scifinder scholar reference 12 science 8 citation

8/9/2019 Scifinder Scholar Reference 12 Science 8 Citation

1/6

Heat capacities and electrical conductivities of 1-ethyl-3-methylimidazolium-based ionic liquids

Ya-Hung Yu, Allan N. Soriano, Meng-Hui Li *

R&D Center for Membrane Technology, Department of Chemical Engineering, Chung Yuan Christian University, Chung Li, Taiwan

a r t i c l e i n f o

Article history:Received 1 July 2008Received in revised form 16 July 2008Accepted 16 July 2008Available online 25 July 2008

Keywords:Heat capacityElectrical conductivity[Emim]-Based ionic liquids

a b s t r a c t

We present the heat capacities and electrical conductivities of ve [Emim] 1-ethyl-3-methylimidazolium-based ionic liquids: [Emim][BF 4] (tetrauoroborate), [Emim][CF 3SO3] (triuoromethanesulfonate),[Emim][C 2N3] (dicyanamide), [Emim][C 2H5SO4] (ethylsulfate), and [Emim][MDEGSO 4] (2-(2-methoxyeth-oxy)ethylsulfate). The heat capacities were measured using a differential scanningcalorimeter (DSC) overthe temperature ranging from (303.2 to 358.2) K. The electrical conductivities were measured over thetemperature ranging from (293.2 to 353.2) K using a commercial conductivity meter. The estimateduncertainties of heat capacity C p and electrical conductivity r measurements were 0.015 kJ kg 1 K 1

and 0.001 mS cm 1 , respectively. The measured C p and r are presented as a function of temperature.The temperature dependency of the C P value was correlated using an empirical equation. A modied ver-sion of VTF-type (VogelTammanFulcher) equation was used to describe the temperature dependency of r values. The correlations give satisfactory results. Also, the results of this study are in good agreementwith the available literature data. The heat capacities and electrical conductivities presented in this workarein good agreement with the availableliterature data. Theresults of this study canbe applied to numer-ous chemical processes, since C p and r data are essential information for rational design.

2008 Elsevier Ltd. All rights reserved.

1. Introduction

Aqueous alkanolamine solutions are industrially effective forCO2 absorption, but this method usually requires higher energyconsumption and operational cost, and also comes with solventpollution. Ionic liquids (ILs), coined as green solvents, have beenrecognized as a versatile alternative to the aqueous alkanolaminesolutions. The IL is a common name given to many different chem-ical compounds, which are composed solely of ions and have melt-ing points around or below room temperature. The maximummelting temperature to be accepted for a compound to be includedin the IL category is about 373 K [1] . The ILs also show thermal sta-bility at high temperatures and at high solubility for both polar andnon-polar organic as well as inorganic substances. Consequently,ILs could be in a position to replace ammable and volatile organicsolvents in chemical processes [2]. Because of these appealingproperties, they could be very useful in the future. A signicantnumber of research groups have already done systematic measure-ment and collection of the thermophysical and transport proper-ties of ILs [215] .

The heat capacity C p and electrical conductivity r are two of thebasic pure component properties for any substance, and theirknowledge is necessary for many engineering applications. Formost ILs, these values are still lacking. As in the case of C p measure-ment, so far the thoroughly studied ILs are ammonium-, pyridini-um-, pyrrolidinium-, bis[(triuoromethyl)sulfonyl]amide-, andimidazolium-based ILs [2,3,5,7,10,12,13,1625] . In the C p measure-ment of imidazolium-based ILs, most of the work clustered on hex-yl- and butyl-3-methylimidazolium [10,1214,17,18] . For the rmeasurement, only those of ammonium-, pyrrolidinium-, andbis[(triuoromethyl)sulfonyl]amide-based have been widely stud-ied, while not much has been studied on imidazolium-based ILs[4,9,11,16,2630] . Therefore heat capacities and electrical conduc-tivities for ve [Emim]-based ILs have been measured. The heatcapacities were measured over the temperature ranging from(303.2 to 358.2) K at atmospheric pressure condition and the elec-trical conductivity over the temperature ranging from (293.2 to353.2) K at atmospheric pressure condition.

