The study of hydrophobic hydration in supercritical water-methanol mixtures.

We investigated hydrophobic hydration and heat capacity (CV) of diluted aqueous solutions of methanol at supercritical region using molecular dynamics method. We performed simulations for several concentrations of methanol and densities of mixtures. Similar to that observed for ambient conditions, the 600 K solution containing 0.12 mole fraction of methanol at the density of 0.98 gm.cm-3 yields the highest CV. The intermolecular structure between water and methanol molecules at this concentration was also found to be enhanced. Hydrophobic hydration, relative to ambient conditions, is diminished slightly at the concentration of Cv maximum and diminishes drastically for the other concentrations.