Solubility of Halogenated Hydrocarbons in Hydrophobic Ionic Liquids

Article pubs.acs.org/jced

Solubility of Halogenated Hydrocarbons in Hydrophobic Ionic Liquids: Experimental Study and COSMO-RS Prediction Saleem S. AlSaleem,† Waleed M. Zahid,† Inas M. AlNashef,‡ and Mohamed K. Hadj-Kali*,§ Department of Civil Engineering, and §Department of Chemical Engineering, King Saud University, P.O. Box 800, Riyadh 11421, Saudi Arabia ‡ Department of Chemical and Environmental Engineering, Masdar Institute of Science and Technology, P.O. Box 54224, Abu Dhabi, United Arab Emirates

Downloaded by TEXAS A&M INTL UNIV on September 4, 2015 | http://pubs.acs.org Publication Date (Web): September 3, 2015 | doi: 10.1021/acs.jced.5b00310

†

ABSTRACT: Halogenated hydrocarbons are members of priority water contaminants because of their negative health and environmental impacts. In this study, the solubility of three halogenated hydrocarbons, namely, carbon tetrachloride, chloroform, and bromoform was measured in 12 hydrophobic ionic liquids (ILs) for temperature ranging between 25 and 45 °C. We investigated the chemical structure and alkyl chain length effect of three different cations (piperidinium, pyrrolidinium, and ammonium-based) paired with bis(trifluoromethylsulfonyl)imide anion. It was found that carbon tetrachloride and bromoform are partially miscible in all tested ILs while chloroform exhibits full miscibility. For ammonium based ionic liquids, the solubility increases with the increase of the cation molecular weight and alkyl chain length. The results indicate that the solubility of the studied halogenated hydrocarbons in methyltrioctylammonium bis(trifluoromethylsulfonyl)imide, octyltriethylammonium bis(trifluoromethylsulfonyl)imide, and 1octyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)-imide is substantial. These results confirm the potential use of ionic liquids as powerful alternative solvents for wastewater treatment. Finally, the predictive capability of COSMO-RS model provided excellent qualitative agreement with experimental data both for temperature dependence and for cations structure effect.

■

INTRODUCTION During the last three decades, the impact of chemical pollution has focused exclusive attention on the “priority” pollutants which include halogenated solvents, insecticides, pesticides, herbicides, hydrocarbons, fertilizers, petroleum products, plastics, industrial intermediates, and polymers.1 These pollutants are recognized as posing risks to human health because of their irreversible effects, toxicity, carcinogenic and mutagenic effects, and their persistence in the environment.2 A wide range of these pollutants is detected in drinking water sources as well as municipal and industrial wastewater. Some of these compounds cannot be removed by conventional treatment processes and some of them pose severe problems in biological treatment systems because of their resistance to biodegradation and/or toxic effects on microbial processes.3,4 An estimated 20 million tons of volatile organic compounds (VOCs) are discharged into the atmosphere each year as a result of industrial processing operations.5 VOCs such as carbon tetrachloride, chloroform, bromoform, bromodichloromethane, dibromochloromethane, 1,1,1-trichloroethane, 1,1,2trichloroethane, 1,1,2,2-tetrachloroethane, and phenols are continuously monitored and reported. In the past decade, owing to their modular nature, ionic liquids (ILs) have been widely investigated as potential alternatives in many important chemical processes6 including liquid−liquid extraction, gas absorption, oxidation−reduction © XXXX American Chemical Society

processes, fuel and solar cells, organometallic synthesis, electrochemical devices, capacitors, lubricants, stationary phases for chromatography, matrices for mass spectrometry, supports for the immobilization of enzymes, as liquid crystals, templates for synthesis nanomaterials and materials for tissue preservation, in catalytic membranes preparation,7−21 and water treatment processes.22 The application of ILs in liquid−liquid extraction has received increasing attention, especially for extracting heavy metal ions, aromatic hydrocarbons, organic acids, amino acids, sulfur compounds in diesel oil, organic compounds in plants, and organics in water.23,24 ILs have seen this significant growth of interest because of their fascinating properties as compared to that of conventional organic solvents since they are nonvolatile, and nonflammable, having extremely high ionic conductivity and high thermal stability with large electrochemical windows.22,25−27 ILs have also been investigated for the treatment of water, produced water, and wastewater9,28−34 since they are able to selectively extract compounds from an aqueous phase and can overcome the disadvantages of currently used treatment processes, for example, complexity of operation, safety issues, and high power consumption. Received: April 2, 2015 Accepted: August 27, 2015

A

DOI: 10.1021/acs.jced.5b00310 J. Chem. Eng. Data XXXX, XXX, XXX−XXX

Journal of Chemical & Engineering Data

Article

Table 1. Specification of All Chemicals Used in This Worka abbreviation

chemical formula

Halogenated Hydrocarbon CCl4 CCl4 CHCl3 CHCl3 CHBr3 CHBr3

carbon tetrachloride chloroform bromoform

molecular weight

CAS No.

source

purity/%

153 119 252

[56-23-5] [67-66-3] [75-25-2]

Merck Merck SigmaAldrich

> 99 > 99 > 97

SigmaAldrich SigmaAldrich

> 99

Solvents isopropyl alcohol

C3H8O

C3H8O

60

[67-63-0]

acetonitrile

C2H3N

C2H3N

41

[75-05-8]

Piperidinium-Based Ionic Liquids C12H22F6N2O4S2 [C4mPip][Tf2N]

436.44

[623580-02-9]

Iolitec

≥ 99

[C3mPip][Tf2N]

C11H20F6N2O4S2

422.41

[608140-12-1]

Iolitec

≥ 99

Pyrrolidinium-Based Ionic Liquids [C8mPyrr][Tf2N] C15H28F6N2O4S2

478.52

[927021-43-0]

Iolitec

≥ 99

[C6mPyrr][Tf2N]

C13H24F6N2O4S2

450.46

[380497-19-8]

Iolitec

≥ 99

[C3mPyrr][Tf2N]

C10H18F6N2O4S2

408.38

[223437-05-6]

Iolitec

≥ 99

Ammonium-Based Ionic Liquids [N8881][Tf2N] C27H54F6N2O4S2 [N8222][Tf2N] C16H32F6N2O4S2 [N4441][Tf2N] C15H30F6N2O4S2 [N4222][Tf2N] C12H24F6N2O4S2 [N2212O1][Tf2N] C10H20F6N2O5S2

648.85 494.56 480.53 438.45 426.40

[375395-33-8] [210230-48-1] [405514-94-5] [--] [464927-84-2]

Iolitec Iolitec Iolitec Iolitec Iolitec

≥ ≥ ≥ ≥ ≥

396.37 396.37

[258273-75-5] [258273-77-7]

