Effect of Solvents and Temperature on Interactions in Binary and

Article Cite This: J. Chem. Eng. Data XXXX, XXX, XXX−XXX

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Effect of Solvents and Temperature on Interactions in Binary and Ternary Mixtures of 1‑Butyl-3-methylimidazolium Trifluoromethanesulfonate with Acetonitrile or/and N,N‑Dimethylformamide Urooj Fatima, Riyazuddeen,* and Naushad Anwar

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Department of Chemistry, Aligarh Muslim University, Aligarh, Uttar Pradesh 202002, India S Supporting Information *

ABSTRACT: The densities ρ, speeds of sounds u, and dynamic viscosities η of the pure ionic liquid (IL) 1-butyl-3-methylimidazolium trifluoromethanesulfonate ([BMIM][CF3SO3]), acetonitrile (ACN), N,N-dimethylformamide (DMF), and of their binary and ternary mixtures as a function of mole fraction of IL/solvent at various temperatures (298.15 to 323.15) K with an interval of T = 5 K and at P = 0.1 MPa have been measured experimentally. The excess molar volumes, VE, excess molar isentropic compressibilities, KES,m and viscosity deviations, Δη have been determined from the measured data of ρ, u, and η of pure [BMIM][CF3SO3], ACN, DMF and of their binary/ ternary mixtures at studied compositions and temperatures. We have also calculated the Gibbs free energy of activation, ΔG* and an excess Gibbs free energy of activation for viscous flow, ΔG*E for the studied binary mixtures. The VE, KES,m and Δη of the studied binary/ternary mixtures are fitted to the Redlich−Kister polynomial equation. The trends of variations of parameters varied with mole fraction of IL and temperature and are discussed in terms of ion−ion, ion−dipole, and dipole−dipole interactions. In this work, we have also applied various semiempirical models to correlate the experimental dynamic viscosity data and evaluated interactional parameters of the studied binary mixtures. The excess molar volumes of each binary system have also been correlated with the Prigogine−Flory−Patterson (PFP) theory and have been found in good agreement with the experimental values.

1. INTRODUCTION Ionic liquids (ILs), a new class of solvents comprising a cation and an anion,1 have the potential to replace volatile organic solvents because of their idiosyncratic properties.2 Their physicochemical properties can be modulated for specific application by combining an enormous range of possible anions and cations, and therefore, they are also called “designer solvents.” Because of their peculiar properties such as negligible vapor pressure they are also termed as “green-solvents”, which leads scientists and industrialists3 to explore new applications. These include their use as catalysts and novel solvents for organic and inorganic synthesis and biocatalysts, their role in the synthesis of nanomaterials,4 extraction processes, and aqueous biophasic systems5, use as an entrainer for liquid−liquid extraction, in extractive distillation, as solvents for catalytic reactions, in solar cells, and as a heat transfer fluid6 and chemical sensor.7 In addition to this, they can interact with high charge and low charge density regions, and complexity in their organization and molecular interaction leads to their development as “nano-structured liquids”.8 The thermophysical properties such as density, speed of sound, viscosity, and their derived parameters are helpful to better understand the nature of ILs−solvent interactions and other structural properties which provide information required for designing, testing, and extending theoretical models which are essential when experimental data are not available.9 Deep knowledge of thermodynamic © XXXX American Chemical Society

and transport properties of ILs and their mixtures also help in designing the technological processes used by industries. On the other hand, by the study of excess/derived properties we may better understand the structural relationship of ILs with the solvents. The imidazolium salt-based ILs are comparatively more versatile than the ILs having other cations and show promising applications in various fields. 1-Butyl-3-methylimidazolium trifluoromethanesulfonate ([BMIM][CF3SO3]) is a hydrophilic, dark yellow odorless liquid having a melting point of −15 C° and is air, water, and thermally stable.2 It is widely used as a green solvent to promote the hydro-alkylation of dicarbonyl compound to process smoothly excellent yield.10 Acetonitrile (ACN) is the main component used in the pharmaceutical industry and shows exceptional solvation ability with respect to a wide range of polar and nonpolar solutes and favorable properties such as low freezing/boiling points, low viscosity,11 and possessing the dipole moment 3.92 D. N,N-dimethylformamide (DMF), having a dipole moment 3.86 D is employed in fertilizers and in the pharmaceutical industry.12 ILs have emerged as an appealing candidate in the field of pharmaceutical industries. Received: March 6, 2018 Accepted: October 23, 2018

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DOI: 10.1021/acs.jced.8b00176 J. Chem. Eng. Data XXXX, XXX, XXX−XXX

Journal of Chemical & Engineering Data

Article

Table 1. Compounds Used with Their CAS Number, Molar Mass, Source, Purification Method, Mass Fraction Purity, and Water Content compounds b

[BMIM][CF3SO3] acetonitrile N,N-dimethylformamide

CASRN

M/g·mol−1

source

purification method

mass fraction puritya

water content

174899-66-2 75-05-8 68-12-2

288.29 41.05 73.09

Sigma-Aldrich Merck Merck

without further purification without further purification without further purification

≥98% ≥99% ≥99%

0.014% (Karl Fischer) ≤0.01% ≤0.01%

a

Purity as stated by supplier. b1-Butyl-3-methylimidazolium trifluoromethanesulfonate.

application in pharmaceutics. Thus, the present study will be helpful in tailoring properties of systems having improved medicinal properties. A number of authors have reported the thermophysical properties of 1-butyl-3-methylimidazolium trifluoromethanesulfonate and its mixtures with different organic solvents/ water2,13−21 at various temperatures. To the best of our knowledge, no work has been reported yet so far on the thermophysical properties of [BMIM][CF3SO3] + ACN/DMF and DMF + ACN binary mixtures and [BMIM][CF3SO3] + ACN + DMF ternary mixtures. The aim of this work is to study on thermophysical properties of ([BMIM][CF3SO3], ACN/DMF binary and ternary mixtures. The ternary mixture was particularly chosen

Figure 1. Structure of [BMIM][CF3SO3].

From a wide range of molecular solvents, we have opted for ACN and DMF as these solvent systems have considerable

Table 2. Densities, ρ/g·cm−3 at Temperature T = (298.15 to 323.15) K and Mole Fraction, x1 for the Binary Mixtures [BMIM][CF3SO3](1) + ACN(2), [BMIM][CF3SO3](1) + DMF (2), and DMF(1) + ACN(2) at Pressure P = 0.1 MPaa x1

T/K = 298.15

T/K = 303.15

0.0000b 0.0911 0.2023 0.3029 0.3998 0.4994 0.5953 0.7029 0.8009 0.9012 1.0000c

0.776714 0.958580 1.074818 1.137118 1.179002 1.211159 1.234144 1.255852 1.271775 1.285588 1.297462

0.771289 0.954576 1.070411 1.132764 1.174936 1.207101 1.230077 1.251972 1.267966 1.281578 1.293465

0.0000 0.1087 0.2030 0.2978 0.4090 0.4969 0.6030 0.6990 0.8090 0.8928 1.0000c

0.943934 1.042017 1.099891 1.142855 1.181650 1.206073 1.230688 1.249538 1.268592 1.281634 1.297462

0.939162 1.037253 1.095218 1.138296 1.177218 1.201732 1.226445 1.245372 1.264499 1.277589 1.293465

0.0000b 0.0989 0.1916 0.2925 0.3932 0.5029 0.6002 0.6931 0.7926 0.8996 1.0000

0.776714 0.802565 0.826376 0.844614 0.865725 0.880889 0.895421 0.907546 0.922026 0.932676 0.943934

0.771289 0.797299 0.821229 0.839435 0.860639 0.875938 0.890518 0.902756 0.917220 0.927901 0.939162

T/K = 308.15 [BMIM][CF3SO3] + ACN 0.765833 0.949838 1.066005 1.128522 1.170953 1.202787 1.225985 1.247896 1.264185 1.277726 1.289467 [BMIM][CF3SO3] + DMF 0.934373 1.032473 1.090532 1.133725 1.172775 1.197383 1.222196 1.241201 1.260403 1.273542 1.289467 DMF + ACN 0.765833 0.792024 0.816008 0.834219 0.855560 0.870924 0.885607 0.897887 0.912402 0.923153 0.934373

T/K = 313.15

T/K = 318.15

T/K = 323.15

0.760339 0.944800 1.061342 1.124168 1.166711 1.198747 1.221914 1.243952 1.260125 1.273980 1.285471

0.754815 0.939614 1.057104 1.120049 1.162771 1.194471 1.217750 1.240121 1.256166 1.270020 1.281473

0.749253 0.934671 1.052928 1.115711 1.158497 1.190694 1.213778 1.236143 1.252288 1.266173 1.277476

0.929577 1.027686 1.085840 1.129149 1.168329 1.193032 1.217945 1.237029 1.256308 1.269496 1.285471

0.924765 1.022884 1.081134 1.124561 1.163873 1.188672 1.213687 1.232852 1.252208 1.265446 1.281473

0.919950 1.018079 1.076424 1.119969 1.159414 1.184309 1.209427 1.228674 1.248108 1.261397 1.277476

0.760339 0.786729 0.810757 0.829087 0.850487 0.865854 0.880698 0.893049 0.907663 0.918366 0.929577

0.754815 0.781363 0.805527 0.823852 0.845354 0.860760 0.875703 0.888143 0.902790 0.913570 0.924765

0.749253 0.776028 0.800222 0.818614 0.840213 0.855738 0.870738 0.883209 0.897991 0.908741 0.919950

Standard uncertainty u: u(T) = 0.01 K, u(P) = 10 kPa, combined expanded uncertainty Uc: Uc(x) = 2 × 10−4, Uc(ρ) = 5 × 10−4 g·cm−3 (level of confidence = 0.95, k = 2). bReference 53. cReference 2 (our earlier published work). a

