Volumetric and viscosity properties for tetraalkylammonium bromides and some ions in PC + THF mixtures at 298.15 K

Abstract

Volumes and viscosities of electrolyte solutions are important for the design of process engineering and for the understanding of ion–solvent and ion–ion interactions. In this work, densities and viscosities for solutions of tetraalkylammonium bromides (tetraethylammonium bromide, tetrapropylammonium bromide, tetrabutylammonium bromide and tetrahexylammonium bromide) in propylene carbonate (PC)+tetrahydrofuran (THF) mixed solvents were determined at 298.15K. These data were combined with the literature values of LiClO4 and LiBr in the same solvents to derive ion partial molar volumes and viscosity B-coefficients of tetraalkylammonium bromides. It was shown that these values for the tetraalkylammonium cations remained constant with the addition of THF in PC based solutions, which indicates the lack of solvation of large tetraalkylammonium cations in the organic solvents. However, those values for Li+, Br− and ClO4− decreased with increasing mole fraction of THF in PC. The ion–solvent interaction effect (Δ), the solvation radius (R±) and solvation number (ns) were also obtained to elucidate the ion–solvent interaction.