Ternary and Quaternary Liquid–Liquid Equilibria for Systems of Water

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Ternary and Quaternary Liquid−Liquid Equilibria for Systems of Water + Methanol + Methylanthranilate + Toluene at Different Temperatures Baohe Wang,* Weili Ran, Yanan Li, Jianping Xiong, and Shaoyuan Li Key Laboratory for Green Chemical Technology of Ministry of Education, Research and Development Center of Petrochemical Technology, Tianjin University, Tianjin, 300072, China ABSTRACT: Liquid−liquid equilibria (LLE) data of one quaternary mixture for water + methanol + methylanthranilate (MA) + toluene and two constituent ternary mixtures for the systems (water + MA + toluene) and (water + methanol + toluene) at (298.15, 313.15, and 323.15) K were measured at atmospheric pressure. The reliability of the experimental LLE data was ascertained through Othmer−Tobias and Bachman correlations. The LLE experimental data for the systems were correlated using the universal quasichemical (UNIQUAC) and nonrandom two-liquid (NRTL) models. The average rootmean-square deviations (RMSDs) of the NRTL and UNIQUAC models were 1.257 and 0.997. Both models accurately correlated the experimental tie-line data, while the correlation of the NRTL model was inferior to that of the UNIQUAC model.

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INTRODUCTION Liquid−liquid phase equilibria (LLE) investigations of multicomponent systems have been the subject of much interest in recent years. Such retrieval in the understanding of the phase behavior of the given systems stems from their importance in rational design of many chemical processes and separation operations. The precise LLE data is necessary to optimize extraction processes.1 The extraction of aromatics from wastewater is an important operation in chemical and petrochemical processes. The design of an apparatus and determination of the optimum operating conditions for aromatic extraction systems require the knowledge of multicomponent liquid−liquid equilibria (LLE) data.2−5 It is worth noting that using a suitable extractant plays an important role in the extraction efficiency of industrial separation processes. The preparation of methylanthranilate (MA) generates a large quantity of wastewater, including a part of methanol and MA.6,7 In view of the high price of MA, the recovery of MA from the wastewater can not only improve economic returns but also will be valuable in environment protection. Thus, choosing an extraction agent to recycle MA from the wastewater containing methanol is important for industrial applications. So we chose to study the quaternary system which is closer to the case of industrial application. We have recently reported LLE data for (water + methanol + MA) at different temperatures.8 Toluene is an aromatic solvent with very low dielectric constants and may be considered as a hydrophobic nonpolar aromatic solvent. From phase equilibrium data, we also learn that it is able to use toluene as extraction to recycle MA from wastewater. In this paper, LLE data at (298.15, 313.15, and 323.15) K were determined for the © 2012 American Chemical Society

systems consisting of two ternary systems for water + toluene + MA, water + methanol + toluene, and one quaternary system for water + methanol + toluene + MA. However, such experimental LLE data are usually not available and therefore should be predicted using various thermodynamic models such as activity coefficient. These models require proper binary interaction parameters, which are not yet available for all aromatic extraction systems. So the LLE experimental data were correlated and predicted using universal quasichemical (UNIQUAC)9 and nonrandom two-liquid (NRTL)10 activity coefficient models, and the parameters of the models were evaluated and reported. To the best of our knowledge, there is no reference in the literature about LLE data of the quaternary systems studied in this work. The experimental data provide a basis for toluene used as a good extractant in this kind of mixtures, which can serve for separation and process design in industrial applications.