B



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Table 3. Speeds of Sound, u/m·s−1 at Temperature T = (298.15 to 323.15) K and Mole Fraction, x1 for the Binary Mixtures [BMIM][CF3SO3](1) + ACN(2), [BMIM][CF3SO3](1) + DMF (2), and DMF(1) + ACN(2) at Pressure P = 0.1 MPaa x1

T/K = 298.15

T/K = 303.15

0.0000b 0.0911 0.2023 0.3029 0.3998 0.4994 0.5953 0.7029 0.8009 0.9012 1.0000c

1278.53 1306.25 1330.84 1347.19 1359.40 1368.60 1375.64 1382.49 1386.57 1389.81 1393.21

1258.37 1289.17 1315.64 1332.96 1346.07 1355.73 1363.10 1370.57 1374.87 1378.39 1382.79

0.0000 0.1087 0.2030 0.2978 0.4090 0.4969 0.6030 0.6990 0.8090 0.8928 1.0000c

1457.14 1449.24 1437.68 1425.69 1415.04 1409.17 1403.05 1399.14 1396.65 1395.02 1393.21

1437.81 1432.14 1421.89 1410.93 1401.23 1395.98 1390.51 1387.01 1384.82 1383.52 1382.79

0.0000b 0.0989 0.1916 0.2925 0.3932 0.5029 0.6002 0.6931 0.7926 0.8996 1.0000

1278.53 1302.51 1322.00 1339.63 1361.63 1377.51 1395.94 1411.39 1429.22 1442.81 1457.14

1258.37 1282.67 1302.28 1320.07 1342.15 1358.13 1376.59 1392.00 1409.88 1423.35 1437.81

T/K = 308.15 [BMIM][CF3SO3] + ACN 1238.17 1272.13 1300.56 1318.83 1332.80 1342.99 1350.71 1358.77 1363.36 1367.03 1371.68 [BMIM][CF3SO3] + DMF 1418.45 1415.16 1406.03 1395.88 1387.25 1382.87 1378.10 1375.05 1373.27 1372.14 1371.68 DMF + ACN 1238.17 1262.86 1282.50 1300.45 1322.61 1338.64 1357.18 1372.56 1390.53 1404.01 1418.45

T/K = 313.15

T/K = 318.15

T/K = 323.15

1218.03 1255.07 1285.49 1304.76 1319.56 1330.27 1338.38 1347.05 1351.97 1355.81 1360.73

1197.87 1238.15 1270.57 1290.79 1306.44 1317.69 1326.16 1335.43 1340.67 1344.72 1349.90

1177.76 1221.28 1255.76 1276.93 1293.39 1305.22 1314.03 1323.85 1329.52 1333.74 1338.78

1399.15 1398.08 1390.43 1381.41 1373.62 1369.71 1365.57 1363.03 1361.70 1360.87 1360.73

1379.92 1381.22 1374.95 1366.96 1360.12 1356.83 1353.31 1351.23 1350.30 1349.72 1349.90

1360.74 1364.47 1359.60 1352.60 1346.70 1344.05 1341.14 1339.54 1339.09 1338.70 1338.78

1218.03 1243.05 1262.78 1280.90 1303.15 1319.19 1337.86 1353.28 1371.27 1384.73 1399.15

1197.87 1223.28 1243.09 1261.35 1283.73 1299.86 1318.60 1334.01 1352.06 1365.49 1379.92

1177.76 1203.45 1223.43 1241.88 1264.36 1280.59 1299.40 1314.79 1332.92 1346.35 1360.74

a Standard uncertainty u: u(T) = 0.01 K, u(P) = 10 kPa, combined expanded uncertainty Uc: Uc(x) = 2 × 10−4, Uc(u) = 0.5 m·s−1 (level of confidence = 0.95, k = 2). bReference 53. cReference 2 (our earlier published work).

solute−solvent interactions occurring between IL and organic solvents. The experimental VE, KEs,m and Δη values have been correlated to the Redlich−Kister polynomial equation for studied binary and ternary systems. The behavior of excess and deviation properties have been discussed in terms of ion−ion, ion-dipole, dipole−dipole, and hydrogen bonding interactions and packing of components in the studied mixtures.22 The semiempirical models, such as Arrhenius,23 Kendall-Monroe,24 Grunberg-Nissan,25 Hind-Ubbelohde,26 Katti-Chaudhary,27 and McAllister28 twointeractional parameter equations have been employed for the correlation of dynamic viscosity data and to determine some interaction parameters of the studied binary systems in term of pure components data. The Prigogine−Flory−Patterson (PFP) theory21,29,30 has also been used to correlate the excess molar volumes, VE of all the studied binary mixtures [BMIM][CF3SO3] + ACN, [BMIM][CF3SO3] + DMF, and DMF + ACN.

to get insight on the effect of two organic solvents on the properties of ILs. In continuation of our earlier project on measurement of thermophysical properties of ionic liquid mixtures, we have experimentally measured the densities (ρ), speeds of sound (u), and dynamic viscosities (η) of pure [BMIM][CF3SO3], ACN, DMF and their binary mixtures [BMIM][CF3SO3](1) + ACN(2), [BMIM][CF3SO3](1) + DMF(2), and DMF(1) + ACN(2) in the range of mole fraction of IL (x1 = 0.0 to 1.0) and their ternary mixture [BMIM][CF3SO3](1) + ACN(2) + DMF(3) in the range of mole fraction of IL (x1 = 0.03 to 0.8) at temperatures (298.15, 303.15, 308.15, 313.15, 318.15, and 323.15) K and at pressure 0.1 MPa. The excess molar volume, VE, excess molar isentropic compressibility, KEs,m and viscosity deviation, Δη values have been determined using the experimental densities, speeds of sound, and dynamic viscosities data of pure components and of their binary/ternary mixtures. We have also calculated the Gibbs free energy of activations, ΔG* and an excess Gibbs free energy of activation for the viscous flow ΔG*E for the studied binary mixtures. These quantities have been employed to discuss the

2. EXPERIMENTAL SECTION 2.1. Materials and Samples Preparation. The detail specifications of [BMIM][CF3SO3], ACN, and DMF are listed C



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Table 4. Viscosities, η/mPa·s, at Temperature T = (298.15 to 323.15) K and Mole Fraction, x1 for the Binary Mixtures [BMIM][CF3SO3](1) + ACN(2), [BMIM][CF3SO3](1) + DMF (2), and DMF(1) + ACN(2) at Pressure P = 0.1 MPaa x1

T/K = 298.15

0.0000b 0.0911 0.2023 0.3029 0.3998 0.4994 0.5953 0.7029 0.8009 0.9012 1.0000c

0.34 0.94 1.74 4.03 6.63 11.09 19.01 29.57 40.36 56.57 82.38

0.0000 0.1087 0.2030 0.2978 0.4090 0.4969 0.6030 0.6990 0.8090 0.8928 1.0000c

0.81 1.80 3.67 5.22 8.68 13.24 20.91 32.59 52.15 68.08 82.38

0.0000b 0.0989 0.1916 0.2925 0.3932 0.5029 0.6002 0.6931 0.7926 0.8996 1.0000

0.34 0.40 0.44 0.48 0.54 0.61 0.65 0.69 0.75 0.79 0.81

T/K = 303.15

T/K = 308.15

T/K = 313.15

[BMIM][CF3SO3] + ACN 0.32 0.31 0.30 0.88 0.83 0.79 1.61 1.58 1.48 3.64 3.30 3.01 5.90 5.26 4.73 9.65 8.46 7.48 16.22 13.86 12.06 24.73 20.90 17.91 33.14 27.82 23.51 45.89 37.70 31.45 66.69 52.86 43.67 [BMIM][CF3SO3] + DMF 0.77 0.72 0.69 1.67 1.55 1.44 3.23 2.93 2.64 4.67 4.20 3.81 7.62 6.73 6.01 11.40 9.92 8.71 17.79 15.23 13.22 27.14 22.89 19.53 42.41 35.16 29.38 54.90 44.83 37.11 66.69 52.86 43.67 DMF + ACN 0.32 0.31 0.30 0.39 0.37 0.35 0.42 0.40 0.39 0.46 0.44 0.42 0.51 0.49 0.46 0.57 0.54 0.51 0.61 0.58 0.55 0.65 0.61 0.58 0.70 0.66 0.63 0.75 0.71 0.69 0.77 0.72 0.69

