Isobaric Vapor–Liquid Equilibrium of Binary and Ternary Systems with

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Isobaric Vapor−Liquid Equilibrium of Binary and Ternary Systems with 2‑Ethoxyethanol + Ethylbenzene + Dimethyl Sulfoxide Li Yuan, Lei Wang, and Peng Bai* School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, China ABSTRACT: Isobaric vapor−liquid equilibrium (VLE) at 100 ± 0.1 kPa for the binary and ternary systems with 2ethoxyethanol + ethylbenzene + dimethyl sulfoxide (DMSO) was determined with a modified Othmer still. All of the binary VLE data passed the Herington test and the Wisniak test. It was determined that 2-ethoxyethanol and ethylbenzene form a binary azeotrope at 127.4 °C, 48.5 mol % 2-ethoxyethanol at 100 ± 0.1 kPa. By adding DMSO as a solvent at 0.50 mass fraction, the binary azeotrope of 2-ethoxyethanol and ethylbenzene was broken successfully. The binary VLE data were correlated with Wilson, nonrandom two-liquid (NRTL), and universal quasichemical activity coefficient (UNIQUAC) models with minor deviations. The correlated binary interaction parameters were then used to predict the ternary VLE behavior, which fit well with the experimental data. These results provide a theoretical basis for the separation of a 2-ethoxyethanol and ethylbenzene mixture with DMSO as a promising solvent in extractive distillation.

1. INTRODUCTION 2-Ethoxyethanol, also known as cellosolve or ethylene glycol monoethyl ether (EGME), ethylbenzene, and dimethyl sulfoxide (DMSO) are important solvents in various industrial applications. 2-Ethoxyethanol has the property to dissolve various kinds of compounds, and therefore it is a multipurpose cleaner used in varnish removers and degreasing solutions.1 Ethylbenzene can be used as a solvent in inks, rubber adhesives, varnishes, paints, and so forth. DMSO is an important polar aprotic solvent as a cleaner in resist stripping applications.2 It is also used as an effective paint stripper. Therefore, mixtures of these solvents may be found in various fields such as paints, varnishes, and printing inks, and so forth. 2-Ethoxyethanol and ethylbenzene have close boiling points, with only a ∼1 °C difference, and form homogeneous minimum boiling azeotropes at 127.8 °C, 46.75 mol % 2ethoxyethanol at 760 mmHg.3 Binary azeotropic data for 2ethoxyethanol and ethylbenzene were measured at several different pressures, 5.85 kPa, 12.45 kPa, 26.02 kPa, 52.06 kPa, and 100.94 kPa, by Li and Gmehling (1998), and it was found that the azeotrope did not disappear at different pressures.4 Therefore, this mixture could not be separated by ordinary distillation or even pressure swing distillation, while extractive distillation, azeotropic distillation, or hybrid process might be options. Besides, VLE data for the binary systems 2ethoxyethanol + DMSO and ethylbenzene + DMSO and ternary system 2-ethoxyethanol + ethylbenzene + DMSO at 100 kPa were not found in the Dortmund Data Bank (DDB) and the National Institute of Standards and Technology (NIST) database, with only binary VLE data of ethylbenzene + DMSO at 95 kPa available.5 In this paper, DMSO is proposed as a solvent to break the azeotrope formed by 2-ethoxyethanol and ethylbenzene due to © 2013 American Chemical Society

its high boiling temperature and molecular polarity. Isobaric vapor−liquid equilibrium (VLE) data for the binary systems 2ethoxyethanol + ethylbenzene, 2-ethoxyethanol + DMSO, and ethylbenzene + DMSO and the ternary system 2-ethoxyethanol + ethylbenzene + DMSO were obtained at 100 ± 0.1 kPa with a modified Othmer still. The Herington test6 and the Wisniak test7 were applied to check the thermodynamic consistency of the VLE data. Additionally, the binary VLE data were correlated with the activity coefficient models Wilson,8 nonrandom twoliquid (NRTL)9 and universal quasichemical (UNIQUAC).10 The three models with their best-fitted binary parameters were applied to predict the VLE of the ternary system, which was then compared with experimental data.