Iolitec Merck

≥ 99 ≥ 98


1-butyl-1-methylpiperidinium bis(trifluoromethylsulfonyl) imide 1-propyl −1- methylpiperidinium bis (trifluoromethylsulfonyl)imide 1-octyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl) imide 1-hexyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl) imide 1-propyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl) imide methyltrioctylammonium bis(trifluoromethylsulfonyl)imide octyltriethylammonium bis(trifluoromethylsulfonyl)imide tributylmethylammonium bis(trifluoromethylsulfonyl)imide butyltriethylammonium bis(trifluoromethylsulfonyl)imide N,N-diethyl-N-methyl-N-(2-methoxyethyl)ammonium bis(trifluoromethylsulfonyl)imide butyltrimethylammonium bis(trifluoromethylsulfonyl)imide ethyl-dimethyl-propylammonium bis(trifluoromethylsulfonyl)imide a

[N4111][Tf2N] [N3211][Tf2N]

C9H18F6N2O4S2 C9H18F6N2O4S2

> 99

99 98 99 99 99

All chemicals were used without any further purification.

hexafluorophosphate [CnMIm][PF6] made the usually soluble ILs immiscible with water.13,39,40 Some researchers concluded that the cation of the ILs controls its physical properties such as melting point, density, or viscosity, whereas the anion of the IL affects the chemical properties and reactions.26 However, it was found that there is no relationship between solubility parameter and alkyl chain length for 1-alkyl derivatives.37 The nature of anion also affects the solubility parameter: the anion with high polarity tends to have a high Hildebrand solubility.37 In addition, some parameters, for instance, temperature of dissolution or reaction and fraction of solvent dissolved in ionic liquid, may influence the Hildebrand solubility parameter.37 It was also reported that higher solubilities were observed with ILs having more hydrophobic character.41 The solubility of ILs in water is another essential property that has to be determined for evaluating their impact on the environment, health, and safety. Studies on the behavior of ILs in water have been conducted by some research groups.6,12,42 Studies in which the cation and/or anion were changed were carried out by Freire et al.43,44 They demonstrated clearly that the size of ILs, hydrophobicity, and hydrogen bonding ability of both cation and anion are the most important factors affecting the solubility of ILs. However, the nature of the anions largely determines the behavior of the IL−water mixture.35,39,40,44,45 In the same manner, Hayyan26 and O’Mahony et al.46 found that [Tf2N]− and [FAP]− anions were the best among other anions in terms of their tendency to make ILs more hydrophobic. The

Nevertheless, only little information about the use of ionic liquids for extracting refractory organics from water is available in the literature.10,29,32,35 To determine the applicability of such a process, it is necessary to know not only viscosity, density, heat capacity, and activity coefficients at infinite dilution but also other thermodynamic properties including solubility and liquid−liquid equilibrium and the interaction of different conditions on each property.4,7,22 For the extraction of organic compounds from aqueous media, ILs with both low water solubility and high water contaminant affinity are required. Therefore, the knowledge of the solubility of water contaminants in hydrophobic ILs prior to their industrial applications is of primary importance.36 However, the understanding of how the physicochemical properties of ionic liquids are used to design or select a promising solvent for an individual application is still relatively unknown.7,22,37 Indeed, Makowska et al.38 investigated the phase behavior of selected imidazolium-based ILs with bis(trifluoromethylsulfonyl)imide anion and chloroform or chloroform/carbon tetrachloride mixed solvent. They found that the impact of the cation on the miscibility is significant. For pure chloroform the system was miscible in a broad temperature range, at least from −23 °C up to 270 °C. However, upon the addition of 7.5% of carbon tetrachloride, a large immiscibility region (“hourglass” type diagram) was observed. It was also found that the solubility of water in ILs decreases with increasing alkyl chain length.37 For example, increasing alkyl chain length from 1 to 9 on 1-alkyl-3-methyl-imadazolium B



Article


Scheme 1. Chemical Structures of Anions and Cations of ILs Used in This Work

and CHBr3 (> 97 wt %) was provided by Sigma-Aldrich (USA). Isopropyl alcohol and acetonitrile (spectroscopy grade) as well as deionized water were used for analysis. All chemicals were used without any further purification. Experimental Protocol. Because of the high affinity of IL to solubilize HHCs, the binary mixture HHC-IL (50 wt %) was initially introduced into 16 mL glass vials, vigorously agitated for 2 h using an IKA KS 4000i shaker/incubator at 300 rpm, and allowed to settle for 30 min before sampling. These shaking and settling periods of time were fixed based on preliminary experimental results: we started with very long time (1 day for shaking and one extra day for settling), then, we reduced this time until we found that 2 h mixing and 30 min settling are enough and give the same solubility values. The high precision analytical balance (±0.1 mg) Precisa XT 220A-FR was used to measure the mass of sample and diluent. A 0.1 g sample was withdrawn from the IL-rich layer using a syringe, mixed thoroughly with 1 g acetonitrile (or isopropyl alcohol) in a 2 mL autosampler glass vial and then analyzed directly by high performance liquid chromatography (HPLC). HPLC Analysis. The HPLC used in this work was an Agilent 1100 system (USA) equipped with a refractive index detector. The mobile phase was acetonitrile (or isopropyl alcohol)/water (75%:25% (v/v)) with a flow rate of 1.4 mL/ min at 30 °C. An aliquot of 5 μL was injected into the HPLC system using an autosampler. All separations were performed using an eclipse XDB-C8 column, 150 mm × 4.6 mm × 5 μm particle size, ZORBAX, Agilent (USA). Data acquisition and processing were accomplished with ChemStation for LC,

critical aspect of their high hydrophobicity is that ILs can be more toxic because they can accumulate in organisms.47 Last but not least, prediction of the solubility of water pollutants in hydrophobic ILs is an important issue for assessment of the potential use of these IL applications in water/wastewater treatment processes due to the scarcity of data in the literature. The objective of this work is to investigate the solubility of halogenated hydrocarbons (HHCs), namely, carbon tetrachloride (CCl 4), chloroform (CHCl3), and bromoform (CHBr3) in selected hydrophobic ionic liquids and determine those that have good solubility. The solubility measurements were conducted at different temperatures in order to select ILs as potential candidates for the extraction of HHCs from water. Piperidinium, pyrrolidinium, and ammonium-based ionic liquid cations paired with bis(trifluoromethylsulfonyl)imide [Tf2N]− ionic liquid anion were used in this study because of their high hydrophobicity.20 The COSMO-RS model was successfully used to qualitatively reproduce our experimental results.

■

EXPERIMENTAL WORK Chemicals. All chemicals used in this work and their specifications are listed in Table 1. Scheme 1 shows the chemical structure of the ions forming the ionic liquids. There are two piperidinium (HPIP) cations, three pyrrolidinium (HPYRR) cations, and seven ammonium-based (HAM) cations. All of these cations were combined with bis(trifluoromethylsulfonyl)imide [Tf2 N] anion. CCl 4 and CHCl3 (> 99 wt %) were provided by Merck (Germany), C



Article

Table 2. Experimental Solubilities (wt %) of CCl4 in Tested ILs at Different Temperatures and Pressure = 0.1 MPaa

a

T/°C

[N8222]

[N4441]

[N4222]

[N2212O1]

[N3211]

[N4111]

[C4mPip]

[C3mPip]

[C8mPyrr]

[C6mPyrr]

[C3mPyrr]

25 35 45

48 52 53

37 41 44

31 33 35

25 27 29

20 23 24

18 19 19

24 30 34

24 29 43

44 50 56

34 38 42

22 28 34

Standard uncertainties u are u(T) = 0.1 K, u(s) = 1 %.

