. Data 2016, 61, 920−927
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the optimally fitted coefficients are listed in Tables 5 and 6 for VE and Δη, respectively. The correlated results are displayed in Figures 3 and 4. The average relative deviations for data correlation are also presented in Tables 5 and 6. The average relative deviation values agreed satisfactorily with the experimental values. The average relative deviations of both VE and Δη were less than 3.5%.
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4. CONCLUSION The experimental values of density and viscosity for the binary mixtures of [Emim][BF4] + DMAC, [Emim][BF4] + DMF, and [Emim][BF4] + DMSO over the entire composition range were determined. Measurements were performed at four temperatures (303.15, 313.15, 323.15, and 333.15 K) and under atmospheric pressure. In this study, measured density and viscosity values decreased at higher temperatures and a lower IL composition. The density and viscosity data obtained were used to calculate the VE and Δη values. Both VE and Δη displayed negative values because of the efficient packing and weakening of interaction of the IL in the binary mixture. The calculated excess properties were fitted to a four-parameter Redlich−Kister equation. The VE and Δη values were satisfactorily correlated and the temperature-dependent parameters were reported.
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ASSOCIATED CONTENT
S Supporting Information *
Density and viscosity comparisons of pure [Emim][BF4], Density and excess molar volume comparisons of [Emim][BF4] + DMSO, data of excess molar volumes, and data of viscosity deviations. The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.jced.5b00753. Supplementary tables and figures (PDF)
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AUTHOR INFORMATION
Corresponding Author
*E-mail:
[email protected]. Notes
The authors declare no competing financial interest.
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REFERENCES
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DOI: 10.1021/acs.jced.5b00753 J. Chem. Eng. Data 2016, 61, 920−927
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DOI: 10.1021/acs.jced.5b00753 J. Chem. Eng. Data 2016, 61, 920−927
