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Vapor−Liquid Equilibria Measurement of (Methanol + Ethanenitrile + Bis(trifluoromethylsulfonyl) Imide)-Based Ionic Liquids at 101.3 kPa Yuxin Zhang, Dan Yu, Fan Guo, Yang Shen, Jiacheng Zhou, Zhuo Li, and Qunsheng Li* State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Box 35, Beijing 100029, China ABSTRACT: Isobaric vapor−liquid equilibria (VLE) data of the ternary system methanol + ethanenitrile +1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide ([EMIM][NTf2]) and methanol + ethanenitrile +1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide ([BMIM][NTf2]) as well as their binary system methanol + ethanenitrile (MeCN) were obtained using a improved Othmer still at 101.3 kPa. Results indicated that the addition of [EMIM][NTf2] or [BMIM][NTf2] can eliminate the azeotropic phenomenon of the binary system of methanol + MeCN when the mole fraction of the ionic liquids reach 0.05. Besides, the measured ternary data were well fitted with the nonrandom two-liquid model.

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INTRODUCTION With increasing environmental concerns, it is necessary to separate the solvent mixtures in order to reuse them.1 However, most of the solvents are azeotropic or close-boiling mixtures. Thus, we could not purify those solvents to the index of requirement only using some simple distillations. Several special distillation techniques have been proposed to solve this difficulty. And in those techniques, the extractive distillation is widely used in industry.2,3 Because of the unique properties of the ionic liquid (IL)extremely low volatility, high thermal and chemical stabilities and is liquid at room temperature, for examplethe ILs have some advantages over traditional entrainer.4 So, the isobaric VLE data containing ILs are necessary for the extractive distillation research and the process design. Ethanenitrile and methanol are extremely important solvents and cosolvents in electrochemistry, high-performance liquid chromatography and spectroscopy. Both of them have been widely used as fine chemicals in chemical and pharmaceutical process.5−7 Industrial synthesis of ethanenitrile contains considerable amounts of impurities which is unsuitable in many applications that require high purity. In order to remove those impurities, methanol has been added as a separating agent.8 This procedure creates a mixture of methanol and ethanenitrile. Furthermore, several chemical industries processes also bring some mixtures of them. However, methanol and ethanenitrile form an azeotrope whose separation is very difficult. As far as we know, there is no isobaric VLE data of methanol + MeCN + IL ternary system. In this study, the isobaric VLE data of methanol + MeCN binary system and their ternary system containing [EMIM][NTf2] or [BMIM][NTf2] were measured at 101.3 kPa. And we also discussed the influence of [EMIM][NTf2] and [BMIM][NTf2] on the VLE data of methanol + MeCN system. © XXXX American Chemical Society

EXPERIMENT Reagents. The solvents used were methanol, ethanenitrile, [EMIM][NTf2], and [BMIM][NTf2]. Methanol was obtained from Beijing Chemical Works, China. Ethanenitrile was obtained by Tianjin Fuchen Chemical Reagents Factory, China. The purities of both chemicals were above 99.5% (weight ratio) checked by gas chromatography. The ILs ([EMIM][NTf2] and [BMIM][NTf2]) were purchase from Shanghai Chengjie Chemical Reagents Factory and the mass fraction purity were over 99.0% checked by liquid chromatography. The water mass fraction were less than 0.052% and 0.054%, respectively, which was measuerd by Karl Fischer moisture titrator. The preprocessing of ILs was using a rotary evaporation (48h, 393.15 K) under a vacuum condition (gauge pressure = −0.1 MPa) in order to remove the trace water and volatile matter. In addition, the used ILs were recycled in the same way after experiment. The details of all materials were aggregated in Table 1. Apparatus and Operation Procedure. The experimental data were determined at 101.3 kPa using the modified Othmer still. The descriptions of this equipment were described in our former papers.9−11 The pressure of this still was controlled at 101.3 kPa with a constant pressure system and was determined using a air-gauge with the standard uncertainty u (0.68 level of confidence) of 0.1 kPa. A mercury-in-glass thermometer was used for measuring equilibrium temperature within accuracy ±0.1 K. All the samples were gravimetrically prepared by an analytical balance (Satorius CP124S, Germany) with an accuracy of 0.1 mg. The mole fraction of ethanenitrile and methanol in samples were quantified by a standard curve which Received: September 16, 2015 Accepted: May 25, 2016