T/K = 318.15

T/K = 323.15

0.29 0.75 1.40 2.75 4.26 6.65 10.56 15.52 20.16 26.58 36.29

0.28 0.71 1.32 2.54 3.88 5.95 9.33 13.54 17.40 22.66 30.57

0.65 1.34 2.40 3.47 5.41 7.74 11.60 16.84 24.86 31.09 36.29

0.62 1.26 2.20 3.17 4.88 6.89 10.21 14.64 21.29 26.39 30.57

0.29 0.33 0.37 0.40 0.44 0.49 0.52 0.55 0.59 0.63 0.65

0.28 0.32 0.35 0.38 0.42 0.46 0.50 0.53 0.56 0.60 0.62

a

Standard uncertainty u: u(T) = 0.01 K, u(P) = 10 kPa, combined expanded uncertainty Uc: Uc(x) = 2 × 10−4, Uc(η) < 1 mPa·s = 0.20 mPa·s, Uc(η) (1−10 mPa·s) = 0.60 mPa·s, Uc(η) (11−50 mPa·s) = 0.80 mPa·s (level of confidence = 0.95, k = 2). bReference 53. c Reference 2 (our earlier published work). Figure 2. Relative percent deviation {100·[(Ylit − Yexpt)/Ylit] (Y = ρ, u, and η)} at T = (298.15 to 323.15) K of experimental values of pure components with literature (a) ρ for [BMIM][CF3SO3]: (Solid) black ■, ref 14; red ●, ref 15; green ▲, ref 16; blue ▼, ref 17 ; aqua ◆, ref 18; purple ◀, ref 19, yellow ▶, ref 20; black ▶, ref 21; red ▼, ref 27; green ◀, ref 28. (Hollow) red □, ref 29; blue ○, ref 30; aqua , ref 32. (ρ for ACN) green ●, ref 34; blue ▲, ref 35; aqua ▼, ref 36; purple ◆, ref 37 ; yellow ◀, ref 38; (ρ for DMF) green ■, ref 40; blue ●, ref 41; aqua ▲, ref 42; purple ▼, ref 43; yellow ◆, ref 44; black ◀, ref 45; red ▶, ref 46. (b) u for [BMIM][CF3SO3]: blue ■, ref 15; orange ●, ref 17; dark green ▲, ref 19; maroon ▼, ref 28; blue ◆, ref 33; (u for ACN) purple ■, ref 35; yellow ●, ref 37; orange ▲, ref 39; (u for DMF) aqua ■, ref 46. (c) η for [BMIM][CF3SO3]: red ■, ref 14; red ●, ref 18; black ▲, ref 27; blue ▼, ref 31; (η for ACN) yellow ■, ref 35; purple ●, ref 36; red ▲, ref 38; (η for DMF) yellow ■, ref 41; black ●, ref 43; purple ▲, ref 44; orange ▼, ref 46.

in Table 1. The water content of pure [BMIM][CF3SO3] was obtained by Karl Fischer Coulometric titrator (C20, Mettler Toledo). All these chemicals were used without further purifications. The 3-D structure of [BMIM][CF3SO3] is shown in Figure 1. All the binary and ternary mixtures were prepared freshly and kept at the desired temperature for a few hours to ensure the complete miscibility of the sample before experiment. The binary mixtures [BMIM][CF3SO3] + ACN, [BMIM][CF3SO3] + DMF, and DMF + ACN and ternary mixture [BMIM][CF3SO3] + ACN + DMF were prepared by weighing on a New classic MS Mettler Toledo electronic digital balance with a precision of 1 × 10−4 g. The combined expanded uncertainty in mole fractions of all the solutions was estimated to be less than 2 × 10−4. 2.2. Apparatus and Measurements. 2.2.1. Density and Speed of Sound Measurements. Experimental measurements D



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Figure 4. Excess molar isentropic compressibilities of (a) [BMIM][CF3SO3] + ACN, (b) [BMIM][CF3SO3] + DMF, (c) DMF + ACN as a function of mole fraction at different temperatures: black ■, 298.15 K; red ●, 303.15 K; green ▲, 308.15 K; blue ▼, 313.15 K; aqua ◆, 318.15 K; and purple ◀, 323.15 K. The symbols represent experimental values, and the solid curves are calculated with the Redlich− Kister equation.

Figure 3. Excess molar volumes of (a) [BMIM][CF3SO3] + ACN, (b) [BMIM][CF3SO3] + DMF, (c) DMF + ACN as a function of mole fraction at different temperatures: black ■, 298.15 K; red ●, 303.15 K; green ▲, 308.15 K; blue ▼, 313.15 K; aqua ◆, 318.15 K; and purple ◀, 323.15 K. The symbols represent experimental values and the solid curves are calculated with the Redlich−Kister equation.

of densities and speeds of sound of all pure components, binary mixtures [BMIM][CF3SO3] + ACN, [BMIM][CF3SO3] + DMF, DMF + ACN and ternary mixtures [BMIM][CF3SO3] + ACN + DMF were carried out with a vibrating tube densimeter

(Anton Paar DSA 5000M) having ultrasonic transducer of frequency 3 MHz at temperatures T = (298.15, 303.15, 308.15, 313.15, 318.15 and 323.15) K and at pressure, 0.1 MPa. E



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The densimeter was calibrated for setting each series of experiment with the triple distilled water and dry air at temperatures (298.15, 303.15, 308.15, 313.15, 318.15 and 323.15) K and pressure, 0.1 MPa. The combined expanded uncertainties (level of confidence 0.95, k = 2) associated with measurements of densities and speeds of sound were found to be 5 × 10−4 g·cm−3 and 0.5 m·s−1, respectively. 2.2.2. Dynamic Viscosity Measurements. Experimental measurements of dynamic viscosities of all pure components, binary mixtures [BMIM][CF3SO3] + ACN, [BMIM][CF3SO3] + DMF, DMF + ACN and ternary mixtures [BMIM][CF3SO3] + ACN + DMF were carried out with Anton Paar Lovis 2000 M falling ball automated viscometer at temperatures T = (298.15, 303.15, 308.15, 313.15, 318.15 and 323.15) K and at pressure, 0.1 MPa. The viscometer was calibrated with two standards N-50 and N-80 using capillaries having a diameter 1.59 (dynamic viscosity range = 1−20 mPa·s) and 1.8 mm (dynamic viscosity range = 17−300 mPa·s) and with standard balls at temperatures (298.15, 303.15, 308.15, 313.15, 318.15 and 323.15) K and at pressure 0.1 MPa, respectively. The combined expanded uncertainty (level of confidence = 0.95, k = 2) associated with measurements of viscosity were found to be Uc(η) < 1 mPa·s = 0.20 mPa·s, Uc(η) (1−10 mPa·s) = 0.60 mPa·s, and Uc(η) (11−50 mPa·s) = 0.80 mPa·s. The standard uncertainty in the temperature measurements was found to be 0.01 K.

3. RESULTS AND DISCUSSION 3.1. Binary Systems. 3.1.1. Densities, Speeds of Sound and Dynamic Viscosities. The experimental data of densities, speeds of sound, and dynamic viscosities of pure [BMIM][CF3SO3], ACN, DMF, and their binary mixtures [BMIM][CF3SO3] + ACN, [BMIM][CF3SO3] + DMF, and DMF + ACN in temperature range T = (298.15 to 323.15) K with an interval of 5 K and at pressure 0.1 MPa are reported in Tables 2−4. The measured values of ρ, u and η of pure components [BMIM][CF3SO3], ACN, and DMF have been compared with the literature values15−22,31−50 and reported in Table S1 (Supporting Information). The percent deviations [100·[(Ylit − Yexpt)/Ylit]] (Y = ρ, u, and η)) for ρ in the case of [BMIM][CF3SO3], ACN, and DMF are found to be 0.00 to −0.54%; 0.02 to −0.06%, and 0.11 to −0.08%, respectively (see Figure 2). Similarly, the percent deviations for u for IL, ACN, and DMF are observed in the range of 0.19 to 0.02%; −0.01 to −0.95%, and 5.90%. The percent deviations observed for η lie in the range of 4.86 to −1.51% for IL, 1.97 to −2.99% for ACN, and 0.29 to −9.44% for DMF. The larger deviations observed for dynamic viscosity occur because we have employed the Anton Paar Lovis 2000 M falling ball automated viscometer while other authors have determined the viscosity by ordinary Ubbelohde viscometer. The inconsiderable deviations observed in density and speed of sound measurements may be ascribed either to certain undefined impurities in compounds or due to the use of different experimental methods. 3.1.2. Excess Molar Volumes. For studied binary systems [BMIM][CF3SO3] + ACN, [BMIM][CF3SO3] + DMF, and DMF + ACN, the excess molar volumes, VE have been calculated from the experimental densities by using the following standard equation,

Figure 5. Viscosity deviations of (a) [BMIM][CF3SO3] + ACN, (b) [BMIM][CF3SO3] + DMF, (c) DMF + ACN as a function of mole fraction at different temperatures: black ■, 298.15 K; red ●, 303.15 K; green ▲, 308.15 K; blue ▼, 313.15 K; aqua ◆, 318.15 K and purple ◀, 323.15 K. The symbols represent experimental values, and the solid curves are calculated with the Redlich−Kister equation.

where ρ and ρi are the densities of binary mixtures and pure components i. xi and Mi represent the mole fraction and molar mass of the pure components i, respectively. The VE of [BMIM][CF3SO3] + ACN and DMF + ACN systems are found to be negative at all compositions and

N E

V =

∑ xiMi(ρ−1 − ρi−1) i=1

(1) F



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Table 5. Gibbs Free Energy of Activation, ΔG*/kJ·mol−1, at Temperature T = (298.15 to 323.15) K and Mole Fractions, (x1) for the Binary Mixtures [BMIM][CF3SO3](1) + ACN(2), [BMIM][CF3SO3](1) + DMF (2), and DMF(1) + ACN(2) at Pressure P = 0.1 MPa x1

T/K = 298.15

T/K = 303.15

0.0000 0.0911 0.2023 0.3029 0.3998 0.4994 0.5953 0.7029 0.8009 0.9012 1.0000

−49.8413 −47.2549 −50.1843 −39.9924 −36.8135 −32.9925 −28.7575 −25.7642 −22.9977 −19.1988 −15.0538

−50.7690 −48.1868 −51.1586 −40.9026 −37.7106 −33.8709 −29.6141 −26.6071 −23.8258 −20.0039 −15.8337

0.0000 0.1087 0.2030 0.2978 0.4090 0.4969 0.6030 0.6990 0.8090 0.8928 1.0000

−48.5146 −44.8342 −37.2245 −39.0237 −35.5294 −31.8335 −29.0376 −24.9556 −20.1571 −17.5372 −15.0538

−49.4572 −45.7663 −38.1102 −39.9345 −36.4241 −32.7078 −29.9001 −25.7947 −20.9675 −18.3324 −15.8337