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EXPERIMENTAL SECTION Chemicals. Methanol, MA, and toluene were purchased from Tianjin Reagent Company (China) with nominal minimum purities of 99.8, 99.8, and 99.8 mass %, respectively and distilled water was used. The purities determined by a GC analysis were 99.8 mass % for MA and more than 99.8 mass % for methanol and toluene. All chemicals were used without further purification. Received: October 9, 2011 Accepted: November 12, 2012 Published: November 20, 2012 3309

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Apparatus and Procedure. The experimental procedure in ternary sample mixture preparation was described in a previous work.8 To reduce the balance vapor pressure of the mixture within the equilibrium still, a little nitrogen was added to the system equilibrium still. The pressure inside the equilibrium still was kept constant, and the temperature in the cell was kept constant by circulating water from a water bath. The jackets were thermostatically controlled using a controller mounted on a water bath. The equilibrium experiments were carried out in equilibrium still including a jacketed glass cell, a thermostatically controlled water bath, a magnetic agitator, and a gas chromatography. The pressure inside the equilibrium still was kept constant, and the temperature of the bath was controlled to ± 0.1 K. The prepared mixtures were introduced into the equilibrium still and were agitated vigorously at least 5 h to mix the compounds sufficiently and then settled at least 8 h for complete phase separation. A series of LLE measurements were carried out by changing either the temperature or the composition of the mixtures. The quaternary mixtures were prepared by mixing the binary mixtures of methanol and water whose compositions are M1, M2, and MA recorded as M3, and then toluene stepwise to cover the two-phase regions. Figure 1 shows a schematic representation of the quaternary system of water + methanol + MA + toluene. The approximate values of M1, M2, and M3 are 0.50, 0.75, and 0.25, respectively.

To obtain the uncertainty in the equilibrium mass fraction values, we prepared several ternary mixtures with very wellknown concentrations by mass. These mixtures were investigated with the chromatographic method, and their chromatographic concentrations were compared with those obtained by mass. This comparison showed that the reported mass fraction values had an uncertainty of ± 0.01.

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RESULTS AND DISCUSSION Experimental Data. The LLE compositions for the two ternary systems water + toluene + MA and water + methanol + toluene at (298.15, 313.15, and 323.15) K are presented in Tables 1 and 2, respectively. The experimental data of the two ternary systems of (water + toluene + MA) and (water + methanol + toluene) are plotted in Figures 2 to 4 and Figures 5 to 7, respectively. Table 1. LLE Data for the Ternary System of Water (1) + Toluene (2) + MA (3) at Atmospheric Pressurea organic phase (I) T/K

w1

298.15

0.0097 0.0036 0.0014 0.0013 0.0012 0.0011 0.0010 0.0008 0.0007 0.0005

313.15

0.0179 0.0018 0.0007 0.0007 0.0007 0.0009 0.0005 0.0008 0.0007 0.0008 0.0008

323.15

0.00059 0.0015 0.0016 0.0017 0.0019 0.0024 0.0027 0.0039 0.0052 0.0072 0.0083 0.0089 0.0246

Figure 1. Schematic representation of the quaternary system of water + methanol + MA + toluene at 298.15 K.

The sample mixtures, withdrawn from the upper and lower phases by using a syringe, were analyzed separately by a gas chromatograph (Agilent 6820) equipped with a thermal conductivity detector (TCD). A 30 m long HP-Innowax polyethylene glycol capillary column (0.32 mm i.d., 0.5 μm film thickness) for TCD was utilized to separate components of samples using a temperature programming method. The temperatures of the detector and injection port were 523.15 K and 553.15 K, respectively. The accuracy was estimated to be ± 0.01 K. Injections were conducted on the split 1/30 mode. Hydrogen was used as a carrier at a rate of 0.1 cm3·min−1. To obtain a calibration curve for each component by the internal standard method, a Sartorius electronic balance with an accuracy of ± 0.0001 g was used to weigh the chemicals with the highest accuracy. On the other hand, to obtain overall mixtures for LLE studies, we weighed the components with the lowest balance accuracy. For the four components, linear correlations always provided the best chromatographic fit for the calibration curves. Three or four analyses were performed for each sample to obtain a mean mass fraction value with a repeatability better than 1 %.