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Table 1. Specifications of Chemical Samples chemical name

molecular formula

CAS

methanol ethanenitrile

CH4O C2H3N

67-56-1 75-05-8

([EMIM] [NTf2]a ([BMIM] [NTf2]b

C8H11O4N3S2F6

174899-82-2

C10H15O4N3S2F6

174899-83-3

mass fraction purity

Source Beijing Chemical Works Tianjin Fuchen Chemical Reagents Factory Shanghai Chengjie Chemical Reagents Factory Shanghai Chengjie Chemical Reagents Factory

purification method

final water mass fraction

analysis method

0.995f 0.995f

none none

0.00047 0.00034

GC,c KFe GC,c Kfe

0.99g

rotary evaporation under a vacuum rotary evaporation under a vacuum

0.00052

LC,d KFe

0.00054

LC,d KFe

0.99g

a

[EMIM][NTf2] = 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide. b[BMIM][NTf2] = 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide. cGC = gas chromatography. dLC = liquid chromatography. eKF = Karl Fischer titration. fChecked by GC. g Checked by LC.

was acquired from a series of standard samples. The concreteness of the operation procedure are described in the previous publications.12,13 The vapor and liquid phase equilibrium composition of every experimental points were analyzed by a SP7800 gas chromatograph (China), which have a TCD detector, a Porapak-Q column and the carrier gas was hydrogen. The column is 3 m long and the external diameter of it is 3 mm. The flow rate of hydrogen is 50 cm3 min−1. The temperature of the gasify room, column and detector were 443.15 K, 393.15 K, and 453.15 K, respectively. In the experiment, we used silica wool as a ionic liquid trap which was located between the injector and the chromatographic column for the purpose of eliminating the influence of ILs on the gas chromatography. With this method, we could not need to consider the presence of IL in the result of the analysis, which we were able to experimentally prove. The silica wool was replaced termly to take precautions against the ionic liquids from coming into the chromatographic column. Every experimental point was measured at least five times so that the standard deviation of the components was lower than 0.001 and the max deviation between the measured value and actual component was 0.002 mole fraction.

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Table 2. Vapor−Liquid Equilibrium Data for Temperature T, Liquid-Phase Mole Fraction x, Vapor-Phase Mole Fraction y, and Activity Coefficient γ for the Methanol(1) + Ethanenitrile(2) System at 101.32 kPaa T/K

x1

y1

γ1

354.25 347.85 343.45 341.15 339.35 338.20 337.80 337.45 337.15 336.85 336.65 336.55 336.70 337.00 337.45 337.85

0.000 0.086 0.190 0.284 0.386 0.498 0.548 0.598 0.646 0.700 0.748 0.802 0.854 0.902 0.948 1.000

0.000 0.252 0.414 0.508 0.576 0.638 0.658 0.688 0.714 0.742 0.768 0.804 0.838 0.884 0.934 1.000

2.003 1.756 1.575 1.409 1.266 1.205 1.171 1.138 1.105 1.079 1.057 1.029 1.016 1.003 1.000

γ2 1.000 1.008 1.031 1.059 1.132 1.230 1.309 1.358 1.430 1.537 1.658 1.790 1.994 2.098 2.222

a Standard uncertainties u are u(T) = 0.1 K and u(P) = 0.1 kPa and the combined standard uncertainties are uc(x1) = uc(y1) = 0.002.

RESULT AND DISCUSSION

Experimental VLE Results. The VLE data of the methanol + MeCN binary system were determined at 101.3 kPa, and the results were summarized in Table 2 where the temperature of equilibrium is represented by T, the x1, and y1 are the mole fraction of methanol in the liquid and vapor phases. Besides, the binary data were confronted with those in the literature,14−18 which was shown in Figure 1 and Figure 2. The binary data show a azeotropy point at T = 336.58 K and x1 = 0.808, which can be interpolated using the experimental values. The azeotropic data19 were listed in Table 3 and showed in Figure 2. It could be illustrated that our measurement data were quite consistent with the data listed in the literature. To be more precise, the max absolute deviation (Δy1) between the computed by the nonrandom two-liquid model and determined mole factions of methanol in the vapor phase was lower than 0.001 and maximum relative deviation (δy1) was less than 0.027, which indicated that the reliability of our apparatus is high. The binary experimental value were checked using the integral method gave by Herington to confirm thermodynamic consistency. In this method, the number of (D − J) is required to be less than 10, which was calculated by the following equations. In the equations, Tmax is the highest equilibrium temperature and Tmin is the lowest quilibrium temperature

Figure 1. Absolute deviations Δy1 = y(exptl) − y(calcd) and relative deviations δy1 = (y(exptl) − y(calcd))/y(calcd) between the mole fraction of methanol calculated by NRTL model and measured in the vapor phase for the binary system of methanol (1) + ethanenitrile (2) at 101.3 kPa: ■, Δy1 of this work with error bars representing the expanded uncertainty (0.95 level of confidence); □, δy1 of this work; ●, Δy1 of ref 14 with the y(calcd) getting from the same ref; ○, δy1 ref 14 with the y(calcd) getting from the same ref.