0.0000 0.0989 0.1916 0.2925 0.3932 0.5029 0.6002 0.6931 0.7926 0.8996 1.0000

−49.8413 −51.3219 −51.0107 −50.9213 −50.5346 −50.2708 −50.0140 −49.7542 −49.5683 −49.2997 −48.5146

−50.769 −52.2663 −51.956 −51.8689 −51.4817 −51.2184 −50.9617 −50.7017 −50.5161 −50.2473 −49.4572

T/K = 308.15 [BMIM][CF3SO3] + ACN −51.6967 −49.1187 −52.1330 −41.8128 −38.6076 −34.7494 −30.4706 −27.4500 −24.6539 −20.8090 −16.6136 [BMIM][CF3SO3] + DMF −50.3999 −46.6984 −38.9959 −40.8453 −37.3188 −33.5821 −30.7625 −26.6338 −21.7779 −19.1276 −16.6136 DMF + ACN −51.6967 −53.2108 −52.9013 −52.8165 −52.4287 −52.1659 −51.9093 −51.6491 −51.4638 −51.1949 −50.3999

T/K = 313.15

T/K = 318.15

T/K = 323.15

−52.6244 −50.0506 −53.1073 −42.7230 −39.5047 −35.6278 −31.3271 −28.2929 −25.4820 −21.6141 −17.3935

−53.5521 −50.9825 −54.0817 −43.6332 −40.4017 −36.5063 −32.1836 −29.1358 −26.3101 −22.4192 −18.1734

−54.4798 −51.9144 −55.0560 −44.5434 −41.2988 −37.3847 −33.0401 −29.9787 −27.1382 −23.2243 −18.9533

−51.3425 −47.6305 −39.8816 −41.7561 −38.2134 −34.4564 −31.6249 −27.4729 −22.5882 −19.9228 −17.3935

−52.2851 −48.5625 −40.7673 −42.6669 −39.1081 −35.3307 −32.4874 −28.312 −23.3986 −20.7181 −18.1734

−53.2278 −49.4946 −41.6530 −43.5777 −40.0028 −36.2050 −33.3498 −29.1511 −24.209 −21.5133 −18.9533

−52.6244 −54.1552 −53.8466 −53.7641 −53.3757 −53.1135 −52.8569 −52.5965 −52.4116 −52.1424 −51.3425

−53.5521 −55.0997 −54.7919 −54.7118 −54.3227 −54.0611 −53.8046 −53.5439 −53.3594 −53.09 −52.2851

−54.4798 −56.0441 −55.7372 −55.6594 −55.2697 −55.0086 −54.7522 −54.4914 −54.3071 −54.0375 −53.2278

reported in Table S2 of Supporting Information, and the graphs are plotted in Figure 3a−c. 3.1.3. Excess Molar Isentropic Compressibilities. The isentropic compressibility, κS is defined as

temperatures. The negative deviations from ideality, observed for these systems, may be attributed to the higher degree of iondipole interactions in IL + ACN and dipole−dipole interactions in the DMF + ACN system. These negative values of VE may also arise due to the compact packing in solutions owing to accommodation of molecules of one component into interstitial vacancies of the structural network of other component. The larger negative values of VE for [BMIM][CF3SO3] + ACN than those for [BMIM][CF3SO3] + DMF may be attributed to occupation of voids in [BMIM][CF3SO3] more effectively by the ACN molecules as compared to DMF molecules, thereby reducing the volume of the mixture to a larger extent. However, for [BMIM][CF3SO3] + DMF, the VE vary from negative to positive, and the positive values are found at x1 ≥ 0.53. The positive VE may be ascribed to the disruption of components in the solution, that is, the breaking of molecular association which is held by weaker forces such as dipole−dipole, dipole−induced dipole interactions, van der Waals forces or may be due to the specific geometry of molecule which resists the proximity of constituent molecules. The VE values decrease with an increase in temperature for all the studied systems. The values are

κS = (1/Vm)(∂Vm/∂p)S = 1/ρ(∂ρ /∂p)S

(2)

For the pure components and their binary mixtures, the isentropic compressibilities have been determined from the measured density and speed of sound data of pure components and mixtures using the following Newton−Laplace equation22 κS = 1/(ρ ·u 2)

(3)

The molar isentropic compression, Ks,m is defined as Ks , m = −(∂Vm/∂p)S = Vm. κS = Vm2 /Mm. u 2

(4)

KEs,m

The excess molar isentropic compressibility, of binary solutions have been calculated using the following equation KsE, m = Ks , m − Ksid, m

(5)

where the values for ideal solutions, using the following expression22 G

Kids,m

have been calculated



Article

where Vidm, αid, Eidmand Cpid are the molar volume, isobaric thermal expansivity, molar isobaric expansion, and molar isobaric heat capacity of the ideal mixture, respectively. The method for the calculation of Vidm, αid, Eidm, and Cpid have been reported in our earlier publication.30 The experimental data of molar heat capacities, Cp of [BMIM][CF3SO3], ACN, and DMF have been taken from the literature.51−54 The KES,m for [BMIM][CF3SO3] + ACN and DMF + ACN systems have been found to be negative over the entire range of mole fraction and at all temperatures, whereas for [BMIM][CF3SO3] + DMF, the values are found to be negative up to x1= 0.99 and above this mole fraction these become positive at all temperatures (Figure 4). The negative deviations from ideality may be attributed to stronger interactions in the IL−solvent/ solvent−solvent system, thereby reducing the volume of mixture to a larger extent. The KES,m of [BMIM][CF3SO3] + ACN are more negative than therefore [BMIM][CF3SO3] + DMF and DMF + ACN which may be ascribed to the stronger force of attraction between the IL and ACN as ACN molecules occupy voids in IL more effectively than DMF. For the system DMF + ACN, the smaller magnitude of KES,m suggest the weaker interaction in the system. The positive value of KES,m above x1 = 0.99 in case of [BMIM][CF3SO3] + DMF may be due to weakening of molecular association which are held by weaker forces either by van der Waals forces or by dipole−dipole or dipole−induced dipole interactions. The similar trend of variation has been observed for VE values in the case of [BMIM][CF3SO3] + DMF system; that is, the VE values also change from negative VE to positive (above x1= 0.53). 3.1.4. Viscosity Deviations. Viscosity deviations, Δη for the binary mixtures [BMIM][CF3SO3] + ACN, [BMIM][CF3SO3] + DMF and DMF + ACN have been calculated from the experimental values of η of pure and binary mixtures using the following expression N

Δη = η −

∑ xiηi i=1

where ηi is the dynamic viscosity of pure component i, η is the dynamic viscosity of binary mixtures, and xi is the mole fraction of the pure component i. The Δη values for the studied binary mixtures have been reported in Table S4 (Supporting Information) and graphs between Δη and mole fraction, x1 of IL/DMF have been plotted in Figure 5a−c. The Δη values have been found to be negative for [BMIM][CF3SO3] + ACN and [BMIM][CF3SO3] + DMF, whereas they are positive for the DMF + ACN system at all compositions and temperatures, and these values increase with an increase in temperature. The deviations in viscosity may be explained by considering two factors: (a) the difference in size and shape of the component molecules and (b) specific interactions between unlike molecules.55 The negative values of Δη for [BMIM][CF3SO3] + ACN and [BMIM][CF3SO3] + DMF reveal the strong ion−dipole interactions between the IL and solvent molecules present in the systems. In addition, it may be due to the optimum accommodation of solvent molecules into the interstitial vacancies of the structural network of IL molecules. On the other hand, the positive values of Δη for DMF + ACN system may be due to weaker dipole−dipole, dipole− induced dipole interactions, and van der Waals forces in the system. This indicates that specific forces are not responsible for the viscosity deviation in the system. In the case of [BMIM][CF3SO3] + ACN, the values of Δη are relatively more negative

Figure 6. Excess Gibbs free energies of activation (a) [BMIM][CF3SO3] + ACN, (b) [BMIM][CF3SO3] + DMF, (c) DMF + ACN as a function of mole fraction at different temperatures: black ■, 298.15 K; red ●, 303.15 K; green ▲, 308.15 K; blue ▼, 313.15 K; aqua ◆, 318.15 K and purple ◀, 323.15 K.

Ksid, m

= x1Ks ,1 + x 2Ks ,2

(7)

ÄÅ ÉÑ ÅÅ x (E )2 Ñ x 2(Em ,2)2 (Emid)2 ÑÑÑ ÅÅ 1 m ,1 ÑÑ + T ÅÅÅ + + id ÅÅ Cp1 Cp2 Cp ÑÑÑÑ ÅÇ Ö (6)

H



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Table 6. Coefficients of Redlich−Kister Equation for Excess Molar Volumes, VE/m3·mol−1, Excess Molar Isentropic Compressibilities KEs.m/m3·mol−1·Pa−1, Viscosity Deviations Δη/mPa·s and their Standard Deviations (σ) at Temperature T = (298.15 to 323.15) K for the Binary Mixtures [BMIM][CF3SO3] (1) + ACN (2), [BMIM][CF3SO3] (1) + DMF (2), and DMF (1) + ACN (2) Systems at Pressure P = 0.1 MPa T/K

