Thermodynamic properties of MCl (M = Na, K, Rb, Cs) plus tetramethylurea plus water ternary system at 298.2 K

For this article, a number of thermodynamic properties for MCl (M = Na, K, Rb, Cs) in tetramethylurea (TMU)water ternary systems were investigated through potentiometric method at the temperature of 298.2 K. To fit experiment data, the Pitzer equation and the extended Debye-Huckel equation were used. The mean activity coefficients, together with excess Gibbs free energy, osmotic coefficients and standard solubility product of ternary systems are calculated. The variation of these properties in this epsilon(r)-decreasing co-solvent (TMU-H2O) is discussed from the aspect of ion radius, relative permittivity, ion-ion interactions and ion-solvent in the solution. (C) 2019 Elsevier B.V. All rights reserved.