2. EXPERIMENTAL SECTION 2.1. Purity of Components. Analytical reagents, ethylbenzene, 2-ethoxyethanol, and DMSO, supplied by Kermel Chemical Co. Ltd., were used after further purification with batch rectification and dehydrated with 3A molecular sieves. The purity of components was then checked by gas chromatography and the water content by a Karl Fischer moisture meter. The purity of the chemicals was further verified by comparing their measured density (ρ) at 298.15 K and normal boiling point (Tb) at 101.3 kPa with corresponding literature values. The density of pure components was measured by a KEM DA-510 density meter and normal boiling point by a modified Othmer still. The physical properties of the purified materials are listed in Table 1. Received: July 23, 2013 Accepted: September 26, 2013 Published: October 10, 2013 3216

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Table 1. Physical Properties of Experimental Components at 101.3 kPaa ρ/g·cm−3 (293.15 K)

Tb/°C component

purity mass %

water mass %

exp.

lit. b

2-ethoxyethanol

99.88

0.03

135.2

135.3

ethylbenzene

99.76

0.03

136.1

DMSO

99.92

0.04

189.1

136.2b 136.16d 189.04f

exp.

lit.

0.92892

0.92959b 0.92572c 0.86274b 0.8622e 1.09040f 1.0947g

0.86364 1.09248

Standard uncertainties u are u(T) = 0.1 K, u(purity) = 0.001; u(water) = 0.0001; u(ρ) = 0.00001. Tb, normal boiling point; ρ, density. bFrom ref 3. From ref 12. dFrom ref 13. eFrom ref 14. fFrom ref 15. gFrom ref 16.

a c

Instrument Co., Ltd. The column was SE-54 (30 m × 0.32 mm × 0.5 μm) capillary column, and high-purity nitrogen (99.999 %) was used as the carrier gas with a flow rate of 30 cm3·min−1. The GC data was processed at a Zhida N-2000 chromatography station (Zhejiang University). The deviation between measured and actual composition was calibrated with working curves, which were obtained from sets of gravimetrically prepared standard solutions covering the whole composition range. For each sample, the final composition was determined as the mean of three replications. The standard uncertainty of the mole fraction of the components in the measured samples was estimated to be 0.001.

2.2. Apparatus and Procedures. An all-glass circulation type of modified Othmer still was used to measure the VLE data, as shown in Figure 1. The pressure was maintained at 100

3. RESULTS AND DISCUSSION 3.1. Experimental Data. To test the reliability of the experimental instrument and the operation procedures, VLE data of methanol and ethanol were measured at 101.3 kPa and compared with literature data.11 The mean absolute deviation was determined to be 0.14 K in equilibrium temperature and 0.0082 in vapor phase composition. This good agreement indicated that the VLE system used was reliable. The binary VLE data at 100 kPa of 2-ethoxyethanol + ethylbenzene, 2-ethoxyethanol + DMSO, and ethylbenzene + DMSO are shown in Table 2. The VLE data for the ternary system 2-ethoxyethanol + ethylbenzene + DMSO at 100 kPa are listed in Table 3. The thermodynamic consistency of the experimental data for binary systems was verified with the Herington test6 and Wisniak test.7 The Herington test checks the thermodynamic consistency of the VLE data on the whole, while the Wisniak test conducts the point-to-point test and area test simultaneously. According to the Herington method, the isobaric VLE data were considered thermodynamically consistent if the check result D − J < 10. In the Wisniak test, the deviation E less than 3 to 5 will indicate thermodynamic consistency7, where

Figure 1. Modified Othmer still. 1, heating bar; 2, silicone oil; 3, liquid-phase sampling port; 4, equilibrium chamber; 5, mercury thermometer; 6, condenser; 7, vapor-phase sampling port.

