Densities and Viscosities of Binary Mixtures Containing Diethylene

Oct 10, 2012 - standard deviations. Excess molar volumes, Vm. E , are negative for mixtures of diethylene glycol with 2-propanol up to 2-pentanol and ...
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Densities and Viscosities of Binary Mixtures Containing Diethylene Glycol and 2‑Alkanol Mohammad Almasi* Department of Chemistry, Science and Research Branch, Islamic Azad University, Khouzestan, Iran ABSTRACT: Densities and viscosities for binary mixtures of diethylene glycol with 2-propanol up to 2-heptanol were measured at various temperatures and ambient pressure. From experimental data, excess molar volumes VEm and viscosity deviations Δη were calculated and correlated by the Redlich−Kister equation to obtain the binary coefficients and the standard deviations. Excess molar volumes, VEm, are negative for mixtures of diethylene glycol with 2-propanol up to 2-pentanol and positive for mixtures of 2-hexanol and 2-heptanol. The Peng−Robinson−Stryjek− Vera (PRSV) equation of state (EOS) was used to predict the densities and viscosities of the studied mixtures.

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INTRODUCTION Physicochemical properties such as densities, viscosities, and surface tensions of liquid and liquid mixtures over the whole composition range at different temperatures contribute to the understanding of the types of interactions involved in the solutions as well as being useful for practical chemical engineering purposes. Glycols and their ethers are organic hydrophobic compounds, which have significant industrial applications in the manufacturing of solvents, lubricants, and conditioning agents.1 Cubic equations of state (EOS), introduced for the first time by van der Waals,2 are widely used in the design and analysis of industrial processes, especially for the complex calculations typically required to model systems in the refining and chemical industries.3 To the best of our knowledge, no data on density and viscosity of diethylene glycol + 2-alkanols system have been published. In continuation with preceding papers,4−7 the present paper reports the densities, viscosities, excess molar volumes, and viscosity deviations of mixing for the binary mixtures of diethylene glycol + 2-alkanols at temperatures of (298.15, 303.15, 308.15, and 313.15) K. The results are discussed in terms of intermolecular interactions and structural properties of studied mixtures.

Table 1. Sample Description Table source

initial mass fraction purity

Merck Merck Merck Merck Aldrich Merck

0.99 0.995 0.995 > 0.99 > 0.99 0.995

Ubbleohde viscometer with an uncertainty of ± 2·10−2 mPa·s. In all measurements a thermostat was used at a constant digital temperature of ± 0.01 K. The mixtures were prepared just before use bymass on an electronic balance (Mettler AE 163, Switzerland) accurate to 0.01 mg and kept in airtight stoppered glass bottles to avoid evaporation. The maximum estimated uncertainty in the mole fractions is ± 1·10−4. Experimental procedures in this study essentially are similar to that of our previous works. For more information one can refer to ref 12.

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RESULTS AND DISCUSSION Densities and Excess Molar Volumes. The values of density for binary mixtures are listed in Table 3. Excess molar volumes, VEm for studied mixtures, were calculated at different temperatures by the use of the following equation

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EXPERIMENTAL SECTION The following materials with mass fraction purity were used: diethylene glycol, 2-propanol, 2-butanol, 2-pentanol, 2-heptanol (Merck with mass purity > 0.99) and 2-hexanol (Aldrich with mass purity > 0.99). Reagents employed in present work are included in Table 1. In Table 2 we compared the measured densities and viscosities at various temperatures with values available in the literature;8−11 the resultant values are satisfactory enough. An Anton Paar oscillating U-tube densimeter (DMA 4500 model) with automatic viscosity correction was used in this work. The uncertainty for density measurements was estimated to be ± 5·10−5 g·cm−3. Viscosities were measured with an © 2012 American Chemical Society

chemical name diethylene glycol 2-propanol 2-butanol 2-pentanol 2-hexanol 2-heptanol

2

VmE =

∑ xiMi(ρ−1 − ρi−1) i=1

(1)

where ρ is the density of the mixture, ρi is the density of pure component i, and xi and Mi represent the molar mass and mole fraction of the corresponding components. Received: May 21, 2012 Accepted: October 3, 2012 Published: October 10, 2012 2992

