(367d) Volumetric and Acoustic Properties of Saccharides in Aqueous Solutions Containing Polyethylene Glycols (PEGs)

In order to verify possible effects of the interactions of saccharides with polyethylene glycols, experimental data on density and speed of sound of saccharides in polyethylene glycol solutions (PEG200, PEG300 and PEG400) were determined at different temperatures and concentrations, and at atmospheric pressure (p = 92,3 kPa). Densities and sound velocities of the prepared solutions were obtained using a Density and Sound Velocity Analyzer, manufactured by Anton Paar (Model DAS 5000). The saccharides studied were D(+)-glucose and sucrose. Saccharide solutions were prepared at concentrations of m = (0.1; 0.3; 0.5; 0.7; 0.9; 1.1; 1.3; 1.5 and 1.7) mol·kg^-1 in pure water and in solutions of polyethylene glycols with a concentration of m = (0.025; 0.050; 0.075 and 0.100) mol.kg^-1. Data were determined at temperatures T = (283.15; 288.15; 293.15; 298.15 and 303.15) K. From the experimental results of density and speed of sound, the following thermodynamic properties were calculated: the apparent molar volumes, the partial molar volumes at infinite dilution, the partial molar volumes of transfer of saccharides from water to the PEG solutions, the apparent molar isentropic compressibilities, the partial molar isentropic compressibilities at infinite dilution and the partial molar transfer isentropic compressibilities of saccharides from water to the PEG solutions. The behavior of the volumetric and acoustic properties at infinite dilution leads to the assumption of weak solute-solute interactions and strong solute-solvent interactions. The transfer properties indicate that the hydrophilic-hydrophilic type interactions should prevail in the studied systems, which occur between the hydrophilic groups (-OH, -C=O, -O-) of saccharides and (-OH) of polyethylene glycols.