Solid–Liquid Equilibria for Six Binary Mixtures Involving Heptanedioic

Nov 12, 2012 - 2,3-Dimethylbutanedioic Acid, 2,2-Dimethylbutanedioic Acid, and 3‑Methylheptanedioic Acid. Tzu-Chi Wang,. †. Yi-Ju Li,. † and Yan...
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Solid−Liquid Equilibria for Six Binary Mixtures Involving Heptanedioic Acid, Pentanedioic Acid, Hexanedioic Acid, 2,3-Dimethylbutanedioic Acid, 2,2-Dimethylbutanedioic Acid, and 3‑Methylheptanedioic Acid Tzu-Chi Wang,† Yi-Ju Li,† and Yan-Ping Chen*,‡ †

Department of Chemical and Materials Engineering and Master Program of Nanomaterials, Chinese Culture University, Taipei, Taiwan, Republic of China ‡ Department of Chemical Engineering, National Taiwan University, Taipei, Taiwan, Republic of China ABSTRACT: Solid−liquid equilibrium data for six organic binary mixtures of heptanedioic acid (1) + pentanedioic acid (2) (eutectic temperature TE = 341.9 K, eutectic composition x1E = 0.391), hexanedioic acid (1) + heptanedioic acid (2) (TE = 365.4 K, x1E = 0.239), heptanedioic acid (1) + 2,3-dimethylbutanedioic acid (2) (TE = 348.9 K, x1E = 0.443), heptanedioic acid (1) + 2,2-dimethylbutanedioic acid (2) (TE = 358.8 K, x1E = 0.667), heptanedioic acid (1) + 3-methylpenetandioic acid (2) (TE = 338.8 K, x1E = 0.357), and 2,2-dimethylbutanedioic acid (1) + 3methylpenetandioic acid (2) (TE = 348.3 K, x1E = 0.212) were measured in this study using differential scanning calorimetry (DSC). All six systems show simple eutectic behavior. The experimental data were correlated using the Wilson and nonrandom two-liquid (NRTL) activity coefficient models, and satisfactory results are presented.

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INTRODUCTION As the traditional distillation approach is not applicable for isomeric or thermolabile compounds, crystallization provides an alternative separation process. Solid−liquid equilibrium (SLE) data are essentially required for the design and operation of such processes. The motivation of this study is to measure experimental data for binary mixtures of organic acids that are not available in literature. Experimental methods using the cooling curve or visual measurement are traditionally employed to obtain SLE data.1 Another alternative and fast tool for SLE measurement is differential scanning calorimetry (DSC). The thermal analysis using DSC measures the heat effect during phase transition. The measured peak temperatures and heats of phase transformation are used to determine the phase boundaries of SLE, as reported by Hammami and Mehrotra in early 1990s.2 An example for SLE measurement on binary organic mixtures using DSC is presented by Flotter et al.3 We have also reported our SLE measurements for binary mixtures of organic compounds by applying DSC, and the experimental data were well-correlated by activity coefficient models.4,5 The DSC technique has been further employed to determine SLE of partial solid solution systems or ternary organic systems.6,7 Mathematical models for DSC measurement of SLE have also been developed by taking account of the instrument characteristics.8 We have shown that the eutectic composition can be predicted using limited experimental data from DSC measurement by applying the fractional transformation curve.5,9 © XXXX American Chemical Society

In this study, we measured novel SLE data by the DSC method of six binary organic mixtures: heptanedioic acid (C7H12O4) + pentanedioic acid (C5H8O4), hexanedioic acid (C6H10O4) + heptanedioic acid, heptanedioic acid + 2,3dimethylbutanedioic acid (C6H10O4), heptanedioic acid + 2,2dimethylbutanedioic acid (C6H10O4), heptanedioic acid + 3methylpenetandioic acid (C6H10O4), and 2,2-dimethylbutanedioic acid + 3-methylpenetandioic acid. We applied the Wilson10 and nonrandom two-liquid (NRTL)11 activity coefficient models to correlate the measured SLE data. The eutectic temperatures and compositions for all six binary mixtures are finally demonstrated. It is also observed that the model correlated and experimentally measured eutectic conditions are in satisfactory agreement.