w2

aqueous phase (II) w3

w1

0.0000 0.9903 0.9969 0.4420 0.5544 0.9986 0.6566 0.3420 0.9987 0.7942 0.2045 0.9987 0.8774 0.1214 0.9988 0.8882 0.1107 0.9988 0.8920 0.1070 0.9988 0.9125 0.0867 0.9988 0.9541 0.0452 0.9992 0.9995 0.0000 0.9995 RMSDb = 1.03, RMSDc = 1.48 0.0000 0.9821 0.9942 0.5700 0.4282 0.9982 0.6579 0.3414 0.9982 0.7223 0.2770 0.9984 0.8060 0.1933 0.9984 0.8511 0.1480 0.9984 0.8815 0.1180 0.9985 0.9058 0.0934 0.9985 0.9405 0.0588 0.9988 0.9613 0.0379 0.999 0.9992 0.0000 0.9992 RMSDb = 1.16, RMSDc = 1.32 0.99941 0.0000 0.999 0.9771 0.0214 0.9981 0.9611 0.0373 0.9976 0.9437 0.0546 0.9972 0.9195 0.0786 0.9966 0.8790 0.1186 0.9959 0.8470 0.1503 0.9955 0.7598 0.2363 0.9949 0.6794 0.3154 0.9946 0.5735 0.4193 0.9943 0.5223 0.4694 0.9941 0.4966 0.4945 0.9940 0.0000 0.9754 0.9909 RMSDb = 1.47, RMSDc = 1.08

w2

w3

0.0000 0.0002 0.0002 0.0003 0.0003 0.0004 0.0004 0.0005 0.0005 0.0005

0.0031 0.0012 0.0011 0.0010 0.0009 0.0008 0.0008 0.0007 0.0003 0.0000

0.0000 0.0005 0.0006 0.0006 0.0007 0.0007 0.0007 0.0008 0.0007 0.0007 0.0008

0.0058 0.0013 0.0012 0.0010 0.0009 0.0009 0.0008 0.0007 0.0005 0.0003 0.0000

0.001 0.0010 0.0010 0.0009 0.0009 0.0009 0.0009 0.0009 0.0009 0.0009 0.0009 0.0009 0.0000

0.0000 0.0009 0.0014 0.0019 0.0025 0.0032 0.0036 0.0042 0.0045 0.0048 0.0050 0.0051 0.0091

a

Standard uncertainties u are u(w) = 0.01 and u(T) = 0.1 K, RMSD. Predicted from the UNIQUAC model, RMS. cPredicted from the NRTL model. b

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Table 2. LLE Data for the Ternary System of Water (1) + Methanol (2) + Toluene (3) at Atmospheric Pressurea organic phase (I) T/K

w1

298.15

0.0009 0.0008 0.0008 0.0006 0.0014 0.0019 0.0014 0.0029 0.0028 0.0027 0.0035

313.15

0.0008 0.0012 0.0015 0.0019 0.0022 0.0026 0.0034 0.0047 0.0058 0.0077 0.0121

323.15

0.0009 0.0019 0.0026 0.0035 0.0045 0.0069 0.0118 0.0162 0.0214 0.0352 0.0492

w2

aqueous phase (II) w3

w1

0.0000 0.9991 0.9749 0.0006 0.9986 0.9701 0.0033 0.9959 0.7964 0.0053 0.9941 0.6949 0.0110 0.9876 0.5776 0.0157 0.9824 0.3802 0.0222 0.9764 0.3257 0.0272 0.9699 0.2706 0.0393 0.9579 0.2267 0.0492 0.9481 0.1719 0.0510 0.9455 0.1747 RMSDb = 1.82, RMSDc = 1.15 0.0000 0.9992 0.9992 0.0078 0.9910 0.9142 0.0153 0.9832 0.8419 0.0225 0.9756 0.7795 0.0297 0.9681 0.7252 0.0368 0.9607 0.6773 0.0510 0.9457 0.5967 0.0727 0.9225 0.5027 0.0880 0.9063 0.4525 0.1121 0.8802 0.3900 0.1576 0.8303 0.3090 RMSDb = 1.74, RMSDc = 1.52 0.0000 0.9991 0.9990 0.0135 0.9846 0.9187 0.0271 0.9703 0.8500 0.0410 0.9555 0.7905 0.0551 0.9404 0.7385 0.0845 0.9086 0.6513 0.1315 0.8567 0.5501 0.1646 0.8192 0.4958 0.1988 0.7798 0.4485 0.2692 0.6956 0.3681 0.3236 0.6272 0.3148 RMSDb = 2.56, RMSDc = 1.49