Table 3. Experimental Solubilities (wt%) of CHBr3 in Tested ILs at Different Temperatures and Pressure =0.1 MPaa T/°C 25 35 45


a

[N8222] 38 48 59

[N4441] 36 38 46

[N4222] 45 49 56

[N2212O1] 44 51 56

[N3211]

[N4111]

34 41 46

24 29 31

[C4mPip] 47 52 55

[C3mPip] 43 51 58

[C8mPyrr] 52 64 68

[C6mPyrr] 48 48 57

[C3mPyrr] 39 45 54

Standard uncertainties u are u(T) = 0.1 K, u(s) = 1 %.

revision A.10.02 software. Solutions of pure HHCs with predetermined concentrations were used for HPLC calibration. During preparation of HPLC samples, both isopropyl alcohol (C3H7OH) and acetonitrile (CH3CN) were used as solvents. Five ILs, [C3mPip][Tf2N], [C3mPyrr][Tf2N], [N4222][Tf2N], [N2212O1][Tf2N], and [N3211][Tf2N], did not dissolve in isopropyl alcohol while they dissolved rapidly in acetonitrile. For ILs that are soluble in both diluents, results using isopropyl alcohol were in agreement with those obtained using acetonitrile. The solubility measurements were performed at three temperatures, 25, 35, and 45 °C, and at atmospheric pressure. The solubility value at each temperature was determined as the average of at least two independent measurements and the results were identical within 1 wt % uncertainty.

■

RESULTS AND DISCUSSION Solubility Results. Solubility measurements for CCl4, CHCl3, and CHBr3 expressed in weight percent (wt %), are listed in Table 2 and Table 3 at different temperatures. Results for CHCl3 are not shown in these tables because it was totally miscible with all ILs investigated in this work except with [C3mPyrr][Tf2N]. Examination of these tables revealed several trends depending on the structure of the ionic liquid as well as on a particular HHC. As can be seen clearly in Figures 1a and 2a, it was found that in most cases the solubility increased with temperature as well as by increasing the alkyl chain length of the cation. However, the increase in solubility was not uniform. Moreover, for two ionic liquids, [C6mPyrr][Tf2N] and [N4111][Tf2N], the solubility was constant in a certain temperature range. This strange behavior is in agreement with results reported in the literature for similar HHCs with imidazolium-based ILs.38 It was also found that the solubility of CHBr3 was higher than that of CCl4 in most cases. The solubility of CHCl3 in [C3mPyrr] was 0.37, 0.77, and 0.80 wt % at 25 °C, 35 °C, and 45 °C, respectively. On the other hand, all studied HHCs were totally miscible in [N8881][Tf2N] (even CCl4 which is nonpolar) while the solubility in [N4111][Tf2N] was the lowest. The results clearly indicate that the solubility of the studied HHCs in [N8881][Tf2N], [N8222][Tf2N], and [C 8mPyrr][Tf2N] is substantial. However, it is worth mentioning that the order of solubility obtained with these HHCs is similar to their solubility order in water where CHCl3 is more soluble than CHBr3 which is more soluble than CCl4 as reported by Watts.48 However, the value of solubility in ILs is much higher than that in water. One important property that

Figure 1. (a) Experimental and (b) calculated solubilities (wt %) of CCl4 and CHBr3 in different HAM-ILs at different temperatures.

can affect the solubility of HHCs in ILs is their polarity and ability to form hydrogen bonds with the IL. Solubility versus Polarity. The HHCs used in this study can be classified into polar and nonpolar compounds: CCl4 is nonpolar while CHCl3 is more polar than CHBr3.36 Kamlet− Taft parameters are probably the most widely used empirical scales of solvent polarity. Kamlet et al.49 have examined solvent polarities using solvatochromic probes (dyes) and they have defined three parameters: (i) hydrogen bond donor ability (α) which indicates the solvent’s ability to donate a proton, (ii) hydrogen bond acceptor ability (β), and (iii) dipolarity/ polarizability (π*). It is worth mentioning that the Kamlet− Taft parameters for ILs are scarce. Table 4 shows those parameters available in the literature for limited number of ILs investigated in this work, as well as for HHCs, acetonitrile, and water. It can be seen from this table that α values for CCl4, CHBr3, and CHCl3 are respectively 0.00, 0.05, and 0.20 which is in accordance with the polarity magnitude of these compounds. The relation between Kamlet−Taft parameters for representative ILs, HHCs, acetonitrile, and water are plotted in Figures 3 to 5. Figure 3 depicts the relationship between α and β. Groups of ILs are in the middle of the graph, at the left of the D



Article


Figure 3. Hydrogen bond donor and hydrogen bond acceptor Kamlet−Taft parameters for studied ILs and HHCs: ◆, HHCs; ■, ILs; ▲, acetonitrile; ●, water.

Figure 2. (a) Experimental and (b) calculated solubilities (wt %) of CCl4 and CHBr3 in different HPIP-ILs and HPYRR-ILs at different temperatures.

Table 4. Viscosity and Kamlet−Taft Parameters for Some ILs, HHCs, Acetonitrile, and Water at 25 °C viscosity liquid

Kamlet−Taft parameters

cP

α

β

π*

0.00 0.20 0.05

0.10 0.10 0.05

0.2863 0.5863 0.6263

0.52 1.00

0.35 0.33

0.9366 0.9351

0.52

0.37

0.9351

0.39

0.55

0.8769

0.70 0.41

0.51 0.46

0.9069 0.8969

HHCs CCl4 CHCl3 CHBr3

Figure 4. Kamlet−Taft parameters hydrogen bond donor and dipolarity/polarizability for studied ILs and HHCs: ◆, HHCs; ■, ILs; ▲, acetonitrile; ●, water.

ILs [C4mPip][Tf2N] [C3mPip][Tf2N] [C8mPyrr][Tf2N] [C6mPyrr][Tf2N] [C4mPyrr][Tf2N] [C3mPyrr][Tf2N] [N8881][Tf2N] [N8222][Tf2N] [N6661][Tf2N] [N4441][Tf2N] [N2212O1][Tf2N] [N4111][Tf2N] [N3211][Tf2N] acetonitrile water a

18264 15065 14047 10120 8567 6365 53268a 20267 70a

386 6971 11667 0.47 8367 Traditional Organic Solvents 0.19 1.17

water has higher α and π* than ILs, HHC, and acetonitrile. Figure 4 and Figure 5 indicate that the ILs have almost the same π*. As a result, α should be addressed when studying the solubility of compounds in ILs. Note that all ILs illustrated are piperidinium, pyrrolidinium, and ammonium cation based, hydrophobic, and paired with the [Tf2N] anion. Even with this

0.9769

0.40 0.47

0.7563 1.0963

At 303 K.

