Activity coefficients at infinite dilution, physicochemical and thermodynamic properties for organic solutes and water in the ionic liquid ethyl-dimethyl-(2-methoxyethyl)ammonium trifluorotris-(perfluoroethyl)phosphate
Introduction
In this work the activity coefficients at infinite dilution for different organic solutes and water in the ionic liquid ethyl-dimethyl-(2-methoxyethyl)ammonium trifluorotris(perfluoroethyl)phosphate, [COC2N1,1,2][FAP] were determined within the temperature range from (318.15 to 368.15) K using inverse gas chromatography (IGC). This is a continuation of our systematic study on thermodynamic properties of ionic liquid. Our recent research focuses on ionic liquids with the [FAP]− and [NTf2]− anions and cations with methoxyethyl substituent, namely: 4-(2-methoxyethyl)-4-methylmorpholinium trifluorotris(perfluoroethyl)phosphate, [COC2mMOR][FAP] [1]]; 1-(2-methoxyethyl)-1-methylpiperidinium trifluorotris(perfluoroethyl)phosphate, [COC2mPIP][FAP] [2]]; 1-(2-methoxyethyl)-1-methylpyrrolidinium trifluorotris(perfluoroethyl)phosphate, [COC2mPYR][FAP] [3]]; 4-(2-methoxyethyl)-4-methylmorpholinium bis(trifluoromethylsulfonyl)-amide, [COC2mMOR][NTf2] [4]]; 1-(2-methoxyethyl)-1-methylpiperidinium bis(trifluoromethylsulfonyl)-amide, [COC2mPIP][NTf2] [5]]; 1-(2-methoxyethyl)-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)-amide, [COC2mPYR][NTf2] [6]]. The work noted above [1], [2], [3], [4], [5], [6] concern activity coefficients at infinite dilution. Additionally for these ILs, the ternary (liquid + liquid) equilibria were examined [7], [8], [9], [10], [11], [12], [13].
Additionally, based on retention data, the (gas + liquid) partition coefficients, KL, and basic thermodynamic functions such as partial molar excess Gibbs , enthalpy and entropy at infinite dilution were determined for [COC2N1,1,2][FAP].
Ionic liquids have several particular properties such as a wide temperature range of the liquid state; high thermal stability; high conductivity and a wide electrochemical window; adjustable physicochemical properties by modification of the structure of both the cation as well as the anion, or by mixing two or more different ionic liquids; and extremely low vapour pressure [14], [15], [16](for example 10−3 to 10−1 Pa above T = 400 K for imidazolium ionic liquids [17]]). For environmental reasons, the last mentioned property is especially important since it prevents volatilization of these compounds to the atmosphere. Therefore the ILs can be used as solvents in extraction processes. To use an IL as an extractant, the information about interactions of the IL with different compounds is needed. Such information is provided from measurements. From the values of activity coefficients at infinite dilution, the selectivity () and capacity () can be directly calculated for different separation problems. Ionic liquids are considered as entrainers in separation of sulfur compounds from fuels [18], [19], [20], [21]. Therefore the values of selectivity and capacity for alkanes/thiophene extraction problems were calculated for the IL investigated and compared to other [FAP]− anion based ILs. [22], [23], [24], [25], [26].
Section snippets
Materials
The ionic liquid [COC2N1,1,2][FAP] had a purity of >0.995 mass fraction and was supplied by Merck. The water content was analysed by the Karl-Fischer titration technique described previously [11]. The results obtained have shown the water content to be less than 200 · 10−6. Density as a function of temperature, necessary to calculate KL, was measured previously [11]. Due to the high purity of solutes and in fact that the IGC technique separated any impurities on the column solutes were used
Results and discussion
The experimental activity coefficients at infinite dilution in [COC2N1,1,2][FAP] for 65 organic solutes and water within the temperature range from (318.15 to 368.15) K are presented in table 1. Table 2S provides information about the mean column pressure, , inlet column pressure, pi, outlet column pressure, po and standard state of solutes at given temperatures. Over the experimental temperature range, the logarithm of is a linear function of inverse temperature, therefore results obtained
Conclusions
Activity coefficients at infinite dilution and the (gas + liquid) partition coefficients for various solutes in the ionic liquid ethyl-dimethyl-(2-methoxyethyl)ammonium trifluorotris(perfluoroethyl)phosphate were measured by inverse gas chromatography technique at wide temperature range. It was found that interactions with wide range of compounds for investigated IL is similar to previously investigated [COC2mPIP][FAP] and [COC2mPYR][FAP] ILs. Additionally the extraction properties of
Acknowledgement
Funding for this research was provided by the National Science Centre in years 2011–2014 (Grant No. 2011/01/B/ST5/00800).
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2021, Journal of Chromatography ACitation Excerpt :In some cases, the system constants are projected values for solid or semi-solid ionic liquids at 25°C. The system constants for the ionic liquids in Table 9 at a reference temperature of 25°C are collected in Table 10 [4,34,35,38,47,51–53,55,71,82,91,93,100,107,109,111,115,117,120,121,123–125,127,133,146,149,155,156,162,165,166,174,176,178–180,182,187,189,190,195,200,202,204,206,208,209,217–219,223,225,228,233,260–270]. The results for trihexyl(tetradecyl)phosphonium camphorsulfonate and lactate were removed from the discussion that follows as the b system constant is negative and unrealistic based on chemical principles [219].
Characterization of the solubilizing ability of tetraalkylammonium ionic liquids containing a pendant alkyl chain bearing a basic N,N-dimethylamino or N,N-dimethylaminoethoxy functionality
2019, Journal of Molecular LiquidsCitation Excerpt :To provide as large of comparison as possible, we have searched the published literature to see if experimental data exists for other IL pairs. Our literature search found infinite dilution activity coefficient for solutes dissolved in several Ils containing an ether oxygen atom [47–53]; however, data for the non‑oxygen analog could be found for only two pairs of Ils, namely the pair of 1-propyl-1-methylpiperidinium bis(trifluoromethylsulfonyl)imide, [PMPip]+[Tf2N]− [42] and 1-methoxyethyl-1-methylpiperidinium bis(trifluoromethylsulfonyl)imide, [MeoeMPip]+[Tf2N]− [52], and pair of 1-propyl-1-methylpyrrolidium bis(trifluoromethylsulfonyl)mide, [PMPyrr]+[Tf2N]− [29] and 1-(2-methoxyethyl)-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)amide, [MeoeMPyrr]+[Tf2N]− [50]. The calculated differences at 328.15 K for these later two pairs of ILs are given in the second and third columns of Table 6.
Separation of thiophene, or benzothiophene from model fuel using glycols. Liquid–liquid phase equilibria and oxidative desulfurization study
2019, Fluid Phase EquilibriaCitation Excerpt :Due to the extremely low volatility and other unique properties, ionic liquids (ILs) are intensively studied [10], including in the process of fuel desulfurization. Experimental work in this area includes measurements of activity coefficients at infinite dilution [11–17] and measurements of phase equilibria in binary- and ternary systems [18–30]. Literature data show that ionic liquids exhibit high values of selectivity coefficients, which is promising from the point of view of fuel desulfurization processes.
Activity coefficients at infinite dilution of various organic solutes in the deep eutectic solvent (tetramethylammonium chloride + 1,6 hexanediol in the 1:1 molar ratio)
2019, South African Journal of Chemical Engineering
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