Key words: molecular dynamics, modeling, solvation, dilute aqueous solutions, normal conditions, supercritical conditions, water-ethanol solutions, water-guaiacol solutions, water-phenol solutions, lignin, self-diffusion coefficient, clustering
Using a classical molecular dynamics method structures of 2 wt. % water solutions of
ethanol, phenol and o-methoxyphenol (guaiacol) were modeled in NVT-ensemble at
densities 0.997 and 0.133 g cm-3 that corresponds to normal (298 K; 0.1 MPa) and
supercritical (673 K; 23.0 MPa) conditions. Self-diffusion coefficients for individual
components in solutions, radial distribution functions for oxygen atoms of water
molecules, for oxygen atoms in hydroxy-groups and for centers of masses in phenol
molecules are calculated. A possibility of molecule clusterization for diluted substances
is analyzed. The data obtained indicate the heterogeneity of solutions in which clusters
of different composition and structure can exist. It was found that under normal
conditions clustering of up to seven ethanol and phenol molecules can occur, and
dimer formation was detected under SC-conditions. The structural features of solutions
under normal and SC-conditions were compared. The difference between the water
shells of ethanol and phenols molecules was demonstrated. Under normal conditions,
stable shells of water molecules form around ethanol molecules. For phenols, the solvate
shells are unstable and a tendency to clusterization of organic molecules is pronounced.
doi:10.1134/S1990793120070209