[DCA]-based ionic liquids for the extraction of sulfur and nitrogen compounds from fuels: Activity coefficients at infinite dilution

Journal Pre-proof [DCA]-based ionic liquids for the extraction of sulfur and nitrogen compounds from fuels: Activity coefficients at infinite dilution Urszula Domańska, Michał Wlazło, Monika Karpińska PII:

S0378-3812(19)30486-8

DOI:

https://doi.org/10.1016/j.fluid.2019.112424

Reference:

FLUID 112424

To appear in:

Fluid Phase Equilibria

Received Date: 18 September 2019 Revised Date:

21 November 2019

Accepted Date: 22 November 2019

Please cite this article as: U. Domańska, Michał. Wlazło, M. Karpińska, [DCA]-based ionic liquids for the extraction of sulfur and nitrogen compounds from fuels: Activity coefficients at infinite dilution, Fluid Phase Equilibria (2019), doi: https://doi.org/10.1016/j.fluid.2019.112424. This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. © 2019 Published by Elsevier B.V.

Fluid Phase Equilibria

[DCA]-based ionic liquids for the extraction of sulfur and nitrogen compounds from fuels: activity coefficients at infinite dilution Urszula Domańskaa,b*, Michał Wlazłoc, Monika Karpińskac,d a

Industrial Chemistry Research Institute, Rydygiera 8, 01-793 Warsaw, Poland.

b

Thermodynamic Research Unit, School of Chemical Engineering, University of KwaZulu-

Natal, Howard College Campus, King George V Avenue, Durban 4001, South Africa. c

Department of Physical Chemistry, Faculty of Chemistry, Warsaw University of Technology,

Noakowskiego 3, 00-664 Warsaw, Poland. d

The Kielanowski Institute of Animal Physiology and Nutrition, Polish Academy of Sciences,

Instytucka 3, 05-110 Jabłonna, Poland.

Received: 18 September 2019 Keywords: Ionic liquids [N-C3CNPy][DCA] and [N-C3CNMPyr][DCA]

Activity coefficients at infinite dilution Thermodynamics Extraction

*

Corresponding author

E-mail address: [email protected] (U.Domańska).

1

ABSTRACT Some petroleum processes need the removal of low level aromatic-sulfur and nitrogen compounds for many products, which are extremely important according to the new strict environmental regulations to reduce sulfur and nitrogen content compounds in liquid fuels. Thus the new, alternative solvents such as ionic liquids (ILs) have been proposed. ILs reveal a high selectivity and capacity of extraction of sulfur- and nitrogen-compounds from alkanes with little solvent loss during the process. The measurements of activity coefficients γ 13∞ at infinite dilution of different solutes in the IL shows the effect of interactions between organic solutes, or water on the interfacial and bulk properties of the IL. The new (3cyanopropyl)pyridinium

dicyanamide,

[N-C3CNPy][DCA]

and

(3-

cyanopropyl)methylpyrrolidinium dicyanamide, [N-C3CNMPyr][DCA] were investigated in this work. The data were obtained using the gas-liquid chromatography technique. Measurements were undertaken at six temperatures, in 10 K intervals, in the range of (318.15 to 368.15) K. The solutes studied included both non-polar and polar compounds, as alkanes, alkenes, alkynes, as well as aromatic hydrocarbons, alcohols, water, ethers, ketones, and esters. The most important solutes used were thiophene, pyridine, and 1-nitropropane. Densities, ρ, measurements for a range of temperatures, T (298.15 -368.15) K for the chosen ILs were undertaken at pressure, p = 101 kPa. The gas-liquid partition coefficients, K L at infinite dilution were calculated. The fundamental thermodynamic functions such as partial molar excess Gibbs energy, enthalpy and entropy at infinite dilution were calculated from the experimental data measurements to discuss the interaction between solutes and the ILs. The values of selectivity and capacity for three separation cases, viz. heptane/thiophene, heptane/pyridine, and heptane/1-nitropropane were calculated from γ 13∞ values and compared to literature data for dicyanamide-based ILs. The Abraham solvation parameter model was

2

presented for all solutes. The obtained results indicated that [N-C3CNPy][DCA] has large selectivity and capacity values for all three of the separation cases studied.

3

1.

Introduction In recent years, the deep desulfurization of diesel fuel has become the most studied process

with different techniques (extraction, liquid-liquid separation, oxidative desulfurization, adsorption). The emission of sulphur- and nitrogen- compounds from petrol and diesel oils, which is linked to acid rain phenomena, plays a crucial role in pollution problems of large conglomerates. From decades the new regulations regarding of sulfur content in fuels are restricted in USA and Europe [1,2]. Ionic liquids (ILs) have the ability of extracting aromatic sulfur- and nitrogen-containing compounds at ambient conditions. Additionally, ILs are immiscible with fuel, are non-volatilate and can be regenerated and recycled by solvent washing. At present, hydrodesulfurization (HDS) processes is the established method used in some industrial technologies to remove organic sulphur-compounds but without polycyclic organic sulfides such as thiophene, benzothiophene, methyldibenzothiophenes, 4,6dibenzothiophenethiols, thioethers, and disulfides [3]. The HDS technology needs high temperature, high pressure, large reactor volumes, and expensive active catalyst [3]. Therefore, new scientific achievements for deep desulfurization and denitrogenation of fuels have become very important. The use of ILs as a ne solvents is suggested by many authors [416]. Preliminary information about suitable solvents for separation can be obtained from activity coefficients at infinite dilution ( γ 13∞ ) measurements using the gas-liquid chromatography (GLC) technique. The information obtained from infinite dilution activity coefficients is generally the first step in the engineering design process to determine the most suitable extraction and separation processes. The use of predictive models, such as Mo UNIFAC, PC SAFT, or COSMO RS are to date not accurate and reliable enough for the design of separation processes and restricted to the description of simple systems only [17-20]. Thus, the importance and need for experimental data is observed.

4

Solvent suitability can also be determined from liquid-liquid phase equilibrium measurements in ternary systems (LLE) [21-28]. The suitability of using four different, more specific

ILs,

such

as

trisfluorotris(perfluoroethylphosphate methylmorpholinium

4-(2-methoxyethyl)-4-methylmorpholinium [COC2MMOR][FAP],

bis{(trifluomethyl)sulfonyl}imide

methoxyethyl)-1-methylpyrrolidinium [COC2MPYR][FAP]

4-(2-methoxyethyl)-4-

[COC2MMOR][NTf2],

1-(2-

trisfluorotris(perfluoroethylphosphate,

and

1-(2-methoxyethyl)-1-methylpyrrolidinium

bis{(trifluomethyl)sulfonyl}imide [COC2MPYR][NTf2] as solvents in liquid–liquid extraction at T = 298.15 K was presented by our group [21,22]. The results in that research showed that out of these four ILs, the [COC2MMOR][NTf2] was the best solvent for the sulfur compounds/aliphatic hydrocarbons separation [21,22]. Attractive extraction selectivities were obtained

for

1-ethyl-3-methylimidazolium

bis{(trifluoromethyl)sulfonyl}imide,

[EMIM][NTf2] ([23] and references therein), 1-ethyl-3-methylimidazolium thiocyanate, [EMIM][SCN] [7] and 1,3-dimethylimidazolium methylphosphonate [DMIM][MP] [7]. The pyrrolidinium-based ILs with different anions [25], or 1-alkylpiperidinium-based [28], or 1alkylcyanopyridinium-based ILs [27] have been studied in our laboratory in ternary LLE {IL + thiophene, or benzothiophene + heptane) with high selectivities, especially for 1alkylcyanopyridinium-based ILs [27]. Even better results of extraction of thiophene and benzothiophene were obtained with 1-ethyl-3-methylimidazolium tricyanomethanide, [EMIM][TCM] IL [26]. Promising results were obtained with tricyanomethanide-based, [TCM]- and dicyanamide-based [DCA]- ILs in ternary LLE [10]. The investigated in that work ILs revealed as high as 78 and 87 mass % of extracted thiophene and benzothiophene, respectively. The selectivity was in the order [M3BPY][DCA] ~ [BMIM][TCM] > [M4BPY][DCA] > [M4BPY][SCN] > [BMIM][DCA] > [BMIM][SCN] [7]. Many works reported that there is a great potential for using ILs with cyano group, CN- in the cation, or in

5

the anion as good solvents for the separation of sulfur compounds from aliphatic hydrocarbons due to their remarkable selectivity towards sulfur compounds [11,21,22,25,26]. ∞ Selectivities, S12∞ = γ 13∞ / γ 23 and capacities, k 2∞ = 1 / γ 2∞ for the heptane/thiophene separation

problem, calculated from the limiting activity coefficient at T = 328.15 K for the best [DCA]based ILs are as follows: for [N-C3OHMMor][DCA] ( S12∞ = 417, k 2∞ = 0.32 at T = 308.15K) [29], [EMMor][DCA] ( S12∞ = 273, k 2∞ = 0.42) [30], [N-C3OHPy][DCA] ( S12∞ = 163, k 2∞ = 0.37) [31], [N-C3OHMIM][DCA] ( S12∞ = 156, k 2∞ = 0.39) [29], and for [N-C3CNMIM][DCA] ( S12∞ = 138, k 2∞ = 0.41) [32]. The aim of this study is to overcome the solvent separation ability for new [DCA]-based ILs by an analysis of their selectivities and capacities, calculated from γ 13∞ values. Solutes, heptane, thiophene, pyridine, 1-nitropropane used in this work are model substances for fuel and sulphur- or nitrogen-organic compounds, respectively. In this work we continue our investigations on the measurements of γ 13∞ and an analysis of the obtained selectivities and capacities for heptane/thiophene heptane/pyridine, and heptane/1-nitropropane separation processes. This work proposes to study a particular type of ILs, synthesized in our laboratory, (3-cyanopropyl)pyridinium

dicyanamide,

[N-C3CNPy][DCA]

and

(3-

cyanopropyl)methylpyrrolidinium dicyanamide, [N-C3CNMPyr][DCA] as a function of temperature at ambient pressure to compare the results with data previously measured in our laboratory. According to many sources in literature, the high interaction of cyano group of the IL is causing the strong interaction between the cation of the IL and aromatic compounds. In this paper we report the activity coefficients, γ 13∞ at infinite dilution, the gas-liquid partition coefficients K L and thermodynamic functions at infinite dilution for all measured solutes. The thermodynamic properties obtained are analyzed with regard to the intermolecular

6

interactions. The Abraham solvation parameter model was also presented for all solutes. The densities of the ILs were performed as a function of temperature.

2.

Materials and methods

2.1.

Chemicals

The ILs used in this work were synthesized in our laboratory. Synthesis, 1H NMR, 13C NMR spectra were described earlier [33]. The structure, name, abbreviation and molar mass results and purification method and purity are shown in Table 1. The different solutes, purchased from Aldrich or Fluka, had purities better than 0.97 mass fraction and were used without further purification due to the fact that the GLC technique separates any impurities on the column. The specification and purity is shown in Table 1S in the Supplementary Material (SM).

