Abstract:
Choline-amino acid based ionic liquids (CHAAILs) are well-established eco-friendly chemicals. However, the high viscosity of pure ionic liquids limits their industrial applications. Instead, ionic liquid-containing solutions are more frequently used. For example, the mixture of CHAAILs and water has already been used in biomass processing and extraction. However, there are only few studies on the physicochemical properties of aqueous solutions of CHAAILs, especially on migration properties such as viscosities (
η ) and electrical conductivities (
к ), which are important physical and chemical parameters for the industrialization of ionic liquids, and also for their mass transfer rate. Herein, we synthesized two CHAAILs, cholinium glycinate(ChGly) and cholinium analinate (ChAla). The viscosities and the electrical conductivities of ChGly+H
2O and ChAla+H
2O systems were determined at 288.15—323.15 K. The changes in viscosity and electrical conductivity of these systems with temperature were described by the Arrhenius equation and VFT equation, respectively. The viscosity and conductivity of the CHAAILs+H
2O mixtures decreased and increased with temperature, respectively. The excess viscosity (Δ
η ) of the systems was calculated and correlated by the Redlich-Kister equation, resulting in a negative deviation, which increased with decreasing temperature as well as the increase in alkyl chain length of amino acid anion. The relationship between molar electrical conductivities and viscosities of CHAAILs+H
2O mixtures was correlated by the Walden rule. The results suggest that the binary system of ChAla+H
2O has good ionicity.