scholarly journals Density, speed of sound, refractive index and activity coefficients at infinite dilution for ionic liquids

2018 ◽  
Author(s):  
◽  
Ncomeka Mgxadeni

In this study the experimental density, speed of sound, and refractive index for binary mixtures of an ionic liquid (IL): 1-butyl-3-methylimidazolium nitrate and activity coefficients at infinite dilution of organic solutes in the ionic liquid: 1-butyl-3-methylimidazolium hydrogen sulfate were determined. The density, speed of sound, and refractive index of 1-butyl-3-methylimidazolium nitrate in pyridine or acetonitrile or thiophene have been reported at T = 298.15 K, 303.15 K, 308.15 K, 313.15 K and 318.15 K using an Anton Paar DSA 5000M vibrating U-tube densimeter and a RXA 156 refractometer. The derived properties namely: excess molar volume, isentropic compressibility and change in refractive index were calculated from density, speed of sound and refractive index, respectively. The results are discussed in terms of molecular interactions (hydrogen bond, dipole-dipole, or ion-solvent or interactions). The negative deviation of excess molar volume and the positive deviation in change in refractive index clearly indicates the strong interaction of 1-butyl-3-methylimidazolium nitrate with pyridine or acetonitrile or thiophene in solution. The positive values of isentropic compressibility for the system indicates that the mixtures were more compressible than the ideal mixture. The Redlich Kister smoothing polynomial was used to fit the excess molar volume and deviation in isentropic compressibility data. The Lorentz-Lorenz equation was used to predict the experimental density, or refractive index data and to correlate the excess molar volume. Gas liquid chromatography was used to determine activity coefficients at infinite dilution for 28 polar and non-polar organic solute: alkanes, cycloalkanes, alkenes, alkynes, aromatic hydrocarbons, alcohols, aldehydes, thiophene, pyridine and acetonitrile in an IL: 1-butyl-3- methylimidazolium hydrogen sulfate ([BMIM][HSO4]). The measured values of activity coefficients at infinite dilution for the solutes in [BMIM][HSO4] were carried out at T = (313.15, 323.15, 333.15) K. Partial molar excess enthalpies at infinite dilution of the organic solutes in the ionic liquid have been calculated from the temperature dependence of activity coefficients at infinite dilution. The selectivity and capacity values for separation problems namely: hexane/benzene, heptane/benzene, cyclohexane/benzene, ethanol/benzene, heptane/pyridine, heptane/thiophene and methanol/acetone at T = 323.15 K were calculated and compared to literature values for similar ionic liquids, sulfolane and N-methyl-2- pyrolidinone (NMP). The IL [BMIM][HSO4] gave both the highest selectivity and limiting capacity for the heptane/thiophene separation and would therefore be a suitable entrainer for this separation. New data from this study reveals that [BMIM][HSO4] may be proposed as a replacement solvent for the separation of sulphur or nitrogen compounds from alkanes.

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Maninder Kumar ◽  
V. K. Rattan

Density, refractive index, speed of sound, and viscosity have been measured of binary mixture dimethylsulfoxide (DMSO) + isopropylbenzene (CUMENE) over the whole composition range at 298.15, 303.15, 308.15, and 313.15 K and atmospheric pressure. From these experimental measurements the excess molar volume, deviations in viscosity, molar refractivity, speed of sound, and isentropic compressibility have been calculated. These deviations have been correlated by a polynomial Redlich-Kister equation to derive the coefficients and standard error. The viscosities have furthermore been correlated with two or three parameter models, that is, herric correlation and McAllister model, respectively.


RSC Advances ◽  
2016 ◽  
Vol 6 (35) ◽  
pp. 29172-29181 ◽  
Author(s):  
Xuzhao Yang ◽  
Hao Song ◽  
Jun Wang ◽  
Wenyuan Zou

Excess molar volume VEm for the system of [MPiC6Py][NTf2]2 (1) + MeCN (2) at various temperatures; solid line, Redlich–Kister correlation.