w2

w3

0.0246 0.0284 0.2022 0.3034 0.4112 0.5882 0.6149 0.6536 0.6700 0.6510 0.6610

0.0005 0.0015 0.0014 0.0017 0.0112 0.0316 0.0594 0.0758 0.1033 0.1771 0.1643

0.0000 0.0844 0.1556 0.2164 0.2686 0.3139 0.3877 0.4677 0.5060 0.5473 0.5849

0.0008 0.0014 0.0026 0.0041 0.0062 0.0087 0.0155 0.0296 0.0415 0.0628 0.1061

0.0000 0.0794 0.1467 0.2042 0.2538 0.3341 0.4206 0.4623 0.4948 0.5387 0.5570

0.0010 0.0019 0.0033 0.0053 0.0077 0.0146 0.0293 0.0419 0.0567 0.0932 0.1282

Figure 2. LLE for the ternary system of water (1) + toluene (2) + MA (3) at 298.15 K: ■, experimental data in this work; ---, calculated curves by the NRTL model; , calculated curves by the UNIQUAC model.

Figure 3. LLE for the ternary system of water (1) + toluene (2) + MA (3) at 313.15 K: ■, experimental data in this work; ---, calculated curves by the NRTL model; , calculated curves by the UNIQUAC model.

a

Standard uncertainties u are u(w) = 0.01, u(T) = 0.1 K, RMSD. Predicted from the UNIQUAC model, RMSD. cPredicted from the NRTL model. b

The mutual solubility of water and methanol, toluene, and water at 298.15 K are listed in Table 3. The tie-line results for the water + methanol + toluene system were in good agreement with the reported values11−13 at the diluted region of methanol as shown in Figure 5. The experimental tie-line data for the methanol + toluene + water + MA at (298.15, 313.15, and 323.15) K are shown in Table 3. The reliability of the experimental data can be ascertained by applying the Othmer−Tobias equation or Bachman equation.14,15 The equations are represented, respectively, as follows: ⎛1 − w Ι ⎞ ⎛ 1 − x ΙΙ ⎞ 4 3 ⎟ ⎜⎜ ⎟⎟ = + ln⎜⎜ ln a b ⎟ Ι ΙΙ ⎝ w4 ⎠ ⎝ x3 ⎠

(1)

⎛ wΙ ⎞ w4 Ι = A + B⎜⎜ 4ΙΙ ⎟⎟ ⎝ w3 ⎠

(2)

Figure 4. LLE for the ternary system of water (1) + toluene (2) + MA (3) at 323.15 K: ■, experimental data in this work; ---, calculated curves by the NRTL model; , calculated curves by the UNIQUAC model.

where w4I is the mass fraction of toluene in the solvent- rich phase; w3II is the mass fraction of water in the water-rich phase; the letters a, b, A, and B are constants of the equations of Othmer−Tobias and Bachman, respectively. The parameters of the Othmer−Tobias and Bachman equations are listed in Table 3311

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component i in two coexistent liquid phases of a system at equilibrium are listed as the following,

(γixi)1 = (γixi)2

(3)

∑ xi1 = ∑ xi 2

(4)

γi1

Here and γi are the corresponding activity coefficients of component i in phases 1 and 2, and xi1 and xi2 are the mole fractions of component i in the system in phases 1 and 2, respectively. The key to solve the equations is to calculate the activity coefficients. The LLE experimental data are used to correlate the interaction parameters between methanol + toluene + water + MA; these in turn are used to determine the activity coefficients from NRTL and UNIQUAC equations. The adjustable parameters of the NRTL and UNQUAC models are defined, respectively, as follows,

Figure 5. LLE for the ternary system of water (1) + methanol (2) + toluene (3) at 298.15 K: ■, experimental data in this work; ■, experimental data in ref 13; ---, calculated curves by the NRTL model; , calculated curves by the UNIQUAC model.