2.2. Water content The water content of the solvents was analyzed by the Karl-Fischer titration technique (method TitroLine KF). The sample of IL, or solvent was dissolved in methanol and titrated in steps of 0.0025 cm3. The uncertainty on the water content was u (w.c.) = 10 ppm for the 3 cm3 sample of IL injected. The water content in ILs was < 500 x10-6 in mass fraction.

2.3. Density measurements The density of the ILs was measured using an Anton Paar GmbH 4500 vibrating-tube densimeter (Graz, Austria), thermostated over a temperature range of (298.15-368.15) K. Two integrated Pt-100 platinum thermometers provided good precision in temperature control internally (T± 0.01 K). The densimeter has an automatic correction for the viscosity of the 7

sample. The apparatus is precise to within 1⋅10-5g cm-3, and the uncertainty of the measurements was estimated to be u (ρ) = ± 1.1· 10−3g cm-3. The densimeter’s calibration was performed at atmospheric pressure using doubly distilled and degassed water (PURE LAB Option Q Elga Water System), specially purified benzene (CHEMIPAN, Poland 0.999), and dried air. The densities of ILs are listed in Table 2. The only literature data was found for [NC3CNPy][DCA], ρ/g cm–3 = 1.168 at 293.15 K, which agreed very well to our measurements [34] and for [N-C3OHPy][DCA], ρ/g cm–3 = 1.17636 at 298.15 K [31]. The information in the whole temperature range for [N-C3OHPy][DCA] is shown in Table 2S and in Fig. 1S in the SM [31].

2.4. Apparatus and experimental procedure Experiments were performed using a Perkin Elmer Clarus 500 gas chromatograph equipped with a thermal conductivity detector (TCD). The data were collected and processed using the TotalChrom Workstation software. The column preparation and the packing method used in this work have been described in detail in our previous work [30,31]. Glass columns of length 1 m, with a 4 mm internal diameter were used. The solid support Chromosorb W/AW-DCMS 100/120 mesh was supplied by Sigma-Aldrich. Coating of the solid support material with the IL was performed by dispersing a certain portion of the IL in methanol, followed by evaporation of the solvent using a rotary evaporator. The masses of the stationary phase and of the solid support were weighed with a precision ±0.0001 g, achieving an uncertainty in the IL loading on the column in the order of 2 × 10–4mmol. The solvent loading on the column for [N-C3CNPy][DCA] was 50.30% and 45.42% mass percent, and for [N-C3CNMPyr][DCA] it was 44.88% and 49.82% mass percent. In our experimental work we always use the large column loading, which prevents possible residual adsorption of solute onto the column packing. The methanol was completely evaporated from the IL-coated solid support prior to 8

column fabrication. Prior to each experiment, the column was conditioned by blowing hot carrier gas through it at a high flow rate (~2.0 cm3⋅s–1) at T = 370 K for about 8 h. The pressure drop (pi – po) was varied between 10 and 80 kPa depending on the flow rate of the carrier gas. The inlet pressure, pi, was measured by a pressure gauge installed on the gas chromatograph with an uncertainty of ±0.1 kPa and the outlet pressure, po, was measured using an Agilent Precision Gas Flow Meter having an uncertainty of ±0.07 kPa. The mean column pressure, p inlet column pressure, pi, outlet column pressure, po and standard state of solutes at given temperatures and standard state are listed in Table 3S in the SM. Helium was the carrier gas used in the measurements. The flow rate of carrier gas was determined using an Agilent precision gas flow meter, which was placed at the outlet after the detector and had an uncertainty of ±0.1 ml min–1. The flow rate was set for a series of runs and was allowed to stabilize for at least 15 min before any γ 13∞ determinations were made. Solute injections ranged from 0.01 to 0.3 µl and can be considered to be at “infinite dilution” on the column. Temperature-dependent experiments were carried out in 10 K steps from (318.15 to 368.15) K. The temperature of the column was maintained constant to within ±0.02 K. Each experiment was repeated at a given temperature, two to three times to establish reproducibility. Retention times were generally reproducible to within 10–3 to 10–2 min depending upon the temperature and the individual solute. At each temperature, values of the dead time, tG, equivalent to the retention time of a completely non-retained component were also measured. While our GC was equipped with a TCD detector, air was used as a nonretainable component. The estimated overall error in γ 13∞ was less than 3%, taking into account the possible errors in determining the column loading, the retention times, and solute vapor pressure. The resultant activity coefficient values as a function of temperature are

9

summarized in Tables 3 and 4 for [N-C3CNPy][DCA] and [N-C3CNMPyr][DCA], respectively.

3. Theoretical basis The well known equations developed by Everett [35] and Cruickshank et al. [36] were used as in all our works to calculate γ 13∞ for solutes in ILs:

(

)

(

 n RT  p * B − V * p J 3 2 B12 − V1∞ ln γ 13∞ = ln 3 *  − 1 11 1 + o 2 RT RT  V N p1 

)

(1)

In this expression, n3 is the number of moles of solvent on the column packing, R is the Universal Gas Constant, T is the column temperature, VN denotes the net retention volume of the solute, p1* is the saturated vapor pressure of the solute at temperature T, B11 is the second virial coefficient of pure solute, V1* is the molar volume of the solute, po is the outlet pressure, p o J 23 is the mean column pressure, B12 (where the subscript “2” refers to the carrier gas, in

this case helium) is the mixed second virial coefficient of the solute and carrier gas, and V1∞ is the partial molar volume of the solute at infinite dilution in the solvent. The thermophysical properties required in developing the activity coefficients at infinite dilution were calculated using equations and constants known from literature [37]. The values of B12 were calculated using the Tsonopolous equation [38]. Most of the calculated data were presented in our earlier work [39]. The pressure correction term, J 23 , is given by:

2 ( pi / po ) − 1 3 ( p i / p o )2 − 1 3

J 23 =

(2)

10

The net retention volume of the solute, VN, is given by:

V N = ( J 23 ) −1U o (t R − t G )

(3)

where tR and tG are the retention times for the solute and an unretained gas, respectively, and Uo is the column outlet flow rate, corrected for the vapor pressure of water by:  p T U o = U 1 − w  po  T f 

(4)

where Tf is the temperature at the column outlet, pw is the vapor pressure of water at Tf, and U is the flow rate measured with the flow meter. While the activity coefficients at infinite dilution are determined as a function of temperature, ln γ 13∞ can be split to its respective partial molar excess thermodynamic functions:

ln γ 13∞ =

∆H 1E ,∞ ∆S1E ,∞ − RT R

(5)

Assuming that the temperature dependence follows a linear van’t Hoff plot:

ln γ 13∞ = a T + b

(6)

the partial molar excess enthalpy, ∆H1E , ∞ = Ra , at infinite dilution can be obtained from the slope.

11

(

)

The gas-liquid partition coefficient K L = c1L c1G for a solute partitioning between a carrier gas and the ILwas calculated from the solute retention according to the following equation

(

 V ρ  P J 3 2 B12 − V1∞ ln (K L ) = ln N 3  − o 2 RT  m3 

)

(7)

In which ρ3 is the density of the IL and m3 is the mass of the IL and V1∞ is the partial molar volume of the solute at infinite dilution.

3.1. The Abraham solvation parameter model The Abraham solvation parameter model is presented by the eqn. (8) [40,41]:

Log KL = c + e E + s S + a A + b B + l L

(8)

The independent variables in eqn. (8) are the solute descriptors [40-45], which are as follow: E is the solute excess molar refraction in units of (cm3 mol–1)/10, S is the solute dipolarity/polarizability, A and B are the overall or summation solute hydrogen bond acidity and basicity, and L is the logarithm of the gas-hexadecane partition coefficient at temperature T = 298 K. Solute descriptors are available for more than 4000 organic and organometallic compounds. The six regression coefficients (c, e, s, a, b, and l) relate to the properties of the solvent phase and they are determined by regression analysis from experimental KL values. The c coefficient is the model constant taking into account opposing contributions of different effects: e – interactions with lone pair electrons, s – dipole-type interactions, a and b – the hydrogen-bond basicity and acidity of the stationary phase respectively, l – cavity formation and dispersion interactions.

12

4. Results and discussion

Densities of [N-C3CNPy][DCA] and [N-C3CNMPyr][DCA] were measured in this work as a function of temperature and are listed in Table 2 together with the information from literature for one data point. The density measurements were carried out in the temperature range from (298.15 to 368.15) K at pressure p = 101 kPa. The values obtained at T = 298.15 K are 1.16664 g cm–3 and 1.09640 g cm–3for [N-C3CNPy][DCA] and [N-C3CNMPyr][DCA], respectively. The average values of γ 13∞ for the measured solutes in [N-C3CNPy][DCA] and [NC3CNMPyr][DCA], determined at six temperatures in a range of temperature from (318.15 to 368.15) K at pressure p = 101 kPa are listed in Tables 3 and 4, respectively. An analysis of the values of γ 13∞ shows large differences in possible interaction between a solute and the IL at infinite dilution. The data for [N-C3CNPy][DCA] shows almost two times larger values of γ 13∞ for the non-polar solutes in comparison with

[N-C3CNMPyr][DCA], which means much lower

interaction between the pyridinium-based cation with hydrocarbons than those of the pyrrolidinium-based cation. Aromatic hydrocarbons show also higher values of γ 13∞ for [NC3CNPy][DCA] in comparison with [N-C3CNMPyr][DCA], but the differences are not so large. The interaction between solutes and the IL for polar substances, such as alcohols and water is similar for both ILs. Important values of the discussed in this paper solutes at T = 328.15 K are: for heptane γ 13∞ = 702 or γ 13∞ = 417 in [N-C3CNPy][DCA] and [NC3CNMPyr][DCA], respectively; for thiophene γ 13∞ = 3.14 or γ 13∞ = 1.98 in [N-C3CNPy][DCA] and [N-C3CNMPyr][DCA], respectively; for pyridine γ 13∞ = 2.02 or γ 13∞ = 3.08 in [N-

13

C3CNPy][DCA] and [N-C3CNMPyr][DCA], respectively and for 1-nitropropane γ 13∞ = 1.54 or