± 0.1 kPa during the measurement process by a pressure control system. The equilibrium temperature was measured with a calibrated mercury thermometer with an accuracy of 0.1 K. For each binary and ternary point tested, a fresh mixture of ∼40 mL prepared via weighing with a balance was added in the still before the external heater was turned on. Liquid and vapor condensate samples were taken at the same time when the fluctuation in equilibrium temperature was within 0.1 K in 30 min interval, by which the system was considered as VLE state. Three consecutive samples were taken for analysis at each experimental point. 2.3. Methods of Analysis. The qualitative analysis of the binary and ternary samples was conducted in SP-6890 gas chromatography (GC) equipped with a flame ionization detector (FID), manufactured by Shandong Rainbow Chemical

1

D = 100·

J = 150 ·

|∫ ln(γ1/γ2) dx1| 0 1

∫0 |ln(γ1/γ2)| dx1

(1)

Tmax − Tmin (T /K) Tmin

(2)

E = 100·

1

1

1

1

|∫ Li dx1 − ∫ Wi dx1| 0 0

∫0 Li dx1 + ∫0 Wi dx1 Li = 3217

∑ TkoxkΔsko/∑ xkΔsko − T

(3) (4)

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⎡ V L(p − ps ) ⎤ i ⎥ ̂ = x γϕ sps exp⎢ i ϕiyp ii i i i ⎢⎣ ⎥⎦ RT

Table 2. Isobaric VLE Data of Binary Systems 2Ethoxyethanol + Ethylbenzene, 2-Ethoxyethanol + DMSO, and Ethylbenzene + DMSO at 100 kPaa T/K 407.0 404.9 402.9 401.7 401.0 400.7 400.6 400.5 400.8 401.2 401.9 403.1 404.8 406.3 407.3 410.3 415.1 420.3 425.9 435.4 438.4 443.7 447.7 451.6 455.8 458.7 460.9 410.0 411.5 412.6 415.7 418.3 421.7 429.8 436.4 440.5 451.6 455.1 459.1

x1

γ1

y1

2-Ethoxyethanol (1) + Ethylbenzene (2) 0.9782 0.9507 1.0018 0.8984 0.8155 0.9977 0.8065 0.7010 1.0163 0.7262 0.6383 1.0669 0.6622 0.5781 1.0832 0.5752 0.5332 1.1611 0.5529 0.5210 1.1840 0.4817 0.4843 1.2672 0.3810 0.4243 1.3905 0.3192 0.3989 1.5409 0.2508 0.3445 1.6569 0.1543 0.2637 1.9859 0.0991 0.1874 2.0849 0.0533 0.1207 2.3846 0.0290 0.0661 2.3282 2-Ethoxyethanol (1) + DMSO (2) 0.9318 0.9923 0.9938 0.8314 0.9755 0.9504 0.7267 0.9443 0.9064 0.6370 0.9037 0.8459 0.4848 0.7925 0.7538 0.4199 0.7386 0.7495 0.3427 0.6454 0.6996 0.2784 0.5502 0.6632 0.2047 0.4338 0.6450 0.1372 0.3171 0.6342 0.0860 0.1970 0.5857 0.0419 0.0967 0.5596 Ethylbenzene (1) + DMSO (2) 0.8524 0.9377 1.0661 0.7658 0.9106 1.1072 0.6884 0.8963 1.1777 0.5356 0.8523 1.3274 0.4471 0.8345 1.4564 0.3745 0.7988 1.5274 0.2343 0.6912 1.7326 0.1578 0.5912 1.8840 0.1364 0.5401 1.8131 0.0439 0.2732 2.2325 0.0320 0.2108 2.1943 0.0169 0.1212 2.1983

γ2

(6)

where p and T are the system pressure and temperature at equilibrium, respectively; xi and yi are the liquid and vapor mole fractions of component i at equilibrium; γi is the activity coefficient; ϕ̂ i is the vapor-phase fugacity coefficient; ϕsi is the pure component fugacity coefficient at saturation; psi is the pure component pressure; VLi is the liquid molar volume; R is the universal gas constant. At low pressure, the Poynting factor exp[VLi ((p − psi )/RT)] approximately equals to 1. Besides, the vapor phase could be considered as ideal gas, and the pressure dependence of liquid phase fugacity could be neglected. Therefore, eq 6 can be simplified as:

