The study of thermodynamic properties of the ternary (1-ethyl-3-methylimidazolium hydrogen sulfate + lithium chloride + water) system and corresponding binary systems at different temperatures and ambient pressure

• Vapor pressure of H2O in ([Emim][HSO4] + LiCl + H2O) at T = 298.15 K is measured.
• The Pitzer, Pitzer-Archer and modified-Pitzer models are correlated to osmotic coefficients.
• The mean activity coefficients have been calculated.
• The densities of ([Emim][HSO4] + LiCl + H2O) measured at T = (293.15–313.15) K.
• The equation was reported by Redlich-Mayer is used for correlation of Vφ values.

Thermodynamic properties of ionic liquid, 1-ethyl-3-methylimidazolium hydrogen sulfate ([Emim][HSO4]) in lithium chloride (LiCl) aqueous solutions have been investigated. Osmotic and activity coefficients of the ternary system ([Emim][HSO4] + LiCl + H2O) and their corresponding binary mixtures at T = 298.15 K are evaluated using isopiestic method. Using these data, the vapor pressures for these systems are determined. For binary systems, the Pitzer, Pitzer-Archer and modified-Pitzer models are satisfactorily correlated to the osmotic coefficients data. The Scatchard neutral-electrolyte model is fitted to the osmotic coefficients for ternary systems and corresponding mean activity coefficients for the binary and ternary systems are appraised. The densities of the ternary system ([Emim][HSO4] + LiCl + H2O) are measured at T = (293.15–313.15) K using a vibrating U-tube densimeter. Based on experimental density data, the apparent molar volumes, Vφ, are computed. The equation that reported in Redlich-Meyer article was used to correlate the Vφ values and apparent molar volumes at infinite dilution, Vφ0, are also calculated. Our results showed a negative transfer volume of [Emim][HSO4] from water to the aqueous (LiCl) solution which decreases by enhancing the (LiCl) mass fraction and temperature. The solute–solvent interactions and structure making or breaking ability of 1-ethyl-3-methylimidazolium hydrogen sulfate have been discussed in details.

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