γ 13∞ = 2.12 in [N-C3CNPy][DCA] and [N-C3CNMPyr][DCA], respectively. For all these solutes, the interaction with the ILs is almost the same for both ILs discussed. This my suggests that the differences in selectivity will be not very large for the selected ILs. Similar values were observed in our earlier work for 1-benzyl-3-methylimidazolium dicyanamide, [BzMIM][DCA]. For example for pyridine it was ( γ 13∞ = 1.03) at T = 328.15 K [46]. The influence of the alkyl chain length in a series of alkanes, cycloalkanes, alkenes, alkynes, aromatic hydrocarbons (increasing radicals), alcohols, ethers, and ketones drawn from Tables 3 and 4 shows that the γ 13∞ values increase with the alkyl chain length, which is an indication of the decrease of interactions between the solute and the IL at infinite dilution. Furthermore, despite the lower number of alkyl chains, the higher measured retention time is an evident observation of the decrease of the γ 13∞ values, and of an increase in the interactions between the IL and solute. The strongest interaction (the lowest values of γ 13∞ at all temperatures) is observed for water ( γ 13∞ = 0.434) and ( γ 13∞ = 0.338) for [N-C3CNPy][DCA] and [N-C3CNMPyr][DCA], respectively. The largest values of γ 13∞ provide the initial information about the lower interactions. As for all ILs, measured by us, the largest values are observed for nonane ( γ 13∞ = 1390), or ( γ 13∞ = 928), decane ( γ 13∞ = 1839), or ( γ 13∞ = 1329), and dec-1-ene ( γ 13∞ = 1077), or ( γ 13∞ = 695) for [NC3CNPy][DCA] and [N-C3CNMPyr][DCA], respectively. The values for [BzMIM][DCA] were lower: for nonane ( γ 13∞ = 332), for decane ( γ 13∞ = 509) and dec-1-ene ( γ 13∞ = 220) at T = 328.15 K [46]. An interesting features worth to be mentioned are the values obtained for the IL, 1allyl-3-methylimidazolium dicyanamide, [AMIM][DCA], which shows the same relations in

14

the interactions for the measured solutes. Strong interactions of [AMIM][DCA] were observed with water ( γ 13∞ = 0.341 at T = 328.15 K), all alcohols, thiophene, pyridine and 1nitropropane with γ 13∞ < 2 at T = 328.15 K [47]. Nonetheless, the low values of γ 13∞ for polar solutes such as thiophene, pyridine, and 1-nitropropane obtained for the measured ILs suggest the high potential for the extraction of these compounds from alkanes, which is important in petrochemical processes, e.g. desulphurization and denitrification of fuels. The endothermic and exothermic effects accompanying the interactions of solutes with the IL are presented in Figs 2S-15S in the SM. These diagrams show the plot of the natural logarithm of the γ 13∞ as a function of the inverse absolute temperature for all investigated solutes. The γ 13∞ values decrease with an increasing temperature for alkanes, alkenes, cycloalkanes and cylcloalkenes (see Figs. 2S and 3S in the SM for [N-C3CNPy][DCA] and Figs. 9S and 10S for [N-C3CNMPyr][DCA]). The opposite influence of temperature is presented for alkynes in both ILs (see Figs. 3S and 10S in the SM) and for aromatic hydrocarbons (see Figs. 4S and 11S in the SM). Only for propylbenzene and isopropylbenzene in [N-C3CNPy][DCA] the γ 13∞ values decrease with an increasing temperature as it is illustrates in Fig. 4S in the SM. The values of γ 13∞ for methanol and water (Fig 5S and 12S in the SM) as well as for diethyl ether, di-iso-propyl ether and MTBE (Fig 6S and 13S in the SM) for both ILs increase with an increasing temperature. The values of γ 13∞ for esters, ketones, THF, 1,4-dioxane and thiophene in both ILs increase with an increasing temperature (see Fig. 7S for [N-C3CNPy][DCA] and Figs. 14S and 15S for [N-C3CNMPyr][DCA] in the SM). The gas-liquid partition coefficient, K L , calculated from eqn. 7 is an important property of the IL. This property shows the suitability of the IL for particular application in extraction. The data for [N-C3CNPy][DCA] and [N-C3CNMPyr][DCA], are listed in Tables 5 15

and 6. From these Tables we can see that the lowest values are observed for alkanes ( K L = 0.927 and K L = 1.43 for heptane at T = 328.15 K in [N-C3CNPy][DCA] and [NC3CNMPyr][DCA], respectively) cycloalkanes, cylcloalkenes, alkenes, alkynes and ethers. The large values of K L are observed for water ( K L = 2158 and K L = 2533 at T = 328.15 K in [N-C3CNPy][DCA] and [N-C3CNMPyr][DCA], respectively), for 1-pentanol ( K L = 824 and K L = 1265 at T = 328.15 K in [N-C3CNPy][DCA] and [N-C3CNMPyr][DCA], respectively),

and for 1-nitropropane ( K L = 753 and K L = 1001 at T = 328.15 K in [N-C3CNPy][DCA] and [N-C3CNMPyr][DCA], respectively). These values are much lower than those observed for [AMIM][DCA] [47]. The large K L values correspond to a large affinity of the solute to the liquid phase. The K L value increases with a decrease of temperature and with an increase of the alkane chain length for alkanes, alkenes, alkynes, cycloalkanes, alcohols, esters and ethers. The K L values increase with an increase of the radicals in the aromatic compounds. Table 7 lists the partial molar excess Gibbs energies, ∆G1E,∞ , at infinite dilution, the partial molar excess enthalpies, ∆ H 1E, ∞ , at infinite dilution, and the partial molar excess entropies at infinite dilution, Tref ∆S1E , ∞ , for all the solutes studied at reference temperature T = 328.15 K. These thermodynamic functions describe the interaction between solute and the IL and are an important pointer in determining the suitability of the IL for extraction. The ∆G1E,∞ was calculated from the temperature dependence of γ 13∞ from eqns. 5 and 6. The values of ∆G1E,∞ are positive for all solutes except methanol, water for both ILs and acetonitrile in

pyrrolidynium-based IL. This is similar to the earlier measured data for [BzMIM][DCA] [46] and [AMIM][DCA] [47]. The infinite dilution activity coefficient values are lower than one for these solutes, i.e. γ 13∞ < 1, which corresponds to the (IL + solute) binary system with negative deviations from Raoult's law. For the remaining solutes, including decane ( ∆G1E,∞ =

16

20.5 kJ mol-1 and ∆G1E,∞ = 19.6 kJ mol-1 in [N-C3CNPy][DCA] and [N-C3CNMPyr][DCA], respectively) positive deviations from ideality are obtained. The partial excess molar enthalpies at infinite dilution, ∆ H 1E, ∞ , determined from the Gibbs-Helmholtz equation exhibit negative values for alkynes, aromatic hydrocarbons (excluding propylbenzene and isopropylbenzene in [N-C3CNPy][DCA]), esters some ethers, ketones and 1-nitropropane for both ILs. For these solutes relatively strong energetic solute-solvent interactions are observed. Additionally, there are negative ∆ H 1E, ∞ values for both ILs with water and methanol. As expected, the ILs used in this work, exhibits possible π - π, or n - π interactions with most of the solutes, which leads to negative values of ∆ H 1E, ∞ and

Tref ∆S1E , ∞ . Mainly for aliphatic

hydrocarbons, the endothermic interaction, resulting from the energetic weakness of their interaction with the IL is observed. The partial excess molar entropies at infinite dilution, Tref ∆S1E , ∞ , are small and negative for almost all solutes studied for both ILs. The solution of the majority of the solutes in both ILs is accompanied by entropy losses, which may suggest that the solute molecule arranges itself in the IL structure.

5. Separation of heptane/thiophene, heptane/pyridine and heptane/1-nitropropane The comparison of the values of activity coefficients, γ 13∞ for both ILs measured in this work with similar [DCA]- based ILs such as [N-C3OHPY][DCA] [31], [N-C3CNMIM][DCA] [48], [BMPy][DCA] [49] and [BMPyr][DCA] [50] is presented in Fig.1. As we can see, the highest values of γ 13∞ for almost all solutes are for [N-C3CNPy][DCA] and lower than these values (stronger interaction) are for [N-C3CNMPyr][DCA]. The lowest values (the stronger interaction) was however observed for [BMPy][DCA] [49]. To make the analysis of the

17

performance of the [N-C3CNPy][DCA] and [N-C3CNMPyr][DCA] ILs as an extraction solvents for the discussed in this work separation processes, the characteristic parameters for the separation, the selectivity ( S 12∞ = γ 1∞ / γ 2∞ ) and the capacity ( k 2∞ = 1 / γ 2∞ ) were calculated from the experimental γ 13∞ values. The results are presented in comparison with different ILs for heptane (1)/thiophene (2) at temperature T = 328.15 K, along with literature data for some ILs with the same anion, [DCA]-. The analysis presented in Fig. 2 included [NC3OHMMor][DCA]

[29],

[N-C3OHMIM][DCA]

[29],

[EMMor][DCA]

[30],

[N-

C3OHPy][DCA] [31], [EMIM][DCA] [32], [BzMIM][DCA] [46] [AMIM][DCA] [47], [NC3CNMIM][DCA] [48], [BMPy][DCA] [49], [BMPyr][DCA] [50], [C2OHMIM][DCA] [51], [C2ClMIM][DCA] [51], and [BMIM][DCA] [52]. The list of ILs cations and anions used in comparison of γ 13∞ , S12∞ and k12∞ with their abbreviations and structures is shown in Table 5. Studying the effect of the cation structure on the extractive properties we can observed from Fig. 2 that the best selectivity for heptane (1)/thiophene (2) at temperature T = 328.15 K is for [N-C3OHMMor][DCA] [29], [N-C3CNMIM][DCA] [48] and for [EMMOR][DCA] [30]. The ILs used in this work have selectivity >200, but lower than those observed for ILs mentioned above. In addition, to evaluate the potential of the ILs to be used at industrial scale, a comparison of capacity has to be performed. The best capacities were observed for [BMPYR][DCA] [50] and [BMPy][DCA] [49] but with very low selectivity, lower than < 100. Fig. 3 presents selectivity and capacity of the extraction of pyridine from heptane at temperature T = 328.15 K. The best selectivity is for [N-C3OHMMor][DCA] [29] and for [C2OHMIM][DCA] [51]. The best capacity is observed for [BMPy][DCA] [49] and for [BMIM][DCA] [52], again with the selectivity lower than < 100. Better results for the ILs, measured in this work, were for [N-C3CNPy][DCA] with the selectivity larger than >300. 18

Fig. 4 presents selectivity

and capacity for heptane/1-nitropropane problem at

temperature T = 328.15 K. The results are similar to mentioned above. High selectivity was obtained also for [N-C3CNMIM][DCA] [48]. Table 8 presents the results for all three separation processes, discussed in this work, at temperature T = 328.15 K. Even though the experimental data present large discrepancies among different literature sources, one can conclude that the selectivities for the heptane (1)/thiophene (2) separation, obtained with morpholinium-based ILs is high with the best value for the [N-C3OHMMor][DCA] ( S12∞ = 274; k12∞ = 0.30) [29] and for the [EMMor][DCA] ( S12∞ = 273; k12∞ = 0.42) [30]. The selectivity for [N-C3CNPy][DCA] is larger than that for [NC3CNMPyr][DCA] ( S12∞ = 224; k12∞ = 0.32). The largest values of selectivity for the heptane (1)/pyridine (2) separation are also for [NC3OHMMor][DCA] ( S12∞ = 514; k12∞ = 0.56) [29] and for [C2OHMIM][DCA] ( S12∞ = 485; k12∞ = 0.77) [51]. The selectivity for [N-C3CNPy][DCA] is larger than that for [NC3CNMPyr][DCA] ( S12∞ = 348; k12∞ = 0.50). The largest values of selectivity for the heptane (1)/1-nitropropane (2) separation are for [N-C3CNMIM][DCA] ( S12∞ = 287; k12∞ = 0.44) [48] and for [N-C3OHMMor][DCA] ( S12∞ = 276; k12∞ = 0.30) [29]. The selectivity for [N-C3CNPy][DCA] is larger than that for [NC3CNMPyr][DCA] ( S12∞ = 228; k12∞ = 0.46). Summing up, for all three separation cases, the [DCA]--based ILs used in this work reveal large selectivities and acceptable capacities. This is the result of the interaction of thiophene, pyridine and 1-nitropropane with [DCA]--based ILs. It is widely known that alkanes

are not soluble in the ILs. The introduction of a OH or CN group in the

morpholinium, or imidazolium, or pyridinium or pyrrolidinium cation slightly increases selectivity and the capacity, especially for morpholinium-based ILs.