IL group the HHCs group, and solubility increases if the hydrogen bond donor of the ILs and HHCs are close to each other. CHCl3 and acetonitrile have almost similar hydrogen bond donors (α of CHCl3 and acetonitrile are 0.2 and 0.19, respectively) and this results in full miscibility of CHCl3 and acetonitrile with selected ILs. Also, changing β does not affect the solubility of CCl4 as it does CHCl3. On the other hand, ILs have hydrophobic characteristics due to the α of water being higher than that of the ILs. This is again applicable to the relationship between α and π* illustrated in Figure 4. Note that,

Figure 5. Kamlet−Taft parameters hydrogen bond acceptor and dipolarity/polarizability for studied ILs and HHCs: ◆, HHCs; ■, ILs; ▲, acetonitrile; ●, water. E




Article

information, the exact effect of solvent polarity parameters on solubility needs more investigation. It was reported in the literature that π* is relatively high for all studied ILs (including imidazolium, ammonium, and pyridinium cation based ILs) and varies with both anion and cation. On the other hand, it was found that α depends mainly on the cation while β depends on the anion.50 Lee and Prausnitz51 showed that the length of the alkyl chain on the cation has a significant influence on α, but only a small influence on β and π*. Similarly, the high miscibility of CHCl3 could be attributed to its ability to form hydrogen bonds and its relative higher polarity compared with the other studied compounds. In addition, this may explain why, generally, polar CHBr3 is more soluble than nonpolar CCl4. Solubility versus Viscosity of ILs . Some ILs tested in this work are highly viscous (such as [N8881][Tf2N] and [N4441][Tf2N]). This is probably due to the effect of the cation, since the [Tf2N] anion-based ILs are in general less viscous than other anions.52 However, this property did not affect the solubility values. It affected only the mixing degree of the solution. The viscosity values reported in the literature were listed in Table 4. Solubility versus Alkyl Chain Length of the Cation. It is obvious that the solubility of HHCs increases with the molecular weight of the ILs. The relationship between solubility and alkyl chain length of the cation substituents is illustrated by plotting solubility versus number of carbon atoms in ILs. Figure 6 shows this relationship for CCl4 and CHBr3 with ammonium-

Figure 7. Solubility of CCl4 and CHBr3 as a function of number of carbon atoms in in the cation of HPIP-ILs and HPYRR-ILs at 25 °C: ◆, CCl4; ▲, CHBr3.

This is clearly due to the difference in chemical structure of the cation. For example, CCl4 solubility in [N3211][Tf2N] and [N4111][Tf2N] at 25 °C were 20 and 18 wt %, respectively (Table 2). Till this point, no evidence can support this phenomena except the nature of unsymmetrical structural of both [N3211][Tf2N] and [N4111][Tf2N]. In contrast, [C3mPip][Tf2N] and [C3mPyrr][Tf2N] have a small difference between their molar mass and the same alkyl chain length on the cation, and they have a small difference in their solubility with CCl4. The solubilities in [C3mPip][Tf2N] and [C3mPyrr][Tf2N] at 25 °C were 24 wt % and 22 wt %, respectively (Table 2). The difference is due to the nature of the cation structure of both [C3mPip][Tf2N] and [C3mPyrr][Tf2N]. In addition, it seems that the increase in alkyl chain length by one in [C4mPip][Tf2N] and [C3mPip][Tf2N] does not affect the solubility of CCl4 nor does the presence of a C−O−C bond in [N2212O1][Tf2N] (Scheme 1 and Table 2). As for CHBr3, it was totally miscible with [N8881][Tf2N]. The trend of solubility with decreasing MW of HAM-ILs was not very clear as in the case of CCl4. The same behavior was reported by Passos et al.53 who conducted a systematic study on the effect of the cation alkyl side chain length on the partitioning of a series of alkaloids−nicotine, caffeine, theophylline, and theobromine−in six methylimidazolium chloride ILs ([Cnmim][Cl]) with different alkyl chain lengths, for example, n = 4, 5, 6, 7, 8, and 10. They observed a maximum in the partition coefficient with [C6mim][Cl]. As mentioned earlier, the solubility values of CHBr3 in [N3211][Tf2N] and [N4111][Tf2N] were different although the two ILs have the same molar mass. The solubility in [N3211][Tf2N] and [N4111][Tf2N] at 25 °C were 34 wt % and 24 wt %, respectively (Table 3). It can be seen from Figures 1a and Figure 2a that the decrease of solubility with decreasing molar mass of HPYRR-ILs and HPIP-ILs is not the same for all HHCs. Solubility versus Temperature. Again, it can be seen from Figures 1a and 2a that the increase of solubility of HHCs with temperature does not follow the same trend for all ILs. The measured solubility data were fitted using the Arrhenius equation:23,54

Figure 6. Solubility of CCl4 and CHBr3 as a function of number of carbon atoms in the cation of HAM-ILs at 25 °C: ◆, CCl4; ▲, CHBr3.

based ILs, and Figure 7 shows the same relationship with piperidinium- and pyrrolidinium-based ILs. For example, the increase in alkyl chain length by one carbon atom in [C4mPip] compared to that in [C3mPip] increases the solubility by 4 wt %. For ammonium-based ILs, it was found that the solubility can exceed more than 50 wt % depending on the cation structure. In the case of the HAM-IL containing 16 carbon atoms, the solubility of CCl4 was almost twice higher than that in ionic liquids containing nine carbon atoms. In the case of the HPYRR-IL containing 15 carbon atoms, the solubility of CCl4 was 40% higher than that in HPYRR-IL containing 10 carbon atoms (Figure 7). In addition, it was found that the chemical structure of the IL affects the solubility. For example, [N3211][Tf2N] and [N4111][Tf2N] have the same molar mass and the same number of carbon atoms but have different HHCs solubility.

ln(x) = A − F

EA RT

(1) DOI: 10.1021/acs.jced.5b00310 J. Chem. Eng. Data XXXX, XXX, XXX−XXX


Article


Figure 8. Solubility of CCl4 and CHBr3 at different temperatures in HAM-ILs: ◆, [N8222][Tf2N]; ■, [N4441][Tf2N]; [N2212O1][Tf2N]; ∗, [N3211][Tf2N]; ●, [N4111][Tf2N].