τij = aij +

2

bij T

τij = exp(aij + bij /T )

(5) (6)

where aij and bij are the binary parameters and T is the temperature. These parameters were determined by minimizing the deviation between the experimental data and the model calculated values. The binary interaction parameters of both models were calculated using Aspen Plus software. The regression method was the least-squares method based on maximum likelihood principles. The Britt−Luecke algorithm was employed to obtain the model parameters with the Deming initialization method. In the process of regression calculations, the parameter of those two models in eqs 5 and 6, the value of the nonrandomness parameter of the NRTL model, α, was fixed at 0.3, and for the UNIQUAC model, the pure component structural parameters (r, q) are listed in Table 5. The values of the binary parameter are listed in Table 6. The binary and ternary LLE data were correlated with the NRTL and UNIQUAC models. Minimizing the differences between the experimental and the calculated mass fractions for each component determined the constituent binary parameters of both models over all of the measured LLE data of the systems. The optimization results were judged by calculating the corresponding root-mean-square deviation (RMSD) values using the following equation:

Figure 6. LLE for the ternary system of water (1) + methanol (2) + toluene (3) at 313.15 K: ■, experimental data in this work; ---, calculated curves by the NRTL model; , calculated curves by the UNIQUAC model.

RMSD =

⎛ (wi ,exp − wi ,cal)2 ⎞ ⎟ ⎜ ∑ ⎜∑ ∑ ⎟ 8N ⎠ k ⎝ j i

(7)

where N is the total number of tie-lines, subscript exp denotes the experimental mass fraction, subscript cal is the calculated mass fraction, and subscripts i, j, and k denote the component, phase, and tie-line, respectively, and i = 1 to 3 for ternary mixtures or i = 1 to 4 for quaternary mixtures, j = 1, 2 (phases), and k = 1, 2, ..., n (tie-lines). The values of interaction parameters for the NRTL and UNIQUAC models are shown in Table 6. These parameters are used to calculate LLE tie lines for the present systems. Figures 2 to 4 and Figures 5 to 7 also compare the calculated curves from the NRTL and UNIQUAC models with the experimental results for the ternary system (water + MA + toluene) and (water + methanol + toluene). The RMSD values between the observed and the calculated mass fractions of both the NRTL and the UNIQUAC models are listed in Table 6. The average RMSDs of NRTL and

Figure 7. LLE for the ternary system of water (1) + methanol (2) + toluene (3) at 323.15 K: ■, experimental data in this work; ---, calculated curves by the NRTL model; , calculated curves by the UNIQUAC model.

4. All of the squares of the linear correlation coefficients (R2) are greater than 0.956. The standard deviations (SDs) are less than 0.232. These results suggest that it is reasonable to accept the LLE data of the considered systems as reliable. LLE Calculations. The relationship of liquid−liquid equilibrium can be represented with an activity coefficient model. In this model, the basic relationships for every 3312

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Table 3. LLE Data of Methanol (1) + Toluene (2) + Water (3) + MA (4) at Atmospheric Pressurea aqueous phase (I)

organic phase (II)