19

6. Results of the Abraham Solvation Parameter Model

The linear solvation energy relationship (LFER) system constants as a function of temperature for the [N-C3CNPy][DCA] and [N-C3CNMPyr][DCA] ILs, investigated in this work, are presented in Tables 9 and 10. The solute descriptors are listed in Table 6S in the SM. The analysis of the selectivity of solvents and ILs towards pairs of gaseous compounds in terms of the log KL values was shown by Abraham and Acree [43]. The results of calculations are presented in Figs. 5 and 6. Table 5S in the SM presents cations of the discussed ILs. This work is the continuation of the presentation of the Abraham solvation parameter model for new, synthesized by us ILs. In our earlier work, the description was presented for 1-ethyl-3methylimidazolium tricyanomethanide [53], 1-ethyl-3-methylimidazolium tetracyanoborate [39],

1-butyl-4-methylpyridinium

tricyanomethanide,

1-butyl-3-methylimidazolium

tricyanomethanide [54], 1-butyl-1-methylpyrrolidynium tetracyanoborate [55], for 1-butyl-1methylpiperidynium bis{(trifluoromethyl)sulfonyl}imide in comparison with 1-butyl-1methylpiperidynium thiocyanate [56], for [DoMIM][NTf2] [57], and for [N-C3OHPY][DCA] [31].

7. Conclusions In this work, we have studied the potential use of (3-cyanopropyl)pyridinium dicyanamide, [N-C3CNPy][DCA] and (3-cyanopropyl)methylpyrrolidinium dicyanamide, [NC3CNMPyr][DCA] in three processes of separation, viz. heptane/thiophene, heptane/pyridine

and heptane/1-nitropropane as a model compounds for the desulfurization and denitrogenation of fuels. The data of the activity coefficients at infinite dilution were obtained using the gasliquid chromatography technique for 60 solutes in both ILs at six temperatures ranging between (318.15 and 368.15) K. In addition, densities of both ILs were measured as a 20

function of temperature. The interactions of various types of organic solutes and water with two ionic liquids at infinite dilution were discussed and shown with regard to the activity coefficients at infinite dilution, the gas liquid-partition coefficients and the thermodynamic functions at infinite dilution. Using the reported experimental data, along with other data from literature, the impact of the ILs cation in the three chosen separation problems was analyzed. The reported results show high values of selectivity for both ILs used with larger effects for [N-C3CNPy][DCA]. The presence of the CN group in the cation increased the selectivity in

both ILs in comparison with the simple pyridinium-based and pyrrolidinium-based cations of the ILs.

Supplementary Material: The sources and mass fraction purities of materials. Mean column pressure, p , inlet column pressure, pi, outlet column pressure, po and standard state of solutes at given temperatures, at standard state. Densities of ILs as a function of temperature. Plots of ln(γ13∞) versus 1/T for the organic solutes in ILs. The list of ILs cations and anions used in comparison of γ 13∞ , S12∞ and k12∞ with their abbreviations and structures. Solute descriptors for equation of the Abraham Solvation Model. Supplementary data associated with this article can be found, in the online version, at http:/dx.doi.org/ Acknowledgements This work has been supported by the National Science Center (NCN) in Poland in the years 2017–2020 (UMO-2016/23/B/ST5/00145). CRediT author statement Urszula Domańska: Conceptualization, Methodology, Supervision, Writing- Reviewing and Editing, Funding acquisition. Michal Wlazło: Metodology, Data curation, Visualization, Investigation. Monika Karpińska: Metodology, Formal analysis, Investigation, Validation.

21

Conflict of interest The authors have no conflict of interest. Appendix A. Supplementary data Supplementary data to this article can be found online at https://

References [1] Regulatory Impact Analysis of the United States Environmental Protection Agency EPA420-R00-026. [2] Directive of the European Parliament and of the Council, Brussels COM (11.05.2001) 241 final (BS EN 590-2004/DIN EN 590-2004), Automotive Fuels, Diesel, Requirements and Test Methods; and 2003/17/EC OJ L 76, 22.3.2003, p. 10. [3] M. Te,

C. Fairbridge, Z. Ring, Oxidation reactivities of dibenzothiophenes in

polyoxometalate/H2O2 and formic acid/H2O2 systems, Z. Appl. Catal. A, Gen. 219 (2001) 267-270. [4] J. Eβer, P. Wasserscheid, A. Jess, Deep desulfurization of oil refinery streams by extraction with ionic liquids, Green Chem. 6 (2004) 316-322. [5] Q. Wang, L. Lei, J. Zhu, B.Yang, Z. Li, Deep desulfurization of fuels by extraction with 4dimethylamminopyridinium-based ionic liquids (Conference paper), Energy and Fuels 27 (2013) 4617-4623. [6] Ch, Li, D. Li, Sh. Zou, Zh. Li, J. Yin, A. Wang, Y. Cui, Zh. Yao, O. Zhao, Extraction desulfurization process of fuels with ammonium-based deep eutectic solvents, Green Chem. 15 (2013) 2793-2799. [7] K. Kędra-Królik, F. Mutelet, J-N, Joubert, Extraction of thiophene or pyridine from n-

22

heptane using ionic liquids. Gasoline and diesel desulfurization, Ind. Eng. Chem. Res. 50 (2011) 2296-2306. [8] P.S. Kulkarni, C.A.M. Afonso, Deep desulfurization of diesel fuel using ionic liquids: current status and future challenges, Green Chem. 12 (2010) 1139-1149. [9] Ch. Yansheng, L. Changping, J. Qingzhu, L. Qingshan, Y. Peifang, L. Xiumei, U. WelzBiermann, Desulfurization by oxidation combined with extraction using acidic roomtemperature ionic liquids, Green Chem. 13 (2011) 1224-1229. [10] A.R. Hansmeir, G.W. Meindersma, A.B. de Haan, Desulfurization and denitrogenation of gasoline and diesel fuels by means of ionic liquids, Green Chem. 13 (2011) 1907-1913. [11] G.W. Meindersma, B.T.J. Simons, A.B. de Haan, Physical properties of 3-methyl-Nbutylpyridinium tetracyanoborate and 1-butyl-1-methylpyrrolidinium tetracyanoborate and ternary LLE data of [3-mebupy]B(CN)4 with an aromatic and an aliphatic hydrocarbon at T = 303.2 K and 328.2 K and p = 0.1 MPa, J. Chem Thermodyn. 43 (2011) 1628-1640. [12] C. Zhang, X. Pan, F. Wang, X. Liu, Extraction-oxydation desulfurization by pyridinium based task specific ionic liquids. Fuel 102 (2012) 580-584. [13] Y. Nie, Y. Dong L., L. Bai, H. Dong, X. Zhang, Fast oxidative desulfurization of fuel oil using dialkylpyridinium tetrachloroferrates ionic liquids, Fuel 103 (2013) 997-1002. [14] M. Larriba, P. Navarro, J. Garcia, F. Rodríguez, Liquid-liquid extraction of toluene from heptane using [emim][DCA], [bmim][DCA], and [emim][TCM] ionic liquids, Ind. Eng. Chem. Res. 52 (2013) 2714-2720. [15] P. Verdía, E.J. González, B. Rodríguez-Cabo, E. Tojo, Synthesis and characterization of new polysubstituted pyridinium-based ionic liquids: application as solvents on desulfurization of fuel oils, Green Chem. 13 (2011) 2768-2776.

23

[16] U. Domańska, M. Wlazło, Effect of the cation and anion of the ionic liquid on desulfurization of model fuels, Fuel 134 (2014) 114-125. [17] E.V. Lukoshko, F. Mutelet, K. Paduszyński, U. Domańska, Phase diagrams of binary systems containing tricyanomethanide-based ionic liquids and thiophene or pyridine, Fluid Phase Equilib. 399 (2015) 105-114. [18] U. Domańska, K. Paduszyński, M. Królikowski, A. Wróblewska, Separation of 2phenylethanol from water by liquid-liquid extraction with ionic liquids - new experimental data and modelling with modern thermodynamic tools, Ind. Eng. Chem. Res. 55 (2016) 55, 5736-5747. [19] M. Wlazło, E.I. Alevizou, E.C. Voutsas, U. Domańska, Prediction of ionic liquids phase equilibrium with the COSMO-RS model. Fluid Phase Equilib. 426 (2016)16-31. [20] U. Domańska, M. Wlazło, K. Paduszyński, Extraction butan-1-ol from aqueous solution using ionic liquids: an effect of cation revealed by experiments and thermodynamic models, Sep. Pur. Techn. 196 (2018) 71-81. [21]

A.

Marciniak,

M.

Królikowski,

Ternary

(liquid

+

liquid)

equilibria

of

{trisfluorotris(perflouroethyl)phosphate based ionic liquids + thiophene + heptane, J. Chem Thermodyn. 49 (2012) 154-158. [22]

A.

Marciniak,

M.

Królikowski,

Ternary

liquid-liquid

equilibria

of

bis(trifluoromethylsulfonyl)amide based ionic liquids + thiophene + n-heptane. The influence of cation structure, Fluid Phase Equilib. 321 (2012) 59-63. [23] B. Rodríguez-Cabo, A. Arce, A. Soto, Desulfurizarion of fuel-oils with [C2mim][NTf2]: a comparative study, J. Chem. Thermodyn. 57 (2013) 248-255. [24] B. Rodríguez-Cabo, A. Arce, A. Soto, Desulfurization of fuels by liquid-liquid extraction with 1-ethyl-3-methylimidazolium ionic liquids, Fluid Phase Equilib. 356 (2013) 126-135.

