Densities and Viscosities of the Binary and Ternary Aqueous Solutions

Article pubs.acs.org/jced

Densities and Viscosities of the Binary and Ternary Aqueous Solutions of Pyrrolidone-Based Ionic Liquids at Different Temperatures and Atmospheric Pressure Zhen-Yu Yang, Yu-Feng Hu,* Zhi-Xin Wang,* Yu Sun, Chen-Chen Jiang, and Yu-Fei Chen State Key Laboratory of Heavy Oil Processing and High Pressure Fluid Phase Behavior & Property Research Laboratory, China University of Petroleum, Beijing 102249, China ABSTRACT: The densities and viscosities of the ternary solutions [NCyP][p-TSA] (1-cyclohexyl-2-pyrrolidinone p-toluenesulfonate) + [NCyP][BSA] (1-cyclohexyl-2-pyrrolidinone benzenesulfonate) + H2O and [NMP][p-TSA] (1-methyl-2-pyrrolidinone p-toluenesulfonate) + [NMP][BSA] (1-methyl-2pyrrolidinone benzenesulfonate) + H2O and their binary subsystems at (298.15, 303.15, and 308.15) K and atmospheric pressure were measured. The simple equations developed for mixed electrolyte solutions have been invoked to predict the densities and viscosities for these ionic liquid solutions. The predicted values agree well with the experimental data, indicating that the examined properties of the ternary aqueous solutions of pyrrolidone-based ILs can be well predicted from the corresponding data of their binary subsystems of equal ionic strength using simple equations.

1. INTRODUCTION Ionic liquids (ILs) are formed entirely by ions and have low melting points (≤ 373.15 K).1,2 ILs have many remarkable properties such as low vapor pressure,3 high thermal stability,4,5 nonflammability,6 wide electrochemical window,7 enhanced solvent quality,8 and tunable nature.9 Therefore, ILs have gathered a lot of attention for potential applications in various fields10−16 such as food industry,10 extraction processes,11 nuclear science,12 biotechnology,13 etc. Designing an industrial process requires knowing a series of physical properties of the involved materials. The physical properties of ILs are remarkably affected by the existence of water.17−19 Furthermore, applications of ILs in the fields of colloid and surfactant,20,21 extraction processes,11 and biotechnology13 require investigating the properties of aqueous solutions of ILs. Therefore, the physical properties of aqueous solutions of ILs have received a lot of attentions.22−28 For example, Gόmez et al.29 have reported the densities and viscosities of binary aqueous solutions of 1-hexyl-3-methylimidazolium chloride ([C6mim]Cl + H2O) and 1-methyl-3-octylimidazolium chloride ([C8mim]Cl + H2O) over the whole composition range in the (298.15 to 343.15) K temperature range. Zhang et al.,30 Ries et al.,31 and Ge et al.32 have measured the densities, viscosities, and conductivities of the systems 1-n-alkyl-3-methylimidazolium tetrafluoroborate/trifluoromethanesulfonate + H2O as a function of temperature. Up to now a lot of novel ILs including pyrrolidone-based ILs have been synthesized, which have potential applications in fuel cell devices, thermal transfer fluids, and acid-catalyzed systems.33−36 However, the physical properties of aqueous solutions of these ILs are rarely reported. It is difficult to measure the properties for aqueous solutions of all kinds of IL mixtures. Therefore, it is essential is to predict/ © 2014 American Chemical Society

estimate the properties of aqueous solutions of IL mixtures in terms of the properties of aqueous solutions of a single IL. In the case of electrolyte solutions, such predictions/estimations can be achieved simply, for example, by invoking the equations of Patwardhan and Kumar37,38 and the semi-ideal solution theory.39−42 It is notable that the semi-ideal solution theory39−42 has been shown to work well for the properties of aqueous solutions of nonelectrolyte mixtures,39,43 of electrolyte mixtures,41 and of (electrolyte + nonelectrolyte) mixtures.44 More recently, our group has successfully extended some of the abovementioned equations to mixed solutions of ILs.27,28,45 In this study, the densities and viscosities of aqueous solutions of pyrrolidone-based ILs were measured at different temperatures and atmospheric pressure. The examined solutions include the ternary solutions [NCyP][p-TSA] + [NCyP][BSA] + H2O and [NMP][p-TSA] + [NMP][BSA] + H2O and the binary subsystems [NCyP][p-TSA] + H2O, [NCyP][BSA] + H2O, [NMP][p-TSA] + H2O, and [NMP][BSA] + H2O. Furthermore, all the measured data were used to test the predictability of the above-mentioned equations.

2. EXPERIMENTAL SECTION 2.1. Chemicals. NMP, NCyP, p-TSA·H2O, BSA, acetone, and toluene were supplied by Shanghai Jingchun Chemical Co., Ltd., Shanghai, China. All materials were of analytical grade and were used without further purification. Deionized water was used in all experiments. Received: February 1, 2013 Accepted: February 21, 2014 Published: March 5, 2014 1094

dx.doi.org/10.1021/je4002009 | J. Chem. Eng. Data 2014, 59, 1094−1104

Journal of Chemical & Engineering Data

Article

Table 1. Experimental Densities of the Binary Systems [NCyP][p-TSA] + H2O, [NCyP][BSA] + H2O, [NMP][p-TSA] + H2O, and [NMP][BSA] + H2O at Different Temperatures and at the Pressure p = 0.1 MPaa mo,b [NCyO][p‑TSA] mol·kg

0.0502 0.1025 0.1513 0.1991 0.2492 0.3015 0.3524 0.4007 0.4491 0.4976 0.5503 0.6019 0.6492 0.7521 0.8074 0.9012 1.0023 1.1991 mo,b [NCyO][p‑TSA] mol·kg

ρo,b 298.15

−1

g·cm 1.00025 1.00322 1.00586 1.00858 1.01141 1.01432 1.01703 1.01946 1.02174 1.02393 1.02630 1.02847 1.03043 1.03470 1.03700 1.04082 1.04483 1.05136 ρo,b 298.15

−1

0.0499 0.1012 0.1588 0.1983 0.2691 0.3004 0.3421 0.3980 0.4495 0.5139 0.6053 0.6615 0.7504 0.7605 0.8335 0.9023 1.0067 1.2007

ρo,b 303.15 0.99876 1.00160 1.00430 1.00695 1.00976 1.01257 1.01523 1.01748 1.01979 1.02192 1.02426 1.02637 1.02829 1.03251 1.03474 1.03855 1.04252 1.04895 ρo,b 303.15 g·cm

