Volumetric and viscosity properties of glycine in ionic liquid + water solutions at 298.15 K

Abstract

Densities and viscosities for the glycine + 1-alkyl-3-methylimidazolium bromide ([Cnmim]Br, n = 2, 4, 6) ionic liquids (ILs) + water systems were measured at 298.15 K. Meanwhile, the apparent molar volumes, VΦ, infinite dilution apparent molar volumes, VΦ0, standard volumes of transfer, ΔtVΦ0, of glycine and volumetric interaction parameters were further calculated. The viscosity B-coefficients of glycine in the aqueous IL solutions were calculated by using the Jones-Dole equation. The results show that both VΦ0 and ΔtVΦ0 values for glycine are positive and increase with increasing IL concentrations and follow the order: [C2mim]Br > [C4mim]Br > [C6mim]Br. However, the B-coefficients at given molalities of the ILs are in the order: [C2mim]Br < [C6mim]Br < [C4mim]Br. These phenomena are discussed and interpreted by means of the structural hydration interaction model and aggregation behavior of the [C6mim]Br in water. This work provides the important basic data for the understanding of the interaction between the ILs and amino acids/proteins and for the design of industrial processes.