24

[25] U. Domańska, E.V. Lukoskho, M. Królikowski, Separation of thiophene from heptane with ionic liquids, J. Chem. Thermodyn. 61 (2013) 126-131. [26] M. Królikowski, K. Walczak, U. Domańska, Solvent extraction of aromatic sulfur compounds from n-heptane using 1-ethyl-3-methylimidazolium tricyanomethanide ionic liquid, J. Chem. Thermodyn. 65 (2013) 168-173. [27] U. Domańska, K. Walczak, M. Zawadzki, Separation of sulfur compounds from alkanes with 1-alkylcyanopyridinium-based ionic liquids, J. Chem. Thermodyn. 69 (2014) 27-53. [28] M. Wlazło, D. Ramjugernath, P. Naidoo, U. Domańska, Effect of the alkyl side chain of the 1-alkylpiperidinium-based ionic liquids on desulfurization of fuels, J. Chem. Thermodyn. 72 (2014) 31-36. [29] M. Karpińska, M. Wlazło, M. Zawadzki, U. Domańska, Separation of binary mixtures hexane/hex-1-ene, cyclohexane/cyclohexene and ethylbenzene/styrene based on gamma infinity data measurements, J. Chem. Thermodyn. 118 (2018) 244-254. [30] U. Domańska, M. Karpińska, M. Wlazło, Thermodynamic study of melecular interaction-selectivity in separation processes based on limiting activity coefficients, J. Chem. Thermodyn. 121 (2018) 112-120. [31] U. Domańska, M. Wlazło, M. Karpińska, M. Zawadzki, Separation of binary mixtures hexane/hex-1-ene. cyclohexane/cyclohexene and ethylbenzene/styrene based on limiting activity coefficients, J. Chem. Thermodyn. 110 (2017) 227-236. [32] A-L. Revelli, F. Mutelet, J.-N. Jaubert, M. Garcia-Martinez, L.M. Sprunger, W.E. Acree, Jr., G.A. Baker, Study of Ether-, Alcohol-, or Cyano-Functionalized Ionic Liquids Using Inverse Gas Chromatography, J. Chem. Eng. Data 55 (2010) 2434-2443. [33] M. Karpińska, M. Wlazło, M. Zawadzki, U. Domańska, Liquid-liquid separation of hexane/hex-1-ene and cyclohexane/cyclohexene by dicyanamide-based ionic liquids, J. Chem. Thermodyn. 116 (2018) 299-308.

25

[34] Q. Zhang, Z.Li, J. Zhang, S. Zhang, L. Zhu, J.Yang, X. Zhang, Y. Deng, Physicochemical properties of nitrile-functionalized ionic liquids, J. Phys. Chem. B 11 (2007) 2864-2872. [35] D. H. Everett, Effect of gas imperfectionon gas-liquid chromatography measurements: a refined method for determining activity coefficients and second virial coefficients, Trans. Faraday Soc. 61 (1965) 1637-1645. [36] A. J. B. Cruickshank, B. W. Gainey, C. P. Hicks, T. M. Letcher, R. W. Moody and C. L. Young, gas-liquid chromatographic determination of cross-term second virial coefficients using glycerol. Benzene + nitrogen and benzene + carbon dioxide at 500C, Trans. Faraday Soc. 65 (1969) 1014-1031. [37] DIPR Project 801, full version; Design Institute for Physical Properties Research, sponsored by AICHE (2005; 2008; 2009; 2010). Online version available at: http://knovel.com/web/portal/browse/display?_ext_knovel_display_bookid=1187&verticalid= 0. [38] B. E. Poling and J. M.Prausnitz, Properties of Gases and Liquids, The. [online]. McGraw-Hill Publishing, 2001. Available from: http://lib.myilibrary.com?ID=91317. [39] U. Domańska, M. Królikowska, W. E. Acree Jr., and G. A. Baker, Activity coefficients at infinite dilution measurements for organic solutes and water in the ionic liquid 1-ethyl-3 methylimidazolium tetracyanoborate, J. Chem. Thermodyn. 43 (2011) 1050-1057. [40] M.H. Abraham, Scales of solute hydrogen-bonding: their construction and application to physicochemical and biochemical processes, Chem. Soc. Rev. 22 (1993) 73–83. [41] M.H. Abraham, A. Ibrahim, A.M. Zissimos, Determination of sets of solute descriptors from chromatographic measurements, J. Chromatogr. A 1037 (2004) 29–47.

26

[42] W.E. Acree Jr., M.H. Abraham, The analysis of solvation in ionic liquids and organic solvents using the Abraham linear free energy relationship, J. Chem. Technol. Biotechnol. 81 (2006) 1441–1446. [43] M.H. Abraham, W.E. Acree Jr., Comparative analysis of solvation and selectivity in room temperature ionic liquids using the Abraham linear free energy relationship, Green Chem. 8 (2006) 906–915. [44] L.M. Grubbs, S. Ye, M. Saifullah, M.C. McMillan-Wiggins, W.E. Acree Jr., M.H. Abraham, P. Twu, J.L. Anderson, Correlations for describing gas-to-ionic liquid partitioning at 323 K based on ion-specific equation coefficient and group contribution versions of the Abraham model, Fluid Phase Equilib. 301 (2011) 257–266. [45] C.F. Poole, S.N. Atapattu, S.K. Poole, A.K. Bell, Determination of solute descriptors by chromatographic methods, Anal. Chim. Acta 652 (2009) 32-53. [46] M. Karpińska, M. Wlazło, D. Ramjugernath, P. Naidoo, U. Domańska, Assesment of certain ionic liquids for Separation of binary mixtures based on gamma infiniti data measurements, RSC Advances 7 (2017) 7092-7107. [47] M. Wlazło, J. Gawkowska, U. Domańska,

Separation based on limiting activity

coefficients of various solutes in 1-allyl-3-methylimidazolium dicyanamide ionic liquid, Ind. Eng. Chem. Res. 55 (2016) 5054-5056. [48] K. Paduszyński, M. Królikowski, An effect of cation's cyano group on interactions between organic solutes and ionic liquids elucidated by thermodynamic data at infinite dilution, J. Mol. Liq. 243 (2017) 726-736. [49] M. Królikowski, M. Królikowska, The study of activity coefficients at infinite dilution for organic solutes and water in 1-butyl-4-methylpyridinium dicyanamide,[B4MPy][DCA] using GLC, J. Chem. Thermodyn. 68 (2014) 138-144. 27

[50] A. Blahut, V. Dohnal, Interactions of volatile organic compounds with the ionic liquid 1butyl-1-methylpyrrolidinium dicyanamide, J. Chem. Eng. Data 56 (2011) 4909-4918. [51] K. Paduszyński, M. Królikowska, Effect of Side Chain Functional Group on Interactions in Ionic Liquid Systems: Insights from Infinite Dilution Thermodynamic Data, J. Phys. Chem. B 121 (2017) 10133-10145. [52] U. Domańska, M. Wlazło, M. Karpińska, Activity coefficients at infinite dilution of organic solvents and water in 1-butyl-3-methylimidazolium dicyanamide. A literature review of hexane/hex-1-ene, Fluid Phase Equilib. 417 (2016) 50-61. [53] M. Karpińska, M. Wlazło, U. Domańska, Separation of binary mixtures based on gamma infinity data using [EMIM][TCM] ionic liquid and modelling of thermodynamic functions, J. Molec. Liq. 225 (2017) 382-390. [54] E. Lukoshko, F. Mutelet, U. Domańska, Experimental and theoretically study of interaction between organic compounds and tricyanomethanide based ionic liquids, J. Chem. Thermodyn. 85 (2015) 49-56. [55] U. Domańska, M. Królikowski, W.E. Acree Jr., Thermodynamics and activity coefficients at infinite dilution measurements for organic solutes and water in the ionic liquid 1-butyl-1-methylpyrrolidinium tetracyanoborate, J. Chem. Thermodyn. 43 (2011) 1810-1817. [56] K. Paduszyński, U. Domańska, Limiting activity coefficients and gas–liquid partition coefficients of various solutes in piperidinium ionic liquids: measurements and LSER calculations, J. Phys. Chem. B 115 (2011) 8207-8215. [57] U. Domańska, M. Wlazło, Thermodynamics and limiting activity coefficients measurements for organic solutes and water in the ionic liquid 1-dodecyl-3-methylimidzolium bis(trifluoromethylsulfonyl) imide, J. Chem. Thermodyn. 103 (2016) 76-85.

28

Table 1 The name, abbreviation, structure, supplier, molar mass, mass fraction purity, water content and purification method of investigated ionic liquids. Structure

+

N

CN

M/(g mol-1)

(3-cyanopropyl)pyridinium dicyanamide, [N-C3CNPy][DCA]

213.24

495x 10-6

Purification method/meth od of analysis Low pressure 24 h 320 K (Analysis: 1 HNMR, 13 CNMR, ChA)

N N+

CN

N-

(3cyanopropyl)methylpyrrolidi nium dicyanamide, [N-C3CNMPyr][DCA] Synthesis [33]

N

Mass fraction purity /water content (mass fraction) >0.95/

Synthesis [33]

NN

Name, abbreviation, supplier,

N

29

219.29

>0.97/ 495x 10-6

Low pressure 24 h 320 K (Analysis: 1 HNMR, 13 CNMR, ChA)

Table 2 Density, ρ as a function of temperature, T for investigated ILs [N-C3CNPy][DCA] and [Na C3CNMPyr][DCA] at pressure p = 101 kPa.

[N-C3CNPy][DCA]

[N-C3CNMPyr][DCA]

T/K ρ/g cm–3

a

b

ρ/g cm–3

298.15b

1.16664b

1.09640

303.15

1.16348

1.09353

308.15

1.16033

1.09067

313.15

1.15720

1.08784

318.15

1.15411

1.08502

323.15

1.15103

1.08222

328.15

1.14798

1.07945

333.15

1.14495

1.07668

338.15

1.14195

1.07394

343.15

1.13896

1.07120

348.15

1.13598

1.06847

353.15

1.13301

1.06575

358.15

1.13006

1.06305

363.15

1.12712

1.06036

368.15

1.12419

1.05768

Standard uncertainties u are u (T) = ± 0.1 K u (ρ) = ± 1.1· 10−3 g cm−3, u (p) = ±1 kPa.

ρ/g cm–3 = 1.168 at 293.15 K in Ref. [34].