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Table 2. Densities, ρ, and Viscosities, η, of Pure Components at Various Temperatures ρ/(g·cm−3) T/K

exptl

lit.

exptl

lit.

diethylene glycol

298.15 303.15 308.15 313.15 298.15 303.15 308.15 313.15 298.15 303.15 308.15 313.15 298.15 303.15 308.15 313.15 298.15 303.15 308.15 313.15 298.15 303.15 308.15 313.15

1.1124 1.1098 1.1056 1.1023 0.7811 0.7766 0.7719 0.7674 0.8030 0.7982 0.7936 0.7891 0.8054 0.8012 0.7967 0.7925 0.8101 0.8061 0.8021 0.7980 0.8132 0.8093 0.8050 0.8011

1.11285a 1.10928a 1.10569a 1.10209a 0.78126a 0.77697c 0.77259c 0.76832c 0.80241c 0.79896c 0.79418c 0.79007c 0.80524d 0.80090b 0.7966d

27.15 21.87 17.26 14.81 2.05 1.80 1.56 1.39 3.10 2.60 2.15 1.73 3.50 2.80 2.33 1.99 4.10 3.41 2.82 2.22 5.02 4.15 3.75 2.85

27.93b 21.754b 17.364b 14.70b 2.043a 1.767c 1.524c 1.367c 2.998c 2.498c 2.054c 1.798c 3.478d 2.774b

2-propanol

2-butanol

2-pentanol

2-hexanol

2-heptanol

a

η/(mPa·s)

chemical

0.81014d 0.8064b 0.80175e 0.7984b 0.81333d 0.80488e

Figure 2. Viscosity deviations Δη vs mole fraction of diethylene glycol, for binary mixtures of diethylene glycol with □, 2-propanol; ●, 2butanol; ■, 2-pentanol; ▲, 2-hexanol; ◊, 2-heptanol; at 298.15 K. The solid curves were calculated from coefficients of eq 2 given in Table 4.

4.100d 3.33b 2.920e 2.29b 5.088e 3.683e

Reference 8. bReference 9. cReference 10. dReference 6. eReference 11.

Figure 3. Densities ρ vs mole fraction of diethylene glycol for binary mixtures of diethylene glycol with 2-pentanol at 298.15 K. ●, experimental data; - - -, calculated by PRSV CEOS.

Figure 1. Excess molar volumes VEm vs mole fraction of diethylene glycol for binary mixtures of diethylene glycol with ⧫, 2-propanol; △, 2-butanol; ■, 2-pentanol; ●, 2-hexanol; □, 2-heptanol; at 298.15 K. The solid curves were calculated from coefficients of eq 2 given in Table 4.

Excess molar volumes for binary mixtures of diethylene glycol + 2-alkanols at T = 298.15 K are plotted in Figure 1. The uncertainty for excess molar volume is ± 1·10−3 cm3·mol−1. The VEm values were fitted to the following type of Redlich− Kister polynomial,13

Figure 4. Viscosities vs mole fraction of diethylene glycol for binary mixtures of diethylene glycol with 2-pentanol at ●, 298.15 K; ■, 303.15 K; △, 308.15 K ; ⧫, 313.15 K; , predicted by PRSV CEOS.

N

Y E = x1(1 − x1) ∑ Ak (1 − 2x1)k k=0

method. The values of this parameter are listed in Table 4. Standard deviation values were obtained by this equation

(2)

where VEm ≡ VEm or Δη and x1 is the mole fraction of diethylene glycol. Coefficients of Ak were evaluated by the least-squares

σ = [∑ (Y − Ycal)2 /(n − p)]1/2 2993

(3)

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Table 3. Densities, ρ, and Viscosities, η, for the Binary Mixtures as a Function of the Mole Fraction x1 of Diethylene Glycola x1

ρ/(g·cm−3)

