A volumetric and viscosity study for the binary mixtures of 1-hexyl-3-methylimidazolium tetrafluoroborate with some molecular solvents

Information on the interactions between ionic liquids and molecular solvents are essential for the understanding of the function of ionic liquids in related procedures, and excess properties are sensitive probe for these interactions. In this work, excess molar volume (V-m(E)) and excess logarithmic viscosity ((In eta)(E)) for the binary mixtures of 1-hexyl-3-methylimidazolium tetrafluoroborate ([C(6)mim][BF4]) with butanone, ethyl acetate, butylamine, and tetrahydrofuran have been determined from density and viscosity measurements in the whole composition range at the temperature of 298.15K. It is found that for the studied systems, the values of V-m(E) are negative but those of (In eta)(E) are positive in the whole concentration range. The V-m(E) values show their minimum at the ionic liquid mole fraction of 0.3, and (In eta)(E) values exhibit a maximum at the same composition. The absolute values of V-m(E) follow the sequence: tetrahydrofuran > butanone > ethyl acetate > butylamine for the binary systems, whereas the values of (In eta)(E) decrease in the order: tetrahydrofuran > butylamine > ethyl acetate > butanone. The results have been analyzed through the ion-dipole interaction, the hydrogen bonding, the packing efficiency and the ion-pairs exist in the ionic liquid. (C) 2011 Elsevier Ltd. All rights reserved.