30

Table 3 The experimental activity coefficients at infinite dilution γ 13∞ for the solutes in ionic liquid [NC3CNPy][DCA] at different temperatures for the hypothetical liquid at zero pressure. a T/K Solute 318.15

328.15

338.15

348.15

358.15

Heptane

777

702

638

Octane

1071

997

Nonane

1480

Decane

930

869

818

1390

1315

1244

1182

1130

1943

1839

1745

1655

1578

1512

Cyclohexane

193

176

161

148

137

127

Methylcyclohexane

308

289

271

255

242

230

Cycloheptane

235

221

208

197

187

178

Cyclooctane

326

303

285

267

253

239

Cyclohexene

55.8

53.9

52.3

368.15

50.6

Hept-1-ene

322

312

301

292

284

Oct-1-ene

521

495

472

450

432

415

Dec-1-ene

1166

1077

1002

934

880

828

Pent-1-yne

18.8

19.6

20.3

21.0

21.7

22.4

Hex-1-yne

32.5

33.8

35.0

36.2

37.4

38.5

Hept-1-yne

59.4

60.9

62.4

63.6

65.0

66.2

Oct-1-yne Benzene

112 6.14

113

114

6.20

6.26

115 6.31

116 6.37

117 6.44

Toluene

10.1

10.3

10.6

10.8

11.0

11.3

Ethylbenzene

21.2

21.1

21.0

20.9

20.9

20.8

o-Xylene

14.0

14.2

14.3

14.5

14.6

14.7

m-Xylene

18.6

18.8

18.9

19.1

19.2

19.4

p-Xylene

17.6

17.7

17.9

17.9

18.0

18.1

Propylbenzene

43.0

42.2

41.5

40.9

40.3

39.7

iso-Propylbenzene

40.3

39.6

39.1

38.6

38.2

37.7

Styrene

8.89

9.04

31

9.17

9.31

9.44

9.58

T/K Solute α-Methylstyrene

318.15

328.15

338.15

348.15

358.15

368.15

14.9

15.4

15.9

16.4

17.0

17.4

Thiophene

3.03

3.14

3.26

3.37

3.47

3.57

Pyridine

1.97

2.02

2.08

2.14

2.18

2.24

Methanol

0.762

0.766

0.769

0.773

0.775

0.779

Ethanol

1.63

1.60

1.57

1.55

1.52

1.50

Propan-1-ol

2.69

2.61

2.55

2.48

2.43

2.38

Propan-2-ol

3.05

2.94

2.85

2.76

2.68

2.61

Butan-1-ol

4.57

4.37

4.20

4.04

3.90

3.77

Butan-2-ol

4.63

4.47

4.31

4.18

4.05

3.94

2-Methyl-1-propanol

4.71

4.45

4.23

4.04

3.86

3.71

tert-Butanol

4.67

4.54

4.43

4.32

4.23

4.14

Pentan-1-ol

7.37

7.05

6.76

6.49

6.26

6.06

Water

0.428

0.434

0.440

0.446

0.452

0.458

Methyl acetate

3.42

3.56

3.68

3.82

3.94

4.07

Methyl propanoate

6.42

6.62

6.81

7.00

7.19

7.36

Methyl butanoate

12.2

12.4

12.6

12.8

13.0

13.1

Ethyl acetate

7.40

7.62

7.82

8.04

8.22

8.42

Vinyl acetate

5.73

5.90

6.05

6.19

6.32

6.48

Tetrahydrofuran

3.85

3.97

4.08

4.17

4.27

4.36

1.4-Dioxane

1.78

1.91

2.04

2.17

2.30

2.43

tert-Butyl methyl ether tert-Butyl ethyl ether

39.0 142

40.1

41.1

139

136

42.2 133

43.2

44.2

131

tert-Amyl methyl ether

68.1

69.5

70.8

72.0

73.2

74.3

Diethyl ether

32.3

33.1

33.9

34.8

35.6

36.3

Di-n-propyl ether

155

150

146

142

Di-iso-propyl ether

169

157

147

138

Di-n-butyl ether

417

405

395

385

138

135

375

368

Acetone

1.99

2.07

2.15

2.23

2.32

2.39

Pentan-2-one

6.65

6.77

6.88

7.00

7.11

7.20

Pentan-3-one

6.68

6.89

7.06

7.23

7.40

7.56

32

T/K Solute 318.15

328.15

338.15

348.15

358.15

368.15

Butanal

4.52

4.66

4.78

4.90

5.03

5.15

Acetonitrile

1.15

1.20

1.24

1.28

1.32

1.36

1-Nitropropane

3.01

3.08

3.13

3.20

3.26

3.31

a

Standard uncertainties u are u( γ 13∞ ) = 3%, u(T) = 0.02 K.

33

Table 4 The experimental activity coefficients at infinite dilution γ 13∞ for the solutes in ionic liquid [NC3CNMPyr][DCA] at different temperatures for the hypothetical liquid at zero pressure. a T/K Solute 318.15

328.15

338.15

348.15

358.15

368.15

Heptane

283 464

417

379

346

Octane

704

640

587

541

500

465

Nonane

1031

928

842

767

704

649

Decane

1489

1329

1198

1085

988

906

Hexane

Cyclopentane

81.2

70.3

61.8

96.0

89.3

Cyclohexane

104

Methylcyclohexane

180

168

156

147

138

Cycloheptane

138

128

119

111

104

Cyclooctane

197

184

174

164

156

Hex-1-ene

104

100

Cyclohexene

35.5

34.6

83.6

78.5

96.9

93.7

90.9

33.7

32.9

32.2

74.0 130 98.1 148

31.6

Hept-1-ene

184

172

162

152

144

137

Oct-1-ene

300

281

265

250

237

226

Dec-1-ene

731

695

664

634

609

586

Pent-1-yne

10.0

10.4

10.8

11.2

11.6

12.0

Hex-1-yne

17.2

17.7

18.1

18.6

19.0

19.5

Hept-1-yne

31.2

31.8

32.3

32.7

33.2

33.6

Oct-1-yne

56.2

56.3

56.4

56.5

56.6

56.7

Benzene

3.60

3.73

3.85

3.98

4.10

4.22

Toluene

6.41

6.62

6.83

7.02

7.23

7.42

Ethylbenzene o-Xylene

12.1 9.10

12.3

12.5

9.34

9.58

12.7 9.82

12.8

13.0

10.1

10.3

m-Xylene

11.6

11.9

12.2

12.4

12.7

12.9

p-Xylene

11.2

11.4

11.6

11.8

12.1

12.3

Propylbenzene

23.0

23.1

23.2

23.3

23.4

23.5

34

T/K Solute iso-Propylbenzene

318.15

328.15

338.15

348.15

358.15

368.15

21.4

21.5

21.7

21.9

22.0

22.2

Styrene

5.19

5.41

5.61

5.81

α-Methylstyrene

8.76

9.23

9.69

Thiophene

1.88

1.98

2.08

2.18

2.28

2.38

Pyridine

1.48

1.54

1.60

1.65

1.71

1.77

Methanol

0.571

0.581

0.591

0.599

0.608

0.617

Ethanol

1.12

1.12

1.11

1.11

1.11

1.11

Propan-1-ol

1.70

1.69

1.69

1.68

1.67

1.67

Propan-2-ol

1.87

1.85

1.84

1.82

1.81

1.80

Butan-1-ol

2.8

2.74

2.68

2.64

2.59

2.55

Butan-2-ol

2.71

2.68

2.65

2.62

2.60

2.58

2-Methyl-1-propanol

2.70

2.63

2.57

2.51

2.46

2.41

tert-Butanol

2.60

2.59

2.57

2.56

2.55

2.54

Pentan-1-ol

4.29

4.19

4.11

4.02

3.95

3.88

Water

0.326

0.338

0.349

0.36

0.371

0.382

Methyl acetate

2.604

2.732

2.860

2.983

3.108

3.231

Methyl propanoate

4.50

4.69

4.88

5.06

5.24

5.43

Methyl butanoate

7.98

8.23

8.48

8.72

8.94

9.17

Ethyl acetate

5.263

5.437

5.613

5.784

5.951

6.122

Vinyl acetate

3.87

4.03

4.19

4.35

4.49

4.64

Tetrahydrofuran

2.85

2.96

3.09

3.21

3.33

3.45

1.4-Dioxane

1.42

1.52

1.62

1.73

1.83

1.93

10.1

6.01 10.6

6.22 11.1

tert-Butyl methyl ether

23.5

23.9

24.2

24.6

24.9

25.2

tert-Butyl ethyl ether

80.8

78.7

76.8

75.1

73.5

71.9

tert-Amyl methyl ether

40.7

40.7

40.8

40.9

41.0

41.1

Diethyl ether

21.2

21.2

21.2

21.2

21.2

21.2

Di-n-propyl ether

90.5

86.2

82.3

78.9

75.8

73.0

Di-iso-propyl ether

95.0

91.6

88.4

85.5

83.0

Di-n-butyl ether Acetone

263 1.53

243

225

1.60

35

1.67

210 1.74

196 1.81

184 1.88

T/K Solute 318.15

328.15

338.15

348.15

358.15

368.15

Pentan-2-one

4.58

4.70

4.83

4.96

5.08

5.20

Pentan-3-one

4.53

4.70

4.86

5.03

5.19

5.35

Butanal

3.17

3.27

3.36

3.46

3.55

3.64

Acetonitrile

0.876

0.91

0.941

0.973

1.00

1.04

1-Nitropropane

2.04

2.12

2.19

2.26

2.33

2.40

a

Standard uncertainties u are u( γ 13∞ ) = 3%. u(T) = 0.02 K

36

Table 5 The experimental gas-liquid partition coefficients KL for the solutes in ionic liquid [NC3CNMPy][DCA] at different temperatures. T/K Solute 318.15

