Volumetric and Viscometric Behavior of Binary Systems 2-Butanol +

Article pubs.acs.org/jced

Volumetric and Viscometric Behavior of Binary Systems 2‑Butanol + PEG 200, + PEG 400, + Tetraethylene Glycol Dimethyl Ether, and + N‑Methyl-2-pyrrolidone

Nikola V. Ž ivković,‡ Slobodanh S. Šerbanović,† M. Lj. Kijevčanin,† and E. M. Ž ivković*,† †

Faculty of Technology and Metallurgy, University of Belgrade, Karnegijeva 4, 11120 Belgrade, Serbia Vinča Institute of Nuclear Sciences, University of Belgrade, P.O. Box 522, 11001 Belgrade, Serbia

‡

S Supporting Information *

ABSTRACT: Experimental data on densities, viscosities, and refractive indices of binary mixtures with 2-butanol and polyethylene glycols of different molecular weights, tetraethylene glycol dimethyl ether, or N-methyl-2-pyrrolidone, were determined in the temperature interval from 288.15 K to 323.15 K and at atmospheric pressure. Excess molar volumes, viscosity deviations, and deviations in refractive indices were computed from these data and correlated with the Redlich−Kister polynomial equation. The obtained results allowed the interpretation of specific inter- and intramolecular interactions.

(ΔG*E), and deviations in refractive index (ΔηD), correlated afterward with the Redlich−Kister equation.5

1. INTRODUCTION Sulfur dioxide (SO2) is one of the greenhouse gases produced by burning of fossil fuels (coal, oil). The existing flue gas desulfurization processes, that is, the most widespread lime/ limestone scrubbing procedure, have a drawback of producing large volumes of solid waste. An alternative has been found in regenerative processes among which organic solvents are often used as absorbents. Because of its favorable properties, all of the substances studied in this paper could be used as solvents in flue gas desulfurization processes. Some of the studied substances have already found industrial application, while the others have been investigated1 as a more suitable alternative to fluids conventionally used in regenerative processes for SO2 removal. Polyethylene glycol (PEG) has many favorable properties2 which make it suitable for various industrial applications. The main advantages of PEG for desulfurization processes are the high solubility of SO2 and ability of desorption, which decrease energy demands during absorption and regeneration stages of the process. Tetraethylene glycol dimethyl ether (TEGDME) is a polar solvent which has already found commercial application in a regenerative process for SO2 removal.3 However, it has been stated4 that TEGDME is not selective to sulfur dioxide and other gaseous components are also absorbed, so as an alternative N-methyl-2-pyrrolidone (NMP) has been suggested. NMP is a water miscible solvent with a mild amine odor, industrially already used as a solvent in Lurgi’s Purisol process, particularly suited for the selective desulfurization of gases from oil refineries or coal burning power plants. This work reports experimental density, viscosity, and refractive index data for binary mixtures 2-butanol + PEG 200, + PEG 400, + TEGDME, or + NMP at eight temperatures T = (288.15, 293.15, 298.15, 303.15, 308.15, 313.15, 318.15, and 323.15) K and at atmospheric pressure. The obtained values were used to calculate excess molar volumes (VE), viscosity deviation (Δη), excess Gibbs (free) energy of activation of viscous flow © 2013 American Chemical Society

2. EXPERIMENTAL SECTION Chemicals used in the investigation of thermophysical properties presented in this work were supplied by various producers: PEG 200 and PEG 400 by Sigma Aldrich, 2-butanol (w = 0.995) and NMP (w = 0.99) by Merck, and TEGDME (w = 0.99) by Acros Organics. Chemicals were used as received without additional purification. Sample information is given in Table 1. Table 1. Sample Information chemical name

source

2-butanol PEG 200a PEG 400b TEGDMEc NMPd

Merck Sigma Aldrich Sigma Aldrich Acros Organics Merck

initial mass fraction purity

purification method

0.995

none none none none none

0.99 0.99

a

PEG 200 = polyethylene glycol 200. bPEG 400 = polyethylene glycol 400. cTEGDME = tetraethylene glycol dimethyl ether. dNMP = N-methyl-2-pyrrolidone.

A comparison of our experimental data with literature values at 298.15 K showed satisfactory agreement with differences less than 0.6 kg·m−3 for density data, within 2·10−4 for refractive indices, and within 1.5·10−2 mPa·s for viscosity values of less viscous fluids (Table S1, Supporting Information). For fluids Received: April 30, 2013 Accepted: November 6, 2013 Published: November 21, 2013 3332

dx.doi.org/10.1021/je400486p | J. Chem. Eng. Data 2013, 58, 3332−3341

Journal of Chemical & Engineering Data

Article

Table 2. Densities ρ, Dynamic Viscosities η, and Refractive Indices nD for Binary Mixture 2-Butanol (1) + PEG 200 (2), as a Function of 2-Butanol Mole Fraction (x1), at T = (288.15 to 323.15) K and Atmospheric Pressurea 10−3·ρ x1

kg·m

η

−3

10−3·ρ

η mPa·s

nD

30.829 25.774 21.146 17.104 13.752 10.782 8.1996 6.1309 4.5101 3.1197 2.0803

1.45478 1.45140 1.44804 1.44370 1.43903 1.43348 1.42726 1.41977 1.41168 1.40225 1.39086

