Density and surface tension of pure ionic liquid 1-butyl-3-methyl-imidazolium l-lactate and its binary mixture with alcohol and water

• Density and surface tension of [bmim][l-lactate] and its mixtures with alcohol/water were measured.
• Physicochemical properties of pure ionic liquid and its mixtures were discussed.
• The excess properties of [bmim][l-lactate] + alcohol show some differences with those of [bmim][l-lactate] + water.

The density and surface tension of the pure ionic liquid 1-butyl-3-methyl-imidazolium l-lactate were measured from T (293.15 to 343.15) K. The coefficient of thermal expansion, molecular volume, standard entropy, lattice energy, surface entropy, surface enthalpy, and enthalpy of vaporization were calculated from the experimental values. Density and surface tension were also determined for binary mixtures of {1-butyl-3-methyl-imidazolium l-lactate + water/alcohol (methanol, ethanol, and 1-butanol)} systems over the whole composition range from T (298.15 to 318.15) K at atmospheric pressure. The partial molar volume, excess partial molar volume and apparent molar volume of the component IL and alcohol/water in the binary mixtures were discussed as well as limiting properties at infinite dilution and the thermal expansion coefficients of the four binary mixtures. The surface properties of the four binary mixtures were also discussed.