Temperature and composition dependences of volumetric properties of (water + 1,2-propanediol) binary system

Abstract

The experimental data on the density of aqueous solutions of 1,2-propanediol over the whole concentration range are performed at different temperatures (278.15, 288.15, 298.15, 308.15, 323.15 and 333.15) K and atmospheric pressure. The density was measured also for the diluted solutions at temperatures from 274.15 to 283.15K with 1K step for examination of 1,2-propanediol influence on the temperature of maximal density (TMD) of water. The apparent molar volume of the mixture components, Vφ,i, the partial molar volumes, Vi, and the partial molar isobaric expansions, Ep,i, were calculated depending on concentration and temperature. The following volumetric parameters were determined for infinite diluted solutions: the partial molar volumes of the mixture components, Vi∞, and the partial molar isobaric expansions, EP,i∞. The results obtained were discussed in terms of solute-solvent and solute-solute interactions. The literature data on the above volume properties of (water+1,2-propanediol) mixture were reviewed. The character of disturbing influence of 1,2-propanediol on the structure of water was established using different approaches to analysis of the volumetric properties. It was shown that the criteria of hydrophobicity examined resulted in contradictory conclusions. Therefore those criteria are to be considered simultaneously for drawing reasonable conclusions.