24.954 21.007 17.360 14.148 11.455 9.0474 6.9371 5.2190 3.8542 2.6661 1.7662

1.45307 1.44973 1.44624 1.44192 1.43722 1.43162 1.42536 1.41787 1.40969 1.40005 1.38851

20.490 17.358 14.436 11.842 9.6472 7.6691 5.9222 4.4809 3.3191 2.2938 1.5116

1.45134 1.44809 1.44447 1.44011 1.43540 1.42978 1.42347 1.41595 1.40766 1.39790 1.38617

17.043 14.608 12.222 10.087 8.2696 6.6183 5.1385 3.8962 2.9082 1.9997 1.3033

1.44962 1.44649 1.44268 1.43827 1.43354 1.42787 1.42151 1.41409 1.40566 1.39570 1.38372

mPa·s

nD

x1

kg·m−3

86.065 69.375 55.011 42.501 32.860 24.701 18.032 12.980 9.2783 6.3614 4.2905

1.46176 1.45826 1.45512 1.45094 1.44636 1.44092 1.43489 1.42759 1.41973 1.41056 1.39959

0.0000 0.1041 0.2067 0.3096 0.4069 0.5078 0.6077 0.7066 0.8041 0.9027 1.0000

1.112396 1.094757 1.075403 1.053537 1.030336 1.003010 0.972100 0.936952 0.896864 0.849453 0.794003

64.498 52.198 41.898 32.783 25.673 19.642 14.475 10.555 7.6286 5.2488 3.5763

1.46000 1.45652 1.45334 1.44913 1.44454 1.43906 1.43300 1.42567 1.41778 1.40853 1.39748

0.0000 0.1041 0.2067 0.3096 0.4069 0.5078 0.6077 0.7066 0.8041 0.9027 1.0000

1.108420 1.090792 1.071427 1.049537 1.026325 0.998977 0.968044 0.932869 0.892717 0.845223 0.789609

49.465 40.690 32.973 26.065 20.509 15.845 11.810 8.7003 6.2493 4.3704 2.9542

1.45825 1.45480 1.45156 1.44733 1.44269 1.43719 1.43113 1.42373 1.41578 1.40647 1.39534

0.0000 0.1041 0.2067 0.3096 0.4069 0.5078 0.6077 0.7066 0.8041 0.9027 1.0000

1.104439 1.086802 1.067431 1.045523 1.022296 0.994928 0.963961 0.928744 0.888523 0.840919 0.785109

38.700 32.112 26.129 20.957 16.719 13.035 9.7969 7.2725 5.2399 3.6813 2.4687

1.45651 1.45310 1.44980 1.44550 1.44084 1.43532 1.42918 1.42174 1.41373 1.40439 1.39314

0.0000 0.1041 0.2067 0.3096 0.4069 0.5078 0.6077 0.7066 0.8041 0.9027 1.0000

1.100454 1.082808 1.063426 1.041499 1.018252 0.990857 0.959851 0.924583 0.884276 0.836543 0.780499

288.15 K 0.0000 0.1041 0.2067 0.3096 0.4069 0.5078 0.6077 0.7066 0.8041 0.9027 1.0000

1.128288 1.110682 1.091316 1.069467 1.046286 1.018982 0.988115 0.953036 0.913024 0.865760 0.810654

0.0000 0.1041 0.2067 0.3096 0.4069 0.5078 0.6077 0.7066 0.8041 0.9027 1.0000

1.124314 1.106712 1.087348 1.065494 1.042312 1.015007 0.984137 0.949058 0.909039 0.861763 0.806620

0.0000 0.1041 0.2067 0.3096 0.4069 0.5078 0.6077 0.7066 0.8041 0.9027 1.0000

1.120348 1.102732 1.083366 1.061515 1.038329 1.011020 0.980143 0.945045 0.905018 0.857716 0.802502

0.0000 0.1041 0.2067 0.3096 0.4069 0.5078 0.6077 0.7066 0.8041 0.9027 1.0000

1.116372 1.098738 1.079388 1.057530 1.034339 1.007024 0.976132 0.941007 0.900961 0.853614 0.798302

308.15 K

293.15 K

313.15 K

298.15 K

318.15 K

303.15 K

a

323.15 K

Standard uncertainties u for each variable are u(T) = 0.01 K, u(p) = 5 %, and u(x1) = 0.0001, and the combined expanded uncertainties Uc are Uc(ρ) = ± 2·10−2 kg·m−3, Ur(η) = ± 1.0 %, and Uc(nD) = ± 6·10−5, with a 0.95 level of confidence (k ≈ 2).

conducted on a Stabinger SVM 3000/G2 viscometer. Preparation of mixtures was done gravimetrically on a Mettler AG 204 balance. The balance precision is 1·10−7 kg, and the standard uncertainty of the calculated mole fraction is estimated as ± 1·10−4. The combined expanded uncertainty in density is within ± 2·10−2 kg·m−3 with a 0.95 level of confidence (k ≈ 2). The uncertainty in excess molar volume is evaluated as ± 7·10−9 m3·mol−1. The estimated

with higher viscosities (PEG 200 and PEG 400), differences between measured and literature data are around 2 % deviation. Instruments used in this research and measuring procedures are described in one of our previous papers.6 Density measurements were performed on Anton Paar DMA 5000 densimeter, refractive indices were measured on an Anton Paar RXA-156 refractometer, and viscosity measurements were 3333