The ILs that have been investigated are listed in table 1 . Thestructures of cations and anions are shown in gure 1 . In orderto check the accuracy of the apparatus and the experimental pro-cedures used, heat capacity and electrical conductivity of standardmaterials have also been measured. Water was used to check theheat capacity measurements and the standard KCl solution forelectrical conductivity measurements.

0021-9614/$ - see front matter 2008 Elsevier Ltd. All rights reserved.doi:10.1016/j.jct.2008.07.013

* Corresponding author. Tel.: +886 3 265 4109; fax: +886 3 265 4199.E-mail address: [email protected] (M.-H. Li).

J. Chem. Thermodynamics 41 (2009) 103108

Contents lists available at ScienceDirect

J. Chem. Thermodynamics

j ou r na l ho m e page : www. e l s ev i e r. com/ loca t e / j c t
mailto:[email protected]://www.sciencedirect.com/science/journal/00219614http://www.elsevier.com/locate/jcthttp://www.elsevier.com/locate/jcthttp://www.sciencedirect.com/science/journal/00219614mailto:[email protected]


2/6

2. Experimental

2.1. Chemicals

All ILs used in this work were supplied by TCI Co. Table 1 showsthe purity of the ILs that were used without further puricationsince the experiments required a small amount of sample. The li-quid water used for the calibration of the calorimeter was deion-ised, with a resistivity of 18.3 M X cm and with a total organiccarbon mass fraction of less than 1.5 10 10 produced by BarnsteadThermodyne, model Easy Pure 1052. The standard KCl solutionused for the calibration of the cell of the conductivity meter wassupplied by Merck, with c = 0.1 mol L 1 and electrolytic conduc-tivity of 1.415 mS cm 1 at T = 298.15 K.

2.2. Heat capacity measurements

The heat capacity was measured using the differential scanningcalorimeter consisting of a DSC-2010 and a thermal analysis con-troller from TA Instruments. The DSC operating range is from theroom temperature to T = 998 K. Both the temperatures and theheat ow associated with the transitions in materials can be easilyand rapidly measured with the system. The DSC operates with atemperature repeatability of 0.1 K. Calorimetric sensitivity is1 l W (rms) with a precision of 0.01 kJ kg 1 K 1 based on themeasurements of metal samples. The purge gas was nitrogen witha ow rate of 40 cm 3 min 1. The heating rate was set to be5 K min 1. By using the sample encapsulating press, the liquid

sample was prepared in a hermetic sample pan. The internal vol-ume of the hermetic pan was approximately 10 mm 3. Sample mass

was in the range (15 to 20) mg. Five replicate runs were carried outfor each measurement. The apparatus and the experimental proce-dures are the same as those described by Chiu et al. [31] .

2.3. Electrical conductivity measurements

The electrical conductivity was measured using a SC-170 con-ductivity meter manufactured by Suntex. The uncertainty of theconductivity measurement is 0.001 mS cm 1 for readings below50 mS cm 1 . The temperature was monitored using a digital ther-mometer (model 3002, CROPICO), with an uncertainty of 0.01 K. Axed volume of sample (3 cm 3) was placed in a test tube andplaced in a water bath where the temperature was controlled.The conductivity cell was rst adjusted to zero in the air followedby the calibration of standard KCl solution before the sample wasput in. The calibration of this equipment is the same as those de-scribed by Widegren et al. [4]. The conductivity cell was thenwashed with deionised water and ethanol to remove any adheringIL, and dried. To preserve the conductivity cell it was placed inwater or in dry air before it was used for the next measurement.The measurements were done in ve replicate runs.

