Density, Speed of Sound, and Viscosity of Aqueous Solutions Containing 1-Alkyl-4-methylpyridinium Bromide, Lactic Acid, and Polyethylene Glycol

Abstract

The effect of some 1-alkyl-4-methylpyridinium based ionic liquids on the thermodynamic and transport properties of l(+)-lactic acid in aqueous polyethylene glycol solutions have been studied. Density, speed of sound, and viscosity of l(+)-lactic acid in the aqueous solutions of polyethylene glycol, (polyethylene glycol + 1-hexyl-4-methylpyridinium bromide) and (polyethylene glycol + 1-octyl-4-methylpyridinium bromide) were measured at T = (288.15, 298.15, 308.15, and 318.15) K. Apparent molar volume, transfer apparent molar volume, apparent molar isentropic compressibility and viscosity B-coefficient of l(+)-lactic acid were calculated using experimental data and were discussed in terms of solute–solute and solute–solvent interactions. The results indicate that solute–solvent interactions were decreased by increasing the concentration of ionic liquid, length of alkyl group of ionic liquid, and temperature.