2012 ◽  
Author(s):  
◽  
Zikhona Tywabi

In this work, the binary and ternary excess molar volumes have been calculated from the density, ρ, measurements using an Anton Paar (DMA 38) vibrating tube digital densimeter. One component of the ternary systems studied was an ionic liquid. The ionic liquid used is methyl trioctylammonium bis(trifluoromethylsulfonyl)imide [MOA]+[Tf2N]-. Binary excess molar volumes were obtained for (1-butanol + ethyl acetate) and (2-butanol + ethyl acetate) systems at T = (298.15, 303.15, and 313.15) K. Ternary excess molar volumes were obtained for the mixtures {[MOA]+[Tf2N]- + 2-propanol or 1-butanol or 2-butanol + ethyl acetate} at T = (298.15, 303.15, and 313.15) K. The Redlich-Kister equation was fitted to the calculated binary excess molar volume data to obtain the fitting parameters which were used to calculate the partial molar volumes at infinite dilution. The calculated partial molar volume was used to better understand the intermolecular interactions of each component at infinite dilution. The Redlich-Kister parameters were also used in the Cibulka equation and the Cibulka equation was used to correlate the ternary excess molar volume data to give the fitting parameters. The binary excess molar volumes,VmE , for the (1-butanol + ethyl acetate) and (2-butanol + ethyl acetate) are positive at each temperature over the entire composition range. At high mole fractions of the alcohol for the binary systems (2-propanol or 1-butanol or 2-butanol + ethyl acetate), VmE is positive again, similar to the Cibulka ternary correlation. The positive V E m values are due to the breaking of intermolecular interactions in the pure components during the mixing process. The ternary excess molar volume,V E 123 , values are negative for all mole fractions. The negative values are due to a more efficient packing and/ or attractive intermolecular interactions in the mixtures than in the pure liquid. There is also a contraction in volume which can be attributed to electron-donor-acceptor type interactions between the ionic liquid and 2-propanol or 1-butanol or 2-butanol as well as ethyl acetate.


2016 ◽  
Author(s):  
◽  
Mbalenhle B. Nduli

The thermophysical properties of the binary mixtures containing biofuel components derived from biomass were determined. Experimental densities, speed of sound, and refractive indices for the binary mixtures (methanol or 1-ethyl-3-methylimidazolium acetate [EMIM][OAc] + furfural or furfuryl alcohol ) were measured at T = (298.15, 303.15, 308.15, 313.15 and 318.15) K. From the experimental data, excess molar volume, E m V , isentropic compressibility, s  , molar refractions, R, and deviation in refractive index, Δn, were calculated. The excess molar volumes were found to be negative for all systems studied. The isentropic compressibility were found to be both positive for the whole composition and temperature range and increases slightly with increasing temperature. The deviation in refractive index was positive over the whole composition range. The obtained values of excess molar volumes and changes of refractive index on mixing were satisfactorily correlated by the Redlich–Kister equation. The Lorentz–Lorenz equation was applied to predict the density and calculate the excess molar volume of the binary mixtures.


2019 ◽  
Vol 25 (2) ◽  
pp. 154-164
Author(s):  
Hemayat Shekaari ◽  
Mohammed Taghi Zafarani-Moattar ◽  
Seyyedeh Narjes Mirheydari ◽  
Elnaz Mazaher Haji Agha

Background: The thermophysical properties of 1-octyl-3-methylimidazolium salicylate as an active pharmaceutical ingredient based on ionic liquid have been investigated in the presence of aqueous solutions of glycine. Therefore, the scope of this article was to determine these properties by measuring the densities, speeds of sound, viscosities, electrical conductances and refractive indices for ternary (glycine + 1-octyl-3-methylimidazolium salicylate + water) soloutions at T = 298.15 K. Methods: A commercial density and speed of sound measurement apparatus was used to measure the density and speed of sound data. Viscosities, electrical conductivities and refractive indices of the studied solutions were measured using digital viscometer, conductivity meter and refractometer, respectively. Results: Variety of properties such as partial molar volume of transfer ∆traV0ϕ, partial molar isentropic compressibility of transfer ∆traK0ϕ, viscosity B-coefficients of transfer ∆traB, ion association constants (KA) and molar refraction RD were determined to investigate the solute-solute and solute-solvent interactions in these systems. Conclusion: The positive values of transfer properties including partial molar volume of transfer (∆traV0ϕ), partial molar isentropic compressibility of transfer (∆traK0ϕ), and viscosity B-coefficients of transfer (∆traB) indicated that in these systems, the ion-polar and polar-polar interactions are dominant. The calculated hydration number showed that dehydration of glycine occurs in presence of this ionic liquid.


2010 ◽  
Author(s):  
◽  
Indra Bahadur

The thermodynamic properties of mixtures involving ionic liquids (ILs) with alcohols or alkyl acetate or nitromethane at different temperatures were determined. The ILs used were methyl trioctylammonium bis(trifluoromethylsulfonyl)imide ([MOA]+[Tf2N]-) and 1-butyl-3- methylimidazolium methyl sulphate [BMIM]+[MeSO4]-. The ternary excess molar volumes (�������� E ) for the mixtures {methyl trioctylammonium bis (trifluoromethylsulfonyl)imide + methanol or ethanol + methyl acetate or ethyl acetate}and (1-butyl-3-methylimidazolium methylsulfate + methanol or ethanol or 1-propanol + nitromethane) were calculated from experimental density values, at T = (298.15, 303.15 and 313.15) K and T = 298.15, respectively. The Cibulka equation was used to correlate the ternary excess molar volume data using binary data from literature. The �������� E values for both IL ternary systems were negative at each temperature. The negative contribution of �������� E values are due to the packing effect and/or strong intermolecular interactions (ion-dipole) between the different molecules. The density and speed of sound of the binary solutions ([MOA]+[Tf2N]- + methyl acetate or ethyl acetate or methanol or ethanol), (methanol + methyl acetate or ethyl acetate) and (ethanol + methyl acetate or ethyl acetate) were also measured at T = ( 298.15, 303.15, 308.15 and 313.15) K and at atmospheric pressure. The apparent molar volume, Vφ , and the apparent molar isentropic compressibility, κφ , were evaluated from the experimental density and speed of sound data. A Redlich-Mayer type equation was fitted to the apparent molar volume and apparent molar isentropic compressibility data. The results are discussed in terms of solute-solute, solute- solvent and solvent-solvent interactions. The apparent molar volume and apparent molar isentropic compressibility at infinite dilution, ��φ �� and κφ ��, respectively of the binary solutions have been calculated at each temperature. The ��φ �� values for the binary v systems ([MOA]+[Tf2N]- + methyl acetate or ethyl acetate or methanol or ethanol) and (methanol + methyl acetate or ethyl acetate) and (ethanol + methyl acetate or ethyl acetate) are positive and increase with an increase in temperature. For the (methanol + methyl acetate or ethyl acetate) systems ��φ �� values indicate that the (ion-solvent) interactions are weaker. The κφ �� is both positive and negative. Positive κφ ��, for ([MOA] + [Tf2N]- + ethyl acetate or ethanol), (methanol + ethyl acetate) and (ethanol + methyl acetate or ethyl acetate) can be attributed to the predominance of solvent intrinsic compressibility effect over the effect of penetration of ions of IL or methanol or ethanol. The positive κφ �� values can be interpreted in terms of increase in the compressibility of the solution compared to the pure solvent methyl acetate or ethyl acetate or ethanol. The κφ �� values increase with an increase in temperature. Negative κφ ��, for ([MOA] + [Tf2N]- + methyl acetate or methanol), and (methanol + methyl acetate) can be attributed to the predominance of penetration effect of solvent molecules into the intra-ionic free space of IL or methanol molecules over the effect of their solvent intrinsic compressibility. Negative κφ �� indicate that the solvent surrounding the IL or methanol would present greater resistance to compression than the bulk solvent. The φ �� values decrease with an increase in the temperature. The infinite dilution apparent molar expansibility, ��φ �� , values for the binary systems (IL + methyl acetate or ethyl acetate or methanol or ethanol) and (methanol + methyl acetate or ethyl acetate) and (ethanol + methyl acetate or ethyl acetate) are positive and decrease with an increase in temperature due to the solution volume increasing less rapidly than the pure solvent. For (IL + methyl acetate or ethyl acetate or methanol or ethanol) systems ��φ �� indicates that the interaction between (IL + methyl acetate) is stronger than that of the (IL + ethanol) or (IL + methanol) or (IL + ethyl acetate) solution. For the (methanol + methyl acetate or ethyl acetate) systems ��φ �� values vi indicate that the interactions are stronger than (ethanol + methyl acetate or ethyl acetate) systems.


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