2.3762 2.0209 1.8175 1.6068 1.5493 1.3747 1.3441 1.2518 1.1603 1.0891 1.0583 1.0184 1.0065 0.9947 1.0024

yp = xiγipis i

(7)

The vapor pressure of pure component was calculated by means of the extended Antoine equation, with parameters obtained from the databank of Aspen Physical Property System, as listed in Table 5. The equation for the extended Antoine vapor pressure model is:

0.5509 0.6026 0.7120 0.7747 0.8784 0.8989 0.9225 0.9516 0.9752 0.9670 0.9934 1.0059

ln Pis = Ai +

Bi Gi + DiT + Ei ln T + FT i T + Ci

Tmin ≤ T ≤ Tmax

(8)

The experimental activity coefficient calculated with eq 7 is listed in Tables 2 and 3. 3.3. Correlation of Binary VLE. The experimental data of three binary systems of 2-ethoxyethanol + ethylbenzene, 2ethoxyethanol + DMSO, and ethylbenzene + DMSO were correlated with the Wilson, NRTL, and UNIQUAC models by Aspen V7.1. In the regression calculation, the maximum likelihood objective function was minimized by manipulating the physical property parameters and the estimated value, while at the same time subject to the constraints of phase equilibrium. The maximum likelihood objective function is expressed as:

2.0807 1.7875 1.5012 1.2926 1.1163 1.0739 1.0428 1.0274 0.9989 1.0413 1.0151 1.0001

⎡⎛ exp 2 ⎛ pexp − pest ⎞2 Ti − Tiest ⎞ i ⎟ ⎢ Q=∑ ⎜ ⎟ + ⎜⎜ i ⎟ ⎢⎝ σ σ ⎠ ⎝ ⎠ T p i=1 ⎣ n

2 ⎛ xiexp − xiest ⎞2 ⎛ yiexp − yiest ⎞ ⎤ ⎥ ⎜ ⎟ +⎜ ⎟ +⎜ ⎟⎥ σx σy ⎝ ⎠ ⎝ ⎠⎦

(9)

a

Standard uncertainties u are u(T) = 0.1 K, u(P) = 0.1 kPa, u(x) = 0.001, and u(y) = 0.001.

Wi =

RT ⎛ ⎜∑ xk ln γk − ∑ xk Δsko ⎝

∑ xk ln

yk ⎞ ⎟ xk ⎠

where n is the number of experimental points; T, p, x, and y are the equilibrium temperature, pressure, liquid mole fraction, and vapor mole fraction, respectively; superscripts exp and est denote experimental and estimated values; σ is the standard deviation of the indicated data. The correlated binary interaction parameters of the Wilson, NRTL, and UNIQUAC models are listed in Table 6, together with the root-meansquare deviations in temperature and vapor phase mole fraction. The azeotropic temperature and composition of 2-ethoxyethanol + ethylbenzene at 100 ± 0.1 kPa here is 127.4 °C, 48.5 mol % 2-ethoxyethanol, determined with the NRTL model, which gives the least correlation error. This is in line with the reported data at a slightly different pressure which is 127.90 °C, 46.32 mol % at 100.94 kPa.4 The experimental T−x−y diagrams of binary systems 2-ethoxyethanol + ethylbenzene,

(5)

Tok is the boiling point of component k; Δsok is the molar entropy of vaporization of component k; xk and yk are liquid and vapor phase molar fractions; R is the universal gas constant; T is the temperature; i denotes each experimental point. In this work, the check results of D − J and E for three binary systems passed the tests, and the results are listed in Table 4. These results indicate that the experimental results are thermodynamically consistent. 3.2. VLE Model. The basic VLE relationship for each component i in a mixture system can be expressed generally as: 3218

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Table 3. Isobaric VLE Data of Ternary System 2-Ethoxyethanol (1) + Ethylbenzene (2) + DMSO (3) at 100 kPaa

a

T/K

x1

x2

y1

y2

γ1

γ2

γ3

435.6 433.8 432.1 431.0 429.1 427.1 426.5 425.8 424.1 422.9 421.5 420.3 420.1

0.4598 0.4459 0.4235 0.4042 0.3712 0.3241 0.3156 0.2926 0.2463 0.2045 0.1335 0.0605 0.0346

