Effect of Ammonium Salts on the Volumetric and Viscometric Behavior of D(+)-Glucose, D(−)-Fructose and Sucrose in Aqueous Solutions at 25°C

Abstract

Apparent molar volumes, V φ, and viscosity, η, of D(+)-glucose, D(−)-fructose and sucrose in water and in 0.02, 0.05, 0.5, 1.0 and 2.0 mol·kg−1 aqueous solutions of ammonium bromide, tetraethylammonium bromide and tetra-n-butylammonium bromide have been determined at 25 °C from density and efflux time measurements by using a vibrating-tube digital densimeter and a capillary viscometer, respectively. Partial molar volumes, \(\mathop V\nolimits_{2,m}^o\), at infinite dilution that were extrapolated from the V φ data were used to obtain the corresponding transfer volumes, \(\Delta_{{\rm tr}} \mathop V\nolimits_{2,m}^o\), for saccharides from water to different aqueous solutions of co-solutes. The Jones-Dole equation viscosity B-coefficients were obtained from the viscosity data. Positive values of \(\Delta_{{\rm tr}} \mathop V\nolimits_{2,m}^o\) were obtained for the saccharides in the presence of ammonium bromide, whereas both positive and negative \(\Delta_{{\rm tr}} \mathop V\nolimits_{2,m}^o\) values were obtained in the presence of tetraethylammonium and tetra-n-butylammonium bromides. The negative \(\Delta_{{\rm tr}} \mathop V\nolimits_{2,m}^o\) values at very low concentrations have small magnitudes. Volumetric interaction coefficients have been calculated by using the McMillan-Mayer theory and Gibbs energies of activation of viscous flow have been calculated by using Feakin’s transition-state theory equation. The parameters obtained from the volumetric and viscometric studies were used to understand various mixing effects due to the interactions between saccharides and ammonium salts in aqueous solutions.