(505a) Viscosity, Density And Excess Volume Of Acetone + Carbon Dioxide Mixtures At High Pressures

The density and viscosity of acetone, carbon dioxide, and acetone + carbon dioxide mixtures containing 10, 25, 50, and 75 wt % carbon dioxide were determined at nominal temperatures of 325, 348, 373, and 398 K and at pressures up to 35 MPa using a falling-cylinder type high-pressure viscometer. The densities were in the range of 0.66-0.91 g/cm3, while the viscosities were in the range of 0.05-0.38 mPa?s. The densities of carbon dioxide and acetone + carbon dioxide mixtures were found to show crossovers at around 18 MPa for mixtures with CO2 content less than 50 wt % and at around 23 MPa for mixtures with CO2 content greater than 50 wt % at 325 K, which shift to higher pressures with temperature. Acetone displayed higher viscosities than the mixtures. At 325 K, the mixtures were found to show negative excess volumes at all compositions for pressures lower than 28 MPa. The excess volumes become less negative with increasing pressure and above 28 MPa are positive for high carbon dioxide content, and at pressures above 55 MPa become positive over wide range of compositions. Assessments of several mixing rules for viscosity show that logarithmic equations work well at low temperatures, while simple linear combinations of viscosity or kinematic viscosity work better at higher temperatures.

Viscosity of the mixtures could be correlated with temperature, pressure, or density. The flow activation volumes given by the viscosity-pressure correlation were in the range from 5 ? 41 cm3/mol while the flow activation energies from viscosity-temperature correlation were in the range of 5 ? 10 kJ/mol. The close-packed volume shows a decrease with addition of carbon dioxide from 0.98 for acetone to 0.45 g/cm3 for carbon dioxide. There were no direct correlations between excess viscosity and excess volume.