Adsorption of CO2 gas on two adsorbents with different surface energies, i.e., silica gel and activated carbon was studied at various temperatures. Isosteric adsorption heats were calculated from the isotherms. Adsorption enthalpies were measured directly by gas microcalorimetry at 298 K as a function of equilibrium pressure and, consequently, the amount of material adsorbed. It was established that in the case of activated carbon, an apolar adsorbent, differential adsorption enthalpy calculated from isosteric adsorption heat is in good agreement with the values determined by gas microcalorimetry. A significant difference was observed, however, in the case of the polar silica gel where specific interactions may be expected to arise between the surface and CO2 molecules. The thermodynamically consistent Toth equation  has been applied to the measured isotherms and the parameters ofthat also indicate the specific interactions mentioned above.
|Number of pages||14|
|Journal||ACH - Models in Chemistry|
|Publication status||Published - Dec 1 1997|
ASJC Scopus subject areas