A0

VE

298.15 303.15 308.15 313.15 318.15 323.15

−6.214 −6.509 −6.754 −7.037 −7.327 −7.675

VE

298.15 303.15 308.15 313.15 318.15 323.15

−0.350 −0.499 −0.621 −0.737 −0.874 −0.968

VE

298.15 303.15 308.15 313.15 318.15 323.15

−1.084 −0.503 −0.348 −0.317 −0.936 −0.253

KEs,m

298.15 303.15 308.15 313.15 318.15 323.15

−117.826 −124.150 −130.751 −137.534 −144.831 −152.350

KEs,m

298.15 303.15 308.15 313.15 318.15 323.15

−30.962 −32.031 −33.128 −34.241 −35.377 −36.556

KEs,m

298.15 303.15 308.15 313.15 318.15 323.15

−29.570 −31.673 −33.890 −36.229 −38.719 −41.326

Δη

298.15 303.15 308.15 313.15 318.15 323.15

−117.822 −92.617 −70.277 −56.074 −44.848 −36.348

Δη

298.15 303.15 308.15 313.15 318.15 323.15

−114.226 −89.642 −67.717 −53.884 −42.844 −34.698

Δη

298.15 303.15

0.112 0.264

A1

A2

[BMIM][CF3SO3] + ACN 2.414 0.1980 2.048 0.2938 2.143 −0.3361 2.067 −0.5704 2.432 −1.2844 2.421 −1.6616 [BMIM][CF3SO3] + DMF 4.238 1.805 4.099 1.758 3.890 1.911 3.791 1.544 3.673 1.474 3.611 0.975 DMF + ACN 0.872 0.002 0.396 −0.028 0.243 −0.030 0.236 −0.058 0.693 −0.218 0.152 −0.061 [BMIM][CF3SO3] + ACN −0.052 0.032 −0.073 0.055 −0.074 0.050 0.111 −0.059 −0.070 0.038 −0.071 0.026 [BMIM][CF3SO3] + DMF 0.021 0.004 −0.005 0.027 −0.024 0.034 −0.020 0.032 −0.029 0.035 −0.024 0.026 DMF + ACN 0.032 −0.022 0.008 −0.017 −0.033 −0.009 −0.045 −0.009 −0.090 0.001 −0.123 0.007 [BMIM][CF3SO3] + ACN 74.053 31.398 59.589 21.607 52.886 18.111 44.299 13.229 38.485 10.205 32.826 7.466 [BMIM][CF3SO3] + DMF 68.987 70.600 54.185 52.605 43.416 41.913 34.828 32.445 28.576 25.399 23.626 20.639 DMF + ACN −0.058 0.053 −0.120 0.167 I

A3

0.001 −0.008 0.053 −0.003 −0.020 0.068

0.032 0.038

B1

σ

0.8076 0.8349 0.8129 0.8061 0.7676 0.7571

0.024 0.025 0.026 0.025 0.030 0.036

0.730 0.738 0.791 0.763 0.765 0.721

0.014 0.012 0.012 0.016 0.024 0.034

−0.140 −0.617 −0.745 −0.777 −0.363 −0.836

0.006 0.008 0.010 0.007 0.009 0.009

0.658 0.659 0.659 0.658 0.659 0.659

0.001 0.001 0.001 0.001 0.001 0.001

0.494 0.495 0.494 0.493 0.492 0.491

0.0003 0.0003 0.0004 0.0004 0.0004 0.0004

0.242 0.245 0.248 0.250 0.252 0.254

0.001 0.001 0.002 0.002 0.002 0.002

−1.008 −1.007 −1.067 −1.079 −1.113 −1.129

0.704 0.623 0.479 0.423 0.372 0.378

−0.895 −0.881 −0.859 −0.839 −0.824 −0.806

0.745 0.519 0.425 0.312 0.236 0.188

−0.008 1.274

0.001 0.001



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Table 6. continued T/K

A0

A1

A2

A3

B1

σ

0.057 0.095 0.198 0.200

−0.003 −0.000 0.022 0.007

−0.364 0.085 0.916 0.726

0.001 0.001 0.001 0.001

DMF + ACN 308.15 313.15 318.15 323.15

−0.029 −0.060 −0.104 −0.089

0.076 0.136 0.249 0.900

Table 7. Interactional Parameters and Standard Deviations (σ) for Grunberg−Nissan (G−N), G12, Hind−Ubbelohde (H−U), H12, Katti−Chaudhary (K−C), Wvis/RT, Mc Allister(A12 and A21), Arrhenius (Ar), and Kendall−Monroe (K−M) at Temperatures T = (298.15 to 323.15) K for Binary Mixtures [BMIM][CF3SO3](1) + ACN(2), [BMIM][CF3SO3](1) + DMF(2), and DMF(1) + ACN(2) at Pressure P = 0.1 MPa G−N T/K

H−U σ

G12

H12

298.15 303.15 308.15 313.15 318.15 323.15

3.33 3.26 3.34 3.32 3.32 3.32

1.09 0.95 0.80 0.70 0.61 0.54

−21.42 −16.25 −10.38 −7.54 −5.16 −3.54

298.15 303.15 308.15 313.15 318.15 323.15

2.55 2.45 2.48 2.42 2.39 2.35

0.86 0.63 0.57 0.44 0.36 0.30

−6.92 −4.75 −1.20 −0.13 0.86 1.47

298.15 303.15 308.15 313.15 318.15 323.15

0.62 0.63 0.65 0.67 0.69 0.72

0.004 0.01 0.01 0.01 0.01 0.01

0.638 0.613 0.589 0.567 0.548 0.530

K−C ∑

Wvis/RT

hN ΔS* yz i ΔH * zz expjjj − V T { k RT

Ar

K−M

A12

A21

σ

σ

σ

0.234 0.232 0.230 0.229 0.227 0.225

0.328 0.323 0.320 0.317 0.314 0.311

0.43 0.39 0.33 0.29 0.23 0.17

3.21 2.63 2.30 1.97 1.71 1.51

1.98 1.50 0.89 0.62 0.39 0.24

0.212 0.210 0.208 0.206 0.205 0.203

0.306 0.304 0.301 0.297 0.295 0.292

0.18 0.16 0.13 0.11 0.08 0.05

3.80 3.03 2.60 2.17 1.85 1.59

1.59 1.18 0.91 0.68 0.52 0.41

0.448 0.448 0.445 0.442 0.437 0.435

0.491 0.487 0.485 0.484 0.478 0.475

0.006 0.005 0.003 0.003 0.002 0.001

0.03 0.03 0.02 0.02 0.02 0.02

0.02 0.02 0.01 0.02 0.02 0.01

ÄÅ É ÅÅ ij N yzÑÑÑÑ ÅÅ E j z * j z Å ΔG = RT ÅÅln ηV − jj∑ xi ln ηiVi zzÑÑÑÑ j zÑÑ ÅÅ ÅÇ k i=1 {ÑÖ

(10)

where ηi, Vi, and xi are dynamic viscosity, molar volume, and mole fraction of pure components, respectively, while η and V are dynamic viscosity and molar volume of the binary system, respectively. T and R are the absolute temperature and the universal gas constant, respectively. For the studied binary mixtures, the values of Gibbs free energy of activation, ΔG* have been reported in Table 5, and the values activation parameters ΔH*, ΔS*, and ΔG*E for all the systems are reported in Table S5 and S6 (Supporting Information); and the plots of ΔG*E are depicted in Figure 6a−c. The values of ΔG* are found to be negative for all the studied systems, whereas the excess Gibbs free energy of activation was found to be positive at all temperatures and over the entire mole fraction range suggesting that there exist strong interactions between the solute and the solvent molecules. The ΔS* values show the effect of reorganization of solvents in the bulk of solution from the ground state to transition state for all the binary mixtures. 3.1.6. Application of Redlich−Kister Polynomial Equation. The experimental VE, KES,m, and Δη data have been fitted to the following Redlich−Kister polynomial equation,57

(8)

Herein, the enthalpy of activation, ΔH* and entropy of activation, ΔS* for the viscous flow for each studied binary system have been calculated using the following Eyring equation,47 η=

σ

[BMIM][CF3SO3] + ACN 1.85 4.25 1.32 1.48 4.18 1.13 0.91 4.25 0.95 0.69 4.22 0.82 0.49 4.21 0.71 0.36 4.20 0.62 [BMIM][CF3SO3] + DMF 1.37 3.09 0.83 1.01 2.98 0.60 0.89 3.01 0.54 0.69 2.95 0.42 0.57 2.67 0.29 0.48 2.87 0.29 DMF + ACN 0.004 0.668 0.01 0.01 0.680 0.004 0.01 0.696 0.01 0.01 0.712 0.01 0.01 0.732 0.01 0.01 0.753 0.01

than those for [BMIM][CF3SO3] + DMF, and this may be due to higher degree of association in the [BMIM][CF3SO3] + ACN system. 3.1.5. Gibbs and Excess Free Energies of Activation. The values of activation parameters can be explained in terms of the relative effect of solute and solvent on ground and transition states, respectively. The difference between these two states is the activation energy required for the molecules to overcome the attractive forces between molecules. The Gibbs free energy of activation, ΔG*, has been calculated using the standard thermodynamic equation, ΔG* = ΔH * − T ΔS*

McAllister

(9)

where η, h, N, and V are the viscosity of studied binary mixtures, Planck’s constant, Avogadro constant, and molar volume, respectively. On the basis of the theory of absolute reaction rate, the excess Gibbs free energy of activation for viscous flow ΔG*E can be evaluated by using the following expression56

m

Y = x1(1 − x1) J

∑i = 0 Ai (2x1 − 1)i n

1 + ∑ j = 1 Bj (2x1 − 1) j

(11)



Article

where Y = VE or KES,m or Δη. The Ai and Bj are adjustable parameters and x1is the mole fraction of [BMIM][CF3SO3]/ DMF; m and n are the degrees of a polynomial. Ai and Bj have been obtained by fitting eq 11 to the experimental data by leastsquares regression method. The optimum numbers of Ai coefficients have been determined from an examination of values of standard deviations. The standard deviation, σ has been calculated using the following equation ÄÅ p ÑÉÑ1/2 ÅÅ ÑÑ Å σ(Y ) = ÅÅÅÅ∑ (Ycal − Yexp)2 /(p − (m + n + 1))ÑÑÑÑ ÑÑ ÅÅ i = 1 ÑÖ ÅÇ

