Dd. Do et Hd. Do, A NEW ADSORPTION-ISOTHERM FOR HETEROGENEOUS ADSORBENT BASED ON THE ISOSTERIC HEAT AS A FUNCTION OF LOADING, Chemical Engineering Science, 52(2), 1997, pp. 297-310
A new adsorption isotherm model is proposed in this paper for a hetero
geneous solid. The basis of this isotherm equation is that the degree
of heterogeneity is reflected through the variation of the isosteric h
eat of adsorption with respect to loading. This degree as well as the
pattern of heterogeneity is assumed to be independent of adsorbate use
d. The influence of the adsorbate on the isotherm will be through the
interaction energy at zero loading as well as parameters which reflect
the way in which the adsorbate fits into the adsorption sites. The re
sulting isotherm equation is very general, and under certain condition
s it reduces to many isotherms commonly used in the literature, such a
s the Langmuir, Langmuir-Freundlich, Toth, Fowler-Guggenheim and Nitta
et al. equations. The new isotherm is tested with adsorption isotherm
data of many adsorbates on various samples of activated carbon and ze
olite, and the parameters extracted for these adsorbates shed some lig
ht on the system heterogeneity. Implications of this new isotherm are
discussed in this paper. Copyright (C) 1996 Elsevier Science Ltd.