0.99998 1.00271 1.00580 1.00795 1.01173 1.01331 1.01542 1.01829 1.02080 1.02387 1.02817 1.03076 1.03466 1.03506 1.03820 1.04105 1.04523 1.05261

ρo,b 308.15

mo,b [NCyP][BSA]

−3

mol·kg 0.99702 0.99985 1.00249 1.00510 1.00784 1.01060 1.01312 1.01541 1.01758 1.01970 1.02189 1.02396 1.02585 1.03001 1.03232 1.03616 1.04019 1.04640 ρo,b 308.15

0.0509 0.1005 0.1478 0.1987 0.2532 0.3009 0.3497 0.4013 0.4514 0.5008 0.5492 0.6024 0.6506 0.7603 0.7986 0.9023 0.9974 1.1989 mo,b [NCyP][BSA]

−3

0.99853 1.00047 1.00401 1.00637 1.01016 1.01173 1.01371 1.01641 1.01889 1.02188 1.02617 1.02865 1.03258 1.03300 1.03601 1.03867 1.04261 1.05061

ρo,b 298.15

−1

g·cm 0.99945 1.00285 1.00540 1.00793 1.01059 1.01305 1.01550 1.01826 1.02107 1.02374 1.02644 1.02939 1.03186 1.03745 1.03918 1.04364 1.04735 1.05463 ρo,b 298.15

mol·kg−1 0.99606 0.99866 1.00230 1.00465 1.00834 1.00985 1.01183 1.01442 1.01677 1.01963 1.02390 1.02641 1.03021 1.03065 1.03359 1.03634 1.04036 1.04817

0.0521 0.1042 0.1369 0.2057 0.2512 0.2984 0.3556 0.4028 0.4537 0.5093 0.6018 0.6492 0.7511 0.8129 0.8710 0.9001 1.0189 1.1990

ρo,b 303.15

ρo,b 308.15

−3

0.99789 1.00135 1.00396 1.00642 1.00902 1.01132 1.01384 1.01655 1.01924 1.02203 1.02455 1.02742 1.02991 1.03510 1.03689 1.04109 1.04452 1.05223 ρo,b 303.15

0.99597 0.99903 1.00185 1.00455 1.00724 1.00949 1.01174 1.01430 1.01692 1.01952 1.02206 1.02491 1.02747 1.03283 1.03462 1.03892 1.04251 1.04968 ρo,b 308.15

g·cm−3 1.00025 1.00316 1.00490 1.00879 1.01109 1.01359 1.01655 1.01890 1.02144 1.02416 1.02861 1.03083 1.03550 1.03824 1.04072 1.04202 1.04701 1.05433

0.99854 1.00168 1.00346 1.00707 1.00923 1.01155 1.01441 1.01670 1.01925 1.02214 1.02663 1.02891 1.03354 1.03623 1.03849 1.03967 1.04427 1.05206

0.99669 0.99993 1.00157 1.00483 1.00669 1.00884 1.01159 1.01374 1.01636 1.01921 1.02382 1.02628 1.03078 1.03329 1.03554 1.03666 1.04112 1.04961

a The standard uncertainties (u) are u(T) = 0.01 K, u(m) = 1.0·10−4 mol·kg−1, and u(p) = 1.0 kPa, respectively. The combined expanded uncertainty (Uc) is Uc(ρ) = 5.0·10−5 g·cm−3 (0.95 level of confidence). mo and ρo are the molality and the density of the binary solution.

2.2. Syntheses of NCyP- and NMP-Based ILs. The procedure for synthesis of the NCyP-based ILs with different anions was as follows. Acetone and an equimolar amount of NCyP and a given acid were mixed and stirred for 4−6 h at room temperature. The resulting viscous liquid was homogeneous and light yellow. Then, the mixed solution was dried under vacuum at 333.15 K using a rotary evaporator. The remaining solution was cooled to room temperature, and the solid IL was obtained. The product was washed by toluene more than three times to remove residual material. Then the product was filtered from solution and dried under vacuum for more than 72 h at 343.15 K. The procedure for synthesis of a NMP-based IL was similar to that for synthesis of a NCyP-based IL. The obtained [NCyP][p-TSA] is a gray solid, and [NCyP][BSA], [NMP][p-TSA], and [NMP][BSA] are white solids at room temperature. The newly prepared

ILs were also dried by a 3 Å molecular sieve for more than 2 days before their use. 2.3. DSC Measurements, 1H Spectra Measurements, and Elemental Analyses. The DSC measurements were performed from (143.15 to 423.15) K, with a TA Q2000 DSC (differential scanning calorimetry) calorimeter, using a heating rate of 10 K·min−1 and helium as a purge gas. D2O was used as the solvent and all the 1H spectra were collected at room temperature using a JEOL ECA-600 NMR spectrometer. Elemental analyses were carried out on a Elementar Vario ELIII instrument. 2.4. Preparation of Aqueous Solutions of ILs. The procedures for preparing aqueous solutions of ILs are similar to those used in previous studies.27,28,43 Deionized water and newly produced ILs were used to prepare binary aqueous solutions using a Sartorius CT225D balance with the precision of ± 5·10−5 g. Then, known amounts of corresponding binary solutions were 1095



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Table 2. Experimental Viscosities of the Binary Systems [NCyP][p-TSA] + H2O, [NCyP][BSA] + H2O, [NMP][p-TSA] + H2O, and [NMP][BSA] + H2O at Different Temperatures and at the Pressure p = 0.1 MPaa mo,b [NCyO][p‑TSA] mol·kg

0.0502 0.1025 0.1513 0.1991 0.2492 0.3015 0.3524 0.4007 0.4491 0.4976 0.5503 0.6019 0.6492 0.7521 0.8074 0.9012 1.0023 1.1991 mo,b [NCyO][p‑TSA] mol·kg

ηo,b 298.15

−1

ηo,b 308.15

mo,b [NCyP][BSA]

mPa·s 0.9563 0.9991 1.0352 1.0820 1.1343 1.1856 1.2402 1.2888 1.3375 1.3829 1.4355 1.4852 1.5374 1.6475 1.7149 1.8288 1.9657 2.2331 ηo,b 298.15

−1

0.0499 0.1012 0.1588 0.1983 0.2691 0.3004 0.3421 0.3980 0.4495 0.5139 0.6053 0.6615 0.7504 0.7605 0.8335 0.9023 1.0067 1.2007