η/(mPa·s)

x1

Diethylene Glycol (1) + 2-Propanol (2), T/K = 298.15 0.0000 0.7811 2.06 0.0808 0.8149 2.71 0.1599 0.8469 3.59 0.2398 0.8778 4.73 0.3501 0.9183 6.67 0.4399 0.9496 8.59 0.5596 0.9888 11.59 0.6499 1.0168 14.20 0.7396 1.0432 17.08 0.8501 1.0739 21.04 0.9402 1.0974 24.61 1.0000 1.1124 27.15 T/K = 303.15 0.0000 0.7767 1.79 0.0808 0.8102 2.54 0.1599 0.8418 3.38 0.2398 0.8724 4.35 0.3501 0.9127 5.93 0.4399 0.9439 7.44 0.5596 0.9833 9.80 0.6499 1.0115 11.84 0.7396 1.0382 14.10 0.8501 1.0695 17.19 0.9402 1.0938 19.94 1.0000 1.1091 21.87 T/K = 308.15 0.0000 0.7718 1.56 0.0808 0.8052 2.22 0.1599 0.8365 2.89 0.2398 0.8670 3.63 0.3501 0.9073 4.83 0.4399 0.9385 6.00 0.5596 0.9781 7.84 0.6499 1.0064 9.47 0.7396 1.0334 11.27 0.8501 1.0652 13.70 0.9402 1.0898 15.82 1.0000 1.1056 17.26 T/K = 313.15 0.0000 0.7674 1.38 0.0808 0.8005 1.90 0.1599 0.8317 2.52 0.2398 0.8620 3.25 0.3501 0.9022 4.41 0.4399 0.9334 5.49 0.5596 0.9731 7.09 0.6499 1.0014 8.44 0.7396 1.0288 9.89 0.8501 1.0611 11.84 0.9402 1.0862 13.58 1.0000 1.1023 14.81 Diethylene Glycol (1) + 2-Butanol (2), T/K = 298.15 0.0000 0.8027 3.10 0.0808 0.8294 3.69 0.1598 0.8553 4.42 0.2398 0.8813 5.33 0.3494 0.9164 6.94 0.4399 0.9449 8.61 0.5591 0.9819 11.34 0.6501 1.0097 13.86

ρ/(g·cm−3)

η/(mPa·s)

Diethylene Glycol (1) + 2-Butanol (2), T/K = 298.15 0.7399 1.0367 16.72 0.8499 1.0692 20.75 0.9399 1.0953 24.46 1.0000 1.1124 27.15 T/K = 303.15 0.0000 0.7983 2.60 0.0808 0.8248 3.10 0.1598 0.8505 3.69 0.2398 0.8763 4.41 0.3494 0.9113 5.69 0.4399 0.9398 7.03 0.5591 0.9778 9.25 0.6501 1.0049 11.31 0.7399 1.0323 13.64 0.8499 1.0651 16.88 0.9399 1.0917 19.80 1.0000 1.1091 21.87 T/K = 308.15 0.0000 0.7936 2.15 0.0808 0.8199 2.65 0.1598 0.8455 3.17 0.2398 0.8712 3.77 0.3494 0.9062 4.77 0.4399 0.9347 5.79 0.5591 0.9719 7.44 0.6501 1.0001 8.98 0.7399 1.0276 10.74 0.8499 1.0609 13.24 0.9399 1.0879 15.56 1.0000 1.1056 17.26 T/K = 313.15 0.0000 0.7891 1.73 0.0808 0.8153 2.22 0.1598 0.8407 2.74 0.2398 0.8663 3.31 0.3494 0.9012 4.25 0.4399 0.9298 5.16 0.5591 0.9671 6.62 0.6501 0.9954 7.93 0.7399 1.0231 9.42 0.8499 1.0568 11.50 0.9399 1.0842 13.42 1.0000 1.1023 14.81 Diethylene Glycol (1) + 2-Pentanol (2), T/K = 298.15 0.0000 0.8054 3.20 0.0811 0.8278 3.85 0.1598 0.8499 4.44 0.2399 0.8729 5.12 0.3501 0.9051 6.37 0.4398 0.9319 7.79 0.5599 0.9687 10.37 0.6501 0.9971 12.90 0.7399 1.0258 15.92 0.8499 1.0618 20.26 0.9399 1.0919 24.28 1.0000 1.1124 27.14 T/K = 303.15 0.0000 0.8012 2.80 0.0811 0.8235 3.17 0.1598 0.8455 3.55 2994

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Table 3. continued x1

ρ/(g·cm−3)

η/(mPa·s)

x1

T/K = 303.15 0.2399 0.8684 4.05 0.3501 0.9006 5.03 0.4398 0.9275 6.17 0.5599 0.9642 8.30 0.6501 0.9928 10.35 0.7399 1.0217 12.81 0.8499 1.0581 16.33 0.9399 1.0883 19.56 1.0000 1.1091 21.87 T/K = 308.15 0.0000 0.7966 2.33 0.0811 0.8189 2.84 0.1598 0.8408 3.29 0.2399 0.8635 3.79 0.3501 0.8957 4.58 0.4398 0.9226 5.42 0.5599 0.9595 6.90 0.6501 0.9881 8.33 0.7399 1.0174 10.08 0.8499 1.0539 12.72 0.9399 1.0847 15.31 1.0000 1.1056 17.26 T/K = 313.15 0.0000 0.7925 1.99 0.0811 0.8146 2.47 0.1598 0.8365 2.93 0.2399 0.8592 3.44 0.3501 0.8913 4.26 0.4398 0.9182 5.08 0.5599 0.9552 6.46 0.6501 0.9839 7.74 0.7399 1.0131 9.22 0.8499 1.0500 11.36 0.9399 1.0811 13.35 1.0000 1.1023 14.81 Diethylene Glycol (1) + 2-Hexanol (2), T/K = 298.15 0.0000 0.8101 4.10 0.0809 0.8288 4.55 0.1597 0.8477 4.82 0.2398 0.8678 5.08 0.3501 0.8969 5.69 0.4398 0.9219 7.08 0.5602 0.9576 9.89 0.6501 0.9859 12.70 0.7403 1.0159 16.04 0.8502 1.0548 20.63 0.9398 1.0886 24.55 1.0000 1.1124 27.15 T/K = 303.15 0.0000 0.8061 3.41 0.0809 0.8247 3.81 0.1597 0.8435 4.10 0.2398 0.8635 4.33 0.3501 0.8925 4.92 0.4398 0.9176 5.96 0.5602 0.9532 8.00 0.6501 0.9816 10.17 0.7403 1.0117 12.83 0.8502 1.0509 16.56 0.9398 1.0849 19.77

ρ/(g·cm−3)

η/(mPa·s)

T/K = 303.15 1.0000 1.1091 21.87 T/K = 308.15 0.0000 0.8021 2.82 0.0809 0.8203 3.14 0.1597 0.8391 3.38 0.2398 0.8589 3.66 0.3501 0.8878 4.24 0.4398 0.9127 5.11 0.5602 0.9484 6.73 0.6501 0.9769 8.48 0.7403 1.0072 10.47 0.8502 1.0466 13.38 0.9398 1.0811 15.70 1.0000 1.1056 17.26 T/K = 313.15 0.0000 0.7980 2.22 0.0809 0.8161 2.56 0.1597 0.8347 2.78 0.2398 0.8544 3.06 0.3501 0.8831 3.63 0.4398 0.9082 4.50 0.5602 0.9437 6.00 0.6501 0.9723 7.37 0.7403 1.0027 8.96 0.8502 1.0425 11.21 0.9398 1.0775 13.29 1.0000 1.1023 14.81 Diethylene Glycol (1) + 2-Heptanol (2), T/K = 298.15 0.0000 0.8132 5.02 0.0807 0.8294 5.22 0.1596 0.8461 5.27 0.2397 0.8641 5.38 0.3501 0.8909 5.94 0.4398 0.9144 6.95 0.5602 0.9489 9.32 0.6501 0.9771 11.89 0.7402 1.0077 15.13 0.8501 1.0488 19.86 0.9397 1.0857 24.15 1.0000 1.1124 27.14 T/K = 303.15 0.0000 0.8093 4.15 0.0807 0.8252 4.45 0.1596 0.8418 4.66 0.2397 0.8598 4.89 0.3501 0.8865 5.44 0.4398 0.9101 6.21 0.5602 0.9445 7.87 0.6501 0.9728 9.69 0.7402 1.0036 12.04 0.8501 1.0449 15.65 0.9397 1.0821 19.20 1.0000 1.1091 21.87 T/K = 308.15 0.0000 0.8050 3.48 0.0807 0.8209 3.98 0.1596 0.8375 4.23 0.2397 0.8553 4.39 0.3501 0.8819 4.70 0.4398 0.9053 5.20 2995

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Table 3. continued x1 0.5602 0.6501 0.7402 0.8501 0.9397 1.0000 0.0000 0.0807 a

ρ/(g·cm−3)

η/(mPa·s)

T/K = 308.15 0.9398 0.9682 0.9991 1.0406 1.0784 1.1056 T/K = 313.15 0.8011 0.8170

x1

6.43 7.84 9.71 12.54 15.27 17.26

0.1596 0.2397 0.3501 0.4398 0.5602 0.6501 0.7402 0.8501 0.9397 1.000

2.85 3.04

ρ/(g·cm−3)

η/(mPa·s)

T/K = 313.15 0.8335 0.8512 0.8777 0.9012 0.9355 0.9639 0.9949 1.0366 1.0746 1.1023

3.21 3.42 3.87 4.45 5.64 6.89 8.46 10.82 13.10 14.81

x1 is mole fraction of diethylene glycol in the (diethylene glycol + 2-alkanol) solutions. Standard uncertainties u are u(T) = 0.01 K, u(x) = 0.0001, the combined expanded uncertainty Uc(ρ) = 2·10−2 kg·m−3 and for viscosity the relative combined expanded uncertainty Ur(η) = 0.02 (0.95 level of confidence).

Table 4. Parameters Ak and Standard Deviations σ for Diethylene Glycol + 2-Alkanols at Different Temperatures diethylene glycol + 2-propanol

VEm

−1

(cm ·mol ) 3

△η (mPa·s)

diethylene glycol + 2-butanol

VEm (cm3·mol−1)

△η (mPa·s)

diethylene glycol + 2-pentanol

VEm (cm3·mol−1)

△η (mPa·s)

diethylene glycol + 2-hexanol

VEm (cm3·mol−1)

△η (mPa·s)

diethylene glycol + 2-heptanol

VEm (cm3·mol−1)

△η (mPa·s)

T/K

A0

A1

A2

σ

298.15 303.15 308.15 313.15 298.15 303.15 308.15 313.15 298.15 303.15 308.15 313.15 298.15 303.15 308.15 313.15 298.15 303.15 308.15 313.15 298.15 303.15 308.15 313.15 298.15 303.15 308.15 313.15 298.15 303.15 308.15 313.15 298.15 303.15 308.15 313.15 298.15 303.15 308.15 313.15

−1.821 −1.213 −0.885 −0.610 −18.271 −13.017 −10.108 −7.283 −1.411 −1.014 −0.731 −0.403 −20.851 −16.587 −12.512 −9.627 −0.815 −0.605 −0.322 −0.161 −24.772 −20.743 −14.774 −10.657 0.4041 0.648 1.085 1.462 −29.239 −23.186 −16.887 −13.363 0.893 1.220 1.532 1.818 −32.394 −24.274 −18.541 −15.355

0.021 −0.011 −0.008 −0.006 −0.010 0.789 0.522 −0.003 −0.015 −0.025 −0.023 −0.008 2.246 1.272 2.448 1.765 −0.013 −0.006 −0.001 −0.003 4.838 2.925 5.416 2.727 0.008 0.022 0.023 −0.017 0.992 2.355 0.935 1.488 0.027 0.088 0.042 −0.120 5.032 7.803 7.341 4.166

0.045 0.027 0.006 0.005 −0.268 0.860 2.111 −0.288 0.025 −0.001 −0.015 0.0061.163 2.059 1.022 0.798 −0.015 −0.001 −0.006 −0.0007 4.924 3.608 1.125 1.280 −0.018 0.012 0.097 0.061 12.937 9.776 7.220 2.756 −0.094 0.064 0.200 −0.126 9.716 3.677 6.013 2.171

0.004 0.002 0.004 0.006 0.002 0.001 0.006 0.002 0.002 0.002 0.003 0.004 0.003 0.001 0.006 0.004 0.002 0.003 0.004 0.006 0.005 0.003 0.003 0.004 0.006 0.004 0.003 0.002 0.01 0.008 0.007 0.01 0.004 0.003 0.003 0.006 0.001 0.005 0.004 0.006

where Y and Ycal are the experimental and calculated data, respectively. Values of standard deviation are present in Table 4.