0.0030 0.0165 0.0364 0.0543 0.0843 0.1269 0.1328 0.1537 0.1992 0.2366 0.2988 0.3693 0.3900

0.7518 0.6946 0.6284 0.5678 0.4842 0.4010 0.3796 0.3398 0.2688 0.2203 0.1484 0.0663 0.0288

0.0271 0.0876 0.1702 0.2333 0.3316 0.4167 0.4473 0.4839 0.5515 0.6138 0.6878 0.7632 0.7871

0.7499 0.7495 0.7472 0.7286 0.7124 0.7137 0.7054 0.6944 0.6841 0.6983 0.7495 0.7644 0.5839

4.6275 2.8363 2.6000 2.4522 2.3494 2.0583 2.1423 2.0370 1.8677 1.8029 1.6566 1.5328 1.5045

0.8922 0.9271 0.8985 0.9152 0.8939 0.9336 0.8994 0.9327 1.0019 0.9535 0.9695 1.0446 1.1250

Standard uncertainties u are u(T) = 0.1 K, u(P) = 0.1 kPa, u(x) = 0.001, and u(y) = 0.001.

Table 4. Thermodynamic Consistency Test Results system

D

J

D−J

L

W

E

2-ethoxyethanol + ethylbenzene 2-ethoxyethanol + DMSO ethylbenzene + DMSO

1.73

2.55

−0.82

5.66

5.90

2.08

10.49

18.50

−8.01

1.25

1.29

1.57

6.13

17.96

−11.83

14.61

15.60

3.28

Table 5. Parameters of Extended Antoine Equation temperature unit property unit C1 C2 C3 C4 C5 C6 C7 C8 C9

2-ethoxyethanol

ethylbenzene

DMSO

K kPa 213.8122 −13517.0 0.0 0.0 −30.0620 2.78350·10−5 2.00000 214.150 569.000

K kPa 82.1552 −7733.70 0.0 0.0 −9.91700 5.98600·10−6 2.000000 178.200 617.150

K kPa 49.3652 −7620.60 0.0 0.0 −4.62790 4.38190·10−7 2.00000 291.670 729.000

Figure 2. Plot of experimental and correlated VLE data, 2ethoxyethanol (1) + ethylbenzene (2). ■, experimental x1; ▲, experimental y1; magenta solid line, calculated x1; blue dashed line, calculated y1.

2-ethoxyethanol + DMSO, and ethylbenzene + DMSO, together with correlated curve with Wilson model are shown in Figures 2, 3, and 4, respectively. There was no significant

Table 6. Correlation Parameters and Root-Mean-Square Deviations (RMSD) for the Binary Systems correlation parameters model Wilsonc NRTLd UNIQUACe

aij 1.4975 0.7678 0.2935

Wilson NRTL UNIQUAC

−1.8919 0.7473 −1.1280

Wilson NRTL UNIQUAC

−2.3746 0.0491 1.4658

aji

bij

RMSD bji

2-Ethoxyethanol (1) + Ethylbenzene (2) −0.3096 −845.22 −53.228 −0.8919 −157.58 604.07 0.3718 144.99 −273.72 2-Ethoxyethanol (1) + DMSO (2) 2.3321 808.24 −1623.22 −2.0819 186.80 288.66 0.8413 182.20 −56.494 Ethylbenzene (1) + DMSO (2) 0.1205 447.71 −770.58 1.6516 738.76 −843.81 −0.7823 −1141.1 564.95