Figure 9. Solubility of CCl4 and CHBr3 at different temperatures in ILs: ◆, [C4mPip][Tf2N] ■, [C3mPip][Tf2N] [C6mPyrr] [Tf2N]; ∗, [C3mPyrr] [Tf2N]).

where x is the solubility in mole fraction, EA is the activation energy for dissolution, R is the universal gas constant 8.314J/ mol. K, T is the temperature in K, and A is a correlation parameter. The solubility data for CCl4 and CHBr3 are plotted versus (1/T) according to eq 1 and presented as solid lines in Figure 8 and Figure 9. The data show a good degree of linearity. In general, it was observed that the activation energy for dissolution is less in ILs having higher molecular weight. It was also noted that solubility in ILs with high molecular weight is less sensitive to change in temperature. The calculated activation energy of dissolution ranged between 1.1 kJ/mol for CHCl3 in [N4111][Tf2N] to 14 kJ/mol for CCl4 in [C3mPip][Tf2N]. To the best of our knowledge there is no available activation energy data related to systems involving HHCs and ILs. For the sake of comparison, the activation energy of O2 dissolution in different ILs [C6mPyrr][Tf2N] and 1-(3-methoxypropyl)-1-methylpiperidinium ([MOPMPip][Tf2N]) was found to be between 18.5 and 30.99 kJ/mol,26 while the solubility of O2 in the tested ILs is much lower than that for HHCs. Solubility Prediction Using COSMO-RS. COSMO-RS stands for COnductor-like Screening MOdel for Real Solvents. COSMO-RS is a two-step approach: (i) quantum mechanics’ calculation of molecules using density functional theory, and (ii) statistical thermodynamics of the molecular interactions. In COSMO-RS, molecules are placed in a conductor as the reference state. The basic idea of COSMO-RS is to quantify the interaction energy of interacting species in terms of its polarization charge densities, σ and σ′. The molecular interactions represented in COSMO-RS are the electrostatic misfit energy, hydrogen bond interaction, and van der Waals interaction.55 COSMO-RS parameters are based on a large

▲,

▲,

[N4222][Tf2N]; ×,

[C8mPyrr] [Tf2N] ×,

database of experimental data; they are universal and do not require to be reparameterized to specific systems unlike the conventional approaches such as NRTL and UNIQUAC activity coefficient models. The polarization charge density σ is the only descriptor determining the interaction energies in the COSMO-RS model. σ-Profile is a distribution function or histogram which gives the relative amount of surface with polarity σ in the molecule, while σ-potential is the chemical potential of a segment which describes the affinity of the solvent for a molecular surface of polarity σ. It should be noted that in σ-profile, negative σ represents positive polarities, and vice versa. Meanwhile, σ-potential describes the affinity of a solvent for a molecular surface of polarity σ. A lower μ(σ) value at a particular σ implies better affinity for that polarity, and vice versa. Reports on successful application of the COSMO-RS model for predicting thermodynamic data of systems containing ILs is considerable.56 In particular, COSMO-RS has been used to predict liquid−liquid equilibria (LLE) data for binary and ternary systems containing ILs. However, in most cases, the results were only qualitatively agreeable to experimental data. Indeed, Ferreira et al.57 used COSMO-RS to model LLE for 150 binary (hydrocarbon + IL) systems, and the results of the modeling work were compared with published experimental data. It was concluded that the COSMO-RS model has limitations in predicting LLE data for systems with large mutual solubility but provides good quantitative agreement with experimental data for less miscible systems. Banerjee et al.58 used a special version of COSMO-RS, which was parametrized for LLE prediction of neutral compounds, to predict the activity coefficient at infinite dilution in phosphonium-based ILs and yielded overall absolute average deviation (AAD) within 16%, which is satisfactory considering the model being ab-initio with G




Article

Figure 10. Sigma profiles of (a) ammonium-based cations, (b) piperidinium and pyrrolidinium-based cations, (c) halogenated hydrocarbons, and (d) bis(trifluoromethylsulfonyl)imide anion.

parametrization file BP_TZVP_C30_1301.ctd.62 The σ-profiles, σ-potentials, and the binary liquid−liquid equilibrium phase diagram were retrieved from COSMOthermX software. COSMO-RS Results and Discussion. Prior to extensive comparisons between COSMO-RS predictions and the available experimental data, geometry optimizations of cations alone and anions alone were performed to determine the stable geometry of ILs. The σ-profiles of all species involved are shown in Figure 10. The vertical dashed lines indicate the threshold for hydrogen-bond interaction energy, where peaks at σ > + 0.0084 e Å−2 indicate the presence of a hydrogen-bond acceptor group in the species, and peaks at σ < −0.0084 e Å−2 indicate the presence of a hydrogen-bond donor group in the species. As mentioned previously, negative σ values represent positive polarities, and vice versa. Indeed, all cations (ammonium-based in Figure 10a as well as piperidinium and pyrrolidinium-based cations in Figure 10b) show a peak at negative σ values. The large σ-profile of [N8881] cation reflects its relative big size compared to other cations. The σ-profiles of HHC studied in this work (Figure 10c) show three peaks for both chloroform and bromoform in the nonpolar region corresponding to the carbon, chlorine atoms and carbon, bromine atoms, respectively. The small peak located at −0.014 e Å−2 in the hydrogen bond donor region for both components indicates their acidic character and polarity which is associated with the hydrogen atom. On the other hand, the σ-profile of carbon tetrachloride is located only in the nonpolar region reflecting the symmetric and nonpolar character of this molecule. As consequence, the absence of a noticeable peak in the hydrogen bond acceptor region (σ > + 0.0082 e Å−2) of the σprofile of these three compounds indicates that all of them do not show hydrogen-bond acceptor capacity. Therefore, from

no special parametrization for specific systems. More recently, a systematic thermodynamic analysis was carried out by Gonzalez-Miquel et al.59 for selecting cations and anions to enhance the absorption of more than 2400 VOC-IL mixtures, by combining 9 solutes and 270 ILs (including HHCs such as CCl4 and CHCl3), at low concentration in gaseous streams. As a result of this analysis, an attempt of classification of VOCs with respect to their potential solubility in ILs was proposed. In this comprehensive study, the sigma-profiles, the activity coefficients and the intermolecular interactions computed with COSMO-RS were used to explain the solubility behavior of the organic compounds in the ILs as well as to propose taskspecific solvents to increase the solubility of VOCs. In the present work, we are particularly interested in the use of COSMO-RS for prediction of LLE data and screening of ILs potential solvents for HHCs using the σ-profile of the species involved. Computation Methodology. The first step in COSMORS is to generate a .cosmo f ile from the optimized geometry of each species involved. Therefore, geometry optimization was performed for each cation, anion, and halogenated hydrocarbon studied in this work. Initial structures for each compound were drawn, and the geometry optimization at the Hartree−Fock level and 6-31G* basis set was then performed. Calculation of geometry optimization at the Hartree−Fock level gives more meaningful and accurate values,60 while the 6-31G* basis set accounts for polarization effect of the species in the complexes. From the optimized geometry for each individual species, a single point calculation was performed with activation of the .cosmo f ile generation using density functional theory with Becke-Perdew functional and triple-ζ valence potential (TZVP) basis set. All of these calculations were performed with Turbomole Software Package.61 Thereafter, the .cosmo f iles were imported into COSMOthermX software package with H



Article


this analysis of σ-profiles, it can be predicted that ILs with hydrogen-bond acceptor groups (which means basic character) might improve the solubility of these HHCs. This wanted basic effect is obtained by the anion group [Tf2N] since its sigma profile shows a prominent peak (located at +0.012 e Å−2) in the hydrogen-bond acceptor region as can be seen in Figure 4d. The overall experimental trend is qualitatively well predicted (Figure 1b and Figure 2b). Indeed, COSMO-RS calculation confirms that CHCl3 is totally miscible in all investigated ILs. It also shows that CHBr3 is more soluble than CCl4. The only discrepancy was observed with CHBr3 in [N8881][Tf2N]: the experimental results show that CHBr3 is totally miscible in this IL while COSMO-RS gives partial solubility. To consolidate the prediction obtained by COSMO-RS calculations by additional quantitative analysis, we have plotted the parity graph which compares the calculated solubilities against the experimental ones. The graphical statistical analysis shown in Figure 11 was done at only 25 °C for carbon

