Adsorption of Supercritical Carbon Dioxide on Silica

In this work, the adsorption isotherms of carbon dioxide on silica have been measured with a gravimetric method at nine different temperature values (from 312 up to 466 K) and at pressure levels up to 366 bar. The adopted technique allows for a direct evaluation of the density that is measured simultaneously to the adsorption load, thus avoiding possible systematic errors arising from the use of an equation of state to calculate density from pressure and temperature data. The enthalpy changes related to the adsorption process have been obtained from a thermodynamic analysis based only on excess properties.