328.15

338.15

348.15

358.15

368.15

Heptane

1.23

0.927

0.719

Octane

2.54

1.77

1.27

0.938

0.707

Nonane

5.22

3.41

2.29

1.59

1.14

0.83

6.93

4.42

2.93

1.99

1.39

Decane

11.3

Cyclohexane

2.53

1.97

1.57

1.27

1.05

0.879

Methylcyclohexane

3.11

2.30

1.73

1.34

1.06

0.847

Cycloheptane

8.00

5.70

4.16

3.12

2.38

1.86

9.27

6.64

4.87

3.66

Cyclooctane

19.6

13.3

Cyclohexene

9.40

6.88

5.16

3.96

Hept-1-ene

2.45

1.75

1.29

0.969

0.746

Oct-1-ene

4.36

3.00

2.12

1.55

1.15

0.879

9.60

6.36

4.36

3.05

2.19

4.82

3.58

2.71

2.10

1.65

7.66

5.43

3.93

2.92

2.22

7.82

5.51

3.96

2.92

7.40

5.16

3.69

Dec-1-ene Pent-1-yne

14.9 6.68

Hex-1-yne

11.1

Hept-1-yne

17.3

11.4

Oct-1-yne

25.9

16.5

10.9

Benzene

79.7

55.5

39.8

29.2

21.9

16.8

95.1

64.4

44.7

31.9

23.3

78.6

53.9

37.9

27.3

71.2

50.0

65.9

45.7

32.3

68.0

47.4

33.8

Toluene

145

Ethylbenzene

184

119

o-Xylene

388

242

m-Xylene

238

150

p-Xylene

240

153

Propylbenzene

227

142

92.0

61.4

42.1

29.8

iso-Propylbenzene

187

118

76.5

51.4

35.5

25.2

Styrene

647

398

156 98.0 100

254

37

104

167

114

79.3

T/K Solute 318.15

328.15

338.15

348.15

358.15

α-Methylstyrene

850

501

307

194

127

Thiophene

188

127

Pyridine

961

613

403

273

Methanol

432

287

197

138

99.6

73.3

Ethanol

386

251

168

116

82.4

59.9

Propan-1-ol

581

362

234

157

Propan-2-ol

260

167

111

Butan-1-ol

930

557

346

224

Butan-2-ol

383

236

152

102

2-Methyl-1-propanol

586

357

227

150

tert-Butanol

171

109

Pentan-1-ol

1432

824

495

310

202

135

Water

3497

2158

1375

904

611

423

87.5

71.8

62.1

76.5

49.2

45.3 190

108 54.3 150 70.4 102 34.9

368.15 85.0 33.8 136

76.5 39.5 104 50.2 72.2 25.5

Methyl acetate

66.4

45.8

32.6

23.7

17.7

13.5

Methyl propanoate

80.5

53.8

37.1

26.3

19.2

14.3

66.5

44.7

31.0

22.0

16.1

Methyl butanoate

102

Ethyl acetate

64.5

43.3

30.0

21.3

15.6

11.6

Vinyl acetate

70.3

47.6

33.3

23.9

17.6

13.2

Tetrahydrofuran

77.9

54.3

38.8

28.5

21.4

16.4

1.4-Dioxane

626

395

257

172

119

83.8

tert-Butyl methyl ether

5.33

3.81

2.81

2.11

1.62

tert-Butyl ethyl ether

2.67

1.94

1.46

1.11

0.872

tert-Amyl methyl ether

8.92

6.12

4.32

3.13

2.33

1.77

Diethyl ether

3.24

2.40

1.81

1.40

1.10

0.884

Di-n-propyl ether

4.60

3.27

2.39

1.79

1.37

1.08

Di-iso-propyl ether

1.96

1.51

1.19

0.953

8.47

5.58

3.80

2.67

1.91

Di-n-butyl ether

13.3

Acetone

110

Pentan-2-one

175

Pentan-3-one

170

76.6

1.27

54.7

40.0

29.9

22.9

115

78.4

54.7

39.2

28.8

111

75.5

52.5

37.3

27.2

38

T/K Solute Butanal Acetonitrile 1-Nitropropane

318.15

328.15

338.15

348.15

358.15

368.15

92.5

63.5

44.9

32.6

24.2

18.3

463

315

221

158

116

1210

753

486

322

220

39

86.9 155

Table 6 The experimental gas-liquid partition coefficients KL for the solutes in ionic liquid [NC3CNMPyr][DCA] at different emperatures. T/K Solute 318.15

328.15

338.15

348.15

358.15

368.15

Hexane

1.05

Heptane

1.88

1.43

1.11

0.876

Octane

3.54

2.52

1.84

1.38

1.06

0.826

Nonane

6.85

4.67

3.27

2.36

1.75

1.32

8.77

5.89

4.08

2.91

2.13

Decane

13.5

Cyclopentane

1.90

1.63

1.42

Cyclohexane

4.29

3.30

2.59

2.06

1.67

1.38

Methylcyclohexane

4.86

3.61

2.75

2.14

1.7

1.37

9.00

6.66

5.04

3.90

3.08

9.89

7.23

5.39

Cycloheptane

12.5

Cyclooctane

29.7

Hex-1-ene Cyclohexene

2.43 13.5

20.0

13.9

1.83

1.41

1.11

0.885

9.82

7.32

5.58

4.34

3.43

Hept-1-ene

3.92

2.9

2.19

1.70

1.34

1.08

Oct-1-ene

6.92

4.83

3.46

2.55

1.92

1.48

8.79

5.87

4.03

2.84

6.14

4.65

3.59

2.82

9.58

7.02

5.26

4.01

9.79

7.10

5.27

9.66

6.96

Dec-1-ene

21.7

13.6

Pent-1-yne

11.5

Hex-1-yne

19.3

13.4

Hept-1-yne

30.0

20.1

13.8

Oct-1-yne

46.9

30.2

20.1

13.7

84.4

59.1

42.4

31.2

23.4

91.3

63.1

44.6

32.3

81.5

56.4

40.0

94.5

65.6

8.29

Benzene

124

Toluene

209

136

Ethylbenzene

294

186

121

o-Xylene

545

335

213

m-Xylene

347

217

139

92.8

63.5

44.6

p-Xylene

346

217

141

94.0

64.6

45.6

40

140

T/K Solute 318.15

328.15

338.15

348.15

358.15

368.15

Propylbenzene

387

237

150

98.3

66.3

45.9

iso-Propylbenzene

323

198

126

83.0

56.3

39.2

Styrene

1012

608

380

245

163

112

α-Methylstyrene

1320

767

462

288

185

123

277

183

125

Pyridine

1171

737

480

322

222

Methanol

527

346

234

163

116

84.6

Ethanol

512

328

217

148

104

74.2

Propan-1-ol

839

511

323

212

144

Propan-2-ol

387

242

157

106

Butan-1-ol

1389

813

496

315

207

Butan-2-ol

599

361

227

148

101

2-Methyl-1-propanol

934

553

342

220

147

tert-Butanol

281

174

113

Pentan-1-ol

2246

1265

746

458

292

193

Water

4196

2533

1584

1024

680

464

Thiophene

Methyl acetate

79.7

87.7

76.0

63.1

73.3

52.9

46.4 157

100 52.4 140 70.2 102 38.0

54.5

38.4

27.7

20.5

15.5

Methyl propanoate

105

69.4

47.4

33.3

24.0

17.7

Methyl butanoate

143

91.5

60.7

41.5

29.2

21.0

Ethyl acetate

82.9

55.4

38.2

27.1

19.7

14.7

Vinyl acetate

95.0

63.6

44.0

31.2

22.7

16.9

Tetrahydrofuran

96.4

66.4

46.9

33.9

25.1

19.0

1.4-Dioxane

718

453

295

198

136

96.2

tert-Butyl methyl ether

8.07

5.85

4.35

3.31

2.58

2.05

tert-Butyl ethyl ether

4.29

3.14

2.36

1.81

1.42

1.14

9.54

6.85

5.04

3.80

2.92

tert-Amyl methyl ether

13.7

Diethyl ether

4.51

3.42

2.66

2.10

1.70

1.39

Di-n-propyl ether

7.19

5.21

3.88

2.95

2.29

1.81

Di-iso-propyl ether

3.18

2.37

1.81

1.41

1.12

8.96

6.38

4.67

Di-n-butyl ether

19.2

12.9

41

3.49

T/K Solute 318.15

328.15

338.15

348.15

358.15

368.15

90.7

64.5

47.0

35.0

26.6

Acetone

131

Pentan-2-one

233

152

102

70.6

50.2

36.5

Pentan-3-one

230

150

100

68.9

48.7

35.1

Butanal

121

42.3

31.3

23.8

Acetonitrile

556

379

265

190

140

104

1634

1001

636

417

282

195

1-Nitropropane

82.7

58.3

42

Table 7 Limiting partial molar excess Gibbs energies ∆G1E , ∞ , enthalpies ∆H1E , ∞ and entropies Tref ∆S1E , ∞ for the solutes in ionic liquids [N-C3CNPy][DCA] and [N-C3CNMPyr][DCA] at the

reference temperature Tref = 328.15 K. [N-C3CNPy][DCA] Solute

Heptane Octane Nonane Decane Cyclopentane Cyclohexane Methylcyclohexane Cycloheptane Cyclooctane Hex-1-ene Cyclohexene Hept-1-ene Oct-1-ene Dec-1-ene Pent-1-yne Hex-1-yne Hept-1-yne Oct-1-yne Benzene Toluene Ethylbenzene o-Xylene m-Xylene p-Xylene Propylbenzene iso-Propylbenzene Styrene α-Methylstyrene Thiophene Pyridine Methanol Ethanol Propan-1-ol Propan-2-ol Butan-1-ol Butan-2-ol 2-Methyl-1-propanol tert-Butanol Pentan-1-ol Water

[N-C3CNMPyr][DCA]

∆G1E , ∞ / kJ

∆H1E , ∞ / kJ

Tref ∆S1E , ∞ /kJ

∆G1E , ∞ / kJ

∆H1E , ∞ / kJ

Tref ∆S1E , ∞ /

mol–1

mol–1

mol–1

mol–1

mol–1

kJ mol–1

17.9 18.8 19.8 20.5 14.1 15.5 14.7 15.6 14.1

8.8 6.4 5.3 4.9 8.1 5.7 5.5 6.0 8.1

-9.05 -12.42 -14.47 -15.59 -5.98 -9.76 -9.25 -9.54 -5.98

10.9 15.7 16.9 19.1 8.12 9.61 11.2 12.9 4.98 6.36 8.32 7.24 8.00 7.84 10.2 10.0 6.01 7.46 3.12 1.92 -0.73 1.28 2.62 2.94 4.02 4.09 4.07 4.13 5.33 -2.28

3.0 3.0 4.4 6.7 -3.4 -3.3 -2.1 -0.9 -0.9 -2.2 0.4 -1.0 -0.9 -0.5 1.6 1.3 -1.4 -3.0 -3.2 -2.5 -0.4 1.6 2.4 3.1 3.7 3.2 4.6 2.3 3.8 -1.3

-7.90 -12.7 -12.5 -12.4 -11.5 -12.9 -13.3 -13.8 -5.90 -8.56 -7.96 -8.25 -8.87 -8.30 -8.66 -8.76 -7.45 -10.5 -6.33 -4.40 0.31 0.27 -0.26 0.12 -0.30 -0.91 0.58 -1.82 -1.50 0.97

16.5 17.6 18.6 19.6 11.6 12.5 14.0 13.2 14.2 12.6 9.67 14.0 15.4 17.9 6.39 7.84 9.44 11.0 3.59 5.16 6.85 6.10 6.76 6.64 8.57 8.37 4.61 6.06 1.86 1.18 -1.48 0.31 1.43 1.68 2.75 2.69 2.64 2.60 3.91 -2.96

9.05 8.08 9.00 9.67 12.2 6.56 6.39 6.67 5.55 3.24 2.30 5.76 5.48 4.32 -3.42 -2.40 -1.41 -0.17 -3.08 -2.85 -1.39 -2.38 -2.07 -1.74 -0.43 -0.72 -3.49 -4.52 -4.55 -3.76 -1.50 0.24 0.41 0.75 1.78 0.95 2.24 0.48 1.97 -3.06

-7.41 -9.55 -9.64 -9.95 0.60 -5.89 -7.59 -6.57 -8.68 -9.33 -7.37 -8.28 -9.90 -13.5 -9.81 -10.2 -10.9 -11.2 -6.67 -8.01 -8.24 -8.47 -8.83 -8.38 -9.00 -9.09 -8.10 -10.6 -6.41 -4.69 -0.02 -0.07 -1.02 -0.93 -0.97 -1.74 -0.39 -2.12 -1.94 -0.10