3. Results and discussion

3.1. Heat capacity

The equations used to represent the C p are the same as those de-scribed by Chiu et al. [31] . The C p of liquid water was measured andcompared to the data of Osborne et al. [32] to verify the accuracy of the DSC. Osborne and co-workers [32] were able to measure theheat capacity of water with an uncertainty of (0.0001 to0.0002) kJ kg 1 K 1 at close intervals of temperature (1 K) byusing a large adiabatic calorimeter. Table 2 shows the comparisonof C p results obtained by Osborne et al. [32] and those obtained inthis study. The average values given in the last column in table 2have an average absolute deviation (AAD) of 0.11 from the avail-able experimental data [32] . The (AAD) is dened as

TABLE 1

Ionic liquids investigated in this work

Ionic liquid Abbreviation Purity, Mass fraction

1-Ethyl-3-methylimidazolium tetrauoroborate [Emim][BF 4] P 0.9701-Ethyl-3-methylimidazolium triuoromethanesulfonate [Emim][CF 3SO3] P 0.9801-Ethyl-3-methylimidazolium dicyanamide [Emim][C 2N3] P 0.9991-Ethyl-3-methylimidazolium ethylsulfate [Emim][C 2H5SO4] P 0.9921-Ethyl-3-methyl imidazol ium 2-(2-methoxyethoxy) e thylsulfate [Emim][MDEGSO 4] P 0.982

FIGURE 1. Cation and anions of the ionic liquids investigated.

TABLE 2Heat capacities C p of water

T /K C p/(kJ kg 1 K 1)

Osborne et al. [32] This study

303.2 4.1785 4.182 0.013 a

308.2 4.1782 4.183 0.013313.2 4.1786 4.182 0.012318.2 4.1795 4.184 0.013323.2 4.1807 4.186 0.013328.2 4.1824 4.187 0.012333.2 4.1844 4.189 0.012338.2 4.1868 4.191 0.012343.2 4.1896 4.194 0.012348.2 4.1928 4.197 0.012353.2 4.1964 4.202 0.012(AAD) 0.11

a Mean value standard deviation.

104 Y.-H. Yu et al. / J. Chem. Thermodynamics 41 (2009) 103108


3/6

AAD 1n X

n

i

je lit e expt ji =e lit ; 1

where e lit is the literature value, e expt is the experimental value, andn is the number of data points. Hence, the measured C p values of li-quid water for temperatures (303.2 to 353.2) K are in good agree-ment with those reported by Osborne et al. [32] . On the basis of comparison with the literature values for water, the uncertaintyof the C p measurements was estimated to be 0.015 kJ kg 1 K 1.

Upon the calibration, the C p values of ve [Emim]-based ionicliquids were then measured at temperatures ranging from (303.2to 358.2) K. To further validate that the measured C p results in thiswork were correct, available literature data were also compared.Among the studied ILs, only [Emim][BF 4] and [Emim][CF 3SO3] haveliterature values available. To this end, [Emim][BF 4] was used todemonstrate the accuracy of our C p measurements through com-parison with the available literature data of Waliszewski et al. [5]At temperatures (303.2, 313.2, 323.2, 333.2, 343.2, and 353.2) K,we report the values of C p for [Emim][BF 4] of (1.547, 1.569, 1.588,1.598, 1.613, and 1.631) kJ kg 1 K 1 , respectively. These valueswere very close to those reported by Waliszewski et al. [5] , whichwere (1.548, 1.565, 1.582, 1.600, 1.619, and 1.639) kJ kg 1 K 1

at the same temperature. As presented in table 4 , the present C pmeasurements are consistent with the C p data of Waliszewski et al. [5] , as shown by the values of (AAD) of 0.67 and 0.49, respec-tively. The data of Waliszewski et al. [5] appear to have slightlyhigher C p values compared to the present C p measurements. Thismay be attributed to the difference in the water content of the IL used in these two studies. The [Emim][BF 4] used by Waliszewskiet al. [5] has a water mass percent of about 0.04, while the[Emim][BF 4] used in this study has a water mass percent of 6 0.9.This observation proved once more why purity is the most seriousone among the many reasons to account for differences in the pub-lished experimental data for thermophysical properties [33] .

The measured C p values of the investigated ILs are presented intable 3 (specic heat capacities) and are also shown in gure 2 (mo-

lar heat capacities). Results are presented between T = (303.2 and358.2) K. The heat capacity increases linearly with an increase inthe temperature. Differences in the heat capacity for the investi-gated ILsare dueto thechanges in theanions. Since theinvestigatedILs have a common cation, the molar heat capacity varies withthe anion, and decreases following the order [MDEGSO 4] >[C2H5SO4] > [CF3SO3] > [C2N3] > [BF4] . The anion types appearto contribute independently to the C p values of the ILs.

As also shown in gure 2 , [Emim][C 2H5SO4] is observed to havethe strongest temperature dependence of C p, while [Emim][MDEG-SO4] has the weakest temperature dependence of C p. For the pur-pose of application, the measured C p values of the investigatedILs are expressed as a function of temperature as follows:

C p;m a b T c T 2 ; 2

where C p,m is the molar heat capacity in (J mol 1 K 1) and T is theabsolute temperature in K. The parameters a , b, and c were deter-mined by tting all the data from this work and from the availableliterature data that were consistent with the present measure-ments. Table 4 shows the results of the calculation of C p,m usingequation (2) based on the selected C p data. As presented in table4, the agreement of C p measurements among different investigatorsis very satisfactory. The determined empirical parameters a, b, and c for each ionic liquid represent well the present experimental resultsand the selected literature data as shown by the overall (AAD) of

about 0.43 for a total of 140 data points, as presented in table 4 .The determined parameters a , b, and c of equation (2) are also pre-sented in table 4 along with the correlation coefcient ( R2). The cor-relation as in equation (2) represents the present experimental datasatisfactorily as well as the selected literature data for the investi-gated systems as shown by the value of R2 equal to unity.

3.2. Electrical conductivity

The r values of the standard KCl solution were measured to cal-ibrate the cell of the conductivity meter. The measurements weredone before the measurements on each sample to ensure thatthe conductivity cell was functioning properly. Table 5 contains a

TABLE 3Heat capacities C p of the investigated ionic liquids

T /K C p/(kJ kg 1 K 1)

[Emim][BF 4] [Emim][CF 3SO3] [Emim][C 2N3] [Emim][C 2H5SO4] [Emim][MDEGSO 4]

303.2 1.547 0.018 a 1.458 0.011 1.851 0.018 1.819 0.009 1.696 0.014308.2 1.558 0.018 1.466 0.011 1.862 0.018 1.827 0.010 1.701 0.014313.2 1.569 0.014 1.473 0.011 1.879 0.018 1.841 0.011 1.706 0.014318.2 1.580 0.017 1.481 0.010 1.891 0.018 1.850 0.012 1.711 0.015323.2 1.588 0.018 1.489 0.011 1.911 0.018 1.868 0.011 1.716 0.015328.2 1.593 0.017 1.497 0.012 1.923 0.018 1.881 0.012 1.720 0.015333.2 1.598 0.018 1.505 0.011 1.934 0.018 1.893 0.012 1.726 0.014338.2 1.608 0.022 1.513 0.009 1.944 0.018 1.905 0.009 1.731 0.014343.2 1.613 0.022 1.521 0.011 1.955 0.018 1.917 0.010 1.736 0.013348.2 1.623 0.022 1.529 0.011 1.969 0.018 1.932 0.008 1.742 0.013353.2 1.631 0.021 1.536 0.013 1.984 0.018 1.951 0.010 1.747 0.012358.2 1.634 0.021 1.544 0.014 1.999 0.019 1.962 0.008 1.753 0.012


300 320 340 360

300

375

450

525

600

T / K

C p

/ ( J m o l - 1 K - 1 )

FIGURE 2. Plot of molar heat capacities against temperature for [Emim]-based ionicliquids obtained from this work: . , [Emim][MDEGSO 4] (M = 338.43); j ,[Emim][CF 3SO3] (M = 260.24); , [Emim][C 2H5SO4] (M = 236.29); N , [Emim][BF 4](MW = 197.97); d , [Emim][C 2N3] (M = 177.21); and lines, calculated using equation(2) .