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EXPERIMENTAL SECTION Hexanedioic acid was purchased from Fluka and Aldrich. All other chemicals were bought from Aldrich. The purity of these chemicals was greater than mass fraction w = 0.99, and they were used without further purification. The DSC equipment (Perkin-Elmer DSC 4000) was first calibrated using pure indium and zinc at a slow heating rate of 1 K·min−1. The determination of the fusion temperature of pure component was from the onset temperatures of the DSC curve. Satisfactory Received: June 27, 2012 Accepted: October 29, 2012

A

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Table 1. Comparison of the Measured Melting Temperatures and Heats of Fusion with Literature Data for Pure Compounds ΔfusHom/kJ·mol−1

Tm/K compound

this study

lit.

this study

lit.

heptanedioic acid

377.4

17

28.8 ± 0.5

pentanedioic acid hexanedioic acid 2,3-dimethylbutanedioic acid 2,2-dimethylbutanedioic acid 3-methylpetanedioic acid

369.1 426.3 392.5 411.0 358.6

27.6218 30.3 ± 0.519 20.918 34.8521 N/A N/A N/A

379.15 377.519 370.0520 425.5021 391.2−395.222 N/A N/A

21.5 35.2 16.9 38.1 30.9

± ± ± ± ±

0.4 0.7 0.3 0.5 0.5

the liquid and solid is neglected:

agreement for the fusion temperatures and heats of fusion with literature data of these two standards were obtained. The melting temperatures and enthalpies of fusion of six pure compounds were then measured using the calibrated DSC. These measured pure fluid properties were compared with literature data as shown in Table 1. Satisfactory agreements on the first three pure fluid properties are observed where literature data are available. The SLE data for six binary mixtures were measured in this study using DSC. The experimental procedures are similar to those in our previous report.9 They include the calibration, pretreatment, and the SLE measurements. Before our SLE experiments, we purged the DSC using nitrogen gas and cleaned it by heating to 673.15 K. The calibration of the DSC was conducted by high-purity indium and zinc. For sample preparation, 4 mg of each binary mixture sample at a specific composition was weighted by a balance (Shimadzu C9AS-AUW220D) with accuracy of ± 0.01 mg. The sample was then sealed in a highpressure aluminum container (Perkin-Elmer). A first heating run at the rate of 10 K·min−1 was employed for each sample to delete the previous thermal histories of DSC. This heating procedure also homogenized the mixture sample. This heating ended at a state that is higher than the melting temperature of the heavy component in the binary mixture. After keeping at this temperature for 1 min, the sample was then cooled at a rate of 10 K·min−1 to 303.15 K and kept at this state for 30 min to complete the pretreatment process. Samples for heptanedioic acid (1) + pentanedioic acid (2) and hexanedioic acid (1) + heptanedioic acid (2) were then heated at the rate of 1 K·min−1. Samples of heptanedioic acid (1) + 2,3-dimethylbutanedioic acid (2), heptanedioic acid (1) + 2,2-dimethylbutanedioic acid (2), heptanedioic acid (1) + 3-methylpenetandioic acid (2), and 2,2dimethylbutanedioic acid (1) + 3-methylpenetandioic acid (2) were heated at a slower rate of 0.5 K·min−1 or 1 K·min−1 to clearly identify the peaks in their DSC curves. The onset temperatures from the measured DSC curves were determined and taken as the eutectic temperature. Following the similar procedure in our previous study,6 the modified peak temperatures from the DSC measurements were reported as the liquidus temperatures. In this study, the uncertainty for temperature measurement is estimated as ± 1 K. The maximum uncertainties for some experimental liquidus and solidus temperatures are (2 and 3) K, respectively. The reproducibility of our experimental results was justified by repeated experiments for each sample mixture. Model and Correlation. The thermodynamic relationship for SLE is obtained by using the equal fugacity criterion.12 It is represented by eq 1 where the difference for heat capacities of

ln(γixi) = −

o ⎛T ⎞ ΔfusHmi m,i − 1⎟ ⎜ ⎠ RTm,i ⎝ T

(1)