43

[N-C3CNPy][DCA] Solute

Methyl acetate Methyl propanoate Methyl butanoate Ethyl acetate Vinyl acetate Tetrahydrofuran 1.4-Dioxane tert-Butyl methyl ether tert-Butyl ethyl ether tert-Amyl methyl ether Diethyl ether Di-n-propyl ether Di-iso-propyl ether Di-n-butyl ether Acetone Pentan-2-one Pentan-3-one Butanal Acetonitrile 1-Nitropropane

[N-C3CNMPyr][DCA]

∆G1E , ∞ / kJ

∆H1E , ∞ / kJ

Tref ∆S1E , ∞ /kJ

∆G1E , ∞ / kJ

∆H1E , ∞ / kJ

Tref ∆S1E , ∞ /

mol–1

mol–1

mol–1

mol–1

mol–1

kJ mol–1

3.46 5.16 6.87 5.54 4.84 3.76 1.77 10.1 13.5 11.6 9.55 13.7 13.8 16.4 1.99 5.22 5.27 4.20 0.50 3.07

-3.4 -2.7 -1.5 -2.5 -2.4 -2.4 -6.0 -2.4 1.9 -1.7 -2.3 2.7 6.1 2.5 -3.6 -1.6 -2.4 -2.5 -3.2 -1.9

-6.86 -7.81 -8.34 -8.06 -7.22 -6.18 -7.76 -12.5 -11.5 -13.3 -11.9 -11.0 -7.74 -13.9 -5.55 -6.78 -7.64 -6.73 -3.72 -4.93

2.74 4.22 5.75 4.62 3.80 2.96 1.14 8.66 11.9 10.1 8.33 12.2 12.3 15.0 1.28 4.22 4.22 3.23 -0.26 2.05

-4.19 -3.63 -2.71 -2.94 -3.52 -3.76 -5.98 -1.33 2.27 -0.22 0.00 4.16 3.22 6.99 -4.00 -2.48 -3.24 -2.69 -3.24 -3.20

-6.94 -7.85 -8.46 -7.56 -7.10 -6.72 -7.12 -9.99 -10.3 -8.33 -8.00 -9.11 -8.00 -7.12 -5.28 -6.70 -7.46 -5.92 -2.98 -5.25

44

Table 8 Selectivities, S12∞ and capacities, k 2∞ for heptane/thiophene, heptane/pyridine and heptane/1nitropropane separation problems for selected ionic liquids at T = 328.15 K. S12∞

k 2∞

Ionic liquid abbreviation heptane / thiophene

heptane / pyridine

heptane / 1-nitropropane

thiophene

pyridine

1-nitropro

Ref.

pane

[N-C3CNPy][DCA]

224

348

228

0.32

0.50

0.46

this work

[N-C3CNMPyr][DCA]

211

271

197

0.51

0.65

0.47

this work

[N-C3OHPy][DCA]

163

298

143

0.37

0.68

0.32

[31]

[N-C3CNMIM][DCA]

268

421

287

0.41

0.65

0.44

[48]

62.2

1.15

1.43

0.87

[49]

[BMPy][DCA]

80.5

100

[BMPyr][DCA] [N-C3OHMMor][DCA]

80.4

‒

‒

1.13

‒

‒

[50]

274

514

276

0.30

0.56

0.30

[29]

[N-C3OHMIM][DCA]

156

285

144

0.39

0.71

0.36

[29]

[C2OHMIM[DCA]

233

485

227

0.37

0.77

0.36

[51]

[C2ClMIM][DCA] [EMMor][DCA]

246

390

251

0.34

0.53

0.34

[51]

273

356

270

0.42

0.55

0.42

[30]

[EMIM][DCA]

109

277

113

0.64

1.63

0.66

[32]

[AMIM][DCA]

122

182

123

0.56

0.83

0.56

[47]

66.6

0.82

1.12

0.76

[52]

91.1

0.69

0.97

0.63

[46]

[BMIM][DCA] [BzMIM][DCA]

71.5 100

98.0 140

45

Table 9 LFER system constants as a function of temperature for ionic liquid [N-C3CNPy][DCA]. System constantsa

Statisticsb

T/K

l

b

a

s

e

c

r2

SD

F

df

318.15

0.443 (0.027) 0.405 (0.026) 0.369 (0.025) 0.337 (0.025) 0.310 (0.025) 0.280 (0.025)

0.345 (0.101) 0.322 (0.097) 0.301 (0.094) 0.285 (0.095) 0.307 (0.096) 0.346 (0.101)

4.16 (0.12) 3.98 (0.12) 3.8 (0.11) 3.65 (0.11) 3.49 (0.11) 3.33 (0.11)

2.98 (0.10) 2.89 (0.09) 2.81 (0.09) 2.73 (0.09) 2.65 (0.09) 2.54 (0.09)

0.546 (0.096) 0.567 (0.092) 0.583 (0.089) 0.601 (0.088) 0.610 (0.088) 0.640 (0.088)

-1.27 (0.10) -1.29 (0.10) -1.30 (0.09) -1.31 (0.10) -1.34 (0.10) -1.34 (0.10)

0.987

0.111

762

52

0.987

0.107

781

52

0.987

0.104

794

52

0.986

0.102

730

51

328.15 338.15 348.15 358.15 368.15 a

0.986 0.984

0.100 0.100

685

49

565

Values in parentheses are standard uncertainties of the parameters.

b

r2, the coefficient of determination; SD, the standard error; F, the F statistic; df, the degrees of freedom.

46

46

Table 10 LFER system constants as a function of temperature for ionic liquid [N-C3CNMPyr][DCA]. System constantsa

Statisticsb

T/K

l

b

a

s

e

c

r2

SD

F

df

318.15

0.456 (0.022) 0.415 (0.021) 0.379 (0.02) 0.341 (0.02) 0.313 (0.019) 0.251 (0.024)

0.407 (0.086) 0.363 (0.082) 0.332 (0.077) 0.298 (0.074) 0.278 (0.074) 0.486 (0.118)

4.19 (0.10) 3.98 (0.1) 3.79 (0.09) 3.60 (0.09) 3.44 (0.09) 3.22 (0.09)

2.85 (0.08) 2.75 (0.08) 2.65 (0.07) 2.56 (0.07) 2.48 (0.07) 2.43 (0.08)

0.639 (0.083) 0.639 (0.078) 0.643 (0.073) 0.652 (0.071) 0.65 (0.07) 0.804 (0.088)

-1.143 (0.078) -1.133 (0.076) -1.131 (0.071) -1.114 (0.072) -1.121 (0.072) -1.178 (0.109)

0.990

0.098

1135

55

0.991

0.092

1126

54

0.991

0.086

1190

54

0.991

0.083

1166

53

0.991

0.081

1086

52

0.987

0.075

531

35

328.15 338.15 348.15 358.15 368.15 a

Values in parentheses are standard uncertainties of the parameters.

b

r2, the coefficient of determination; SD, the standard error; F, the F statistic; df, the degrees of freedom.

47

Figure Captions

Fig. 1. Comparison of γ 13∞ at T = 328.15 K for selected solutes in ionic liquids: (○) [NC3CNPy][DCA]; (□) [N-C3CNMPyr][DCA]; (∆) [N-C3OHPY][DCA] [31]; (◊) [NC3CNMIM][DCA] [48]; (×) [BMPy][DCA] [49]; (+) [BMPyr][DCA] [50]. Fig. 2. Selectivity versus capacity in extraction of heptane/thiophene problem at T = 328.15 K for [DCA]‒ ionic liquids: (●) [N-C3CNPy][DCA]; (■) [N-C3CNMPyr][DCA]; ( ) [NC3OHPy][DCA] [31]; (◊) [N-C3CNMIM][DCA] [48]; (□) [BMPy][DCA] [49]; (×) [BMPyr][DCA] [50]; (○) [N-C3OHMMor][DCA] [29]; (∆) [N-C3OHMIM][DCA] [29]; (▲) [C2OHMIM][DCA] [51]; (♦) [C2ClMIM][DCA] [51]; (‒) [EMMor][DCA] [30]; (+) [EMIM][DCA] [32]; (-) [AMIM][DCA] [47]; ( ) [BMIM][DCA] [52]; (×) [BzMIM][DCA] [46]. Fig. 3. Selectivity versus capacity in extraction of heptane/pyridine problem at T = 328.15 K for [DCA]‒ ionic liquids: (●) [N-C3CNPy][DCA]; (■) [N-C3CNMPyr][DCA]; ( ) [NC3OHPy][DCA] [31]; (◊) [N-C3CNMIM][DCA] [48]; (□) [BMPy][DCA] [49]; (○) [NC3OHMMor][DCA] [29]; (∆) [N-C3OHMIM][DCA] [29]; (▲) [C2OHMIM][DCA] [51]; (♦) [C2ClMIM][DCA]

[51];

(‒)

[EMMor][DCA]

[30];

(+)

[EMIM][DCA]

[32];

(-)

[AMIM][DCA] [47]; ( ) [BMIM][DCA] [52]; (×) [BzMIM][DCA] [46]. Fig. 4. Selectivity versus capacity in extraction of heptane/1-nitropropane problem at T = 328.15 K for [DCA]‒ ionic liquids: (●) [N-C3CNPy][DCA]; (■) [N-C3CNMPyr][DCA]; ( ) [N-C3OHPy][DCA] [31]; (◊) [N-C3CNMIM][DCA] [48]; (□) [BMPy][DCA] [49]; (○) [N-C3OHMMor][DCA] [29]; (∆) [N-C3OHMIM][DCA] [29]; (▲) [C2OHMIM][DCA] [51]; (♦) [C2ClMIM][DCA] [51]; (‒) [EMMor][DCA] [30]; (+) [EMIM][DCA] [32]; (-) [AMIM][DCA] [47]; ( ) [BMIM][DCA] [52]; (×) [BzMIM][DCA] [46].

48

Fig. 5. Calculated versus experimental logarithmic gas-liquid partition coefficients for 57 solutes in [N-C3CNPy][DCA] at T = 328.15 K using the LFER Solvation Model. Fig. 6. Calculated versus experimental logarithmic gas-liquid partition coefficients for 57 solutes in [N-C3CNMPyr][DCA] at T = 328.15 K using the LFER Solvation Model.

49

Fig. 1.

50

Fig. 2.

51

Fig. 3.

52

Fig. 4.

53

Fig. 5.

54

Fig. 6.

55

Author Contribution Statement CRediT author statement Urszula Domańska: Conceptualization, Methodology, Supervision,Writing- Reviewing and Editing, Funding acquisition. Michal Wlazło: Metodology, Data curation, Visualization, Investigation. Monika Karpińska: Metodology, Formal analysis, Investigation, Validation.

Declaration of interests x☐ The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. ☐The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: