High pressure thermodynamic and acoustic properties of decan-1-ol+heptane mixtures. A theoretical and experimental study.

This paper reports a theoretical study of decan-1-ol+heptane and ethanol+heptane systems and experimental data of decan-1-ol+heptane mixtures as a function of temperature and pressure over the whole composition range. The ability of the modifications introduced into the original ERAS model in determining thermodynamic excess properties of decan-1-ol+heptane and ethanol+heptane mixtures at high pressures is tested. This model was found to be sufficient for describing semiquantitatively excess volumes and excess enthalpies and qualitatively excess heat capacities under high pressure. The densities and speeds of sound in decan-1-ol+heptane mixtures were measured over the whole concentration range within the temperature interval from 293 to 318 K at atmospheric pressure and at pressures up to 101 MPa, respectively. The densities, heat capacities and appropriate excesses of these binaries were calculated for the same temperatures and pressures up to 100 MPa. In the calculations the acoustic method was applied. The effects of pressure and temperature on the excess volume, excess enthalpy, and the excess heat capacity of decan-1-ol+heptane mixtures are analyzed and compared with those of ethanol + heptane and dodecane+heptane mixtures. Properties of the alkan-1-ol+alkane mixtures are explained in terms of the self-association of the alkanols, free volume effect and the nonspecific interactions between the alcohol and heptane basing on the results obtained from the modified ERAS model.