Article

Table 3. Densities ρ, Dynamic Viscosities η, and Refractive Indices nD for the Binary Mixture 2-Butanol (1) + PEG 400 (2), as a Function of 2-Butanol Mole Fraction (x1), at T = (288.15 to 323.15) K and Atmospheric Pressurea 10−3·ρ x1

kg·m

η

−3

10−3·ρ

η mPa·s

nD

55.176 48.340 42.566 35.387 29.160 23.982 18.420 13.038 8.5911 4.8011 2.0803

1.46128 1.45907 1.45679 1.45359 1.45060 1.44718 1.44219 1.43519 1.42589 1.41103 1.39086

44.265 38.987 34.497 28.871 23.948 19.826 15.338 10.972 7.2935 4.1104 1.7662

1.45942 1.45729 1.45505 1.45185 1.44880 1.44538 1.44030 1.43330 1.42395 1.40883 1.38851

36.069 31.926 28.365 23.876 19.927 16.577 12.928 9.3313 6.2480 3.5452 1.5116

1.45762 1.45560 1.45335 1.45009 1.44700 1.44352 1.43842 1.43138 1.42198 1.40681 1.38617

29.798 26.569 23.764 20.164 16.931 14.175 11.090 8.0668 5.4332 3.1045 1.3033

1.45582 1.45383 1.45160 1.44833 1.44518 1.44168 1.43654 1.42945 1.42002 1.40453 1.38372

mPa·s

nD

x1

kg·m−3

162.09 138.13 118.55 95.092 75.612 60.070 44.187 29.706 18.568 9.8643 4.2905

1.46867 1.46629 1.46395 1.46083 1.45796 1.45451 1.44978 1.44294 1.43369 1.41930 1.39959

0.0000 0.1104 0.2021 0.3158 0.4162 0.5005 0.5987 0.7012 0.8000 0.9003 1.0000

1.113798 1.104029 1.094485 1.080340 1.064965 1.049174 1.026197 0.994553 0.952558 0.890788 0.794003

119.61 102.85 88.870 71.886 57.573 46.464 34.619 23.531 14.979 8.1141 3.5763

1.46683 1.46443 1.46210 1.45893 1.45608 1.45265 1.44786 1.44098 1.43173 1.41730 1.39748

0.0000 0.1104 0.2021 0.3158 0.4162 0.5005 0.5987 0.7012 0.8000 0.9003 1.0000

1.109706 1.099942 1.090399 1.076255 1.060877 1.045081 1.022095 0.990443 0.948417 0.886590 0.789609

90.503 78.391 68.182 55.664 45.005 36.652 27.621 19.077 12.284 6.7633 2.9542

1.46496 1.46258 1.46031 1.45715 1.45422 1.45080 1.44596 1.43901 1.42977 1.41512 1.39534

0.0000 0.1104 0.2021 0.3158 0.4162 0.5005 0.5987 0.7012 0.8000 0.9003 1.0000

1.105624 1.095850 1.086310 1.072167 1.056785 1.040983 1.017983 0.986314 0.944249 0.882337 0.785109

69.986 60.961 53.387 44.048 36.030 29.423 22.395 15.699 10.218 5.6555 2.4687

1.46312 1.46086 1.45855 1.45537 1.45239 1.44896 1.44407 1.43709 1.42784 1.41314 1.39314

0.0000 0.1104 0.2021 0.3158 0.4162 0.5005 0.5987 0.7012 0.8000 0.9003 1.0000

1.101541 1.091772 1.082230 1.068080 1.052689 1.036879 1.013865 0.982176 0.940050 0.878032 0.780499

288.15 K 0.0000 0.1104 0.2021 0.3158 0.4162 0.5005 0.5987 0.7012 0.8000 0.9003 1.0000

1.130179 1.120418 1.110864 1.096696 1.081311 1.065518 1.042537 1.010874 0.968883 0.907146 0.810654

0.0000 0.1104 0.2021 0.3158 0.4162 0.5005 0.5987 0.7012 0.8000 0.9003 1.0000

1.126084 1.116327 1.106774 1.092609 1.077225 1.061435 1.038460 1.006809 0.964831 0.903115 0.806620

0.0000 0.1104 0.2021 0.3158 0.4162 0.5005 0.5987 0.7012 0.8000 0.9003 1.0000

1.121990 1.112223 1.102672 1.088515 1.073140 1.057347 1.034376 1.002733 0.960761 0.899046 0.802502

0.0000 0.1104 0.2021 0.3158 0.4162 0.5005 0.5987 0.7012 0.8000 0.9003 1.0000

1.117889 1.108125 1.098577 1.084427 1.069055 1.053263 1.030291 0.998650 0.956671 0.894940 0.798302

308.15 K

293.15 K

313.15 K

298.15 K

318.15 K

303.15 K

a

323.15 K


uncertainty in refractive index data is ± 6·10−5 units, and the relative uncertainty in dynamic viscosity values is within ± 1.0 %.

2-butanol + NMP) at eight temperatures T = (288.15, 293.15, 298.15, 303.15, 308.15, 313.15, 318.15, and 323.15) K and atmospheric pressure are presented in Tables 2 to 5. The values of excess molar volume VE, viscosity deviation Δη, excess Gibbs energy of activation of viscous flow ΔG*E, and deviation in refractive index ΔnD are given in Tables S2 to S5 in the Supporting Information.