σy1a

σTb

0.0054 0.0051 0.0051

0.1361 0.1350 0.1359

0.0082 0.0076 0.0090

0.3216 0.4467 0.6533

0.0053 0.0055 0.0054

0.5503 0.5655 0.5472

est 2 1/2 b n exp est 2 1/2 c σy1 = (1/n∑ni=1(yexp 1,i − y1,i ) ) . σT = (1/n∑i = 1(Ti − Ti ) ) . Wilson, ln Aij = ln Vj/(Vi + aij + bij)/T, where Vj and Vi are the pure component liquid molar volumes at system temperature. dNRTL, τij = (aij + bij)/T, the value of αij was fixed at 0.3 for the binary systems; eUNIQUAC, τij = exp((aij + bij)/T). a

3219

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Figure 3. Plot of experimental and correlated VLE data, 2ethoxyethanol (1) + DMSO (2). ■, experimental x1; ▲, experimental y1; magenta solid line, calculated x1; blue dashed line, calculated y1.

Figure 5. Residue curve map with experimental data of the ternary system 2-ethoxyethanol + ethylbenzene + DMSO. ■, experimental liquid phase composition; ▲, experimental vapor phase composition; magenta solid lines, predicted residue curves; blue dashed line, pairs of VLE data.

Figure 4. Plot of experimental and correlated VLE data, ethylbenzene (1) + DMSO (2). ■, experimental x1; ▲, experimental y1; magenta solid line, calculated x1; blue dashed line, calculated y1. Figure 6. Comparison of VLE behavior of binary system 2ethoxyethanol + ethylbenzene, with and without DMSO. ■, experimental data with DMSO; ▲, experimental data without DMSO; blue solid line, calculated data without DMSO; magenta solid line, calculated data with DMSO.

difference in deviations between different correlation models. Therefore, only calculated data with Wilson model was plotted. 3.4. Prediction of Ternary VLE. The obtained binary interaction parameters for Wilson, NRTL, and UNIQUAC models were used to predict the ternary VLE data of 2ethoxyethanol + ethylbenzene + DMSO, which was compared with the experimental data listed in Table 3. The prediction of each experimental point was carried out with ChemCAD 6.0.1 with CAPE-OPEN package exported from Aspen Plus V7.1. The mean absolute deviations of equilibrium temperature and vapor-phase mole fraction are shown in Table 7. All three models gives good prediction with reasonable deviations, with the best result obtained with the Wilson model. Hence, the

Wilson model was applied to predict the residue curve map of the ternary system, as shown in Figure 5, together with experimental data of liquid and gas phase composition. At each liquid-phase composition point, the liquid residue composition with time follows the residue curve toward DMSO as a result of simple, one stage batch distillation. Therefore, according to the mass balance principle, the vapor-phase composition lies on the reverse direction of the tangent line at each liquid phase

Table 7. Mean Absolute Deviations of Equilibrium Temperature and Vapor-Phase Mole Fraction of the Ternary System mean absolute deviations model

σTa/K

ΔmaxT/K

σy1b

Δmaxy1

Δy2b

Δmaxy2

Δy3b

Δmaxy3

Wilson NRTL UNIQUAC

0.2834 0.5238 1.0583

0.5387 0.9513 1.7896

0.0156 0.0151 0.0150

0.0260 0.0249 0.0390

0.0177 0.0125 0.0073

0.0340 0.0264 0.0212

0.0051 0.0041 0.0098

0.0100 0.0123 0.0177

est b n exp est σT = (1/n)∑ni=1|Texp i − Ti |. σy = (1/n)∑i=1|yi − yi |, where n is the number of data points; ΔmaxT and Δmaxy are the maximum temperature and vapor phase composition deviations, respectively.