Y.-H. Yu et al./ J. Chem. Thermodynamics 41 (2009) 103108 105


4/6

sample of the measured r values of standard KCl solution alongwith the r values from the standard analysis done by the chemicalsupplier (Merck Calibration Laboratory for pH value and electricalconductivity). As presented in this table, the present r measure-ments were very close to those by the Merck Calibration Labora-tory, thus validating the present experimental procedure for themeasurements of r data.

Uponthe calibrationof theconductivitymeter cell, the r valuesof the ionic liquids investigated were then measured for temperaturesranging from (293.2 to 353.2) K. To justify further that the r valuesobtained in this work are correct, available literature data were alsocompared.Of the veILs investigated, only two of them have litera-ture values for comparison, viz. [Emim][BF 4] and [Emim][C 2H5SO4].To this end, [Emim][BF 4] was used to showthe accuracyof the pres-ent r values by comparing the r data from this work to theavailableliterature data of Vila et al. [6] . For temperatures of (303.2, 313.2,323.2, 333.2, 343.2, and 353.2) K, this study found that the valuesof r for [Emim][BF 4] were (1.789, 2.320, 2.910, 3.590, 4.350, and5.180) S m 1, respectively. These valuesare very close to those val-uesreportedby Vila etal. [6] , which were(1.788,2.280, 2.850, 3.560,4.350, and 5.220) S m 1 at the same temperature, thus validating

the accuracy of the present r data. The discrepancy in the measure-mentsmay beattributedto thedifferences inpurity of theILs used inthese two studies. Vila et al. [6] used [Emim][BF 4] having a watermass percent of 6 1.0, while this study used [Emim][BF 4] with awater mass percent of 6 0.9. Again, another proof that purity wasoneof themostserious reasons forthe differences in theexperimen-tal data of thermophysical properties [33] .

Our values of the r for the investigated ILs are presented intable 6 and are also shown in gure 3 . Among the investigated

TABLE 4

Molar heat capacity C p,m of the investigated ionic liquids using equation (2)

System T /K No. of data points Reference (AAD) A a A/ (J mol 1 K 1) b A/(J mol 1 K 2)

10 5 c A/(J mol 1 K 3) R2

[Emim][BF 4] 283.15 to 358.15 16 Waliszewski et al. [5] 0.67 279.24 0.10312 66.350 1.0303.2 to 358.2 12 This study 0.49

[Emim][CF 3SO3] 313.13 to 425.15 6 4 Diedrichs and Gmehling [2] 0.60 271.10 0.35907 0.307 1.0303.2 to 358.2 12 This study 0.20

[Emim][C 2N3] 303.2 to 358.2 12 This study 0.11 104.71 0.96220 74.546 1.0[Emim][C 2H5SO4] 303.2 to 358.2 12 This study 0.09 401.52 0.35939 148.871 1.0[Emim][MDEGSO 4] 303.2 to 358.2 12 This study 0.02 531.92 0.03759 58.252 1.0Overall 140 0.43

A Calculated from equation (2) .

TABLE 5

A sample measurement of electrical conductivity r of the standard KCl solution

T /K r /(mS cm 1)

Merck Co. a This study

298.2 1.408 1.411299.2 1.434 1.430301.2 1.491 1.494

303.2 1.547 1.550308.2 1.685 1.680313.2 1.836 1.830318.2 1.981 1.983323.2 2.137 2.140

a Merck Calibration Laboratory for pH value and electrical conductivity.