The melting temperature (Tm) and the molar enthalpy of fusion (ΔfusHom) are pure fluid properties listed in Table 1. At a specified sample composition (x), the activity coefficient (γ) is calculated from eq 1 at the measured liquidus temperature (T). The calculated activity coefficients represented the nonideal solution behavior of the fluid mixture. Commonly used Wilson and NRTL activity coefficient models were applied for data correlation. The Wilson equations are written as: ⎞ ⎛ Λ12 Λ 21 ln γ1 = −ln(x1 + Λ12x 2) + x 2⎜ − ⎟ Λ 21x1 + x 2 ⎠ ⎝ x1 + Λ12x 2 (2)

⎞ ⎛ Λ12 Λ 21 ln γ2 = −ln(x 2 + Λ 21x1) − x1⎜ − ⎟ Λ 21x1 + x 2 ⎠ ⎝ x1 + Λ12x 2 (3)

Λ12 =

V2 ⎛ λ12 − λ11 ⎞ ⎟ exp⎜ − V1 ⎝ RT ⎠

(4)

Λ 21 =

V1 ⎛ λ 21 − λ 22 ⎞ ⎟ exp⎜ − V2 ⎝ RT ⎠

(5)

R is the gas constant in eqs 4 and 5. The available liquid molar volumes of pure fluids (V1 and V2) are obtained from DIPPR.13 Otherwise, they are calculated using Elbro’s group contribution method.14 The two adjustable parameters in the Wilson model are (λ12 − λ11)/R and (λ21 − λ22)/R. The activity coefficients from the other NRTL model are presented as: ⎤ ⎞2 ⎛ G21 τ12G12 ⎥ ln γ1 = x 2 τ21⎜ ⎟ + ⎢⎣ ⎝ x1 + x 2G21 ⎠ (x 2+x1G12)2 ⎥⎦

(6)

⎤ ⎡ ⎛ ⎞2 G12 τ21G21 ⎥ ln γ2 = x12⎢τ12⎜ ⎟ + ⎢⎣ ⎝ x 2 + x1G12 ⎠ (x1+x 2G21)2 ⎥⎦

(7)

ln G12 = −α12τ12

(8)

⎡

2⎢

τ12 = B

g12 − g22 RT

ln G21 = −α12τ21

τ21 =

g21 − g11 RT

(9)

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Table 2. Measured Solid−Liquid Equilibrium Data for Six Binary Systems: The Eutectic Temperature (TE) and Liquidus Temperature (TL) at 0.1 MPa and Various Compositions (x1) TE/K

100x1 0.00 4.84 9.93 14.99 19.78 25.22 30.26 44.71 49.65 55.59 0.00 4.99 9.98 14.99 30.10 35.06 39.90 44.94 50.10 55.18 0.00 4.79 10.06 15.04 19.81 24.82 30.05 34.61 55.69 a

TL/K

TE/K

100x1

TL/K

100x1

Heptanedioic Acid (1) + Pentanedioic Acid (2) 369.1 60.02 342.3 356.4 N/Aa 341.3 367.9 65.31 341.9 358.7 342.8 364.3 70.09 342.3 360.5 342.7 360.8 75.03 342.5 364.9 342.8 356.0 79.66 342.2 367.5 342.2 354.9 85.12 342.0 370.4 342.9 347.2 89.99 340.6 372.9 342.3 345.6 95.01 341.3 376.2 342.3 349.9 100.00 N/A 377.4 342.6 353.6 Hexanedioic Acid (1) + Heptanedioic Acid (2) N/A 377.4 60.02 366.6 402.2 367.0 375.6 65.11 366.7 405.9 366.0 373.1 70.02 366.0 408.4 366.7 369.7 75.01 366.2 411.6 367.1 374.9 79.99 366.0 414.1 367.1 378.5 85.01 365.6 417.1 367.1 387.7 89.99 367.0 419.7 367.1 389.6 95.00 367.1 422.9 366.7 394.4 100.00 N/A 426.3 367.1 398.4 Heptanedioic Acid (1) + 2,3-Dimethylbutanedioic Acid (2) N/A 392.5 60.39 348.6 357.6 349.7 384.3 64.77 348.8 359.4 350.2 381.2 69.45 347.2 363.6 351.2 377.5 75.07 348.0 365.1 351.1 373.6 80.20 346.44 367.4 348.3 365.1 85.01 348.2 370.0 351.6 363.7 89.71 348.1 372.8 347.1 357.9 95.08 348.5 375.6 348.5 355.7 100.00 N/A 377.4

TE/K

TL/K

100x1

TE/K

Heptanedioic Acid (1) + 2,2-Dimethylbutanedioic Acid (2) 0.00 N/A 411.0 50.68 361.6 5.25 360.5 408.2 55.42 361.3 10.01 361.1 404.6 59.72 361.9 15.03 362.0 402.0 79.96 361.2 19.84 360.8 398.0 84.86 360.9 24.64 361.6 395.4 90.00 359.7 30.52 361.2 393.0 95.06 360.6 35.38 361.6 389.8 100.00 N/A 40.63 361.9 385.9 45.22 361.9 379.7 Heptanedioic Acid (1) + 3-Methylpentanedioic Acid (2) 0.00 N/A 358.6 70.15 340.7 5.08 337.3 356.1 75.24 340.0 9.64 339.2 353.9 79.71 339.4 14.88 339.5 352.5 84.82 338.5 20.16 338.8 349.8 89.47 338.3 25.41 339.3 348.4 94.89 338.0 29.96 339.6 344.3 100.00 N/A 55.38 339.9 351.1 59.00 340.0 354.4 65.19 340.2 356.7 2,2-Dimethylbutanedioic Acid (1) + 3-Methylpentanedioic Acid 0.00 N/A 358.6 65.75 346.8 5.46 346.8 355.6 70.00 347.0 10.17 347.5 353.6 74.50 346.6 35.15 347.2 366.7 79.75 347.1 40.00 347.2 374.1 84.16 345.8 44.83 347.2 372.4 89.95 345.5 50.00 347.3 376.6 94.79 345.5 55.14 347.4 385.1 100.00 N/A 60.05 347.3 388.7

TL/K 375.0 370.7 368.1 366.9 368.9 373.0 373.9 377.4

359.3 362.3 367.0 370.3 372.4 375.4 377.4

(2) 390.7 392.2 396.9 397.7 401.9 404.4 407.4 411.0

N/A: not available. Standard uncertainties u are u(x1) = 0.002, u(T) = 1 K, u(P) = 5 kPa.

NRTL models are listed in Table 3 together with the absolute average deviations in the calculated liquidus temperatures (AADT). Generally, the experimental data are satisfactorily correlated using either the Wilson or NRTL model with their optimal binary parameters. The AADT values presented in Table 3 are from (0.2 to 0.4) K that are acceptable by considering the experimental uncertainty for all six binary mixtures. Simple eutectic behavior is depicted for all six binary systems in this study. The eutectic compositions and temperatures for six binary mixtures in this study are shown in Table 4. They were determined by two approaches: the smoothed curves by applying the Clarke−Glew equation15,16 or the Wilson and NRTL model calculated results. It is shown in Table 4 that the eutectic composition and temperature results from model calculation and experimentally data smoothing are in satisfactory agreement. A typical DSC thermogram in our study for one binary SLE experiment of hexanedioic acid and heptanedioic acid is shown in Figure 1. Graphical presentations for the calculated SLE phase boundaries from the Wilson model and the Clarke− Glew equation for six binary systems of heptanedioic acid (1) + pentanedioic acid (2), hexanedioic acid (1) + heptanedioic acid (2), heptanedioic acid (1) + 2,3-dimethylbutanedioic acid (2), heptanedioic acid (1) + 2,2-dimethylbutanedioic acid (2), heptanedioic acid (1) + 3-methylpenetandioic acid (2), and 2,2dimethylbutanedioic acid (1) + 3-methylpenetandioic acid (2)

The NRTL model has three adjustable binary parameters: (g12 − g22)/R, (g21 − g11)/R, and α12. The nonrandomness factor α12 was set as 0.3 in this study. Both activity coefficient models thus have two adjustable parameters that are optimally fitted by minimizing the objective function (obj) between the calculated and the experimentally measured liquidus temperatures TL: N

obj =

⎛ 1 ⎞⎧ TL(calc) − TL(expt) ⎫ ⎟⎨ ⎬ N ⎠⎩ TL(expt) ⎭

∑ ⎜⎝ k=1

k

(10)

The summation was running over all kth data points. Using the best-fitted binary parameters in the activity coefficient models, the liquidus phase boundaries were determined for each binary mixture in this study. A comparison between the model calculated and experimentally measured SLE results is presented in this study.

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RESULTS AND DISCUSSION The experimentally measured eutectic temperatures (TE) and liquidus temperatures (TL) for six binary mixtures of this study at various compositions (mole fractions) are presented in Table 2. The estimated uncertainties in our measured temperatures and compositions are ± 1 K (with the maximum uncertainty of 2 K) and ± 0.002 mole fraction, respectively. The data correlation results for the best-fitted parameters of the Wilson and C

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Table 3. Optimally Fitted Binary Parameters and the Deviations of Regression from the Wilson and NRTL Models Wilson parameters

NRTL parameter (α12 is 0.3 in this study)

[(λ12 − λ11)/R]/K, [(λ21 − λ22)/R]/K

[(g12 − g22)/R]/K, [(g21 − g11)/R]/K

AADTa/% Wilson

NRTL

Heptanedioic Acid (1) + Pentanedioic Acid (2) −205.10/185.77 143.80/−168.55 0.22 0.22 Hexanedioic Acid (1) + Heptanedioic Acid (2) −321.20/292.92 301.75/−372.57 0.20 0.22 Heptanedioic Acid (1) + 2,3-Dimethylbutanedioic Acid (2) 118.15/−119.74 386.00/−305.29 0.27 0.27 Heptanedioic Acid (1) + 2,2-Dimethylbutanedioic Acid (2) 493.91/−525.51 −669.63/583.29 0.23 0.24 Heptanedioic Acid (1) + 3-Methylpentanedioic Acid (2) 215.79/−316.37 −301.18/138.34 0.19 0.20 2,2-Dimethylbutanedioic Acid (1) + 3-Methylpentanedioic Acid (2) −475.55/442.90 387.28/−477.93 0.40 0.44 a

Figure 1. A typical DSC thermogram for a binary mixture of hexanedioic acid (1) + heptanedioic acid (2) with x1 = 0.6511.

AADT = 100/N∑Nk=1|TL(calc) − TL(expt)/TL(expt)|k.

Table 4. Comparison of the Eutectic Point Results from Different Methods for Three Binary Mixtures method

eutectic composition, x1

TE/K

Heptanedioic Acid (1) + Pentanedioic Acid (2) Wilson model 0.407 342.1 NRTL model 0.409 342.3 Clarke−Glew equation 0.391 341.9 Hexanedioic Acid (1) + Heptanedioic Acid (2) Wilson model 0.240 364.8 NRTL model 0.237 364.4 Clarke−Glew equation 0.239 365.4 Heptanedioic Acid (1) + 2,3-Dimethylbutanedioic Acid (2) Wilson model 0.444 346.0 NRTL model 0.443 346.1 Clarke−Glew equation 0.443 348.9 Heptanedioic Acid (1) + 2,2-Dimethylbutanedioic Acid (2) Wilson model 0.668 358.3 NRTL model 0.666 358.7 Clarke−Glew equation 0.667 358.8 Heptanedioic Acid (1) + 3-Methylpentanedioic Acid (2) Wilson model 0.409 337.2 NRTL model 0.405 337.5 Clarke−Glew equation 0.357 338.8 2,2-Dimethylbutanedioic Acid (1) + 3-Methylpentanedioic Acid (2) Wilson model 0.230 349.1 NRTL model 0.217 349.7 Clarke−Glew equation 0.212 348.3

Figure 2. Comparison of the experimental and calculated liquidus temperature for the binary mixture of heptanedioic acid (1) + pentanedioic acid (2): ●, liquidus temperature; ▲, eutectic temperature; ---, Wilson model; , Clarke−Glew equation.

are shown in Figures 2 to 7, respectively. The eutectic composition and temperature for heptanedioic acid (1) + pentanedioic acid (2) are determined as x1E = 0.391 and TE = 341.9 K. Those for hexanedioic acid (1) + heptanedioic acid (2) are x1E = 0.239 and TE = 365.4 K, for heptanedioic acid (1) + 2,3dimethylbutanedioic acid (2) are x1E = 0.443 and TE = 348.9 K, for heptanedioic acid (1) + 2,2-dimethylbutanedioic acid (2) are x1E = 0.667 and TE = 358.8 K, for heptanedioic acid (1) + 3methylpenetandioic acid (2) are x1E = 0.357 and TE = 338.8 K, and for 2,2-dimethylbutanedioic acid (1) + 3-methylpenetandioic acid (2) are x1E = 0.212 and TE = 348.3 K. The six pure compounds in this study are dicarboxylic acids. The difference in their chemical nature is the chain length and

Figure 3. Comparison of the experimental and calculated liquidus temperature for the binary mixture of hexanedioic acid (1) + heptanedioic acid (3): ●, liquidus temperature; ▲, eutectic temperature; ---, Wilson model; , Clarke−Glew equation.

structure of methyl groups between the acid functional groups at two ends. Pure hexanedioic acid has the highest melting temperature among these six fluids. We thus observe the highest eutectic temperature for the binary mixture of hexanedioic acid (1) + heptanedioic acid (2). Examining the first five binary D

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Figure 7. Comparison of the experimental and calculated liquidus temperature for the binary mixture of 2,2-dimethylbutanedioic acid (1) + 3-methylpentanedioic acid (2): ●, liquidus temperature; ▲, eutectic temperature; ---, Wilson model; , Clarke−Glew equation.

Figure 4. Comparison of the experimental and calculated liquidus temperature for the binary mixture of heptanedioic acid (1) + 2,3dimethylbutanedioic acid (2): ●, liquidus temperature; ▲, eutectic temperature; ---, Wilson model; , Clarke−Glew equation.

well with the decrease of melting temperatures of the other pure components in these binary mixtures. At the simple eutectic point, one pure fluid and a melt with the eutectic composition coexist when the original liquid mixture is cooled down to this eutectic temperature. For a given initial composition of the liquid mixture, say x1 = 0.75, the amount of component 1 that crystallized at the eutectic point is calculated from a simple mass balance. One examination for the eutectic compositions of three binary systems with heptanedioic acid plus 2,3-dimethylbutanedioic acid, 2,2-dimethylbutanedioic acid, or 3-methylpentanedioic acid is discussed. It is noticed that the last three pure components are all with the same molecular weight but different methyl group structures. For a binary system with greater x1 value, a smaller amount of component 1 crystallized at the eutectic temperature is determined from the simple mass balance. It is shown that heptanedioic acid (1) + 2,2-dimethylbutanedioic acid (2) has the greatest x1E value among these three binary mixtures. One possibility may be due to the high melting temperature of 2,2-dimethylbutanedioic acid in comparison to the other two isomers. This results that the crystallization of 2,2dimethylbutanedioic acid is more favorable than the other two isomers as heptanedioic acid is fixed as the first component in these binary systems. We thus have the largest x1E = 0.667 for heptanedioic acid (1) + 2,2-dimethylbutanedioic acid (2). 3Methylpentanedioic acid has the smallest melting temperature in these three isomers. It corresponds to the smallest x1E = 0.357 for heptanedioic acid (1) + 3-methylpentanedioic acid (2) among these three binary systems. The difference for the x1E values of these three systems is also explained from the difference of pure melting temperature of heptanedioic acid and the eutectic temperature. For the binary mixture of heptanedioic acid (1) + 3-methylpentanedioic acid (2), this temperature difference is close to 40 K which is the largest among these three binary systems. This largest temperature difference favors more crystallization of heptanedioic acid than that in the other two systems. We hence observe the smallest x1E = 0.357 for heptanedioic acid (1) + 3-methylpentanedioic acid (2) among these three binary mixtures. Other pure fluid properties and their molecular interactions maybe applied to explain the differences of eutectic temperatures and compositions of these binary mixtures. The present discussion demonstrates that our experimental results are consistent with the trend of pure component melting temperatures.

Figure 5. Comparison of the experimental and calculated liquidus temperature for the binary mixture of heptanedioic acid (1) + 2,2dimethylbutanedioic acid (2): ●, liquidus temperature; ▲, eutectic temperature; ---, Wilson model; , Clarke−Glew equation.

