Adsorption of carbon dioxide at high pressures (1-100 atm) by alumina, determined from measurement of dielectric constant

Abstract

The changes in the apparent dielectric constant of glass powder and of alumina powder on exposure to nitrogen and on exposure to carbon dioxide at 25, 30, 32 and 35°C, have been measured as a function of pressure. A formula has been derived relating the apparent dielectric constant of the powder to the dielectric constant of the material of the powder and that of the fluid in the intergranular space, which enables the adsorption of carbon dioxide to be determined quantitatively. The quantitative determination assumes the dielectric constant of the adsorbate is the same as that of the bulk liquid of the same density, an assumption which is defensible for a non-polar substance such as carbon dioxide. Two main conclusions emerge: (i) the isotherms at temperatures above the critical temperature in the bulk phase, are of the same type as are those below the critical temperature; (ii) the adsorbate is incompressible so that the density of the gas surrounding the adsorbate and in contact with it, can be greater than that of the adsorbate.