ηo,b 303.15 0.8427 0.8853 0.9171 0.9514 0.9897 1.0361 1.0804 1.1229 1.1648 1.2066 1.2543 1.3003 1.3437 1.4403 1.4969 1.5959 1.6997 1.9072 ηo,b 303.15

mol·kg 0.7524 0.7957 0.8304 0.8636 0.8957 0.9333 0.9639 0.9982 1.0292 1.0658 1.1036 1.1446 1.1842 1.2719 1.3229 1.4123 1.5056 1.6876 ηo,b 308.15

0.0509 0.1005 0.1478 0.1987 0.2532 0.3009 0.3497 0.4013 0.4514 0.5008 0.5492 0.6024 0.6506 0.7603 0.7986 0.9023 0.9974 1.1989 mo,b [NCyP][BSA]

0.8355 0.8613 0.8905 0.9097 0.9445 0.9602 0.9826 1.0075 1.0295 1.0578 1.0987 1.1273 1.1695 1.1726 1.2074 1.2439 1.2991 1.4094

ηo,b 303.15

0.9377 0.9703 1.0102 1.0571 1.1097 1.1528 1.1988 1.2468 1.2920 1.3369 1.3832 1.4324 1.4787 1.5876 1.6311 1.7357 1.8376 2.0804 ηo,b 298.15

0.8235 0.8645 0.8892 0.9268 0.9692 1.0092 1.0509 1.0969 1.1405 1.1808 1.2238 1.2684 1.3095 1.4051 1.4420 1.5355 1.6228 1.8104 ηo,b 303.15

0.7579 0.7776 0.8002 0.8164 0.8406 0.8511 0.8691 0.8920 0.9131 0.9369 0.9752 0.9976 1.0361 1.0399 1.0723 1.1057 1.1608 1.2658

0.0521 0.1042 0.1369 0.2057 0.2512 0.2984 0.3556 0.4028 0.4537 0.5093 0.6018 0.6492 0.7511 0.8129 0.8710 0.9001 1.0189 1.1990

0.9266 0.9506 0.9685 1.0028 1.0277 1.0553 1.0825 1.1075 1.1325 1.1602 1.2044 1.2262 1.2766 1.3090 1.3412 1.3581 1.4229 1.5402

0.8213 0.8450 0.8602 0.8912 0.9109 0.9313 0.9567 0.9774 1.0017 1.0252 1.0646 1.0851 1.1299 1.1578 1.1847 1.1985 1.2575 1.3582

ηo,b 308.15

mPa·s

mol·kg−1

mPa·s 0.9405 0.9707 0.9996 1.0208 1.0588 1.0775 1.0997 1.1299 1.1547 1.1914 1.2414 1.2717 1.3192 1.3243 1.3663 1.4107 1.4769 1.6098

ηo,b 298.15

−1

0.7406 0.7786 0.8095 0.8407 0.8758 0.9088 0.9404 0.9772 1.0129 1.0463 1.0830 1.1228 1.1632 1.2488 1.2828 1.3725 1.4485 1.6167 ηo,b 308.15

mPa·s 0.7506 0.7706 0.7809 0.8063 0.8208 0.8393 0.8611 0.8786 0.8972 0.9174 0.9514 0.9692 1.0090 1.0343 1.0591 1.0719 1.1269 1.2189

a The standard uncertainties (u) are u(T) = 0.01 K, u(m) = 1.0·10−4 mol·kg−1, and u(p) = 1.0 kPa, respectively. The combined expanded uncertainty (Uc) is Uc(η) = 1 % (0.95 level of confidence) .mo and ηo are the molality and the viscosity of the binary solution.

mixed to yield the ternary solutions (the uncertainty is ± 5·10−5 mol·kg−1).27,28,43 2.5. Density Measurements. The procedure for density measurements was also similar to that used in our previous measurements.27,28,43,46 The Anton Paar oscillating-tube digital densimeter (DMA-4500) was used. A digital thermometer was used to control the temperature inside the measuring cell of the densimeter, and its precision was ± 0.01 K. The densimeter was calibrated with doubly distilled and deionized water and dry air according to the instrument manual.43,47 The densities thereof as a function of temperature were available in refs.48,49 In addition, hexane50 was also used as a calibration substance. The precision of the density measurements was ± 5·10−5 g· cm−3.27,28,43,46 2.6. Viscosity Measurements. The measurements of viscosities were performed using the methods described in

refs 43 and 51. Four Cannon−Ubbelohde suspended level capillary viscometers (the viscometer constants were 0.003821, 0.004364, 0.005355, and 0.01008 mm2·s−2) were used to measure the viscosities,46,51 and a thermostatic water bath (monitored by a DP95 digital RTD thermometer with an uncertainty of ± 0.01 K, which leaded to a relative standard uncertainty of 0.1 % in the viscosity measurement51) was used to control the experimental temperatures. These capillary viscometers were calibrated and credited by the company, with a stated precision of 0.1 %.51 This leaded to a relative standard uncertainty of less than 0.5 % in the viscosity measurement. After the specific temperature was achieved, a digital electronic watch was used to record the efflux time of the solutions, and the corresponding uncertainty was estimated to be ± 0.01 s, which resulted in a relative standard uncertainty of less than 0.03 % in the viscosity measurement.51 At 1096



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Table 3. The Parameters for the Densities and Viscosities of the Binary Systems [NCyP][p-TSA] + H2O, [NCyP][BSA] + H2O, [NMP][p-TSA] + H2O, and [NMP][BSA] + H2O at Different Temperatures parameter

