Surface concentration build-up during diffusion in porous media with dead-end pore volume: R. C. Goodknight and I. Fatt, J. Phys. Chem., 67, April, 1963, 949–951

Abstract

Adsorption isotherms in the range 195–298K on carbons prepared from cellulose and cellulose triacetate are interpreted in terms of the developments of the Potential theory by Dubinin and Radushkevich. It is shown that the criterion proposed by Dubinin for determining the lower limit of temperature-independence of the characteristic curve, i.e. ΔS < 0, is consistent with the postulates of the Potential theory when T <Tc, but is not generally valid. Application of this criterion to the present study shows that the Dubinin-Radushkevich equation may be applied at pp0 > ca. 10−3. The existence of this limit is attributed to the limitations of the Potential theory when applied to adsorption at very low pressures. In particular, it is suggested that there is a significant contribution from configurational terms to ΔS at low pressures.