Figure 12. COSMO-RS calculated LLE solubility curves of CHBr3 at different temperatures of HAM-ILs: ■, [N4111][Tf2N]; ▲, [N4222][Tf2N]; ●, [N2212O1][Tf2N].

that the polarity of HHCs affected their solubility in the tested ILs except for methyltrioctylammonium bis(trifluoromethylsulfonyl)imide which exhibited total miscibility with both polar and nonpolar HHCs. In contrast, the relatively polar CHCl3 was found to be miscible with 11 out of the 12 tested ILs. Also, an increase in the alkyl chain length of the cation of ILs and consequently its hydrophobic character resulted in an increase in solubility. Moreover, it has been shown that using α, β, and π* for selecting or tailoring the most suitable IL could be a powerful tool to improve and expand the current applications of ILs. Nevertheless, more investigations should be conducted to emphasize the relationship between solvent capability of ILs and these polarity parameters. Finally, the predictive capability of COSMO-RS was evaluated for the description of the investigated solubility providing an acceptable agreement between the model prediction and the experimental data. The model was able to show the correct trends of temperature dependence and alkyl chain length structural variations of the ILs . This proves again that COSMO-RS is a valuable tool for preliminary screening of solvents with no need of extensive experimental data even for systems with novel compounds.

Figure 11. Comparison between COSMO-RS and experimental solubilities of CCl4 at 25 °C in HAM-ILs (◆) and HPIP-ILs and HPYRR-ILs (▲).

tetrachloride hydrocarbon but the same comparison applies for higher temperatures (35 °C and 45 °C) and for bromoform as well, since chloroform has shown total miscibility both experimentally and using COSMO-RS. Indeed, Figure 11 shows a systematic deviation between calculated and experimental data for the whole solubility range. It is also obvious that the COSMO-RS model underestimates the solubility of CCl4 in all ionic liquids investigated in this work. Nevertheless, the good qualitative prediction of COSMO-RS is again confirmed by this plot since an overall positive slope is clear meaning that high experimental solubility is predicted by a relative high calculated solubility and vice versa. More interestingly, while only the solubility of the HHC was measured in the IL, COSMO-RS allows, in addition, the estimation of the solubility of the IL in the halogenated hydrocarbon-rich phase as shown by Figure 12 for bromoform with different ILs as a function of temperature.

■

AUTHOR INFORMATION

Corresponding Author

E-mail: *[email protected]. Funding

The authors are grateful to King Abdulaziz City for Science and Technology, Riyadh, Saudi Arabia (Grant no.T-T-12-0002) for financial support and the Deanship of Scientific Research at King Saud University for participating in funding this work through the group project number RGP-VPP-108. Notes

The authors declare no competing financial interest.

■

ACKNOWLEDGMENTS The authors are grateful to Dr. Sarwono Mulyono from the Chemical Engineering Department, College of Engineering, King Saud University, Saudi Arabia, for his assistance.

■

■

CONCLUSION The effect of the chemical structure of piperidinium, pyrrolidinium, and ammonium cation with [Tf2N] anion, temperature, polarity, and length of chain (molecular mass of IL) on the solubility of HHCs have been assessed and presented. It was found that the solubility increased by increasing the molecular mass of the IL. It was also found

REFERENCES

(1) PME. www.pme.gov.sa (accessed 30 October 2014). (2) Gros, M.; Petrovic, M.; Barceló, D. Analysis of Emerging Contaminants of Municipal and Industrial Origin. . In Handbook of Environmental Chemistry; Petrovic, Springer-Verlag: Berlin Heidelberg, 2008; Vol. 5, pp 37−104. I




Article

deep eutectic solvent−experiments and COSMO-RS prediction. RSC Adv. 2014, 4, 17597−17606. (25) Brennecke, J. F.; Maginn, E. J. Ionic Liquids: Innovative Fluids for Chemical Processing. AIChE J. 2001, 47, 2384−2389. (26) Hayyan, M.; Mjalli, F. S.; Hashim, M. A.; AlNashef, I. M.; AlZahrani, S. M.; Chooi, K. L. Long term stability of superoxide ion in piperidinium, pyrrolidinium and phosphonium cations-based ionic liquids and its utilization in the destruction of chlorobenzenes. J. Electroanal. Chem. 2012, 664, 26−32. (27) Neves, C.; Ventura, S.; Freire, M.; Marrucho, I.; Coutinho, J. Evaluation of Cation Influence on the Formation and Extraction Capability of Ionic Liquid-based Aqueous Two-Phase Systems. J. Phys. Chem. B 2009, 113, 5194−5199. (28) Dai, S.; Ju, Y. H.; Barnes, C. E. Solvent extraction of strontium nitrate by a crown ether using room-temperature ionic liquids. J. Chem. Soc., Dalton Trans. 1999, 8, 1201−1202. (29) Vijayaraghavan, R.; Vedaraman, N.; Surianarayanan, M.; MacFarlane, D. R. Extraction and Recovery of Azo Dyes into an Ionic Liquid, Short communication. Talanta 2006, 69, 1059−1062. (30) Li, C.; Xin, B.; Xu, W.; Zhang, Q. Study on the Extraction of Dyes into a Room-Temperature Ionic Liquid and Their Mechanisms. J. Chem. Technol. Biotechnol. 2007, 82, 196−204. (31) McFarlane, J.; Ridenour, W. B.; Luo, H.; Hunt, R. D.; DePaoli, D. W.; Ren, R. X. Room Temperature Ionic Liquids for Separating Organics from Produced Water. Sep. Sci. Technol. 2005, 40, 1245− 1265. (32) Malefetse, T.; Mamba, B.; Krause, R.; Mahlambi, M. Cyclodextrin-ionic liquid polyurethanes for application in drinking water treatment. Water SA 2009, 35, 729−734. (33) Mahmoud, M. E.; Al-Bishri, H. M. Supported hydrophobic ionic liquid on nano-silica for adsorption of lead. Chem. Eng. J. 2011, 166, 157−167. (34) Fischer, L.; Falta, T.; Koellensperger, G.; Stojanovic, A.; Kogelnig, D.; Galanski, M.; Krachler, R.; Keppler, B. K.; Hann, S. Ionic Liquids for Extraction of Metals and Metal Containing Compounds from Communal and Industrial Waste Water. Water Res. 2011, 45, 4601−4614. (35) Chapeaux, A. Extraction of Alcohols from Water Using Ionic Liquids; Ph.D. Dissertation, University of Notre Dame, Notre Dame, Indiana, USA, 2009. (36) Gordy, W. Spectroscopic Evidence of Hydrogen Bonds: Chloroform and Bromoform in Donor Solvents. J. Chem. Phys. 1939, 7, 163−166. (37) Weerachanchai, P.; Chen, Z.; Leong, S. S. J.; Chang, M. W.; Lee, J.-M. Hildebrand solubility parameters of ionic liquids: Effects of ionic liquid type, temperature and DMA fraction in ionic liquid. Chem. Eng. J. 2012, 213, 356−362. (38) Makowska, A.; Siporska, A.; Kobierska, K.; Szydłowski, J. Phase behavior of 1-alkyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide with chloroform and/or chloroform/carbon tetrachloride mixed solvent. J. Mol. Liq. 2014, 199, 364−366. (39) Ranke, J.; Othman, A.; Fan, P.; Muller, A. Explaining Ionic Liquid Water Solubility in Terms of Cation and Anion Hydrophobicity. Int. J. Mol. Sci. 2009, 10, 1271−1289. (40) Poole, C. F.; Poole, S. K. Extraction of organic compounds with room temperature ionic liquids-Review. J. Chromatogr. A 2010, 1217, 2268−2286. (41) Oliveira, F. S.; Freire, M. G.; Pratas, M. J.; Pauly, J.; Daridon, J. L.; Marrucho, I. M.; Coutinho, J. A. P. Solubility of Adamantane in Phosphonium-Based Ionic Liquids. J. Chem. Eng. Data 2010, 55, 662− 665. (42) Zhou, T.; Chen, L.; Ye, Y.; Chen, L.; Qi, Z.; Freund, H.; Sundmacher, K. An Overview of Mutual Solubility of Ionic Liquids and Water Predicted by COSMO-RS. Ind. Eng. Chem. Res. 2012, 51, 6256−6264. (43) Freire, M. G.; Santos, L. M. N. B. F.; Fernandes, A. M.; Coutinho, J. A. P.; Marrucho, I. M. An overview of the mutual solubilities of water-imidazolium-based ionic liquids systems. Fluid Phase Equilib. 2007, 261, 449−454.