In the mixing of these solutions, the following effects are expected that contribute to VEm and Δη values: (1) specific 2996

dx.doi.org/10.1021/je300827f | J. Chem. Eng. Data 2012, 57, 2992−2998

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positive for mixtures of diethylene glycol with 2-hexanol and 2-heptanol. Viscosity deviations, Δη, are negative over the entire range of the mole fraction. As can be observed in the figures, agreement between experimental data and predicted values by the PRSV EOS is good.

interactions (hydrogen bonding) that occur between OH group of alkanols and oxygen group of diethylene glycol, (2) the existence of unspecific interactions between OH group of diethylene glycol and carbon alkyl chain of alcohols, and (3) the structural contributions that arise from some effects such as interstitial accommodation and changes of free volume. The negative excess molar volumes of diethylene glycol with 2-propanol up to 2-pentanol can be ascribed by the following factors: (1) Chemical interactions caused by polar groups of different molecules present in the solution contain intermolecular interactions between the −OH group of the 2-alkanol and the oxygen atoms (−O−) of the diethylene glycol, causing the formation of strong hydrogen bonds and reducing the volume of the solution. (2) Due to differences in size, free volume, and molar volume of different molecules, one component can placed into the interstitial accommodation of others, and this geometrical fit is consistent with the negative VEm. Positive values of VEm for binary mixtures of diethylene glycol with 2-hexanol and 2-heptanol can be described by considering the steric-hindrance effects of the alkyl chain of the diethylene glycol and of the alkyl chain of the 2- alkanols, because the hydrophobic character of the 2-alkanol is amplified by an increase in chain length, and consequently, the molecular interactions between 2-alkanol and diethylene glycol molecules weaken. Dynamic Viscosities. The experimental viscosities obtained from the measurements of the binary mixtures and pure state are summarized in Table 3. The viscosity deviation can be obtained from the following equation

Δη = η − x1η1 − x 2η2

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AUTHOR INFORMATION

Corresponding Author

*E-mail: [email protected]. Tel.:+ 98-6114431018. Notes

The authors declare no competing financial interest.

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ACKNOWLEDGMENTS The author thanks the University authorities and also Mona Moosavian for providing the necessary facilities to carry out the work.

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REFERENCES

(1) Begum, K. S.; Clarke, J. R.; Ahmed, S. M.; Begum, S.; Saleh, A. M. Densities, Viscosities, and Surface Tensions of the System Water + Diethylene Glycol. J. Chem. Eng. Data 2011, 56, 303−306. (2) van der Waals, J. D. Doctoral Dissertation. Leiden University, Leiden, 1873. (3) Twu, C. H.; Wayne, D. S.; Vince, T. Advanced Cubic Equations of State: When and How to Use Them. Chem. Eng. Prog. 2002, 100, 58−65. (4) Almasi, M.; Shojabakhtiar, M. Excess molar volumes of diisopropylamine + (C1−C5) alkan-1-ols: Application of the ERAS model and cubic EOS. Thermochim. Acta 2011, 523, 105−110. (5) Almasi, M.; Mousavi, L. Excess molar volumes of binary mixtures of aliphatic alcohols (C1−C5) with Nitromethane over the temperature range 293.15 to 308.15 K: Application of the ERAS model and cubic EOS. J. Mol. Liq. 2011, 163, 46−52. (6) Almasi, M.; Sarkoohaki, B. Densities and Viscosities of Binary Mixtures of Cyclohexanone and 2-Alkanols. J. Chem. Eng. Data 2012, 57, 309−316. (7) Almasi, M.; Khosravi, L. Excess molar volumes of 1,3-propanediol + (C1−C5) alkan-1-ols: application of a cubic equation of state. J. Serb. Chem. Soc. 2012, 77, 363−370. (8) Afzal, W.; Mohammadi, A. H.; Richon, D. Volumetric Properties of Mono-, Di-, Tri-, and Polyethylene Glycol Aqueous Solutions from (273.15 to 363.15) K: Experimental Measurements and Correlations. J. Chem. Eng. Data 2009, 54, 1254−1261. (9) Riddick, J. A.; Bunger, W. B.; Sakano, T. K. Organic Solvents: Physical Properties and Methods of Purification, 4th ed.; Wiley: New York, 1986. (10) Lomte, S. B.; Bawa, M. J.; Lande, M. K.; Arbad, B. R. Densities and Viscosities of Binary Liquid Mixtures of 2-Butanone with Branched Alcohols at (293.15 to 313.15) K. J. Chem. Eng. Data 2009, 54, 127−130. (11) Hasan, M.; Shirude, F. D.; Hiray, P. A.; Sawant, B. A.; Kadam, B. U. Densities, viscosities and ultrasonic velocities of binary mixtures of methylbenzene with hexan-2-ol, heptan-2-ol and octan-2-ol at T = 298.15 and 308. Fluid Phase Equilib. 2007, 252, 88−95. (12) Iloukhani, H.; Almasi, M. Densities, viscosities, excess molar volumes, and refractive indices of acetonitrile and 2-alkanols binary mixtures at different temperatures: Experimental results and application of the Prigogine-Flory-Patterson theory. Thermochim. Acta 2009, 495, 139−148. (13) Redlich, O. J.; Kister, A. T. Thermodynamic of nonelectrolyte solutions: algebraic representation of thermodynamic properties and the classification of solutions. Ind. Eng. Chem. 1948, 40, 345−348. (14) Iloukhani, H.; Fattahi, M. Correlation of excess molar enthalpies of cyclopentanone (1) + 1-alkanols (C1−C5) (2) by Peng− Robinson−Stryjek−Vera equation of state and ERAS-model. J. Mol. Liq. 2012, 171, 37−42.