TABLE 6

Electrical conductivities r of the investigated ionic liquids

T /K r /(S m 1)

[Emim][BF 4] [Emim][CF 3SO3] [Emim][C 2N3] [Emim][C 2H5SO4] [Emim][MDEGSO 4]

293.2 1.377 0.009 a 0.834 0.010 1.890 0.013 0.310 0.008 0.110 0.011298.2 1.569 0.010 0.979 0.010 2.200 0.015 0.398 0.009 0.147 0.009303.2 1.789 0.003 1.155 0.012 2.550 0.013 0.493 0.003 0.194 0.009308.2 2.040 0.010 1.340 0.013 2.900 0.010 0.603 0.010 0.244 0.010313.2 2.320 0.013 1.523 0.011 3.290 0.013 0.722 0.010 0.307 0.013318.2 2.590 0.013 1.737 0.011 3.680 0.013 0.852 0.010 0.378 0.011323.2 2.910 0.012 1.936 0.012 4.100 0.014 1.002 0.009 0.459 0.012328.2 3.250 0.012 2.170 0.014 4.540 0.011 1.167 0.009 0.545 0.012333.2 3.590 0.011 2.420 0.013 5.020 0.011 1.341 0.009 0.641 0.011343.2 4.350 0.013 2.940 0.010 5.930 0.012 1.735 0.010 0.859 0.013353.2 5.180 0.011 3.510 0.013 6.860 0.010 2.150 0.010 1.124 0.013


288 306 324 342 360

0.0

1.5

3.0

4.5

6.0

7.5

/

( S m - 1 )

T / K

FIGURE 3. Plot of electrical conductivities against temperature for [Emim]-basedionic liquids obtained from this work: . , [Emim][MDEGSO 4] (M = 338.43); j ,[Emim][CF 3SO3] (M = 260.24); , [Emim][C 2H5SO4] (M = 236.29); N , [Emim][BF 4](MW = 197.97); d , [Emim][C 2N3] (M = 177.21); and lines, calculated using equation(3) .



5/6

ILs, [Emim][C 2N3] has the largest value of r and [Emim][MDEGSO 4]has the smallest value of r . The IL [Emim][C 2N3] has the strongesttemperature dependence on r values, while [Emim][MDEGSO 4]has the weakest temperature dependence on r values.

From the present experimental results, the inuence of the an-ion sizes in the temperature dependence of the electrical conduc-tivity was also interpreted. Generally, lower size moleculesusually have higher ionic mobility and so higher electrical conduc-tivity. This was generally the major observation in the ILs studiedas shown in gure 3 , with some inconsistent behaviour in the caseof [Emim][C 2H5SO4] and [Emim][CF 3SO3] with molar masses as236.29 and 260.24, respectively. This same behaviour, the increaseof r value with the anion size, had been observed and explainedpreviously by Vila et al. [34] when studying the electrical conduc-tivity of a highly concentrated aqueous solution of aluminiumhalide salts and imidazolium-based ionic liquids. In that work,Vila et al. [34] concluded that the anion size has two effects in elec-trical conductivity, i.e., the decrease of the surface electrical chargedensity and the effect of size for dynamical movement (hopping toadjacent holes); thus, a decrease or an increase of r value with theanion size could be observed.

For the purpose of comparison and application, the r values of the studied [Emim]-based ILs are estimated using the method em-

ployed by Vila et al . [6] , in which they employed a modied versionof VTF-type (VogelTammanFulcher) equation, which conse-quently reads

r r 1 exp E a

k BT T g ; 3where r 1 is the maximum electrical conductivity (that it wouldhave at innite temperature) in S m 1 , E a is the activation energyfor electrical conduction (which indicates the energy needed foran ion to hop to a free hole) in meV, kB is the Boltzmanns constant,and T g is the glass transition temperature in K.

Using equation (3), the parameters r 1 , E a, and T g were deter-mined by tting the present r measurements and selected litera-ture data, in which same criteria were used in the selection as

discussed previously. Table 7 contains the results of the calculationof r using equation (3) from the different investigators. As pre-sented in table 7 , the agreement of r measurements among differ-ent investigators is satisfactory. The determined parameters r 1 , E a ,and T g for the investigated ionic liquids are also presented in table7. The determined parameters r 1 , E a , and T g for each ionic liquidcorrelated well with the present r measurements and the availableliterature data as shown by the overall (AAD) of about 0.54% for atotal of 78 data points. It was also observed in table 7 that the max-imum conductivity value r 1 , the maximum E a , and the minimumT g correspond to [Emim][BF 4].

