Effect of temperature, nature of anion and alkyl chain length on the volumetric and acoustic properties of ionic liquid [C<inf>4</inf>C<inf>1</inf>im][MeSO<inf>4</inf>] with alkyl nitriles

Densities (ρ) and speeds of sound (u) of 1-butyl-3-methylimidazolium methyl sulphate, [C4C1im][MeSO4] with acetonitrile (ACN), propionitrile (PCN) and n-butyronitrile (n-BCN) in the complete composition range at temperatures between 298.15 K and 313.15 K with 5 K intervals and atmospheric pressure is reported. Solute-solvent interactions have been evaluated in the mixtures of [C4C1im][MeSO4] with alkyl nitriles by calculating excess volumes (VE) and excess isentropic compressibilities (κsE). The VE and κsE values as a function of mole fraction are correlated using a Redlich-Kister type expression. The excess functions (VE and κsE) are found to be negative over the complete range of mole fraction for the investigated binary solutions. The studied excess properties are found to increase with the increase in the alkyl chain length of alkyl nitriles. The excess thermodynamic properties of the mixed solvents are discussed in relation to intermolecular interactions and structural effects existing between the component molecules. In addition, the effect of the nature of anion of ionic liquid and temperature on the excess thermodynamic properties has been investigated.