w1

w2

w3

0.0000 0.0467 0.0635 0.2072 0.2211 0.2259 0.2854 0.4198

0.0005s 0.0007 0.0011 0.0017 0.0015 0.0007 0.0044 0.0069

0.9985 0.9524 0.9344 0.7896 0.7709 0.7639 0.7064 0.5648

0.0000 0.0467 0.0622 0.2141 0.2311 0.2374 0.3154 0.4006

0.0007 0.0037 0.0011 0.0017 0.0015 0.0015 0.0044 0.0145

0.9983 0.9494 0.9356 0.7823 0.7565 0.7483 0.6764 0.5693

0.0000 0.0367 0.2011 0.2111 0.2141 0.3154 0.4006

0.0007 0.0237 0.0061 0.0051 0.0047 0.0074 0.0145

0.9983 0.9383 0.7819 0.7709 0.7823 0.6764 0.5693

w4

w1

298.15 K 0.0010 0.0000 0.0002 0.0000 0.0010 0.0039 0.0016 0.0085 0.0064 0.0266 0.0095 0.0297 0.0038 0.0142 0.0086 0.0220 RMSDb = 1.24, RMSDc = 1.62 313.15 K 0.0010 0.0000 0.0002 0.0020 0.0011 0.0023 0.0038 0.0124 0.0109 0.0292 0.0129 0.0323 0.0048 0.0202 0.0157 0.0382 RMSDb = 1.68, RMSDc = 2.49 323.15 K 0.0010 0.0000 0.0013 0.0060 0.0109 0.0472 0.0129 0.0312 0.0053 0.0302 0.0083 0.0576 0.0157 0.0382 RMSDb = 1.67, RMSDc = 2.44

w2

w3

w4

0.7885 0.9683 0.7846 0.7815 0.2564 0.0872 0.7773 0.7778

0.0014 0.0006 0.0018 0.0026 0.0093 0.0125 0.0028 0.0034

0.2101 0.0311 0.2098 0.2074 0.7076 0.8706 0.2056 0.1968

0.7838 0.9603 0.7951 0.7819 0.2430 0.0848 0.7773 0.7671

0.0013 0.0046 0.0024 0.0028 0.0214 0.0238 0.0038 0.0043

0.2148 0.0331 0.2003 0.2030 0.7064 0.8591 0.1986 0.1904

0.7838 0.9649 0.2430 0.0753 0.7701 0.7632 0.7671

0.0013 0.0013 0.0214 0.0300 0.0048 0.0079 0.0043

0.2148 0.0278 0.6884 0.8635 0.1948 0.1713 0.1904

a

Standard uncertainties u are u(w) = 0.01, u(T) = 0.1 K. bRMSD is predicted from the UNIQUAC model. cRMSD is predicted from the NRTL model.

Table 4. Constants of the Othmer−Tobias and Bachman Equation for the Water (1) + Methanol (2) + MA (3) + Toluene (4) System at (293.15, 303.15, and 313.15) Ka Othmer−Tobias

Bachman 2

T/K

a

b

R

293.15 303.15 313.15

−1.1025 −1.0239 −0.9328

0.5364 0.5938 0.5649

0.9864 0.9749 0.9684

SD

A

B

R2

SD

0.173 0.2136 0.2318

2.2306 2.2375 2.3648

−1.964 −1.2536 −1.5358

0.9567 0.9629 0.972

0.0146 0.0153 0.0138

a 2

R is the linear correlation coefficient; SD is the standard deviation.

and 323.15) K. LLE data of methanol + toluene + water + MA at atmospheric pressure and T = (298.15, 313.15, and 323.15) K and the predicted results are listed in Table 6. Predicted values were in agreement with the experimental data. So these binary interaction parameters and LLE data are reliable. On the other hand, as seen from Figures 3 to 7 and Tables 3 and 6, good agreements have been obtained for the three ternary systems and the quaternary system using the NRTL and UNIQUAC models. However, the predicted accuracy of UNIQUAC model is better to that of NRTL model. The UNIQUAC model and these multibody interaction parameters obtained in this work can be applied desirably to predict LLE properties of complicated fluid mixtures in separation process.

