SIMPLE DETERMINATION OF EXPERIMENTAL ISOTHERMS USING DIFFUSION DENUDER TUBES

If the internal wall of the diffusion column used in the reversed-flow gas chromatography (RFGC) technique is covered with an adsorbent material or a supported liquid, then isotherm determination becomes much simpler. Diffusion and resistance to mass transfer are not neglected, the sorption effect is non-existent and the pressure gradients are negligible along the bed. The method leads directly to independent experimental isotherms over a wide range of concentrations, without specifying a priori an isotherm equation. The isotherm can also be determined in the presence of a surface reaction of the adsorbate. The necessary theoretical analysis has been developed, and the equations derived were applied to benzene and cyclohexane adsorbed on graphitized carbon black, to ethene, ethyne, propene and sulfur dioxide on marble powder, and to propene on silica gel.