(12)

where p is the number of an experimental data point. The values of the parameters Ai, Bi, and σ have been reported in Table 6. 3.1.7. Viscosity Models. A number of semiempirical models have been used to correlate the experimental viscosities of studied binary mixtures. (i) The empirical cube root formula proposed by Kendall− Monroe is applied to the η of the studied binary systems, [BMIM][CF3SO3] + ACN/DMF and DMF + ACN, 1/3 ηmix = x1η11/3 + x 2η21/3

(13)

where ηmix is the viscosity of the mixtures, η1 and η2 are the viscosities of pure components, while x1 and x2 are the corresponding mole fractions. (ii) The experimental dynamic viscosity data are fitted to a logarithmic relation proposed by Arrhenius: ln η = x1 ln η1 + x 2 ln η2

(14)

where x1, x2, η1, and η2 have the same definition as in eq 7. (iii) Grunberg-Nissan proposed the logarithmic equation relating the viscosity of the liquid mixture and those of its pure components, ln η = x1 ln η1 + x 2 ln η2 + x1x 2G12

(15)

where G12 is the interactional parameter. (iv) The empirical equation suggested by Hind−Ubbelohde is employed for all three studied systems, η = x12η1 + x 22η2 + 2H12x1x 2

(16)

where H12 is an interactional term. (v) Katti−Chaudhary proposed the following equation, ln ηV = x1 ln η1V1 + x 2 ln η2V2 + x1x 2(Wvis/T ) (17)

where Wvis is an interactional term (vi) McAllister proposed the following two-parameter equation which is based on Eyring theory of absolute reaction rates and considers the interactions of both like/unlike components by two-dimensional three-body interactions n

ln ν =

∑

n

xi3

n

ln(νiMi) − ln ∑ xiMi + 3 ∑ ∑

i=1

i=1

Figure 7. Comparison of experimental and calculated dynamic viscosities for (a) [BMIM][CF3SO3] + ACN, (b) [BMIM][CF3SO3] + DMF, (c) DMF + ACN as a function of mole fraction at 298.15 K: black ■, η expt.; red line, η Arhenius; green line, η Kendall-Monroe; blue line, η Katti-Chaudhary; aqua line, η Hind-Ubbelohde; red line, η GrunbergNissan; orange line, η Mc-Allister.

n

xi2xj

ln Aij Mij

i=1 j=1 j≠i

(18)

where Aij is the interaction parameters. The Mij is determined as Mij =

2Mi + Mj 3

studied binary mixtures. The interactional parameters (G12, H12, Wvis, Aij, and Aji) for the studied models along with calculated standard deviations by using eq 15 between ηexpt and ηcal at temperatures (298.15 to 323.15) K are listed in Table 7. The standard deviations were found to be in the range of 1.09 to 0.004 for Grunberg-Nissan, 1.85 to 0.004 for Hind-Ubbelohde,

(19)

where Mi is the molar mass of IL and Mj is the molar mass of the solvent. The above mentioned semiempirical viscosity correlation models have been employed to the dynamic viscosity data of the K



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Table 8. Experimental Excess Molar Volumes, VE(exp), Calculated Excess Molar Volumes, VE(PEP), Interactional Parameter, χ21, Internal, VE(int), Free Volume, VE(fv), Internal Pressure, VE(ip), at Temperature T = (298.15 to 323.15) K and Mole Fraction x1 = 0.2, [BMIM][CF3SO3] (1) + ACN (2), [BMIM][CF3SO3] (1) + DMF (2) and at Mole Fraction x1 = 0.4 DMF (1) + ACN (2) at Pressure P = 0.1 MPa VE(exp)

VE(PEP)

T/K

cm3·mol−1

cm3·mol−1

298.15 303.15 308.15 313.15 318.15 323.15

−2.382 −2.468 −2.559 −2.633 −2.746 −2.869

−2.391 −2.384 −2.482 −2.590 −2.711 −2.351

298.15 303.15 308.15 313.15 318.15 323.15

−0.648 −0.669 −0.690 −0.715 −0.744 −0.760

−0.650 −0.689 −0.729 −0.771 −0.814 −0.859

298.15 303.15 308.15 313.15 318.15 323.15

−0.351 −0.361 −0.375 −0.392 −0.406 −0.421

−0.350 −0.364 −0.380 −0.395 −0.411 −0.429

σa

χ21

VE(int)

VE(fv)

VE(ip)

J·cm−1

cm3·mol−1

cm3·mol−1

cm3·mol−1

−2.190 −2.230 −2.270 −2.290 −2.350 −2.420

−0.705 −0.734 −0.762 −0.792 −0.820 −0.851

0.518 0.494 0.473 0.453 0.426 0.403

−0.919 −0.928 −0.936 −0.947 −0.962 −0.963

−0.239 −0.249 −0.259 −0.268 −0.279 −0.289

0.510 0.509 0.505 0.500 0.498 0.492

−0.160 −0.161 −0.165 −0.172 −0.176 −0.180

−0.101 −0.108 −0.112 −0.117 −0.121 −0.126

−0.087 −0.093 −0.098 −0.103 −0.110 −0.116

[BMIM][CF3SO3] + ACN 0.005 −269.11 0.042 −274.12 0.039 −278.10 0.022 −280.13 0.018 −295.32 0.259 −342.22 [BMIM][CF3SO3] + DMF 0.001 −105.22 0.010 −103.24 0.020 −101.02 0.028 −99.10 0.035 −97.91 0.050 −95.21 DMF + ACN 0.001 −21.22 0.002 −20.80 0.003 −20.61 0.002 −20.83 0.003 −20.54 0.004 −20.41

σ(Y) = [Σi p= 1 (Ycal − Yexp)2/(p − (m + n + 1))]1/2.

a

where xi, Vi*, Vi, Ṽ i, ϕi, Ψi, θi, Si, Pi*, and KT,i are the mole fraction, characteristic volume, molar volume, reduced volume, hard-core volume fraction, molecular contact energy fraction, molecular surface fraction, molecular surface/volume ratio, characteristic pressure, and the isothermal compressibility of pure components, respectively. Ṽ is the reduced volume of the mixtures. The procedure for the calculation of Vi*, Vi, Ṽ i, ϕi, Ψi, θi, Si, Pi*, and kTi are given in our earlier published paper.30 The methods for the calculations of the isobaric thermal expansion coefficient, αi values of pure components [BMIM][CF3SO3], ACN, and DMF are also mentioned in our earlier published paper.30 The data of molar heat capacities, Cp for pure [BMIM][CF3SO3], ACN and DMF have been taken from the literature51−54 and are reported in Table S7 of the Supporting Information. The interactional parameter χ21 is evaluated by fitting the experimental VE(exp) values employing the least-squares method over the whole composition range for each studied binary system at all temperatures and are listed in Table 8. The values of VE(exp) VE(PEP), VE(int), VE(fv), and VE(ip) and σ at x1 = 0.2 for [BMIM][CF3SO3] + ACN and [BMIM][CF3SO3] + DMF systems and at x1 = 0.4 for DMF + ACN system owing to their minimum experimental VE(exp) values, at T = (298.15 to 323.15) K have been reported in Table 8. The experimental and PFP correlated values of VE at x1 ≈ 0.20 are (−2.382, −2.391) cm3·mol−1 with PD ≈ 0.005% for [BMIM][CF3SO3] + ACN and (−0.648, −0.650) cm3·mol−1 with PD ≈ 0.001% for [BMIM][CF3SO3] + DMF; and at x1 ≈ 0.40 the values are (−0.351, −0.350) cm3· mol−1 with PD ≈ 0.001% for DMF + ACN system, respectively at 298.15 K. The experimental and PFP correlated values of VE across the whole mole fraction range at 298.15 K for the [BMIM][CF3SO3] + ACN/DMF and DMF + ACN systems are plotted in Figure 8a−c. The experimental and PFP correlated

1.32 to 0.004 for Katti-Chaudhary, 0.328 to 0.001 for McAllister, 3.80 to 0.02 for Arrhenius, and 1.98 to 0.01 for tthe Kendall− Monroe model, respectively. The comparison of ηexpt and ηcal is plotted across the mole fraction range at 298.15 K and is shown in Figure 7a−c. The Table 7 reveals that the minimum standard deviation has been found in the case of McAllister model for the studied binary mixtures and hence, appears to be a most suitable model for correlating viscosity data. 3.1.8. Application of Prigogine−Flory−Patterson (PFP) Theory. The PFP theory has been applied to analyze and correlate the VE values for ([BMIM][CF3SO3] + ACN/DMF, DMF + ACN) systems at T = (298.15, 303.15, 308.15, 313.15, 318.15, and 323.15) K and at pressure 0.1 MPa. The PFP21,29,30 theory provides a quantitative estimation of different contributions to VE originated from the molecular interaction between the species of different size and shape in binary mixtures having both polar and nonpolar molecules. According to PFP theory, a molecule is considered to be made up of equal segments (isometric portions) in which each segment is capable of interacting with the neighboring site, as every segment is having an intermolecular contact site.22 The three contributions to VE considered are (a) an interactional contribution, VE(int), which is proportional to the only interaction parameter, χ21, (b) a free volume, VE(fv), and (c) internal pressure contribution, VE(ip). The following type of PFP expression has been utilized to compute the VE values in this study.22 E

E

E

V(ip) V(int) V(fv) VE = + + * * * * * * * x1V1 + x 2V 2 x1V1 + x 2V 2 x1V1 + x 2V 2 x1V1 + x 2V 2* =