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The Δη values were correlated to Redlich−Kister polynomial, and coefficients of Ak and standard deviations are given in Table 4. The variations of Δη with mole fraction for all binary mixtures at 298.15 K are shown in Figure 2. It is clear that the values of Δη are negative for all studied mixtures. The negative values of viscosity deviations for the binary systems investigated suggest that the viscosities of associates formed between unlike molecules are relatively less than those of the pure components. The absolute values of Δη for the mixtures fall in the following order: 2-heptanol > 2-hexanol > 2-pentanol > 2-butanol > 2-propanol. Calculation with PRSV CEOS. A detailed description of the Peng−Robinson−Stryjek−Vera cubic equation of state (PRSV CEOS) and the calculation procedures for density and viscosity may be found in the literature.14−16 Necessary data such as critical properties and the Pitzer’s acentric factor of the pure substances for the calculations with PRSV CEOS were taken from ref 17. As an example, Figures 3 and 4 show the density at 298.15 K and viscosity at various temperatures for binary mixtures diethylene glycol + 2-pentanol and predicted values by the PRSV CEOS. From these figures, it is clear that the agreement between experimental data and predicted values by cubic EOS is good.

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CONCLUSION Excess molar volumes and viscosity deviations for mixtures of diethylene glycol and 2-alkanols were obtained from experimental results and fitted by a Redlich−Kister type equation to obtain the binary coefficients and estimate the standard deviations. Excess molar volumes, VEm, are negative for mixtures of diethylene glycol with 2-propanol up to 2-pentanol and 2997

dx.doi.org/10.1021/je300827f | J. Chem. Eng. Data 2012, 57, 2992−2998

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(15) Giro, F.; Gonçalves, M. F.; Ferreira, A. G. M.; Fonseca, I. M. A. Viscosity and density data of the system water + n-pentyl acetate + methanol: Calculations with a modified Redlich−Kwong−Soave equation of state. Fluid Phase Equilib. 2003, 204, 217−232. (16) Fattahi, M.; Iloukhani, H. Excess molar volume, viscosity, and refractive index study for the ternary mixture {2-methyl-2-butanol (1) + tetrahydrofuran (2) + propylamine (3)} at different temperatures. Application of the ERAS-model and Peng−Robinson−Stryjek−Vera equation of state. J. Chem. Thermodyn. 2010, 42, 1335−1345. (17) Yaws, C. L. Yaws Handbook of Thermodynamic and Physical Properties of Chemical Compounds; Norwich: New York, 2004.

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