T/K

parameter

298. 15

303.15

308.15

o ρ[NCyP][BSA] + H2O

298.15

303.15

308.15

0.977440 0.262926 −1.28891 3.42353 −4.56823 3.03359 −0.79559 1.2·10−5

0.980985 0.204887 −1.02961 2.84404 −3.88776 2.63011 −0.700217 2.0·10−5 T/K

0.973968 0.271495 −1.35878 3.66861 −5.00223 3.39612 −0.909093 1.2·10−5

A0 A1 A2 A3 A4 A5 A6 δoρ parameter

0.999633 −0.0841496 0.694725 −2.02417 3.03532 −2.21983 0.607702 3.2·10−5

1.00603 −0.190120 1.24194 −3.42583 4.96711 −3.51361 0.959118 3.0·10−5 T/K

1.02526 −0.424683 2.21524 −5.38111 6.98150 −4.52457 1.15097 3.0·10−5

o ρ[NCyP][p‑TSA] + H2 O

298. 15

303.15

308.15

o ρ[NCyP][BSA] + H2 O

298.15

303.15

308.15


1.00183 −0.0500172 0.261763 −0.428207 0.478767 −0.289769 0.0706000 1.6 × 10−5

1.04870 −0.615030 2.80427 −6.17025 7.41510 −4.57487 1.13445 2.0 × 10−5 T/K

1.03372 −0.484747 2.28270 −5.06249 6.09518 −3.74702 0.922960 2.1 × 10−5


1.00327 −0.0717612 0.388429 −0.764028 0.930354 −0.588700 0.148649 2.1 × 10−5

1.01624 −0.280372 1.52609 −3.79236 5.10822 −3.45563 0.921354 2.6 × 10−5 T/K

1.01793 −0.351681 2.01765 −5.32646 7.45604 −5.18625 1.41316 3.1 × 10−5

o η[NCyP][p‑TSA] + H2 O

298. 15

303.15

308.15

o η[NCyP][BSA] + H2 O

298.15

303.15

308.15

B0 B1 10−1B2 10−2B3 10−2B4 10−1B5 10−1B6 δoη parameter

0.302234 8.06588 −4.01523 1.02567 −1.34007 8.77934 −2.26147 7.0 × 10−4

0.206257 7.29946 −3.35048 0.799355 −0.989834 6.24843 −1.57384 6.0 × 10−4 T/K

0.690155 0.214589 −0.0189025 0.0359678 −0.0840967 0.869230 −0.309026 8.0 × 10−4

B0 B1 10−1B2 10−2B3 10−2B4 10−1B5 10−1B6 δoη parameter

1.18243 −2.98084 1.24954 −0.231036 0.252065 −1.44649 0.350740 7.0 × 10−4

0.156177 7.59935 −3.43660 0.800523 −0.963191 5.88779 −1.43751 7.0 × 10−4 T/K

0.577145 1.39128 −0.511282 0.126219 −0.158223 1.08302 −0.303262 9.0 × 10−4

o η[NCyP][p‑TSA] + H2 O

298. 15

303.15

308.15

o η[NCyP][BSA] + H2 O

298.15

303.15

308.15

B0 B1 10−1B2 10−1B3 10−1B4 10−1B5 B6 δoη

0.696264 2.62692 −1.17275 2.86350 −3.53920 2.19944 −5.36086 6.0 × 10−4

0.770938 0.582908 −0.282810 0.933510 −1.34004 0.925106 −2.41581 7.0 × 10−4

0.610365 1.52650 −0.62323 1.60918 −1.96748 1.21654 2.94027 7.0 × 10−4

B0 B1 B2 10−1B3 10−1B4 10−1B5 10−1B6 δoη

0.853262 0.756542 −3.93305 1.20844 −1.63084 1.04869 −0.252631 7.0 × 10−4

0.778690 0.199830 −0.321151 0.133509 −0.0841509 −0.0242050 0.0338740 4.0 × 10−4

0.570632 1.94142 −8.66363 2.08795 −2.55184 0.156729 −0.376449 3.0 × 10−4

o ρ[NCyP][p‑TSA] + H2 O


T/K

least three times repeated measurements were performed for each sample. The viscosity of the solution is given by43,52,53 η = ηo(ρτ /ρo τo)

(1)

where ηo is the viscosity of water. ρ and ρo are the densities of the experimental solution and water, respectively. τ and τo are the flow times of the solution and water, respectively. The accuracy of the density measurements was ± 5·10−5 g· cm−3, which resulted in a relative standard uncertainty of less than 0.09 % in the viscosity measurement.51 After using standard techniques for the propagation of uncertainty, the estimated overall expanded uncertainty, including efflux time, temperature, the accuracy of the density measurement, and calibration uncertainties, was 1.0 %.51 The viscosities (η) of ethanol, 1propanol, and 2-ethoxyethanol at 298.15 K have been well established.54,55 Therefore, in our preliminary measurements, the

Figure 1. Structures of (1) [NCyP][p-TSA], (2) [NCyP][BSA], (3) [NMP][p-TSA], and (4) [NMP][BSA].

calibrated viscometer was verified by measuring the viscosities of these materials. The results (ηexpt vs ηliter) are 1.0958 vs 1.096154 mPa·s for ethanol, 1.9466 vs 1.946854 mPa·s for 1-propanol, and 1.7842 vs 1.78455 mPa·s for 2-ethoxyethanol, respectively. 1097



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Figure 2. 1H NMR spectra of (a) [NCyP][p-TSA] and (b) [NCyP][BSA].

Hu’s equation41 for viscosity of a mixed IL solution can be written as

3. RESULTS AND DISCUSSION 3.1. Equations for Predictions of Density and Viscosity of Aqueous Solutions of ILs. In following sections, the superscript (o,I) and the subscript MiXi represent the quantities of component MiXi in MiXi + H2O (i = 1, 2) which have the same ionic strength as that of a ternary solution. And the symbols which do not have the superscript (o,I) stand for the corresponding quantities in a ternary solution. The following equation is known as the rule of Patwardhan and Kumar:37 ρ=

∑ YM X /∑ (YM X /ρMo,IX ) i i

i

i i

i

i i

n

ln η =

∑ (x M X /x Mo,IX )ln ηMo,IX i i

i i

i i

i=1

(3)

where x is mole fraction. 3.2. Comparisons with Experimental Values. The measured densities and viscosities of the ternary systems were used to test eqs 2 and 3. The procedure is as follows: (1) Fit the measured values of ρoMiXi and ηoMiXi for the examined MiXi + H2O (i = 1, 2) (see Tables 1 and 2) to eqs 4 and 5:

(2)

with YMiXi = yMiXi + mMiXiMMiXi and YMiXi = IMiXi/I, where y, m, ρ, and M are ionic strength fraction, molality, density, and molar mass, respectively.

ρMo X (calc) =

∑l= 0 Al (mMo X )l/2

(4)

ηMo X (calc) =

∑l= 0 Bl (mMo X )l/2

(5)

i i

i i

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Figure 3. 1H NMR spectra of (a) [NMP][p-TSA] and (b) [NMP][BSA].

