Study of self-di ffusion in two binary solutions, glycerol-water and methanol-water using diff usion-ordered spectroscopy


Department of Chemistry, Sharif University of Technology, Tehran, P.O. Box 11155-9516, Iran.


The concentration and temperature behaviors of the self-diff usion coecient were analyzed in glycerol-water and methanol-water solutions using Di usion-Ordered Spectroscopy (DOSY) experiment. Our results indicate that the self-di usion coecient dips with increasing concentration and decreasing temperature. The concentration behavior shows that there is hydrogen bond interaction between water and alcohol, which declines the self-diff usion coecients of both in the aqueous binary mixtures. The self-diff usion activation energies were estimated 13.6, 29.4, and 32.8 (kJ/mol) for methanol and 24.8, 25.5, and 27.6 (kJ/mol) for water in the methanol-water solutions with 0.03, 0.10, and 0.20 mole fractions of methanol, respectively. The methanol self-di usion activation energy, in the very dilute methanol-water solution (0.03 mole fraction of methanol), is consistent with the formation of iceberg-like structure which helps methanol to di use quickly. The water self-diff usion activation energies indicate that water network is not signi cantly perturbed by methanol and the water molecules di use in the same manner in methanolwater solutions.