a

3220

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(7) Wisniak, J. A new test for the thermodynamic consistency of vapor-liquid equilibrium. Ind. Eng. Chem. Res. 1993, 32 (7), 1531− 1533. (8) Wilson, G. M. Vapor-liquid equilibrium. XI. A new expression for the excess free energy of mixing. J. Am. Chem. Soc. 1964, 86 (2), 127− 130. (9) Renon, H.; Prausnitz, J. M. Local compositions in thermodynamic excess functions for liquid mixtures. AIChE J. 1968, 14 (1), 135−144. (10) Abrams, D. S.; Prausnitz, J. M. Statistical thermodynamics of liquid mixtures: a new expression for the excess Gibbs energy of partly or completely miscible systems. AIChE J. 1975, 21 (1), 116−128. (11) Kurihara, K.; Nakamichi, M.; Kojima, K. Isobaric vapor-liquid equilibria for methanol + ethanol + water and the three constituent binary systems. J. Chem. Eng. Data 1993, 38 (3), 446−449. (12) Carmona, F. J.; González, J. A.; García de la Fuente, I.; Cobos, J. C. Thermodynamic properties of n-alkoxyethanols + organic solvent mixtures. X. Liquid-liquid equilibria of systems containing 2methoxyethanol, 2-(2-methoxyethoxy) ethanol or 2-(2-ethoxyethoxy) ethanol, and selected alkanes. J. Chem. Eng. Data 1999, 44 (5), 892− 895. (13) Xue, G.; Wan, H.; Wang, L.; Guan, G. Vapor−Liquid Equilibrium for 2-Methyl-1-butanol + Ethylbenzene + Xylene Isomers at 101.33 kPa. J. Chem. Eng. Data 2013, 58 (3), 724−730. (14) Chaiyavech, P.; Van Winkle, M. Styrene-Ethylbenzene VaporLiquid Equilibria at Reduced Pressures. J. Chem. Eng. Data 1959, 4 (1), 53−56. (15) Radhamma, M.; Hsieh, C.-T.; Venkatesu, P.; Rao, M. P.; Lee, M.-J.; Lin, H.-m. Isobaric Vapor−Liquid Equilibrium for Dimethylsulfoxide with Chloroethanes and Chloroethenes. J. Chem. Eng. Data 2008, 53 (2), 374−377. (16) Renon, H.; Prausnitz, J. Liquid-liquid and vapor-liquid equilibria for binary and ternary systems with dibutyl ketone, dimethyl sulfoxide, n-hexane, and 1-hexene. Ind. Eng. Chem. Process Des. Dev. 1968, 7 (2), 220−225.

composition point, which is demonstrated in Figure 5. This result indicates that the predicted residue curve represents the experimental data well. As proposed, DMSO was expected to break the azeotropic point formed by 2-ethoxyethanol + ethylbenzene as an extractive solvent. In the ternary experiment, the composition of DMSO was controlled to be 0.50 by mass fraction, instead of mole fraction considering industrial practices. The experimental data of the binary system 2-ethoxyethanol + ethylbenzene and its behavior in ternary system excluding the third components is shown on the y−x diagram in Figure 6, together with calculated data with the Wilson model. It is shown that the azeotrope disappears with the addition of DMSO.

4. CONCLUSIONS Isobaric VLE data of binary systems 2-ethoxyethanol + ethylbenzene, 2-ethoxyethanol + DMSO, and ethylbenzene + DMSO and ternary system 2-ethoxyethanol + ethylbenzene + DMSO were measured at 100 ± 0.1 kPa with a modified Othmer still. All of the binary VLE data passed the Herington test and the Wisniak test. 2-Ethoxyethanol and ethylbenzene form a binary azeotrope at 127.4 °C, 48.5 mol % 2ethoxyethanol at 100 ± 0.1 kPa. The VLE data of the three binary systems were correlated with Wilson, NRTL, and UNIQUAC models, respectively, with binary interaction parameters and deviations presented. The correlated binary parameters successfully predicted the ternary VLE behavior, based on the comparison with the ternary experimental data. By adding the third component DMSO at 0.50 mass fraction, the azeotropic point disappeared, as shown in Figure 6, which provided theoretical basis for the separation of the 2ethoxyethanol and ethylbenzene mixture with DMSO as a promising solvent in extractive distillation.

■

AUTHOR INFORMATION

Corresponding Author

*E-mail: [email protected]. Notes

The authors declare no competing financial interest.

■

ACKNOWLEDGMENTS We are grateful to other members in our laboratory for their help during the preparation of this work and also to the anonymous reviewers for their valuable comments.

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dx.doi.org/10.1021/je4006739 | J. Chem. Eng. Data 2013, 58, 3216−3221