Table 4. Comparisons of the Calculated Values of Mass Fraction (f M) of N and S in the Four Ionic Liquids with the Values Obtained from the Elemental Analyses (100f M) of N

a

(100f M) of S a

ionic liquid

expt.

calc.

purity

[NMP][P-TSA] [NMP][BSA] [NCyP][P-TSA] [NCyP][BSA]

5.08 5.38 4.10 4.22

5.15 5.44 4.12 4.30

0.986 0.990 0.995 0.981

water content a

expt.

calc.

purity

11.67 12.20 9.33 9.69

11.80 12.40 9.42 9.83

0.989 0.984 0.990 0.986

average purity

ppm

0.988 0.987 0.993 0.984

100 150 50 140

Calculated from f M,expt./f M,calc.

o o where moMiXi, ρM , and ηM stand for the molality, iXi(calc) iXi(calc)

The optimum results were achieved by increasing the l values o o − ρoMiXi(expt)|/ρM )/N is less until δoρ,MiXi = ∑i N= 1 (|ρM iXi(calc) iXi(expt)

density, and viscosity of the binary solution MiXi + H2O (i = 1, 2), respectively, and Bl (l = 0, 1, 2, 3, ...) are the fitting parameters.

o o than 10−4 and δoη,MiXi = ∑iN= 1 (|ηM − ηoMiXi(expt.)|/ηM )/N iXi(calc.) iXi(expt.)

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Table 5. Comparisons of Measured and Predicted Densities for the Ternary System [NCyP][p-TSA] (B) + [NCyP][BSA] (C) + H2O at Different Temperatures and at the Pressure p = 0.1 MPaa mB

mC mol·kg

is ∼10−4. The fitted values of Al, Bl, δoρ,MiXi, and δoη,MiXi are listed in Table 3. (2) Calculate the values of mo,I MiXi for the binary solutions according to the ionic strength of the corresponding ternary solution of certain molalities mMiXi (i = 1, 2). o,I (3) The values of ρo,I MiXi and ηMiXi were calculated using eqs 4 and 5 and then were substituted into eqs 2 and 3 to provide the predicted data for the ternary solution. (4) Compare measured and predicted values. The averaged relative difference between predicted and measured values was expressed as43

∑ |δρ,i|/N i=1

0.0201 0.0604 0.1276 0.1857 0.0502 0.1499 0.3037 0.4513 0.0803 0.2422 0.4731 0.7201

0.0801 0.2433 0.4806 0.7215 0.0497 0.1506 0.3014 0.4498 0.0205 0.0599 0.1227 0.1831

303.15 K 0.0201 0.0604 0.1276 0.1857 0.0502 0.1499 0.3037 0.4513 0.0803 0.2422 0.4731 0.7201

0.0801 0.2433 0.4806 0.7215 0.0497 0.1506 0.3014 0.4498 0.0205 0.0599 0.1227 0.1831

308.15 K 0.0201 0.0604 0.1276 0.1857 0.0502 0.1499 0.3037 0.4513 0.0803 0.2422 0.4731 0.7201

0.0801 0.2433 0.4806 0.7215 0.0497 0.1506 0.3014 0.4498 0.0205 0.0599 0.1227 0.1831

∑ |δη,i|/N i=1

δρ,eq2 1.00295 1.01379 1.02922 1.04246 1.00293 1.01362 1.02907 1.04221 1.00299 1.01371 1.02862 1.04230 δρ

−0.00034 −0.00065 0.00018 0.00012 0.00067 −0.00046 −0.00007 0.00085 −0.00006 −0.00041 0.00010 0.00076 3.9·10−4

1.00149 1.01230 1.02622 1.03933 1.00055 1.01158 1.02702 1.03913 1.00091 1.01232 1.02644 1.03908

1.00140 1.01208 1.02717 1.04002 1.00138 1.01192 1.02703 1.03978 1.00144 1.01200 1.02659 1.03987 δρ

−0.00009 −0.00022 0.00093 0.00067 0.00083 0.00034 0.00001 0.00063 0.00053 −0.00032 0.00014 0.00076 4.6·10−4

0.99946 1.00952 1.02381 1.03735 0.99861 1.00902 1.02406 1.03686 0.99872 1.01027 1.02403 1.03691

0.99938 1.01014 1.02471 1.03777 0.99937 1.00998 1.02457 1.03752 0.99942 1.01006 1.02413 1.03761 δρ

−0.00008 0.00061 0.00088 0.00041 0.00076 0.00095 0.00049 0.00064 0.00070 −0.00021 0.00009 0.00068 5.4·10−4

The standard uncertainties (u) are u(T) = 0.01 K, u(m) = 1.0·10−4 mol·kg−1, and u(p) = 1.0 kPa, respectively. The combined expanded uncertainty (Uc) is Uc(ρ) = 5.0·10−5 g·cm−3 (0.95 level of confidence).

4. RESULTS AND DISCUSSION The structures of the examined ILs are depicted in Figure 1. The structures of these ILs were confirmed by 1H NMR spectroscopy. The corresponding spectral properties are as follows (see Figures 2 and 3). [NCyP][p-TSA] (D2O, ppm): δ = 7.5833 (d, 2H), 7.2334 (d, 2H), 3.6022 (m, 1H), 3.3097 (t, 2H), 2.3150 (t, 2H), 2.2679 (s, 3H), 1.8606 (m, 2H), 1.6593 (m, 2H), 1.4992 (m, 2H), 1.2434− 1.3099 (m, 2H), 1.1734−1.2227 (m, 2H), 0.9600−1.0093

(6)

N

δη =

g·cm

−3

a

N

δρ =

ρeq2

298.15 K 1.00329 1.01445 1.02903 1.04233 1.00226 1.01409 1.02914 1.04133 1.00305 1.01412 1.02852 1.04151

Figure 4. Variations of ηoexpt/calc (experimental and calculated values of ηoMiXi) with mo for the binary systems [NMP][p-TSA] + H2O and [NMP][BSA] + H2O at different temperatures: ■, □, (298.15 K); ●, ○, (303.15 K); △, ▲, (308.15 K), experimental values for [NMP][p-TSA] + H2O and [NMP][BSA] + H2O; , −−−, calculated values for [NMP][p-TSA] + H2O and [NMP][BSA] + H2O (lines serve as guides to eyes).

Figure 5. Variations of ηoexpt/calc with mo for the binary systems [NCyP][p-TSA] + H2O and [NCyP][BSA] + H2O at different temperatures: ■, □, (298.15 K); ●, ○, (303.15 K); △, ▲, (308.15 K), experimental values for [NCyP][p-TSA] + H2O and [NCyP][BSA] + H2O; , −−−, calculated values for [NCyP][p-TSA] + H2O and [NCyP][BSA] + H2O (lines serve as guides to eyes).