(3) Stasinakis, A. S. Use of Selected Advanced Oxidation Processes (AOPs) for Wastewater TreatmentA Mini Review. Global NEST J. 2008, 10, 376−385. (4) Kozlecki, T.; Sawinski, W.; Sokotowski, A.; Ludwig, W.; Polowczyk, I. Extraction of organic impurities using 1-butyl-3methylimidazolium hexafluorophosphate [BMIM][PF6]. Pol. J. Chem. Technol. 2008, 10, 79−83. (5) Wang, L.-S.; Wang, X.-X.; Li, Y.; Jiang, K.; Shao, X.-Z.; Du, C.-J. Ionic Liquids: Solubility Parameters and Selectivities for Organic Solutes. AIChE J. 2013, 59, 3034−3041. (6) Deng, Y.; Besse-Hoggan, P.; Husson, P.; Sancelme, M.; Delort, A.-M.; Stepnowski, P.; Paszkiewicz, M.; Goebiowski, M.; Gomes, M. F. C. Relevant parameters for assessing the environmental impact of some pyridinium, ammonium and pyrrolidinium based ionic liquids. Chemosphere 2012, 89, 327−333. (7) Olivier-Bourbigou, H.; Magna, L. Ionic liquids: perspectives for organic and catalytic reactions. J. Mol. Catal. A: Chem. 2002, 182−183, 419−437. (8) Wasserscheid, P.; Welton, T. Ionic Liquids in Synthesis; WileyVCH: Germany, 2002. (9) Rajendran, A. Applicability of an Ionic Liquid in the Removal of Chromium from Tannery Effluents: A green chemical approach. Br. J. Environ. Clim. Change 2010, 4, 100−103. (10) Petra, C.; Katalin, B. Application of Ionic Liquids in Membrane Separation Processes. In Ionic Liquids: Applications and Perspectives; Kokorin, A., Ed.; InTech: 2011; pp 561−586. (11) Tsuda, T.; Hussey, C. L. Electrochemical Applications of RoomTemperature Ionic Liquids. Electrochem. Soc. Interface 2007, 42−49. (12) Siedlecka, E. M.; Czerwicka, M.; Neumann, J.; Stepnowski, P.; Fernández, J. F.; Thöming, J. Ionic Liquids: Methods of Degradation and Recovery. In Ionic Liquids: Theory, Properties, New Approaches; Kokorin, A., Ed.; InTech: 2011; pp 701−722. (13) Han, D.; Row, K. H. Review: Recent Applications of Ionic Liquids in Separation Technology. Molecules 2010, 15, 2405−2426. (14) Sun, W.; Li, Y.; Yang, M.; Li, J.; Jiao, K. Application of Carbon Ionic Liquid Electrode for the Electrooxidative Determination of Catechol. Sens. Actuators, B 2008, 133, 387−392. (15) Taylor, S. A. New Biocatalyst: Myoglobin in Phosphonium Ionic Liquids. M.Sc. Thesis, Department of Chemistry, Simon Fraser University: British Columbia, Canada, 2008. (16) Zhang, S.; Zhang, Z. Selective Sulfur Removal from Fuels Using Ionic Liquids at Room Temperature. Fuel Chem. Division Prepr. 2002, 47, 449−451. (17) Seiler, M.; Jork, C.; Kavarnou, A.; Arlt, W.; Hirsch, R. Separation of Azeotropic Mixtures Using Hyperbranched Polymers or Ionic Liquids. AIChE J. 2004, 50, 2439−2454. (18) Pereiro, A. B.; Rodríguez, A. Applications of Ionic Liquids in Azeotropic Mixtures Separations. In Ionic Liquids: Applications and Perspectives; Kokorin, A., Ed.; InTech: 2011; pp 225−242. (19) Koel, M. Ionic liquids in Chemical Analysis. Crit. Rev. Anal. Chem. 2005, 35, 177−192. (20) Hayyan, M. Generation of Superoxide Ion in Ionic Liquids and Its Application in the Destruction of Hazardous Materials. Thesis, University Of Malaya: Kuala Lumpur, Malaysia, 2012. (21) Meindersma, G. W.; Podt, A.; Klaren, M. B.; Haan, A. Separation of Aromatic and Aliphatic Hydrocarbons with Ionic Liquid. In the AIChE 2004 Annual Meeting, Austin, TX, 2004; University of Twente, Enschede, Netherlands, 2004. (22) Domanska, U.; Marciniak, A. Phase behaviour of 1hexyloxymethyl-3-methyl-imidazolium and 1,3-dihexyloxymethyl-imidazolium based ionic liquids with alcohols, water, ketones and hydrocarbons: The effect of cation and anion on solubility. Fluid Phase Equilib. 2007, 260, 9−18. (23) Chen, D.-x.; OuYang, X.-k.; Wang, Y.-g.; Li-ye, Y.; He, C. Liquid-liquid extraction of caprolactam from water using room temperature ionic liquids. Sep. Purif. Technol. 2013, 104, 263−267. (24) Mulyono, S.; Hizaddin, H. F.; Alnashef, I. M.; Hashim, M. A.; Fakeeha, A. H.; Hadj-Kali, M. K. Separation of BTEX aromatics fromn-octane using a (tetrabutylammonium bromide + sulfolane) J