(Ṽ

1/3

− 1)Ṽ

2/3

−1/3

Ψ2θ1χ21

+

[(4/3)Ṽ − 1]P2* * ̃ ̃ (V − V2)(P1 − P2*)ΨΨ 1 2 + 1 P2*Ψ1 + P1*Ψ2

−1/3 − (V1̃ − V2̃ )2 ((14/9)Ṽ − 1)ΨΨ 1 2 −1/3 [(4/3)Ṽ − 1]Ṽ

(20) L



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contribution in both of the IL + solvent systems (Table 8). The internal pressure, VE(ip), is positive for the system [BMIM][CF3SO3] + ACN/DMF and negative for DMF + ACN systems at all the temperatures, and the values decreases with increasing temperature. 3.2. Ternary Systems. 3.2.1. Experimental and Correlation of Thermophysical Properties. For the ternary mixture, [BMIM][CF3SO3] + ACN + DMF, the densities, speeds of sound, and dynamic viscosities have been reported in Tables 9−11 in the temperature range (298.15 to 323.15) K and at pressure, 0.1 MPa. It has been found that the density, speed of sound, and viscosity values of the studied ternary system increase with an increase in the mole fraction x1 of IL and decrease with increase in temperature, similar to the trend for binary mixtures. The excess molar volumes, excess molar isentropic compressibilities, and the viscosity deviations at temperatures (298.15 to 323.15) K and at 0.1 MPa pressure for the studied ternary mixture have been calculated by using same procedure as reported in our earlier published papers.29,30,56,58,59 The values of VE, KES,m and Δη have been reported in Tables S8−S10 of Supporting Information, and graphs have been plotted in Figures 9−11. The VE values have found to be negative up to x1 = 0.6369 and above this point, the values become positive and show a decreasing trend with an increasing temperature. This trend indicates that the ternary mixtures are not an ideal mixture in terms of binary components. The negative values of VE may be attributed to the compact packing of ACN/DMF in the interstices of [BMIM][CF3SO3], and the ion−dipole interactions between cation of [BMIM][CF3SO3] and ACN/DMF molecule dipoles. Similarly, the values of KES,m are also found to be negative in studied range of mole fractions and temperatures, and these values decrease upon an increase in temperature, whereas the values of Δη for the studied ternary system have been found to be negative in the studied composition range and temperatures and increase with an increase in temperature. On the basis of trends of variations of evaluated parameters, it may be concluded that the addition of the third component modifies the nature and degrees of molecular interactions in binary systems. The VE, KES,m, and Δη values of the ternary system have been fitted to Redlich−Kister polynomial equation51,57of the following type, Y123 = Y12 + Y13 + Y23 + x1x 2x3[A + B(x1 − x 2) + C(x1 − x3) + D(x 2 − x3) + E(x1 − x 2)2 ......] (21) E

or KES,m or Δη for the ternary system and

where Y123 represents V A, B, C, D, and E are the adjustable parameters. The Y12, Y13, and Y23 are the contributions of the excess/deviation properties of the constituent binary mixtures evaluated by the Redlich−Kister equation (eq 11). The adjustable coefficients and standard deviations for the Redlich−Kister equation obtained by the least-squares regression method have been reported in Table 12. The minimum VE values for the ternary system have been found at x1 = 0.33, x2 = 0.52 as −1.30 cm3 mol−1 at 298.15 K. The corresponding correlated VE value with the Redlich−Kister equation is found to be −1.30 cm3 mol−1 with percent deviation −0.02%. Similarly, the minimum KES,m value is found to be at x1 = 0.23, x2 = 0.66 as −29.25 m3·mol−1·Pa−1 at 298.15 K. The corresponding correlated KES,m value is found to be as −29.27 m3·mol−1·Pa−1 with percent deviation 0.07%. The minimum Δη value has been found to be at x1 = 0.61, x2 = 0.17 as

Figure 8. ■, Experimental excess molar volumes; solid line, calculated excess molar volume from the PFP theory; dashed line, interactional contribution; dotted line, free volume contribution; dashed dotted line, internal pressure contribution; for (a) [BMIM][CF3SO3] + ACN, (b) [BMIM][CF3SO3] + DMF, (c) DMF + ACN as a function of mole fraction x1 at T = 298.15 K.

values of VE are very close to each other. The negative value of the cross-interactional parameter, χ21 for studied binary systems shows the specifically strong intermolecular interaction between the IL molecule and the solvents molecule. The negative values of free volume, VE(fv) and their decreasing trend with temperature infer a more distinct thermal effect than that of interactional M



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Table 9. Densities, ρ/g·cm−3, at Temperature T = (298.15 to 323.15) K and Mole Fraction, x1 for the Ternary Mixture [BMIM][CF3SO3](1) + ACN (2) + DMF (3) at Pressure P = 0.1 MPaa x1

x2

T/K = 298.15

T/K = 303.15

T/K = 308.15

T/K = 313.15

T/K = 318.15

T/K = 323.15

0.0301 0.0687 0.1000 0.1345 0.1613 0.1948 0.2336 0.2747 0.3079 0.3344 0.3634 0.3953 0.4305 0.4618 0.4960 0.5316 0.5682 0.6098 0.6369 0.6778 0.7035 0.7318 0.7659 0.7913

0.9323 0.8807 0.8406 0.7959 0.7595 0.7145 0.6624 0.6065 0.5593 0.5196 0.4760 0.4282 0.3754 0.3267 0.2734 0.2476 0.2221 0.1706 0.1591 0.1324 0.1252 0.1042 0.0894 0.0731

0.844244 0.907836 0.952400 0.995374 1.024514 1.056546 1.088188 1.116240 1.135389 1.148816 1.161862 1.174506 1.186763 1.196445 1.205976 1.214983 1.223500 1.232432 1.237932 1.245756 1.250371 1.255151 1.260432 1.263944

0.838992 0.902743 0.947421 0.990507 1.019725 1.051846 1.083576 1.111710 1.130914 1.144384 1.157467 1.170152 1.182448 1.192157 1.201720 1.210753 1.219298 1.228257 1.233777 1.241626 1.246259 1.251058 1.256361 1.259891

0.833699 0.897630 0.942429 0.985627 1.014917 1.047114 1.078919 1.107116 1.126366 1.139866 1.152985 1.165702 1.178035 1.187781 1.197380 1.206457 1.215045 1.224060 1.229613 1.237519 1.242183 1.247017 1.252362 1.255919

0.828396 0.892509 0.937431 0.980745 1.010111 1.042391 1.074276 1.102544 1.121842 1.135378 1.148530 1.161286 1.173658 1.183434 1.193073 1.202186 1.210819 1.219877 1.225467 1.233417 1.238115 1.242981 1.248359 1.251941

0.823060 0.887319 0.932358 0.975797 1.005258 1.037649 1.069653 1.098037 1.117417 1.131013 1.144223 1.157033 1.169454 1.179266 1.188930 1.198063 1.206702 1.215761 1.221342 1.229277 1.233960 1.238810 1.244167 1.247733

0.817708 0.882150 0.927318 0.970893 1.000444 1.032941 1.065056 1.093540 1.112991 1.126638 1.139897 1.152757 1.165223 1.175067 1.184762 1.193917 1.202570 1.211634 1.217209 1.225130 1.229792 1.234616 1.239934 1.243460

a Standard uncertainty u: u(T) = 0.01 K, u(P) = 10 kPa, combined expanded uncertainty Uc: Uc(x) = 2 × 10−4, Uc(ρ) = 5 × 10−4 g·cm−3 (level of confidence = 0.95, k = 2).

Table 10. Speeds of Sound, u/m·s−1, at Temperature T = (298.15 to 323.15) K and Mole Fraction, x1 for the Ternary Mixture [BMIM][CF3SO3](1) + ACN(2) + DMF (3) at Pressure P = 0.1 MPaa x1

x2

T/K = 298.15

T/K = 303.15

T/K = 308.15

T/K = 313.15

T/K = 318.15

T/K = 323.15

0.0301 0.0687 0.1000 0.1345 0.1613 0.1948 0.2336 0.2747 0.3079 0.3344 0.3634 0.3953 0.4305 0.4618 0.4960 0.5316 0.5682 0.6098 0.6369 0.6778 0.7035 0.7318 0.7659 0.7913

0.9323 0.8807 0.8406 0.7959 0.7595 0.7145 0.6624 0.6065 0.5593 0.5196 0.4760 0.4282 0.3754 0.3267 0.2734 0.2476 0.2221 0.1706 0.1591 0.1324 0.1252 0.1042 0.0894 0.0731

1292.71 1301.89 1309.46 1317.84 1324.26 1332.12 1340.87 1349.62 1356.19 1361.11 1366.12 1371.16 1376.15 1380.08 1383.84 1387.20 1390.11 1392.83 1394.33 1396.30 1397.42 1398.61 1400.10 1401.33

1273.47 1283.54 1291.80 1300.90 1307.85 1316.33 1325.72 1335.06 1342.02 1347.21 1352.47 1357.75 1362.94 1367.01 1370.89 1374.36 1377.37 1380.24 1381.88 1384.12 1385.49 1387.03 1389.07 1390.82

1254.58 1265.63 1274.60 1284.41 1291.84 1300.86 1310.80 1320.62 1327.92 1333.35 1338.83 1344.32 1349.71 1353.94 1357.98 1361.60 1364.77 1367.82 1369.59 1372.07 1373.60 1375.35 1377.70 1379.71

1235.67 1247.76 1257.46 1267.99 1275.92 1285.50 1295.98 1306.29 1313.92 1319.57 1325.28 1330.98 1336.57 1340.96 1345.16 1348.94 1352.27 1355.52 1357.43 1360.15 1361.86 1363.83 1366.48 1368.75

1216.86 1229.97 1240.41 1251.67 1260.10 1270.23 1281.26 1292.07 1300.03 1305.91 1311.84 1317.75 1323.55 1328.10 1332.45 1336.38 1339.87 1343.31 1345.36 1348.32 1350.20 1352.40 1355.36 1357.91

1198.07 1212.27 1223.48 1235.48 1244.41 1255.09 1266.66 1277.94 1286.23 1292.34 1298.48 1304.60 1310.60 1315.32 1319.84 1323.93 1327.59 1331.23 1333.42 1336.60 1338.64 1341.01 1344.21 1346.95

a Standard uncertainty u: u(T) = 0.01 K, u(P) = 10 kPa, combined expanded uncertainty Uc: Uc(x) = 2 × 10−4, Uc(u) = 0.5 m·s−1 (level of confidence = 0.95, k = 2).