ρexpt

−1

(7)

with δρ,i = (ρi,(eq2) − ρi,(expt))/ρi,(expt) and δη,i = (ηi,(eq 3) − ηi,(expt))/ ηi,(expt) where N is the number of experimental data points. 1100



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Table 6. Comparisons of Measured and Predicted Densities for the Ternary System [NMP][p-TSA] (B) + [NMP][BSA] (C) + H2O at Different Temperatures and at the Pressure p = 0.1 MPaa mB

mC mol·kg

ρexpt

−1

ρeq2 g·cm

0.0200 0.0602 0.1197 0.1821 0.0503 0.1503 0.3007 0.4524 0.0811 0.2399 0.4806 0.7237

0.0802 0.2426 0.4853 0.7202 0.0499 0.1524 0.3104 0.4498 0.0199 0.0616 0.1189 0.1787

298.15 K 1.00304 1.01405 1.02845 1.04174 1.00299 1.01359 1.02860 1.04188 1.00274 1.01332 1.02797 1.04182

303.15 K 0.0200 0.0602 0.1197 0.1821 0.0503 0.1503 0.3007 0.4524 0.0811 0.2399 0.4806 0.7237

0.0802 0.2426 0.4853 0.7202 0.0499 0.1524 0.3104 0.4498 0.0199 0.0616 0.1189 0.1787

308.15 K 0.0200 0.0602 0.1197 0.1821 0.0503 0.1503 0.3007 0.4524 0.0811 0.2399 0.4806 0.7237

0.0802 0.2426 0.4853 0.7202 0.0499 0.1524 0.3104 0.4498 0.0199 0.0616 0.1189 0.1787

−3

δρ,eq2 1.00273 1.01364 1.02846 1.04158 1.00273 1.01363 1.02874 1.04158 1.00277 1.01357 1.02821 1.04158 δρ

−0.00030 −0.00040 0.00001 −0.00015 −0.00025 0.00004 0.00014 −0.00029 0.00004 0.00024 0.00023 −0.00023 2.0·10−4

1.00154 1.01148 1.02650 1.03946 1.00054 1.01202 1.02664 1.03973 1.00085 1.01163 1.02608 1.03881

1.00086 1.01181 1.02648 1.03922 1.00085 1.01180 1.02676 1.03921 1.00090 1.01174 1.02622 1.03922 δρ

−0.00068 0.00032 −0.00002 −0.00023 0.00031 −0.00022 0.00012 −0.00050 0.00005 0.00011 0.00014 0.00039 2.6·10−4

0.99958 1.00947 1.02381 1.03625 0.99890 1.00978 1.02438 1.03633 0.99840 1.00918 1.02338 1.03640

0.99911 1.00950 1.02394 1.03654 0.99911 1.00950 1.02422 1.03654 0.99915 1.00944 1.02368 1.03654 δρ

−0.00047 0.00003 0.00012 0.00029 0.00021 −0.00028 −0.00016 0.00020 0.00075 0.00026 0.00029 0.00014 3.0·10−4

Figure 6. Comparisons of measured and predicted densities for the ternary system [NCyP][p-TSA] + [NCyP][BSA] + H2O at different temperatures.

Figure 7. Comparisons of measured and predicted densities for the ternary system [NMP][p-TSA] + [NMP][BSA] + H2O at different temperatures.

(t, 2H), 2.6939−2.6974 (s, 3H), 2.3023 (t, 2H), 1.8785−1.8971 (m, 2H). The values of f M (mass fraction) of N and S in the four ILs were calculated according to their “molecular” structures. The results are compared in Table 4 with the corresponding values of f M of N and S in these ILs determined from the elemental analyses. The water contents of these ILs were determined using the Karl−Fisher titration28 and the results are also shown in Table 4. The purity of these ILs determined from these measurements are f M ≥ 0.984. The melting points of [NCyP][p-TSA], [NCyP][BSA], [NMP][p-TSA], [NMP][BSA] are (398.0, 348.0, 397.0, and 343.0) K, respectively. It is clear that the melting points of the [NCyP]+- and [NMP]+-based ILs increase from [BSA]− to [pTSA]−. For the examined ILs with a constant anion, the melting points of ILs decrease in the cation order [NCyP]+ > [NMP]+ (but the effect of the cation on the melting points of the examined ILs is small). The thermal decomposition temperatures of [NCyP][p-TSA], [NCyP][BSA], [NMP][p-TSA], and [NMP][BSA] are (520.2, 522.2, 503.2, and 506.2) K, respectively. Tables 1 and 2 show the measured densities and viscosities of the binary solutions [NCyP][p-TSA] + H2O, [NCyP][BSA] + H2O, [NMP][p-TSA] + H2O, and [NMP][BSA] + H2O at different temperatures. It can be observed that both the densities and viscosities of these solutions decrease with increasing the temperature. And both properties increase with increasing the molality of the IL solute, which are consistent with the

The standard uncertainties (u) are u(T) = 0.01 K, u(m) = 1.0·10−4 mol·kg−1, and u(p) = 1.0 kPa, respectively. The combined expanded uncertainty (Uc) is Uc(ρ) = 5.0·10−5 g·cm−3 (0.95 level of confidence). a

(m, 2H); [NCyP][BSA] (D2O, ppm): δ = 7.6935−7.7032 (d, 2H), 7.4239−7.4525 (m, 3H), 3.5988 (m, 1H), 3.3097 (t, 2H), 3.3104 (t, 2H), 1.8526 (m, 2H), 1.6524 (m, 2H), 1.4912 (m, 2H), 1.2457−1.3076 (m, 2H), 1.1505−1.2147 (m, 2H), 0.9577− 1.0059 (m, 2H); [NMP][p-TSA] (D2O, ppm): δ = 7.6058 (d, 2H), 7.2691 (d, 2H), 3.3650 (t, 2H), 2.7157 (s, 3H), 2.2794− 2.3252 (m, 5H), 1.9083−1.9186 (m, 2H); [NMP][BSA] (D2O, ppm): δ = 7.7077 (d, 2H), 7.4382−7.4386 (m, 3H), 3.3456 1101



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Table 7. Comparisons of Measured and Predicted Viscosities for the Ternary System [NCyP][p-TSA] (B) + [NCyP][BSA] (C) + H2O at Different Temperatures and at the Pressure p = 0.1 MPaa mB

mC mol·kg

−1

ηexpt

Table 8. Comparisons of Measured and Predicted Viscosities for the Ternary System [NMP][p-TSA] (B) + [NMP][BSA] (C) + H2O at Different Temperatures and at the Pressure p = 0.1 MPaa

ηeq3 δη,eq3

mPa·s

0.0201 0.0604 0.1276 0.1857 0.0502 0.1499 0.3037 0.4513 0.0803 0.2422 0.4731 0.7201

0.0801 0.2433 0.4806 0.7215 0.0497 0.1506 0.3014 0.4498 0.0205 0.0599 0.1227 0.1831