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thermodynamic consistency. Furthermore, the experimental data were also verified by the direct method of Van Ness.20 The results of Van Ness direct consistency test were demonstrated in Figure 4. The figure (y1 − x1 vs x1) was demonstrated in

Figure 2. Isobaric VLE diagram for methanol(1) + ethanenitrile(2) system at 101.3 kPa: ●, experimental data ; △, ref 14; □, ref 15; ○, ref 16; ◇, ref 17; ▽, ref 18; ★, azeotropic data of experiment ☆, azeotropic data of ref 19.

Figure 4. Van Ness direct consistency test for methanol(1) + ethanenitrile(2).

Table 3. Azeotropic Data for for Temperature T and VaporPhase Mole Fraction y for the Methanol(1) + Ethanenitrile(2) System T/K

y1

data from

336.60 336.65 336.85 336.58

0.8170 0.8150 0.8109 0.8080

ref 19 ref 19 ref 19 exp

1

D=

∫0 ln(γ1/γ2)dx1 1

× 100

∫0 |ln(γ1/γ2)|dx1 J = 150 ×

Tmax − Tmin Tmin

(1)

(2)

The results of thermodynamic consistency check were shown in Figure 3. The result of test was |D − J| = 2.0653 < 10, which proved that all the measurement data were in conformity to Figure 5. Diagram of y1 − x1 to x1: ■, experimental data ; ○, ref 15; △, ref 16; ☆, ref 17; □, ref 18.

▽,

ref 14;

Figure 5. In a similar way, the equilibria data of methanol(1) + MeCN(2) + [EMIM][NTf2](3) and methanol(1) + MeCN(2) + [BMIM][NTf2](3) ternary systems were determined at 101.3 kPa, in which the ionic liquid mole fraction were kept almost constant in every sets of x3 ≈ 0.05, 0.10, and 0.15. The results of them were listed in Tables 4 and 5, in which x3 represents the mole fraction of ILs in the liquid phase, x1 is the mole fraction of methanol in the liquid phase containing ILs, y1 is the mole fraction of methanol in vapor phase, γ1 and γ2 present the activity coefficient of methanol and ethanenitrile respectively, and α12 is the relative volatility of methanol to ethanenitrile. The activity coefficient γi and the relative volatility of methanol to ethanenitrile (α12) were calculated by the following equation in the cause of reflecting the influence of ionic liquid on solution nonideality and analyze the salt-out effect of ionic liquid on methanol + MeCN

Figure 3. Diagram of ln(γ1/γ2) to x1. C

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Table 4. Vapor−Liquid Equilibrium Data for Temperature T, Liquid-Phase Mole Fraction x, Vapor-Phase Mole Fraction y, Activity Coefficient γ, and Relative Volatility α12 for the Methanol(1) + Ethanenitrile(2)+[EMIM][NTf2](3) Ternary System at 101.32 kPaa

Table 5. Vapor−Liquid Equilibrium Data for Temperature T, Liquid-Phase Mole Fraction x, Vapor-Phase Mole Fraction y, Activity Coefficient γ, and Relative Volatility α12 for the Methanol(1) + Ethanenitrile(2)+[BMIM][NTf2](3) Ternary System at 101.32 kPaa

x3

T/K

x′1

y1

γ1

γ2

α12

x3

T/K

x′1

y1

γ1

γ2

α12

0.050 0.050 0.048 0.050 0.050 0.050 0.050 0.050 0.050 0.100 0.100 0.100 0.100 0.100 0.100 0.100 0.100 0.100 0.150 0.150 0.150 0.150 0.150 0.150 0.150 0.150 0.150

352.75 346.85 343.75 341.25 340.35 339.35 338.68 338.35 338.50 356.25 350.70 346.95 344.35 343.05 341.85 341.05 340.65 340.55 363.75 357.95 352.85 350.25 347.25 345.55 344.45 343.65 343.15