Figure 6. Comparison of the experimental and calculated liquidus temperature for the binary mixture of heptanedioic acid (1) + 3-methylpentanedioic acid (2): ●, liquidus temperature; ▲, eutectic temperature; ---, Wilson model; , Clarke−Glew equation.

mixtures in this study, all with heptanedioic acid as one component, the decreasing trend of eutectic temperatures agrees E

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(12) Prausnitz, J. M.; Lichtenthaler, R. N.; Azevedo, E. G. A. Molecular Thermodynamics of Fluid-Phase Equilibria; Prentice Hall: New York, 1999. (13) Rowley, R. L.; Wilding, W. V.; Oscarson, J. L.; Yang, Y.; Zundel, N. A.; Daubert, T. E.; Danner, R. P. DIPPR Data Compilation of Pure Compound Properties; Design Institute for Physical Properties, AIChE: New York, 2003. (14) Ihmels, E. C.; Gmehling, J. Extension and Revision of the Group Contribution Method GCVOL for the Prediction of Pure Compound Liquid Densities. Ind. Eng. Chem. Res. 2003, 42, 408−412. (15) Hefter, G. T.; Tomkins, R. P. T. Experimental Determination of Solubilities; John Wiley & Sons: Chichester, UK, 2003. (16) Gamsjäger, H.; Lorimer, J. W.; Salomon, M.; Shaw, D. G.; Tomkins, R. P. T. The IUPAC-NIST Solubility Data Series: A Guide to Preparation and Use of Compilations and Evaluations. J. Phys. Chem. Ref. Data 2010, 39 (2), 023101. (17) Jeffrey, G. H.; Vogel, A. I. The Dissociation Constants of Organic Acids. Part XI. The Thermodynamic Primary Dissociation Constants of Some Normal Dibasic Acids. J. Chem. Soc. 1935, 21−30. (18) Cingolani, A.; Berchiesi, G. Thermodynamic Properties of Organic Compounds. Note 1. A DSC Study of Phase Transitions in Aliphatic Dicarboxylic Acids. J. Therm. Anal. 1974, 6, 87−90. (19) Steele, W. V.; Chirico, R. D.; Cowell, A. B.; Knipmeyer, S. E.; Nguyen, A. Thermodynamic Properties and Ideal-Gas Enthalpies of Formation for 1,4-Diisopropylbenzene, 1,2,4,5-Tetraisopropylbenzene, Cyclohexanone, Oxime, Dimethyl Malonate, Glutaric Acid, and Pimelic Acid. J. Chem. Eng. Data 2002, 47, 725−739. (20) Wilhoit, R. C.; Shiao, D. Thermochemistry of Biologically Important Compounds. Heats of Combustion of Solid Organic Acids. J. Chem. Eng. Data 1964, 9, 595−599. (21) Othmer, K. Encyclopedia of Chemical Technology; Inter-Science: New York, 1978. (22) Chemical Book, http://www.chemicalbook.com/ ChemicalProductProperty_EN_CB9167089.htm.

CONCLUSION Solid−liquid equilibrium measurements for six binary mixtures of organic dicarboxylic acids were conducted using DSC. All binary systems show simple eutectic behavior. The measured liquidus temperatures were used in data correlation by the Wilson and NRTL activity coefficient models. Satisfactory correlation results are obtained for both models and their optimally fitted binary parameters are reported. The experimental liquidus results were also fitted by the Clarke−Glew equation. It is also observed that the data smoothing and model calculated eutectic results are in satisfactory agreement. Novel eutectic compositions and temperatures data are finally presented for six binary systems. The differences in their eutectic temperatures and compositions are discussed consistently with the trend of the melting temperatures of pure components.

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AUTHOR INFORMATION

Corresponding Author

*E-mail: [email protected]. Fax: +886-2-2362-3040. Funding

The authors are grateful for the support of this study from the National Science Council, Taiwan, Republic of China. Notes

The authors declare no competing financial interest.

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REFERENCES

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dx.doi.org/10.1021/je200800f | J. Chem. Eng. Data XXXX, XXX, XXX−XXX