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

Densities and viscosities for the glycine + 1-alkyl-3-methylimidazolium bromide ([C(n)mim] Br, n = 2, 4, 6) ionic liquids (ILs) + water systems were measured at 298.15 K. Meanwhile, the apparent molar volumes, VU, infinite dilution apparent molar volumes, V-Phi(0), standard volumes of transfer, Delta V-t(Phi)0, 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 V-Phi(0) and Delta V-t(Phi)0 values for glycine are positive and increase with increasing IL concentrations and follow the order: [C(2)mim] Br > [C(4)mim] Br > [C(6)mim] Br. However, the B-coefficients at given molalities of the ILs are in the order: [C(2)mim] Br < [C(6)mim] Br < [C(4)mim] Br. These phenomena are discussed and interpreted by means of the structural hydration interaction model and aggregation behavior of the [C(6)mim] 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. (C) 2018 Published by Elsevier Ltd.