3. RESULTS AND DISCUSSION The experimentally determined values of density ρ, viscosity η, and refractive index nD for investigated solutions (2-butanol + PEG 200, 2-butanol + PEG 400, 2-butanol + TEGDME, and 3334



Article

Table 4. Densities ρ, Dynamic Viscosities η, and Refractive Indices nD for the Binary Mixture 2-Butanol (1) + TEGDME (2), as a Function of 2-Butanol Mole Fraction (x1), at T = (288.15 to 323.15) K and Atmospheric Pressurea 10−3·ρ

η

−3

x1

kg·m

mPa·s

x1

nD

10−3·ρ

η

kg·m−3

mPa·s

nD

2.6913 2.5133 2.3629 2.2293 2.1114 1.9835 1.8592 1.7622 1.7196 1.7857 2.0803

1.42603 1.42420 1.42212 1.41998 1.41768 1.41473 1.41133 1.40765 1.40302 1.39751 1.39086

2.4258 2.2687 2.1394 2.0219 1.9139 1.7960 1.6814 1.5903 1.5401 1.5751 1.7662

1.42394 1.42209 1.42001 1.41785 1.41550 1.41255 1.40915 1.40543 1.40077 1.39524 1.38851

2.1994 2.0685 1.9487 1.8362 1.7299 1.6288 1.5286 1.4446 1.3849 1.3967 1.5116

1.42183 1.42003 1.41790 1.41571 1.41339 1.41039 1.40698 1.40327 1.39857 1.39300 1.38617

2.0063 1.8916 1.7870 1.6866 1.5907 1.4948 1.4019 1.3198 1.2594 1.2434 1.3033

1.41973 1.41794 1.41580 1.41360 1.41127 1.40823 1.40477 1.40104 1.39628 1.39067 1.38372

288.15 K 0.0000 0.1007 0.2003 0.3015 0.3991 0.5011 0.6024 0.6997 0.7998 0.9004 1.0000

1.015630 1.006229 0.995702 0.983460 0.969921 0.953530 0.934399 0.912674 0.885897 0.852630 0.810654

0.0000 0.1007 0.2003 0.3015 0.3991 0.5011 0.6024 0.6997 0.7998 0.9004 1.0000

1.010995 1.001607 0.991093 0.978877 0.965365 0.949011 0.929939 0.908320 0.881561 0.848418 0.806620

0.0000 0.1007 0.2003 0.3015 0.3991 0.5011 0.6024 0.6997 0.7998 0.9004 1.0000

1.006359 0.996991 0.986495 0.974305 0.960825 0.944498 0.925479 0.903877 0.877228 0.844144 0.802502

0.0000 0.1007 0.2003 0.3015 0.3991 0.5011 0.6024 0.6997 0.7998 0.9004 1.0000

1.001732 0.992377 0.981894 0.969723 0.956258 0.939966 0.920978 0.899430 0.872810 0.839810 0.798302

308.15 K 4.3415 4.0922 3.7925 3.5309 3.3424 3.1569 2.9720 2.8525 2.8737 3.1657 4.2905

1.43450 1.43266 1.43063 1.42851 1.42627 1.42333 1.41994 1.41632 1.41171 1.40624 1.39959

0.0000 0.1007 0.2003 0.3015 0.3991 0.5011 0.6024 0.6997 0.7998 0.9004 1.0000

0.997104 0.987755 0.977280 0.965119 0.951674 0.935407 0.916445 0.894917 0.868357 0.835418 0.794003

3.8338 3.5816 3.3196 3.0990 2.9406 2.7762 2.6102 2.4980 2.4967 2.7050 3.5763

1.43238 1.43054 1.42851 1.42637 1.42412 1.42118 1.41778 1.41418 1.40960 1.40412 1.39748

0.0000 0.1007 0.2003 0.3015 0.3991 0.5011 0.6024 0.6997 0.7998 0.9004 1.0000

0.992481 0.983135 0.972669 0.960509 0.947072 0.930813 0.911860 0.890367 0.863830 0.830950 0.789609

3.3801 3.1575 2.9374 2.7497 2.6034 2.4608 2.3156 2.2105 2.1866 2.3368 2.9542

1.43027 1.42843 1.42637 1.42424 1.42197 1.41902 1.41562 1.41202 1.40743 1.40197 1.39534

0.0000 0.1007 0.2003 0.3015 0.3991 0.5011 0.6024 0.6997 0.7998 0.9004 1.0000

0.987859 0.978511 0.968041 0.955883 0.942446 0.926193 0.907250 0.885759 0.859246 0.826396 0.785109

3.0042 2.8052 2.6274 2.4722 2.3444 2.2046 2.0680 1.9671 1.9330 2.0374 2.4687

1.42815 1.42631 1.42424 1.42210 1.41983 1.41687 1.41347 1.40983 1.40522 1.39977 1.39314

0.0000 0.1007 0.2003 0.3015 0.3991 0.5011 0.6024 0.6997 0.7998 0.9004 1.0000

0.983234 0.973877 0.963397 0.951237 0.937792 0.921533 0.902591 0.881097 0.854581 0.821735 0.780499

293.15 K

313.15 K

298.15 K

318.15 K

303.15 K

a

323.15 K

Standard uncertainties u for each variable are u(T) = 0.01 K, u(p) = 5 %, and ux1) = 0.0001, and the combined expanded uncertainties Uc are Uc(ρ) = ± 2·10−2 kg·m−3, Ur(η) = ± 1.0 %, and Uc(nD) = ± 6·10−5, with a 0.95 level of confidence (k ≈ 2).