4. Conclusions

The heat capacities and electrical conductivities of ve [Emim]-based ILs were measured over the temperature ranging from

(303.2 to 358.2) K and from (293.2 to 353.2) K, respectively. Theheat capacity was measured using a DSC and the electrical conduc-tivity was measured using a conductivity meter. The C p and r val-ues of standard materials have been measured too in order tocheck the accuracy of the apparatus and the experimental proce-dures used. Using (liquid water + KCl) solution as standard materi-als, the accuracy of the apparatus and the experimental proceduresused was justied. The C p and r values from this work are in goodagreement with the available experimental data. The measured C pand r of each IL is expressed as a function of temperature. Anempirical equation was used to correlate the temperature depen-dency of C p values and a modied VTF-type (VogelTammanFul-cher) equation was employed to establish the temperaturedependency of r values. The correlations show satisfactory results.

Acknowledgement

This research was supported by a Grant, NSC 96-2221-E-033-020, of the National Science Council of the Republic of China.

References

[1] R.K. Rogers, K.R. Seddon, Ionic Liquids: Industrial Applications to GreenChemistry, Oxford University Press, Washington, DC, 2002.

[2] A. Diedrichs, J. Gmehling, Fluid Phase Equilibr. 244 (2006) 6877.[3] Z.-H. Zhang, Z.-C. Tan, L.-X. Sun, Y. Jia-Zhen, X.-C. Lv, Q. Shi, Thermochim. Acta

447 (2006) 141146.[4] J.A. Widegren, E.M. Saurer, K.N. Marsh, J.W. Magee, J. Chem. Thermodyn. 37

(2005) 569575.[5] D. Waliszewski, I. Stepniak, H. Piekarski, A. Lewandowski, Thermochim. Acta

433 (2005) 149152.[6] J. Vila, P. Gines, J.M. Pico, C. Franjo, E. Jimenez, L.M. Varela, O. Cabeza, Fluid

Phase Equilib. 242 (2006) 141146.[7] M.E. Van Valkenburg, R.L. Vaughn, M. Williams, J.S. Wilkes, Thermochim. Acta

425 (2005) 181188.[8] J. Troncoso, C.A. Cerdeirina, Y.A. Sanmamed, L. Romani, L.P.N. Rebelo, J. Chem.

Eng. Data 51 (2006) 18561859.[9] H. Tokuda, K. Hayamizu, K. Ishii, M.A.B.H. Susan, M. Watanabe, J. Phys. Chem. B

109 (2005) 61036110.[10] Y.U. Paulechka, G.J. Kabo, A.V. Blokhin, A.S. Shaplov, E.I. Lozinskaya, Y.S.

Vygodskii, J. Chem. Thermodyn. 39 (2007) 158166.[11] J. Sun, M. Forsyth, D.R. MacFarlane, J. Phys. Chem. B 102 (1998) 88588864.

[12] K.-S. Kim, B.-K. Shin, F. Ziegler, Fluid Phase Equilibr. 218 (2004) 215220.[13] C.P. Fredlake, J.M. Crosthwaite, D.G. Hert, S.N.V.K. Aki, J.F. Brennecke, J. Chem.Eng. Data 49 (2004).

[14] A. Fernandez, J.S. Torrecilla, F. Rodriquez, J. Chem. Eng. Data 52 (2007) 19791983.

[15] W.C. Su,C.H.Chou,D.S.H.Wong,M.-H.Li, Fluid Phase Equilibr.252 (2007) 7478.[16] D.R. MacFarlane, P. Meakin, J. Sun, N. Amini, M. Forsyth, J. Phys. Chem. B 103

(1999) 41644170.[17] J.M. Crosthwaite, M.J. Muldoon, J.K. Dixon, J.L. Anderson, J.F. Brennecke, J.

