Measuring the static dielectric constants of pure carbon dioxide and carbon dioxide mixed with ethanol and toluene at elevated pressures

Static dielectric constants (relative permittivities) of binary carbon dioxide/ethanol mixtures and carbon dioxide/toluene mixtures of various compositions at 10 MPa and 313 K, which were experimentally determined, are presented. In addition, the dielectric constant of pure carbon dioxide was measured at temperatures of 293,313 and 336 K in the pressure range of up to 30 MPa. The measurements were conducted with a new type of sensor design. The dielectric constant of pure carbon dioxide shows a pronounced dependence on pressure close to the critical pressure. There is a nearly linear relationship between density and the dielectric constant. The dielectrical behavior of the mixtures of supercritical carbon dioxide with ethanol and toluene is qualitatively very similar to that of liquid benzene/ethanol and benzene/toluene mixtures at normal pressure.