The excess molar volumes VE were determined from the equation: n

VE =

⎡⎛ ⎞ ⎛ ⎞⎤ 1 1 ⎟ − ⎜⎜ ⎟⎟⎥ ⎢⎣⎝ ρ ⎠ ⎝ ρi ⎠⎥⎦

Mi is the molecular weight of component i, and xi is its mole fraction. The viscosity deviations Δη were calculated from the equation: n

∑ xiMi⎢⎜ i=1

Δη = η −

(1)

∑ xiηi i=1

in which ρ and ρi are densities of the solution and the pure component i, n represents the number of components,

(2)

in which η and ηi refer to the viscosity of the mixture and the pure component i. 3335



Article

Table 5. Densities ρ, Dynamic Viscosities η, and Refractive Indices nD for the Binary Mixture 2-Butanol (1) + NMP (2), as a Function of 2-Butanol Mole Fraction (x1), at T = (288.15 to 323.15) K and Atmospheric Pressurea 10−3·ρ x1

kg·m

η

−3

10−3·ρ

η mPa·s

nD

1.4443 1.4266 1.4113 1.3995 1.3932 1.3972 1.4242 1.4888 1.5976 1.7858 2.0803

1.46306 1.45632 1.44987 1.44301 1.43583 1.42867 1.42131 1.41372 1.40626 1.39861 1.39086

1.3464 1.3273 1.3109 1.2970 1.2854 1.2853 1.3034 1.3506 1.4314 1.5658 1.7662

1.46095 1.45416 1.44773 1.44083 1.43366 1.42651 1.41919 1.41155 1.40406 1.39638 1.38851

1.2593 1.2393 1.2213 1.2059 1.1895 1.1863 1.1967 1.2297 1.2864 1.3791 1.5116

1.45891 1.45204 1.44559 1.43868 1.43152 1.42436 1.41701 1.40934 1.40181 1.39408 1.38617

1.1816 1.1608 1.1414 1.1243 1.1040 1.0984 1.1026 1.1238 1.1617 1.2220 1.3033

1.45680 1.44996 1.44350 1.43654 1.42934 1.42215 1.41481 1.40711 1.39955 1.39172 1.38372

mPa·s

nD

x1

kg·m−3

1.9896 1.9841 1.9741 1.9721 2.0052 2.0319 2.1177 2.3023 2.6183 3.2270 4.2905

1.47166 1.46489 1.45851 1.45151 1.44431 1.43715 1.42982 1.42227 1.41487 1.40724 1.39959

0.0000 0.1049 0.2001 0.3009 0.4019 0.5003 0.5995 0.7004 0.7985 0.8990 1.0000

1.019462 0.996845 0.976091 0.953860 0.931323 0.909136 0.886575 0.863468 0.840874 0.817592 0.794003

1.8232 1.8151 1.8015 1.7980 1.8167 1.8385 1.9052 2.0482 2.2900 2.7571 3.5763

1.46952 1.46273 1.45634 1.44937 1.44219 1.43504 1.42772 1.42016 1.41275 1.40512 1.39748

0.0000 0.1049 0.2001 0.3009 0.4019 0.5003 0.5995 0.7004 0.7985 0.8990 1.0000

1.015000 0.992413 0.971652 0.949443 0.926949 0.904800 0.882258 0.859157 0.836567 0.813284 0.789609

1.6795 1.6645 1.6523 1.6470 1.6553 1.6697 1.7198 1.8316 2.0194 2.3684 2.9542

1.46736 1.46061 1.45418 1.44730 1.44013 1.43298 1.42564 1.41806 1.41063 1.40302 1.39534

0.0000 0.1049 0.2001 0.3009 0.4019 0.5003 0.5995 0.7004 0.7985 0.8990 1.0000

1.010533 0.987978 0.967237 0.945050 0.922578 0.900445 0.877912 0.854810 0.832207 0.808882 0.785109

1.5546 1.5376 1.5237 1.5135 1.5159 1.5225 1.5602 1.6455 1.7919 2.0508 2.4687

1.46520 1.45844 1.45203 1.44515 1.43799 1.43083 1.42349 1.41587 1.40842 1.40081 1.39314

0.0000 0.1049 0.2001 0.3009 0.4019 0.5003 0.5995 0.7004 0.7985 0.8990 1.0000

1.006061 0.983533 0.962815 0.940651 0.918196 0.896069 0.873531 0.850415 0.827785 0.804404 0.780499

288.15 K 0.0000 0.1049 0.2001 0.3009 0.4019 0.5003 0.5995 0.7004 0.7985 0.8990 1.0000

1.037298 1.014525 0.993630 0.971257 0.948589 0.926282 0.903599 0.880362 0.857640 0.834259 0.810654

0.0000 0.1049 0.2001 0.3009 0.4019 0.5003 0.5995 0.7004 0.7985 0.8990 1.0000

1.032840 1.010108 0.989247 0.966914 0.944287 0.922020 0.899376 0.876183 0.853510 0.830183 0.806620

0.0000 0.1049 0.2001 0.3009 0.4019 0.5003 0.5995 0.7004 0.7985 0.8990 1.0000

1.028382 1.005691 0.984854 0.962556 0.939970 0.917742 0.895133 0.871975 0.849341 0.826054 0.802502

0.0000 0.1049 0.2001 0.3009 0.4019 0.5003 0.5995 0.7004 0.7985 0.8990 1.0000

1.023925 1.001270 0.980460 0.958194 0.935644 0.913448 0.890869 0.867739 0.845132 0.821864 0.798302

308.15 K

293.15 K

313.15 K

298.15 K

318.15 K

303.15 K

a

323.15 K


The deviations in refractive index were calculated from the refractive index of the mixture (nD) and pure component i (nDi), according to the equation:

Calculation of the excess Gibbs energies of activation of viscous flow ΔG*E is based on the equation: ΔG*E = RT[ln(ηV /η2V2) − x1 ln(η1V1/η2V2)]

(3)

n

ΔnD = nD −

in which V is the molar volume of solution and V1 and V2 denote molar volumes of the mixture’s components.