Table 5. UNIQUAC Structural Parameters of the Used Pure Component component

r

q

water methanol MA toluene

0.92 1.43111 5.56163 3.92

1.4 1.432 4.308 2.97

UNIQUAC models were 1.257 and 0.997. The correlated results were in agreement with the results of the experiments. But the correlation accuracy of NRTL model was inferior to that of UNIQUAC model. Results also showed that experiment data, selected models, and regression methods were reliable. These binary interaction parameters were used to predict LLE data of the quaternary system for water + methanol + toluene + MA at atmospheric pressure and T = (298.15, 313.15,

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CONCLUSIONS LLE data of the quaternary system for water + methanol + MA + toluene and the ternary systems for water + MA + toluene 3313

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Table 6. Values of the NRTL and UNIQUAC Binary Parameters Regressed from LLE Data and RMSD for the Methanol (1) + Toluene (2) + Water (3) + MA (4) System at (293.15, 303.15, and 313.15) K NRTL

UNIQUAC

component

aij

aji

bij

bji

RMSD

aij

aji

bij

bji

RMSD

water−MA water−methanol methanol−MA toluene−MA methanol−toluene water−toluene

−6.98 4.87 −27.27 −7.72 −7.11 1713.30

−8.1 −2.63 4.02 35 −20.68 752.99

4136.9 −1347.5 10001 709.96 2547.6 −37.8

3317.7 838.59 −2028.2 −7041.2 6709.8 −59.4

0.01 1.59 1.48 2.88 1.58 1.62

1.3 0.64 10.34 −15.34 5 1016.32

4.72 −1.07 −13.59 11 4 311.5

−495.39 −322.13 −3191 4629.5 −1472.4 −56.3

−1849.7 432.88 3892.7 −3411.9 −1717.4 −38.1

0.02 1.37 0.93 2.47 1.19 2.03

(10) Renon, H.; Prausnitz, J. M. Local compositions in thermodynamic excess functions for liquid mixtures. AIChE J. 1968, 14, 135−144. (11) Zhao, S. Y.; Chen, H. J.; Chen, X. M.; Zhou, J. Y.; Wang, L. E. Liquid-Liquid Equilibrium of Ternary and Quaternary Systems Including Methyl Acetate, Benzene, Toluene, and Water at 283.2 K under Atmosphere. J. Chem. Eng. Data 2010, 55, 5276−5279. (12) Chen, Y.; Dong, Y. H.; Pan, Z. J. Ternary and Quaternary Liquid-Liquid Equilibria of Water + Methanol + Diisopropyl Ether and Water + Methanol + Diisopropyl Ether + Toluene Mixtures. J. Chem. Eng. Data 2005, 50, 2031−2034. (13) Tamura, K.; Chen, Y.; Yamada, T. Ternary and Quaternary Liquid-Liquid Equilibria for Fuel Additives of the Water + Methanol + Toluene and Water + Methanol + Toluene + Methyl tert-Butyl Ether or tert-Amyl Methyl Ether Systems at 298.15 K. J. Chem. Eng. Data 2001, 46, 1381−1386. (14) Othmer, D. F.; Tobias, P. E. Tie-line Correlation. Ind. Eng. Chem. 1942, 34, 693−700. (15) Yang, Z. D.; Zhu, J. W.; Wu, B.; Chen, K.; Ye, X. H. Liquid− liquid equilibrium for the ternary systems of water + acetyl acetone + propyl acetate at several temperatures. Fluid Phase Equilib. 2011, 304, 7−11.

and water + methanol + toluene at (298.15, 313.15, and 323.15) K were measured at atmospheric pressure. The reliability of the LLE data of the investigated system was inspected by the Othmer−Tobias and Bachman equations. The NRTL and UNIQUAC models were used to correlate the experimental LLE data and the parameters of these models are presented. Both models accurately correlated the experimental tie-line data, while the NRTL model was inferior to that of UNIQUAC model, according to the analysis of the average RMSD.

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AUTHOR INFORMATION

Corresponding Author

*Tel.: +86 22 27406959. Fax: +86 22 27406591. E-mail: [email protected]. Notes

The authors declare no competing financial interest.

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REFERENCES

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dx.doi.org/10.1021/je300585v | J. Chem. Eng. Data 2012, 57, 3309−3314