Article

(44) Freire, M. G.; Carvalho, P. J.; Gardas, R. L.; Marrucho, I. M.; Santos, L. M. N. B. F.; Coutinho, J. A. P. Mutual Solubilities of Water and the [Cnmim][Tf2N] Hydrophobic Ionic Liquid. J. Phys. Chem. B 2008, 112, 1604−1610. (45) Anouti, M.; Jones, J.; Jacquemin, J.; Caillon-Caravanier, M.; Lemordant, D. Aggregation behavior in water of new imidazolium and pyridinium alkylcarboxylates protic ionic liquids. J. Colloid Interface Sci. 2009, 340, 104−111. (46) O’Mahony, A. M.; Silvester, D. S.; Aldous, L.; Hardacre, C.; Compton, R. G. Effect of Water on the Electrochemical Window and Potential Limits of Room-Temperature Ionic Liquids. J. Chem. Eng. Data 2008, 53, 2884−2891. (47) Salminen, J.; Papaiconomou, N.; Kumar, R. A.; Lee, J.-M.; Kerr, J.; Newman, J.; Prausnitz, J. M. Physicochemical properties and toxicities of hydrophobic piperidinium and pyrrolidinium ionic liquids. Fluid Phase Equilib. 2007, 261, 421−426. (48) Watts, R. J. Hazardous Wastes: Sources, Pathways, Receptors; Wiley: USA, 1998. (49) Kamlet, M. J.; Abboud, J. M.; Abraham, M. H.; Taft, R. W. Linear Solvation Energy Relationship. 23. A Comprehensive Collection of the Solvatochromic Parameters, pi*, alpha, beta, and Some Methods for Simplifying Solvatochromic Equation. J. Org. Chem. 1983, 48, 2877−2887. (50) Crowhurst, L.; Mawdsley, P. R.; Perez-Arlandis, J. M.; Salter, P. A.; Welton, T. Solvent-solute interactions in ionic liquidsy. Phys. Chem. Chem. Phys. 2003, 5, 2790−2794. (51) Lee, J.-M.; Prausnitz, J. M. Polarity and hydrogen-bond-donor strength for some ionic liquids: Effect of alkyl chain length on the pyrrolidinium cation. Chem. Phys. Lett. 2010, 492, 55−59. (52) Zhou, Q.; Lu, X.; Zhang, S.; Guo, L. Physicochemical Properties of Ionic Liquids. In Ionic Liquids Further UnCOILed; Wiley: USA, 2014; pp 275−307. (53) Passos, H.; Trindade, M.; Vaz, T.; Costa, L.; Freire, M.; Coutinho, J. The impact of self-aggregation on the extraction of biomolecules in ionic-liquid-based aqueous two-phase systems. Sep. Purif. Technol. 2013, 108, 174−180. (54) Kosobutskii, V. On the Reaction of Superoxide Ion with Organochloric Compounds. Russ. J. Gen. Chem. 2009, 79, 408−413. (55) Klamt, A.; Eckert, F. COSMO-RS: a novel and efficient method for the a priori prediction of thermophysical data of liquids. Fluid Phase Equilib. 2000, 172, 43−72. (56) Diedenhofen, M.; Klamt, A. COSMO-RS as a tool for property prediction of IL mixtures-A review. Fluid Phase Equilib. 2010, 294, 31− 38. (57) Ferreira, A. R.; Freire, M. G.; Ribeiro, J. C.; Lopes, F. M.; Crespo, J. G.; Coutinho, J. A. P. An Overview of the Liquid−Liquid Equilibria of (Ionic Liquid + Hydrocarbon) Binary Systems and Their Modeling by the Conductor-like Screening Model for Real Solvents. Ind. Eng. Chem. Res. 2011, 50, 5279−5294. (58) Banerjee, T.; Sahoo, R. K.; Rath, S. S.; Kumar, R.; Khanna, A. Multicomponent Liquid−Liquid Equilibria Prediction for Aromatic Extraction Systems Using COSMO-RS. Ind. Eng. Chem. Res. 2007, 46, 1292−1304. (59) Gonzalez-Miquel, M.; Palomar, J.; Rodriguez, F. Selection of Ionic Liquids for Enhancing the Gas Solubility of Volatile Organic Compounds. J. Phys. Chem. B 2013, 117, 296−306. (60) Lin, H.; Wu, D.; Liu, L.; Jia, D. Theoretical study on molecular structures, intramolecular proton transfer reaction, and solvent effects of 1-phenyl-3-methyl-4-(6-hydro-4-amino-5-sulfo-2,3-pyrazine)-pyrazole-5-one. J. Mol. Struct.: THEOCHEM 2008, 850, 32−37. (61) TURBOMOLE User Manual, version 6.4; TURBOMOLE GmbH, 2012. (62) COSMOthermX. A Graphical User Interface to the COSMOtherm Program. User Guide, version C30_1301; COSMOlogic GmbH & Co: Burscheider Strasse 515, D-51381 Leverkusen, Germany, 2012. (63) Stenutz. www.stenutz.eu (accessed 30 October 2014). (64) Zhou, Z.-B.; Matsumoto, H.; Tatsumi, K. Cyclic Quaternary Ammonium Ionic Liquidswith Perfluoroalkyltrifluoroborates: Synthesis. Chem. - Eur. J. 2006, 12, 2196−2212.

(65) Yu, G.; Zhao, D.; Wen, L.; Yang, S.; Chen, X. Viscosity of Ionic Liquids: Database, Observation, and Quantitative Structure-Property Relationship Analysis. AIChE J. 2012, 58, 2885−2899. (66) Jessop, P. G.; Jessop, D. A.; Fu, D.; Phan, L. Solvatochromic parameters for solvents of interest in green chemistry. Green Chem. 2012, 14, 1245−1259. (67) Zhang, S.; Sun, N.; He, X.; Lu, X.; Zhang, X. Physical properties of ionic liquids: database and evaluation. J. Phys. Chem. Ref. Data 2006, 35, 1475−1517. (68) Kilaru, P. K.; Scovazzo, P. Correlations of Low-Pressure Carbon Dioxide and Hydrocarbon Solubilities in Imidazolium-, Phosphonium-, and Ammonium-Based Room-Temperature Ionic Liquids. Part 2. Using Activation Energy of Viscosity. Ind. Eng. Chem. Res. 2008, 47, 910−919. (69) Spange, S.; Lungwitz, R.; Schade, A. Correlation of molecular structure and polarity of ionic liquids. J. Mol. Liq. 2014, 192, 137−143. (70) Gurkan, B. E.; Gohndrone, T. R.; McCready, M. J.; Brennecke, J. F. Reaction kinetics of CO2 absorption in to phosphonium based anion-functionalized ionic liquids. Phys. Chem. Chem. Phys. 2013, 15, 7796−7811. (71) Gores, H. J.; Barthel, J.; Zugmann, S.; Moosbauer, D.; Amereller, M.; Hartl, R.; Maurer, A. Liquid Nonaqueous Electrolytes. In Handbook of Battery Materials; Wiley: USA, 2011; pp 525−626.

K


Solubility of Halogenated Hydrocarbons in Hydrophobic Ionic Liquids

Recommend Documents