0.043 0.148 0.255 0.378 0.466 0.580 0.691 0.792 0.894 0.051 0.145 0.257 0.360 0.458 0.562 0.670 0.777 0.886 0.030 0.087 0.199 0.307 0.426 0.530 0.632 0.773 0.870

0.155 0.386 0.510 0.605 0.666 0.715 0.776 0.839 0.910 0.191 0.402 0.532 0.628 0.691 0.734 0.800 0.861 0.927 0.131 0.293 0.464 0.588 0.676 0.746 0.813 0.875 0.933

2.180 1.939 1.669 1.478 1.365 1.226 1.146 1.095 1.046 2.106 1.893 1.624 1.509 1.371 1.242 1.172 1.105 1.048 2.019 1.881 1.556 1.410 1.302 1.231 1.173 1.065 1.027

0.978 0.967 0.976 1.026 1.043 1.170 1.279 1.384 1.509 0.893 0.874 0.888 0.894 0.916 1.018 1.041 1.085 1.120 0.793 0.815 0.827 0.797 0.835 0.846 0.825 0.920 0.879

4.112 3.604 3.031 2.524 2.282 1.818 1.551 1.367 1.198 4.418 3.963 3.288 2.997 2.643 2.143 1.970 1.779 1.634 4.928 4.354 3.473 3.230 2.808 2.600 2.529 2.050 2.066

0.053 0.053 0.053 0.053 0.053 0.053 0.053 0.053 0.053 0.106 0.106 0.106 0.106 0.107 0.106 0.106 0.106 0.106 0.159 0.159 0.159 0.159 0.159 0.159 0.159 0.158 0.159

352.15 347.45 344.25 341.85 340.40 339.35 338.75 338.55 338.65 355.65 350.35 347.00 344.55 343.10 341.55 340.65 340.35 340.25 360.45 357.65 354.55 349.75 348.15 346.25 344.70 342.85 342.75

0.065 0.157 0.258 0.373 0.476 0.582 0.687 0.793 0.896 0.041 0.149 0.249 0.359 0.460 0.560 0.673 0.780 0.888 0.052 0.113 0.193 0.325 0.414 0.553 0.642 0.776 0.893

0.217 0.376 0.499 0.595 0.656 0.721 0.778 0.844 0.910 0.182 0.390 0.493 0.595 0.668 0.734 0.802 0.864 0.924 0.238 0.343 0.464 0.587 0.660 0.748 0.806 0.876 0.937

2.092 1.774 1.619 1.462 1.336 1.252 1.171 1.109 1.055 2.606 1.846 1.585 1.451 1.346 1.288 1.212 1.140 1.075 2.415 1.757 1.550 1.383 1.295 1.180 1.163 1.120 1.046

0.962 0.990 1.003 1.039 1.112 1.171 1.273 1.362 1.555 0.929 0.924 0.969 0.985 1.006 1.043 1.076 1.112 1.227 0.803 0.806 0.796 0.855 0.854 0.883 0.891 0.970 1.036

4.003 3.230 2.868 2.471 2.096 1.856 1.592 1.409 1.174 5.241 3.647 2.941 2.621 2.365 2.164 1.968 1.789 1.527 5.734 4.106 3.623 2.947 2.742 2.396 2.322 2.038 1.782

a

a

Standard uncertainties u are u(T) = 0.1 K and u(P) = 0.1 kPa and the combined standard uncertainties are uc(x1′) = uc(y1) = 0.002 and uc(x3) = 0.001.

γi =

Standard uncertainties u are u(T) = 0.1 K and u(P) = 0.1 kPa and the combined standard uncertainties are uc(x1′) = uc(y1) = 0.002 and uc(x3) = 0.001.

γip xipis

α12 =

of methanol(1) + MeCN(2) system is 1.35%, whereas it is 3.60% for the methanol(1) + MeCN(2) + [EMIM][NTf2](3) system and 2.96% for the methanol(1) + MeCN (2) + [BMIM][NTf2](3).The correlated results are shown in Table 6, with those regressed parameters of each component. The equilibria temperature could be aquired by NRTL model. Besides, the average absolute deviations of methanol in the vapor phase δy and equilibrium temperature δT are shown in the Table 7. The diagram (y1, x1′) in Figures 6 and 7, including the experimental data and the calculated results of the methanol + MeCN + ILs ternary systems, shows that the experimental data are well in agreement with the calculated results. Besides, the figures also illustrate that with the increasing mole fraction of ILs, the methanol content increased in vapor phase. There was a salt-out phenomenon of methanol from the mixture within the whole range of methanol mole fraction. The phenomenon tends to be more noticeable when the mole fraction of ILs increases. Besides, when the mole fraction of ionic liquid reach 0.05, the azeotropic phenomenon of methanol and ethanenitrile can be eliminate. The relative volatility of methanol to ethanenitrile (σ12) is shown in Figure 8 and calculated with eq 2. Compared with [BMIM][NTf2], [EMIM][NTf2] has a higher relative volatility increase of methanol to ethanenitrile. Because of the ratio p1s

(3)

γ1p1s γ2p2s

(4) s

where p is the total pressure of equilibria system; pi is the vapor pressure of pure component i at system temperature, which can be computed by the Antoine equation. The antoine coefficients of methanol and ethanenitrile were taken from the paper.14 Modeling Results. The nonrandom two-liquid model (NRTL) was proposed by Renon and Prausnitz (1968),21 and it was reported to have reproduced various VLE data containing ILs properly.22−26 Therefore, the measurement data for methanol + MeCN and methanol + MeCN + ILs systems were also correlated by the NRTL model. In the NRTL model, nine binary adjustable parameters are needed and the objective function (average relative deviation, ARD) is defined as ARD(%) =

1 N

∑ N

γiexptl − γicalcd γiexptl

× 100% (5)

where N is the number of data points. In this paper, all the parameters were obtained by relating the VLE data and minimizing the objective function. On this occasion, the ARD D

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Table 6. Calculated Values of Binary Parameters Δgij andΔgji and Nonrandomness Factors αij in the NRTL Model i component

j component

αij

Δgij/J·mol−1

Δgji/J·mol−1

methanol(1) methanol(1) ethanenitrile(2) methanol(1) ethanenitrile(2)

ethanenitrile(2) [EMIM][NTf2](3) [EMIM][NTf2](3) [BMIM][NTf2](3) [BMIM][NTf2](3)

0.300 0.471 0.269 0.380 0.330

1846.81 3364.06 −543.88 −2630714.30 −2937877.81

869.51 −4678.78 −7457.01 −3894.01 −6766.74

Table 7. Mean Absobute Deviations, δy and δT, between Experimental and Calculated Values of the Vapor-Phase Mole Fraction and the Equilibriun Temperature

a

system

δya

δTb/K

methanol + ethanenitrile methanol+ ethanenitrile + [EMIM][NTf2] methanol+ ethanenitrile + [BMIM][NTf2]

0.002 0.01 0.006

0.12 0.4 0.64

δy =

( N1 ) ∑ |yexptl − ycalcd |.

b

δT =

( N1 ) ∑ |Texptl − Tcalcd|, where N is

the number of experimental points.

Figure 8. Relative volatilities of methanol(1) to ethanenitrile (2) at different mole fractions of [EMIM][NTf2] and [BMIM][NTf2] at 101.3 kPa: ■, x3 = 0 (IL-free); ●, x3 ≈ 0.050 ([EMIM][NTf2]); ▲, x3 ≈ 0.100 ([EMIM][NTf2]); ◆, x3 ≈ 0.150 ([EMIM][NTf2]); □, x3 ≈ 0.050 ([BMIM][NTf2]); ○, x3 ≈ 0.100 ([BMIM][NTf2]); △, x3 ≈ 0.150 ([BMIM][NTf2]); solid lines, correlated using the NRTL model.

/p2s varies in a small range from 1.73 to 1.94, it could be largely considered as the influence of ionic liquid on the relative volatility depends on the activity coefficients of methanol (γ1) and ethanenitrile (γ2). The activity coefficients of methanol and ethanenitrile basis on different mole fraction of ILs are shown in Figures 9 and 10. It can be seen that with the increase amount of ILs, the activity coefficient of ethanenitrile (γ2) decreased over the whole range of methanol concentrations and significantly declined when the methanol content was greater than 0.6. But the change of the activity coefficient of methanol (γ1) was not evident. Therefore, the effect of lowering γ2 caused the increase of σ12 with the addition of ILs. The diagrams (T, x1′, y1) are presented in Figures 11 and 12, which indicate that the equilibrium temperature of both methanol + MeCN + [EMIM][NTf2] and methanol + MeCN + [BMIM][NTf2] systems rised when the amount of ILs increased.Moreover, when the ILs’ contents are at the same level, the extent of temperature elevation of methanol + MeCN + [EMIM][NTf2] is higher than that of methanol + MeCN + [BMIM][NTf2]. So, the energy consumption with [BMIM][NTf2] is lower compared with [EMIM][NTf2] in the extractive distillation.

Figure 6. Isobaric VLE diagram for methanol(1) + ethanenitrile(2) + [EMIM][NTf2] system at 101.3 kPa: ■, x3 = 0; □, x3 ≈ 0.050; ○, x3 ≈ 0.100; △, x3 ≈ 0.150; solid lines, correlated using the NRTL model.

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CONCLUSIONS In this study, the VLE data (x, y, T) of methanol + MeCN system containing [EMIM][NTf2] or [BMIM][NTf2] were measured at 101.3 kPa. The result correlates with the nonrandom two-liquid model which reproduces the system well. The results indicated that both [EMIM][NTf2] and

Figure 7. Isobaric VLE diagram for methanol(1) + ethanenitrile(2) + [BMIM][NTf2] system at 101.3 kPa: ■, x3 = 0; □, x3 ≈ 0.050; ○, x3 ≈ 0.100; △, x3 ≈ 0.150; solid lines, correlated using the NRTL model.

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Figure 11. T−x1−y1 diagram for methanol(1) + ethanenitrile(2) + [EMIM][NTf2](3) system at 101.3 kPa for different IL mole fractions: ◆, x1 (x3 = 0); ◇, y1 (x3 = 0); ■, x1 (x3 ≈ 0.05); □, y1 (x3 ≈ 0.05); ●, x1 (x3 ≈ 0.10); ○, y1 (x3 ≈ 0.10); ▲, x1 (x3 ≈ 0.15); △, y1 (x3 ≈ 0.15); solid lines, correlated using the NRTL model.

Figure 9. Experimental and calculated activity coefficients of methanol (γ1) and ethanenitrile (γ2) in relation with methanol mole fraction on an IL-free basis for the methanol(1) + ethanenitrile(2) + [EMIM][NTf2](3) system at 101.3 kPa: □, γ1 (x3 = 0); ■, γ2 (x3 = 0); ○, γ1 (x3 ≈ 0.05); ●, γ2 (x3 ≈ 0.05); △, γ1 (x3 ≈ 0.10); ▲, γ2 (x3 ≈ 0.10); ◇, γ1 (x3 ≈ 0.15); ◆, γ2 (x3 ≈ 0.15); solid lines, correlated using the NRTL model.

Figure 12. T−x1−y1 diagram for methanol(1) + ethanenitrile(2) + [BMIM][NTf2](3) system at 101.3 kPa for different IL mole fractions: ◆, x1 (x3 = 0); ◇, y1 (x3 = 0); ■, x1 (x3 ≈ 0.05); □, y1 (x3 ≈ 0.05); ●, x1 (x3 ≈ 0.10); ○, y1 (x3 ≈ 0.10); ▲, x1 (x3 ≈ 0.15); △, y1 (x3 ≈ 0.15); solid lines, correlated using the NRTL model.

Figure 10. Experimental and calculated activity coefficients of methanol (γ1) and ethanenitrile (γ2) in relation with methanol mole fraction on an IL-free basis for the methanol(1) + ethanenitrile(2) + [BMIM][NTf2](3) system at 101.3 kPa: ◇, γ1 (x3 = 0); ◆, γ2 (x3 = 0); □, γ1 (x3 ≈ 0.05); ■, γ2 (x3 ≈ 0.05); ○, γ1 (x3 ≈ 0.10); ●, γ2 (x3 ≈ 0.10); △, γ1 (x3 ≈ 0.15); ▲, γ2 (x3 ≈ 0.15); solid lines, correlated using the NRTL model.

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AUTHOR INFORMATION

Corresponding Author

*Tel.: +86-010-64446523. E-mail: [email protected]. Funding

This work did not have any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

[BMIM][NTf2] showed a consistent salting-out effect on the methanol + MeCN system in the whole concentration range of x1. Besides, the relative volatility of methanol to ethanenitrile can be altered noticeably by the addition of [EMIM][NTf2] or [BMIM][NTf2]. At 101.3 kPa, the azeotrope y disappears when the mole fraction of ILs is up to 0.05. The equilibrium temperature elevates with the increasing concentration of the ILs. The parameters of nonrandom two-liquid model obtained in this study are available for the next research and the process design.

Notes

The authors declare no competing financial interest.

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REFERENCES

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DOI: 10.1021/acs.jced.5b00796 J. Chem. Eng. Data XXXX, XXX, XXX−XXX