298.15 K 0.9741 1.1611 1.4514 1.7615 0.9818 1.1650 1.4669 1.7817 0.9918 1.1766 1.4768 1.8135

0.0201 0.0604 0.1276 0.1857 0.0502 0.1499 0.3037 0.4513 0.0803 0.2422 0.4731 0.7201

0.0801 0.2433 0.4806 0.7215 0.0497 0.1506 0.3014 0.4498 0.0205 0.0599 0.1227 0.1831

303.15 K 0.8628 1.0155 1.2830 1.5531 0.8721 1.0204 1.2933 1.5640 0.8799 1.0267 1.2951 1.5827

0.0201 0.0604 0.1276 0.1857 0.0502 0.1499 0.3037 0.4513 0.0803 0.2422 0.4731 0.7201

0.0801 0.2433 0.4806 0.7215 0.0497 0.1506 0.3014 0.4498 0.0205 0.0599 0.1227 0.1831

308.15 K 0.7788 0.9144 1.1368 1.3863 0.7847 0.9180 1.1384 1.3903 0.7902 0.9233 1.1391 1.4024

mB

mC mol·kg

−1

ηexpt

ηeq3 δη,eq3

mPa·s

0.9756 1.1619 1.4496 1.7602 0.9832 1.1690 1.4627 1.7815 0.9915 1.1809 1.4696 1.8129 δη

0.0015 0.0006 −0.0013 −0.0007 0.0014 0.0034 −0.0029 −0.0001 −0.0003 0.0037 −0.0049 −0.0003 1.8·10−3

0.0200 0.0602 0.1197 0.1821 0.0503 0.1503 0.3007 0.4524 0.0811 0.2399 0.4806 0.7237

0.0802 0.2426 0.4853 0.7202 0.0499 0.1524 0.3104 0.4498 0.0199 0.0616 0.1189 0.1787

298.15 K 0.9560 1.0632 1.2084 1.3702 0.9567 1.0720 1.2206 1.3904 0.9628 1.0790 1.2248 1.4011

0.8671 1.0166 1.2807 1.5516 0.8733 1.0216 1.2875 1.5633 0.8801 1.0309 1.2886 1.5833 δη

0.0050 0.0011 −0.0018 −0.0010 0.0014 0.0012 −0.0045 −0.0005 0.0002 0.0041 −0.0050 0.0004 2.2·10−3

0.0200 0.0602 0.1197 0.1821 0.0503 0.1503 0.3007 0.4524 0.0811 0.2399 0.4806 0.7237

0.0802 0.2426 0.4853 0.7202 0.0499 0.1524 0.3104 0.4498 0.0199 0.0616 0.1189 0.1787

303.15 K 0.8452 0.9446 1.0715 1.2107 0.8497 0.9536 1.0797 1.2174 0.8560 0.9575 1.0909 1.2299

0.7811 0.9143 1.1331 1.3825 0.7855 0.9190 1.1369 1.3894 0.7907 0.9270 1.1357 1.4039 δη

0.0029 −0.0002 −0.0033 −0.0027 0.0010 0.0010 −0.0013 −0.0006 0.0006 0.0040 −0.0030 0.0011 2.2·10−3

0.0200 0.0602 0.1197 0.1821 0.0503 0.1503 0.3007 0.4524 0.0811 0.2399 0.4806 0.7237

0.0802 0.2426 0.4853 0.7202 0.0499 0.1524 0.3104 0.4498 0.0199 0.0616 0.1189 0.1787

308.15 K 0.7713 0.8435 0.9521 1.0714 0.7695 0.8517 0.9612 1.0838 0.7718 0.8569 0.9608 1.0988

0.9532 1.0602 1.2124 1.3678 0.9596 1.0660 1.2255 1.3833 0.9663 1.0725 1.2301 1.3992 δη

−0.0029 −0.0028 0.0033 −0.0018 0.0030 −0.0051 0.0040 −0.0051 0.0036 −0.0060 0.0043 −0.0013 3.6·10−3

0.8467 0.9394 1.0728 1.2083 0.8519 0.9476 1.0854 1.2214 0.8575 0.9554 1.0909 1.2348 δη

0.0018 −0.0055 0.0012 −0.0020 0.0026 −0.0063 0.0053 0.0033 0.0018 −0.0022 −0.0001 0.0040 3.0·10−3

0.7710 0.8437 0.9569 1.0795 0.7738 0.8476 0.9655 1.0895 0.7769 0.8511 0.9676 1.0997 δη

−0.0003 0.0002 0.0050 0.0076 0.0056 −0.0049 0.0045 0.0052 0.0067 −0.0068 0.0070 0.0008 4.6·10−3

a

The standard uncertainties (u) are u(T) = 0.01 K, u(m) = 1.0 × 10−4 mol·kg−1, and u(p) = 1.0 kPa, respectively. The combined expanded uncertainty (Uc) is Uc(η) = 1 % (0.95 level of confidence).

The standard uncertainties (u) are u(T) = 0.01 K, u(m) = 1.0·10−4 mol·kg−1, and u(p) = 1.0 kPa, respectively. The combined expanded uncertainty (Uc) is Uc(η) = 1 % (0.95 level of confidence).

results observed for aqueous solutions of other ILs.29−32 The comparisons of ηoexpt and ηocalc for these systems are shown in Figures 4 and 5. It is clear that the values of ηoexpt at the same T and a constant m are greater in [NCyP][p-TSA] + H2O than in [NCyP][BSA] + H2O. The same trend is observed as [NMP]+ is used in place of [NCyP]+. The measured and predicted densities for the ternary solutions [NCyP][p-TSA] + [NCyP][BSA] + H2O and [NMP][p-TSA] + [NMP][BSA] + H2O at different temperatures are compared in Tables 5 and 6 and Figures 6 and 7. It can be found that the δeq2 ρ

value for the ternary solution [NCyP][p-TSA] + [NCyP][BSA] + H2O remains nearly constant (δeq2 = (4.7 ± 0.8)·10−4) as ρ the temperature increases from (298.15 to 308.15) K. By comparison, the δeq ρ 2 values for the ternary solution [NMP][p-TSA] + [NMP][BSA] + H2O at the three temperatures −4 are slightly smaller (2.0·10−4 ≤ δeq2 ρ ≤ 3.0·10 ). Therefore, the agreements between measured and predicted densities are good. Tables 7 and 8 and Figures 8 and 9 show the comparisons of the measured and predicted viscosities for the ternary solutions

a

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Notes

The authors declare no competing financial interest.