∑ xinDi i=1

3336

(4)



Article

Figure 1. Experimental values of excess molar volume VE as a function of 2-butanol molar fraction x1 for the systems: (a) 2-butanol + PEG 200; (b) 2-butanol + PEG 400; (c) 2-butanol + TEGDME; (d) 2-butanol + NMP at the following temperatures: ◇, 288.15 K; ◆, 293.15 K; ○, 298.15 K; ●, 303.15 K; △, 308.15 K; ▲, 313.15 K; □, 318.15 K; ■, 323.15 K; , RK equation.

The experimentally determined excess molar volumes and the fitting curves calculated from the Redlich−Kister equation are displayed in Figure 1. The excess molar volumes for 2-butanol + PEG 200 and 2-butanol + PEG 400 mixtures are negative for all investigated temperatures and mixture compositions (Figure 1a and b). The VE values are more negative in the mixtures with PEG 400 with the minimum of the curves shifted toward higher 2-butanol mole fractions. With temperature rise the excess molar volume absolute values are increased in both analyzed systems. As already stated in our previous work,9 “the magnitude and the positive sign of excess molar volume VE can arise mainly from the following factors: (i) as a consequence of the rupture of the H bonds in the self-associated alcohol and the physical dipole− dipole interactions among molecules in the pure components; (ii) as a result of predominant intermolecular H bond stretching of the associated alcohol molecules in the presence of other substances; (iii) The steric hindrance due to interstitial accommodation of unlike molecules. The negative contributions are a consequence of the following effects: (i) strong intermolecular interactions attributed to the charge-transfer complex, dipole−dipole and dipole−induced dipole interactions and H-bonding between unlike molecules finally leading to the more efficient packing in the mixture than in the pure liquids; (ii) structural effects which arise from suitable interstitial accommodation giving more compact structure of mixtures”. The obtained results indicate the presence of strong molecular interactions in the mixture. All analyzed components have a good

Our experimental density and viscosity data for the system 2-butanol + TEGDME have been compared with literature values.7 The agreement was found to be satisfactory with differences less than 0.3 % for density data and less than 3.0 % for viscosity data. A comparison of our calculated VE values for the system 2-butanol + NMP with literature data8 has shown higher deviations. Densities and viscosities for systems 2-butanol + PEG 200 and 2-butanol + PEG 400, to our knowledge, have not been measured before. Correlation of excess molar volume VE, viscosity deviation Δη, excess Gibbs energy of activation of viscous flow ΔG*E, and deviation in refractive index ΔnD was done with the Redlich− Kister (RK) equation:5 k

Y = xixj

∑ A p(2xi − 1)p (5)

p=0

in which Y represents V , Δη, ΔG* , or ΔnD, while Ap and k+1 are fitting parameters and their number, optimized by the means of F-test. The values of fitting parameters for all investigated properties are presented in Table S6 in the Supporting Information. The quality of correlation was assessed by calculating the root-mean-square deviations (rmsd) σ, defined by the equation: E

E

m

σ = (∑ (Yexp − Ycal)2 /(m − k))1/2 i=1

(6)

in which m is the number of experimental data points. 3337



Article

Figure 2. Experimental values of viscosity deviation Δη as a function of 2-butanol molar fraction x1 for the systems: (a) 2-butanol + PEG 200; (b) 2-butanol + PEG 400; (c) 2-butanol + TEGDME; and (d) 2-butanol + NMP at the following temperatures: ◇, 288.15 K; ◆, 293.15 K; ○, 298.15 K; ●, 303.15 K; △, 308.15 K; ▲, 313.15 K; □, 318.15 K; ■, 323.15 K; , RK equation.

equilibrium constant of the created complex is reduced with increasing temperature. Domination of the first effect causes the increase in the excess molar volume negative values with temperature rise, which is the case with systems with PEG analyzed here but also with nicotine + PEG 200/PEG 400 binary mixtures,15 while the domination of the second effect results in the reduction of excess molar volume negative values as in the case of the pyridine + PEG 200/PEG 40015 or 1,3-propanediol + PEG 200/PEG 40014 binary mixture. Figure 1c reveals that the excess molar volumes in the 2-butanol + TEGDME binary mixture are positive at all investigated temperatures and for all mixture compositions with maximum of the curves shifted toward the higher TEGDME mole fractions. The temperature rise generally increases VE values although the temperature effect on excess molar volume of this system is relatively weak. Since the conditions exist both for dipole−dipole interactions and hydrogen bonds among the unlike molecules which would lead to negative excess molar volumes, the predominant effect of volume expansion could be the consequence of breaking or stretching of hydrogen bonds between the alcohol molecules and steric hindrance induced by branching. The fact that the branched structure of 2-butanol is unsuitable for effective packing is confirmed by our ongoing investigations on 1-butanol + TEGDME binary system but also by our previous works involving mixtures of 1-butanol or 2-butanol with chloroform.16,17 The solution of 2-butanol and NMP exhibits negative VE values at higher temperatures for all mixture compositions. However, at lower temperatures and over 0.4 alcohol mole

