Effect of hydrophilic additives on volumetric and viscosity properties of amino acids in aqueous solutions at T = (283.15 to 333.15) K

Apparent molar volumes and partial molar volumes at infinite dilution, V¯2∘ for amino acids (glycine, l-valine, l-leucine, l-phenylalanine, and l-aspargine) aqueous solutions in sucrose (0.05 to 0.2 (w/w)), urea (0.05), 2,3-butane diol (0.05) and 2-butoxyethanol (0.05) as additives have been calculated from the experimental densities at T = (283.15 to 233.15) K. Limiting partial molar expansibilities, E2∘, side chain partial molar volumes, V¯2,tr∘ and transfer volumes (from water to aqueous additive environment), ΔVtr∘ for both the amino acids and their side chains have also been calculated. Relative viscosities for same systems were also calculated over the same temperature range and were analyzed in terms of Jones–Dole equation to calculate B-coefficients. The analysis of volumetric functions and B-coefficients suggests that the solute–co-solute interactions are more favored at elevated temperatures and in presence of high concentration of sucrose. Otherwise the hydrophobic side chains facilitate the solute–solute interactions and also time induced hydrophobic hydration in the bulk water.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Densities and viscosities of amino acids in aqueous additive solutions at different temperatures. ► Side chain partial molar volumes, V¯2,tr∘ and transfer volumes ΔVtr∘ were calculated. ► Temperature effect on volumetric functions and B-coefficients were analyzed. ► Hydrophobic side chains facilitate the solute–solute interactions and hydrophobic hydration.