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REFERENCES

(1) Brennecke, J. F.; Maginn, E. J. Ionic liquids: Innovative fluids for chemical processing. AIChE J. 2001, 47, 2384−2389. (2) Dupont, J.; de Souza, R. F.; Suarez, P. A. Z. Ionic liquid (molten salt) phase organometallic catalysis. Chem. Rev. 2002, 102, 3667−3692. (3) Earle, M. J.; Esperanca, J. M. S. S.; Gilea, M. A.; Lopes, J. N. C.; Rebelo, L. P. N.; Magee, J. W.; Seddon, K. R.; Widegren, J. A. The distillation and volatility of ionic liquids. Nature 2006, 439, 831−834. (4) Paulechka, Y. U.; Zaitsau, Dz. H.; Kabo, G. J.; Strechan, A. A. Vapor pressure and thermal stability of ionic liquid 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide. Thermochim. Acta 2005, 439, 158−160. (5) Kosmulski, M.; Gustafsson, J.; Rosenholm, J. B. Thermal stability of low temperature ionic liquids revisited. Thermochim. Acta 2004, 412, 47−53. (6) Ui, K.; Yamamoto, K.; Ishikawa, K.; Minami, T.; Takeuchi, K.; Itagaki, M.; Watanabe, K.; Koura, N. Development of non-flammable lithium secondary battery with room-temperature ionic liquid electrolyte: Performance of electroplated Al film negative electrode. J. Power Sources 2008, 183, 347−350. (7) Kubota, K.; Nohira, T.; Goto, T.; Hagiwara, R. Novel inorganic ionic liquids possessing low melting temperatures and wide electrochemical windows: Binary mixtures of alkali bis(fluorosulfonyl)amides. Electrochem. Commun. 2008, 10, 1886−1888. (8) Welton, T. Room-temperature ionic liquids. Solvents for synthesis and catalysis. Chem. Rev. 1999, 99, 2071−2083. (9) Ahrens, S.; Peritz, A.; Strassner, T. Tunable aryl alkyl ionic liquids (TAAILs): The next generation of ionic liquids. Angew. Chem., Int. Ed. 2009, 48, 7908−7910. (10) Biswas, A.; Shogren, R. L.; Stevenson, D. G.; Willett, J. L.; Bhowmik, P. K. Ionic liquids as solvents for biopolymers: Acylation of starch and zein protein. Carbohydr. Polym. 2006, 66, 546−550. (11) Arce, A.; Rodríguez, O.; Soto, A. A comparative study on solvents for separation of tert-amyl ethyl ether and ethanol mixtures. New experimental data for 1-ethyl-3-methyl imidazolium ethyl sulfate ionic liquid. Chem. Eng. Sci. 2006, 61, 6929−6935. (12) Rao, C. J.; Venkatesan, K. A.; Nagarajan, K.; Srinivasan, T. G.; Rao, P. R. V. Treatment of tissue paper containing radioactive waste and electrochemical recovery of valuables using ionic liquids. Electrochim. Acta 2007, 53, 1911−1919. (13) Roosen, C.; Müller, P.; Greiner, L. Ionic liquids in biotechnology: Applications and perspectives for biotransformations. Appl. Microbiol. Biotechnol. 2008, 81, 607−614. (14) Lewandowski, A.; Swiderska-Mocek, A. Ionic liquids as electrolytes for Li-ion batteriesAn overview of electrochemical studies. J. Power Sources 2009, 194, 601−609. (15) Chiappe, C.; Pieraccini, D.; Saullo, P. Nucleophilic displacement reactions in ionic liquids substrate and solvent effect in the reaction of NaN3 and KCN with alkyl halides and tosylates. J. Org. Chem. 2003, 68, 6710−6715. (16) Gordon, C. M. New developments in catalysis using ionic liquids. Appl. Catal., A 2001, 222, 101−117. (17) Seddon, K. R.; Stark, A.; Torres, M. J. Influence of chloride, water, and organic solvents on the physical properties of ionic liquids. Pure Appl. Chem. 2000, 72, 2275−2287. (18) Carmichael, A. J.; Seddon, K. R. Polarity study of some 1-alkyl-3methylimidazolium ambient-temperature ionic liquids with the solvatochromic dye, Nile Red. J. Phys. Org. Chem. 2000, 13, 591−595.

Figure 8. Comparisons of measured and predicted viscosities for the ternary system [NCyP][p-TSA] + [NCyP][BSA] +H2O at different temperatures.

Figure 9. Comparisons of measured and predicted viscosities for the ternary system [NMP][p-TSA] + [NMP][BSA] +H2O at different temperatures.

[NCyP][p-TSA] + [NCyP][BSA] + H2O and [NMP][p-TSA] + [NMP][BSA] + H2O at different temperatures. The δeq η 3 value for [NCyP][p-TSA] + [NCyP][BSA] + H2O increases with increasing temperature from 1.8·10−3 to 2.2 × 10−3 at (298.15 to 308.15) K. In the case of [NMP][p-TSA] + [NMP][BSA] + 2 H2O, the results are 3.0·10−3 ≤ δeq ≤ 4.6·10−3 which are simρ 27,28,43 ilar to those reported previously.

5. CONCLUSIONS The pyrrolidone-based ILs [NCyP][p-TSA], [NCyP][BSA], [NMP][p-TSA], and [NMP][BSA] were synthesized and characterized. The densities and viscosities were measured for the ternary systems [NCyP][p-TSA] + [NCyP][BSA] + H2O and [NMP][p-TSA] + [NMP][BSA] + H2O and their binary subsystems at (298.15, 303.15, and 308.15) K and atmosphere pressure. These experimental results were subsequently invoked to verify the predictability of the equations established for densities and viscosities of mixed electrolyte solutions. The predicted values are in good agreement with the measured values.

■

ABBREVIATIONS [NCyP][p-TSA]: 1-cyclohexyl-2-pyrrolidinone p-toluenesulfonate [NCyP][BSA]: 1-cyclohexyl-2-pyrrolidinone benzenesulfonate [NMP][p-TSA]: 1-methyl-2-pyrrolidinone p-toluenesulfonate [NMP][BSA]: 1-methyl-2-pyrrolidinone benzenesulfonate

AUTHOR INFORMATION

Corresponding Author

*E-mail: [email protected]. Tel: +86 10 89733846. Funding

The authors thank the National Natural Science Foundation of China (21276271, 21076224, and 21036008) and Science Foundation of China University of Petroleum, Beijing (qzdx2011-01) for financial support. 1103



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Densities and Viscosities of the Binary and Ternary Aqueous Solutions

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