hydrogen bond ability and polar nature: the 2-butanol dipole moment is 1.68 D,10 for TEGDME and NMP dipole moments are 2.45 D11 and 4.09 D,12 respectively, and polarities of PEG 200 and PEG 400 are 3.06−3.94 D and 3.70−4.96 D,13 respectively, which speaks in favor of dipole−dipole interactions between both the unlike and the like molecules. 2-Butanol as monohydroxyl alcohol mainly interacts through its OH groups, forming linear associates. After adding the small amounts of PEG 200/PEG 400, the network of bonds between the alcohol molecules is disrupted, and new bonds between the unlike molecules are formed. The values of excess molar volume confirm the existence of strong attractive forces, hydrogen bonds, and dipole−dipole interactions, in the investigated mixtures with PEG 200 and PEG 400. However, in the case of the 2-butanol + PEG 400 binary system VE values are more negative then in mixture with PEG 200. It was already stated earlier14 that “polymer chain length plays an important role in the VE behavior of the studied solutions. In the solutions of PEG 400 with 1,3propanediol VE are almost two-fold more negative compared to those of PEG 200. These facts speak in the favor of stronger attractive interactions in the case of PEG 400”. Previous investigations of PEG 200 or PEG 400 mixtures with pyridine and nicotine15 also confirmed, by means of Fourier transform infrared spectroscopy, that PEG 400 builds stronger hydrogen bonds. With increasing temperature, the VE values could become more or less negative as a result of two opposing effects: (i) the number of species capable of creating cross-associated complexes increases with temperature, and (ii) the cross-association 3338



Article

Figure 3. Calculated values of energy of activation of viscous flow ΔG*E as a function of 2-butanol molar fraction x1 for the systems: (a) 2-butanol + PEG 200; (b) 2-butanol + PEG 400; (c) 2-butanol + TEGDME; (d) 2-butanol + NMP at the following temperatures: ◇, 288.15 K; ◆, 293.15 K; ○, 298.15 K; ●, 303.15 K; △, 308.15 K; ▲, 313.15 K; □, 318.15 K; ■, 323.15 K; , RK equation.

The excess Gibbs energies of activation of viscous flow (ΔG*E), plotted at Figure 3, are positive for systems with PEG 200 and PEG 400 and negative for systems with NMP over the whole range of mixture compositions and at all temperatures. However, for the 2-butanol + TEGDME binary mixture ΔG*E values are negative at lower temperature but turn to slightly positive values in a TEGDME rich region at temperatures above 318.15 K. Excess Gibbs energy of activation of viscous flow merges energy (enthalpy) and entropy and usually is considered as more suitable thermodynamic property than viscosity deviation for molecular interaction interpretation. In general, positive ΔG*E indicates the existence of strong attractive interactions21 and so qualitatively agrees with the negative VE values as in the case of systems with PEG 200 and PEG 400 analyzed in this work. As temperature is increased, excess Gibbs energies ΔG*E of both solutions become more positive. In systems with TEGDME and NMP the values of ΔG*E are mostly negative which could indicate that dispersion forces are dominant.22,23 With the temperature rise excess Gibbs energies ΔG*E of these systems became less negative, eventually even partly turning to positive for mixture with TEGDME. Since the behavior of VE and ΔG*E in systems with TEGDME and NMP does not comply with the same trend, it could be concluded that the strength of specific interactions or dispersion forces is not the only effect that should be taken into consideration. The molecular size and shape influencing steric hindrances or the ability for effective packing could also be significant. The experimentally determined deviations of refractive indices for the 2-butanol + PEG 200, 2-butanol + PEG 400, 2-butanol + TEGDME, and 2-butanol + NMP solutions and curves

fraction, a positive deviation appears (Figure 1d). In mixtures with alcohols NMP could form hydrogen bonds both through the nitrogen or/and oxygen atom. Alcohol molecules are linked by strong hydrogen bonds but in mixtures with other components tend to dissociate from the polymer aggregates and to form hydrogen bonds with other molecules. The value of the energy of O−H····N hydrogen bonds [(32 to 45) kJ·mol−1]18 significantly exceeded the value of energy of O−H···O [(20 to 25) kJ·mol−1] or N−H···N hydrogen bonds [(8.5 to 13.5) kJ·mol−1].19 Beside this effect, which contributes to volume contraction and negative VE values, volume expansion and positive VE values could be the outcome of breaking the alcohol structure by rupture or stretching of hydrogen bonds and/or steric hindrance induced by branching. This last effect seems to predominate for higher concentrations of 2-butanol and result in positive excess molar volumes, although very small by absolute value. Adding a small amount of alcohol to NMP would result in negative VE values up to the concentration of 2-butanol when steric hindrances become significant and excess molar volume turns positive. In favor to this assertion goes the fact that in mixtures with 1-alcohols (i.e., 1-ethanol20) excess molar volumes are negative over the whole composition range. Viscosity deviations (Δη) of analyzed solutions, displayed in Figure 2, are negative at all investigated temperatures and for all mixture compositions. The system with PEG 400 shows slightly higher negative values of viscosity deviation than the system with PEG 200, while for 2-butanol + TEGDME and 2-butanol + NMP binary mixtures Δη values are significantly lower in comparison with the previous two systems. For all analyzed mixtures negative Δη values are reduced with the temperature rise. 3339



