Standard partial molar volumes and viscosity B-coefficients of ionic liquids [Cnmim]Br (n = 4, 6, 8) in alcohols at 298.15 K.

Volume and viscosity data of ionic liquid (IL)-molecular solvent mixtures are very important for the design of process engineering involving these mixtures. In this work, densities and viscosities for the binary solutions of [C n mim]Br (n = 4, 6, 8) ionic liquids with methanol, 1-propanol, and 1-pentanol have been determined at 298.15 K as a function of IL concentrations. From these experimental data, apparent molar volumes, standard partial molar volumes, and viscosity B -coefficient of ILs were derived. The effect of the alkyl chain length in the imidazolium cation and properties of alcohol on the standard partial molar volumes of ILs and viscosity B -coefficient was discussed. In a given alcohol, the standard partial molar volumes of ILs and viscosity B -coefficient increase linearly with increasing alkyl chain length of ILs. For a given IL, unexpectedly, its standard partial molar volume in the three molecular solvents is not a constant, but increases in the order: 1-pentanol > 1-propanol > methanol. The viscosity B -coefficients of a given IL in the alcohols also change in the same sequential order. These results suggest that the interactions between ILs and the alcohols increase with the decrease of alkyl chain length of the alcohols. [ABSTRACT FROM AUTHOR]