−30.07 mPa·s at 298.15 K. The corresponding correlated Δη value has been found to be −30.01 mPa·s with a percent

deviation of 0.20%. The standard deviations have been found to be 0.002 for the VE, 0.136 to 0.075 for KES,m and 0.002 to 0.001 for N



Article

Table 11. Viscosity, η/mPa·s at Temperature T = (298.15 to 323.15) K and Mole Fraction, x1 for the Ternary Mixture [BMIM][CF3SO3](1) + ACN(2) + DMF (3) at Pressure P = 0.1 MPaa x1

x2

T/K = 298.15

T/K = 303.15

T/K = 308.15

T/K = 313.15

T/K = 318.15

T/K = 323.15

0.0301 0.0687 0.1000 0.1345 0.1613 0.1948 0.2336 0.2747 0.3079 0.3344 0.3634 0.3953 0.4305 0.4618 0.4960 0.5316 0.5682 0.6098 0.6369 0.6778 0.7035 0.7318 0.7659 0.7913

0.9323 0.8807 0.8406 0.7959 0.7595 0.7145 0.6624 0.6065 0.5593 0.5196 0.4760 0.4282 0.3754 0.3267 0.2734 0.2476 0.2221 0.1706 0.1591 0.1324 0.1252 0.1042 0.0894 0.0731

0.50 0.53 0.69 0.99 1.32 1.84 2.59 3.58 4.51 5.35 6.38 7.63 9.18 10.72 12.59 14.75 17.24 20.40 22.69 26.50 29.12 32.24 36.35 39.67

0.47 0.52 0.67 0.95 1.24 1.71 2.38 3.24 4.05 4.78 5.66 6.73 8.04 9.33 10.89 12.69 14.74 17.33 19.19 22.26 24.37 26.86 30.13 32.77

0.45 0.51 0.65 0.91 1.17 1.58 2.17 2.93 3.64 4.28 5.05 5.97 7.10 8.21 9.53 11.04 12.75 14.89 16.41 18.90 20.59 22.58 25.16 27.22

0.43 0.49 0.63 0.86 1.10 1.48 2.00 2.68 3.31 3.87 4.53 5.34 6.32 7.27 8.40 9.68 11.12 12.91 14.18 16.24 17.63 19.26 21.36 23.03

0.41 0.48 0.61 0.82 1.04 1.38 1.85 2.46 3.02 3.51 4.10 4.80 5.66 6.48 7.46 8.56 9.78 11.29 12.35 14.07 15.22 16.56 18.28 19.64

0.39 0.47 0.60 0.80 1.00 1.30 1.72 2.25 2.75 3.18 3.70 4.32 5.06 5.78 6.63 7.59 8.64 9.94 10.85 12.30 13.27 14.40 15.83 16.95

Standard uncertainty u: u(T) = 0.01 K, u(P) = 10 kPa, combined expanded uncertainty Uc: Uc(x) = 2 × 10−4, Uc(η) < 1 mPa·s = 0.20 mPa·s, Uc(η) (1−10 mPa·s) = 0.60 mPa·s, Uc(η) (11−50 mPa·s) = 0.80 mPa·s (level of confidence = 0.95, k = 2).

a

Figure 9. 3D mesh plot for excess molar volumes of [BMIM][CF3SO3] + ACN + DMF as a function of mole fractions (x1) and (x2) at T = 298.15 K.

Figure 10. 3D mesh plot for excess molar isentropic compressibilities of [BMIM][CF3SO3] + ACN + DMF as a function of mole fractions (x1) and (x2) at T = 298.15 K.

Δη. Thus, the correlated values of VE, KES,m, and Δη for the studied ternary system show good agreement with experimental data.

decreasing trend with an increase in temperature. However, for the binary system, [BMIM][CF3SO3] + DMF and the ternary system, [BMIM][CF3SO3] + ACN + DMF, the VE found to be negative at lower values of x1 and on higher concentration it becomes positive, and with an increase in temperature the VE decrease. Furthermore, the KES,m have also been found to be negative at all compositions and temperatures, and they decrease with an increase in temperature for each binary system, whereas

4. CONCLUSION The VE for the studied binary systems, [BMIM][CF3SO3] + ACN and DMF + ACN have been found to be negative at all studied compositions, temperatures, and pressure which show a O



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and increase with an increase in temperature. The ΔG* is found to be negative at all compositions and temperatures and becomes more negative as the temperature increases, whereas the ΔG*E values have been found to be positive across the mole fraction range and at all temperatures and the values increase with temperature for all the studied binary mixtures. The excess/deviation properties illustrate the effect of composition and temperature on the interactions in the studied binary/ternary system. The VE, KES,m and Δη for each binary and the ternary system have been fitted to Redlich−Kister polynomial equation. We have employed semiempirical models, Arrhenius, Kendall−Monroe, Grunberg−Nissan, Hind−Ubbelohde, Katti−Chaudhary, and McAllister for the correlation of dynamic viscosity data and to evaluate some interactional parameters of the studied binary mixtures. The comparative plots of dynamic viscosity versus mole fraction exhibit a good agreement between the experimental and correlated values of η. The Prigogine−Flory−Patterson theory has been applied to correlate the excess molar volumes of [BMIM][CF3SO3] + ACN/DMF and DMF + ACN binary mixtures. The PFP theory is found to be suitable for correlating the VE of [BMIM][CF3SO3] + ACN/DMF and DMF + ACN systems.

Figure 11. 3D mesh plot for viscosity deviation of [BMIM][CF3SO3] + ACN + DMF as a function of mole fractions (x1) and (x2) at T = 298.15 K.

■

for the ternary system, the KES,m values are also found to be negative in the studied range of mole fractions and temperatures and these values decrease with an increase in temperature. Similarly, the Δη have also been found to be negative for the [BMIM][CF3SO3] + ACN, [BMIM][CF3SO3] + DMF, and [BMIM][CF3SO3] + ACN + DMF system and the values increase with an increase in temperature, but for the system, DMF + ACN, the Δη are found to be positive at all compositions and temperatures and increase with an increase in temperature. However, for the ternary mixture the values of Δη are found to be negative in the studied composition range and temperatures

ASSOCIATED CONTENT

S Supporting Information *

The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.jced.8b00176. Comparison table of experimental and literature data along with percent deviations; calculated values of excess molar volumes, excess molar isentropic compressibilities, viscosity deviations, Gibbs free energy of activation, excess Gibbs free energy of activation as functions of mole fraction and temperature for the binary systems; calculated values of excess molar volumes, excess molar

Table 12. Coefficient of the Redlich−Kister Equation for Excess Molar Volumes, VE/cm3·mol−1 Excess Molar Isentropic Compressibilities, 1015·KEs,m/m3·mol−1·Pa−1, Viscosity Deviations, Δη/mPa·s, and the standard deviations (σ) at Temperature T = (298.15 to 323.15) K for the Ternary Mixture [BMIM][CF3SO3](1) + ACN(2) + DMF(3) at Pressure P = 0.1 MPa T/K = 298.15

T/K = 303.15

VE

A B C D E ∑

−313.87 69.13 −719.62 −141.50 243.13 0.002

−249.09 −420.99 −382.38 −704.92 286.99 0.002

KEs,m

A B C D E ∑

−1064.62 −844.74 4033.10 4999.60 −577.09 0.018

−13212.14 24481.26 −3643.40 19238.54 −8554.77 0.075

Δη

A B C D E ∑

−61.65 −619.67 1138.44 28.85 −322.46 0.002

641.71 466.33 −1070.55 −208.09 169.21 0.001

T/K = 308.15

T/K = 313.15

[BMIM][CF3SO3] + ACN + DMF −280.50 −178.15 −302.67 −451.05 −425.22 −538.93 −550.04 −780.97 278.52 351.29 0.002 0.002 [BMIM][CF3SO3] + ACN + DMF 8577.14 4298.43 −34085.51 1110.05 67770.60 −2691.73 131725.87 −5247.68 27054.69 901.46 0.136 0.016 [BMIM][CF3SO3] + ACN + DMF 428.56 122.12 −110.18 −735.84 −323.42 774.95 −275.23 −626.94 45.78 −147.31 0.001 0.001 P

T/K = 318.15

T/K = 323.15

−234.12 −397.97 −499.18 −673.04 330.12 0.002

−220.47 −400.88 −503.18 −672.38 354.18 0.002

5096.18 −2054.35 −2033.78 −2117.45 2385.00 0.015

6498.08 −4094.26 −818.55 −12223.16 2251.23 0.018

215.59 30.44 −128.95 −125.93 −55.21 0.001

129.71 −255.42 274.82 −202.77 −152.71 0.002



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isentropic compressibilities, and viscosity deviations as functions of mole fraction and temperature for the ternary system (PDF)

AUTHOR INFORMATION

Corresponding Author

*E-mail: rz1@rediffmail.com. Funding

Financial support from the UGC (Major Research Project) [F.No. 41-240/2012 (SR)], UGC (SAP DRS-II) and (DST PURSE, FIST) schemes are acknowledged. Notes

The authors declare no competing financial interest.

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ACKNOWLEDGMENTS The authors are thankful to the Chairman, Department of Chemistry, A.M.U., Aligarh, for providing the necessary facility for the compilation of this work.

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