Article

Figure 4. Experimental values of deviation in refractive index ΔnD as a function of 2-butanol molar fraction x1 for the systems: (a) 2-butanol + PEG 200; (b) 2-butanol + PEG 400; (c) 2-butanol + TEGDME; and (d) 2-butanol + NMP at the following temperatures: ◇, 288.15 K; ◆, 293.15 K; ○, 298.15 K; ●, 303.15 K; △, 308.15 K; ▲, 313.15 K; □, 318.15 K; ■, 323.15 K; , RK equation.

in very small absolute VE values, negative for the higher NMP concentrations and positive in the alcohol-rich region, at lower temperatures. All analyzed binary mixtures exhibit positive values of ΔnD over the investigated temperature and composition range which leads to the conclusion that attractive dispersion forces in the mixture are stronger than in the pure components.

computed from the Redlich−Kister equation are plotted in Figure 4. The ΔnD values for these systems are positive at all investigated temperatures and for all mixture compositions. This kind of behavior indicates that the dispersion attractive interactions between the unlike molecules in the mixture are stronger than in the pure components.24,25 In all analyzed binary systems refractive index deviations are slightly influenced by temperature.

■

ASSOCIATED CONTENT

S Supporting Information *

4. CONCLUSIONS Experimental data on density (ρ), viscosity (η), and refractive index (nD), as well as the excess molar volumes (VE), viscosity deviations (Δη), and deviations in refractive indices (ΔnD), calculated from these data and correlated by Redlich−Kister equation, for binary mixtures consisting of 2-butanol and PEG 200, PEG 400, TEGDME, or NMP, in the temperature interval from 288.15 K to 323.15 K and at atmospheric pressure, are presented in this paper. For 2-butanol + PEG 200 or + PEG 400 mixtures excess molar volumes are negative as a result of strong hydrogen bonding and dipole−dipole interactions, and high negative values of viscosity deviations indicate the importance of structural effects and suitable interstitial accommodation of smaller alcohol molecules. In the 2-butanol + TEGDME binary system values of VE are positive at all temperatures and over the whole range of mixture compositions, probably as a result of breaking and stretching of hydrogen bonds between the selfassociated alcohol molecules, although structural effects may also be significant. In 2-butanol + NMP solution positive contributions to excess molar volumes are balanced with negative, which results

Densities ρ, dynamic viscosities η, and refractive indices nD of the pure components studied in this work at 298.15 K; values of excess molar volume VE, viscosity deviation Δη, excess Gibbs energy of activation of viscous flow ΔG*E, and deviation in refractive index ΔnD; and values of fitting parameters for all investigated properties. This material is available free of charge via the Internet at http://pubs.acs.org.

■

AUTHOR INFORMATION

Corresponding Author

*Phone: +381 11 3370429. E-mail address: [email protected]. Funding

The authors gratefully acknowledge the financial support received from the Research Fund of Ministry of Science and Environmental Protection, Serbia and the Faculty of Technology and Metallurgy, University of Belgrade (project no. 172063). Notes

The authors declare no competing financial interest. 3340



■

Article

(19) Funke, H.; Wetzel, W.; Heintz, A. New applications of the ERAS model. Thermodynamics of amine+alkane and alcohol+ amine mixtures. Pure Appl. Chem. 1989, 61, 1429−1439. (20) Garcia-Abiun, A.; Gomez-Diaz, D.; La Rubia, M. D.; Navaza, J. M. Density, Speed of Sound, Viscosity, Refractive Index, and Excess Volume of N-Methyl-2-pyrrolidone + Ethanol (or Water or Ethanolamine) from T = (293.15 to 323.15) K. J. Chem. Eng. Data 2011, 56, 646−654. (21) Misra, V. K.; Vibhu, I.; Singh, R.; Gupta, M.; Shukla, J. P. Ultrasonic velocity, viscosity, density and excess properties of binary mixture of dimethyl sulphoxide with propanoic acid and n-butyric acid. J. Mol. Liq. 2007, 135, 166−169. (22) Oswal, S. L.; Oswal, P.; Gardas, R. L.; Patel, S. G.; Shinde, R. G. Acoustic, volumetric, compressibility and refractivity properties and reduction parameters for the ERAS and Flory models of some homologous series of amines from 298.15 to 328.15 K. Fluid Phase Equilib. 2004, 216, 33−45. (23) Garcia, B.; Alcalde, R.; Leal, J. M.; Matos, J. S. Shear viscosities of the N-methylformamide and N,N-dimethylformamide-(C1-C10)alkan-1-ol solvent systems. J. Chem. Soc., Faraday Trans. 1997, 93, 1115−1118. (24) Prausnitz, J. M.; Lichtenthaler, R. N.; Gomes de Azevedo, E. Molecular Thermodynamics of Fluid Phase Equilibria; Prentice Hall: New York, 1986. (25) Piñeiro, Á .; Brocos, P.; Amigo, A.; Pintos, M.; Bravo, R. Prediction of excess volumes and excess surface tensions from experimental refractive indices. Phys. Chem. Liq. 2000, 38, 251−260.

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Volumetric and Viscometric Behavior of Binary Systems 2-Butanol +

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