Chem. Thermodyn. 37 (2005) 559568.[18] J.D. Holbrey, W.M. Reichert, R.G. Reddy, R.D. Rogers, Ionic Liquids as Green

Solvents: Progress and Prospects, Oxford University Press, Washington, DC,2003.

[19] A.V. Blokhin, Y.U. Paulechka, G.J. Kabo, J. Chem. Eng. Data 51 (2006) 13771388.

[20] Y.U. Paulechka, A.V. Blokhin, G.J. Kabo, A.A. Strechan, J. Chem. Thermodyn. 39(2007) 866877.

[21] Z.-H. Zhang, L.-X. Sun, Z.-C. Tan, F. Xu, X.-C. Lv, J.-L. Zeng, Y. Sawada, J. Therm.Anal. 89 (2007) 289294.

[22] G. Garcia-Miaja, J. Troncoso, L. Romani, J. Chem. Eng. Data 52 (2007) 22612265.

TABLE 7

Electrical conductivity of the investigated ionic liquids using equation (3)

System T /K No. of data points Reference (AAD) a r 1 a/(S m 1) E aa/meV T ga/K

[Emim][BF 4] 258.1 to 433.1 12 Vila et al. [6] 0.93 361.20 91.60 102.66293.2 to 353.2 11 This study 0.74

[Emim][CF 3SO3] 258.1 to 433.1 11 Vila et al. [6] 0.50 98.28 57.34 153.52293.2 to 353.2 11 This study 0.50

[Emim][C 2N3] 293.2 to 353.2 11 This study 0.35 81.77 37.24 178.62

[Emim][C 2H5SO4] 293.2 to 353.2 11 This study 0.29 77.86 52.95 181.85[Emim][MDEGSO 4] 293.2 to 353.2 11 This study 0.44 64.93 57.80 187.89Overall 78 0.54

a Calculated from equation (3) .

Y.-H. Yu et al./ J. Chem. Thermodynamics 41 (2009) 103108 107


6/6

[23] A.A. Strechan, Y.U. Paulechka, A.G. Kabo, A.V. Blokhin, G.J. Kabo, J. Chem. Eng.Data 52 (2007) 17911799.

[24] L.P.N. Rebelo, V. Najdanovic-Visac, Z.P. Visak, M. Nunes da Ponte, J. Szydlowski,C.A. Cerdeirina, J. Troncoso, L. Romani, J.M.S.S. Esperanca, H.J.R. Guedes, H.C. deSousa, Green Chem. 6 (2004) 369381.

[25] M.J. Davila, S. Aparicio, R. Alcalde, B. Garcia, J.M. Leal, Green Chem. 9 (2007)221232.

[26] H. Tokuda, S. Tsuzuki, M.A.B.H. Susan, K. Hayamizu, M. Watanabe, J. Phys.Chem. B 110 (2006) 1959319600.

[27] M. Kanakubo, K.R. Harris, N. Tsuchihashi, K. Ibuki, M. Ueno, J. Phys. Chem. B111 (2007) 20622069.

[28] W. Liu, T. Zhao, Y. Zhang, H. Wang, M. Yu, J. Solution Chem. 35 (2006) 13371346.

[29] J. Vila, P. Gines, E. Rilo, O. Cabeza, L.M. Varela, Fluid Phase Equilibr. 247 (2006)3239.

[30] T. Nishida, Y. Tashiro, M. Yamamoto, J. Fluorine Chem. 120 (2003) 135141.

[31] L.F. Chiu, H.F. Liu, M.-H. Li, J. Chem. Eng. Data 44 (1999) 631636.[32] N.S. Osborne, H.F. Sitmson, D.C. Ginnings, J. Res. Natl. Bur. Stand. 23 (1939)

197260.[33] J. Kumelan, A.P.-S. Kamps, D. Tuma, G. Maurer, J. Chem. Thermodyn. 38 (2006)

13961401.[34] J. Vila, L.M. Varela, O. Cabeza, Electrochim. Acta 52 (2007) 74137417.

JCT 08-235


scifinder scholar reference 12 science 8 citation

Documents