W. Rudzinski et al., A fractal approach to adsorption on heterogeneous solids surfaces. 2. Thermodynamic analysis of experimental adsorption data, J PHYS CH B, 105(44), 2001, pp. 10857-10866
The isotherm equations developed in part I of this publication have been fu
rther generalized to account for the effects of multilayer adsorption. This
was done employing the fractal BET isotherm developed by Fripiat et al. Th
eir BET equation takes into account the geometric effects of fractality on
the formation of second and subsequent layers, but ignores the energetic ef
fects of fractality on adsorption in the first layer, closest to the surfac
e. To correct this, their expression was integrated with the generalized ad
sorption energy distribution developed in part I (Rudzinski, W.; Lee, S.-L.
; Panczyk, T.; Yan, C.-C. S. J. Phys. Chem. B 2001, 105, 10847). Using the
generalized fractal BET equation obtained in this way, we are able to corre
late the experimental data from the lowest pressures investigated up to the
surface loadings approaching coverage by two layers. Two adsorption system
s have been subjected to this analysis. One was nitrogen adsorbed on a comm
ercially available silica, and the second nitrogen adsorbed by a commercial
ly available activated carbon. As a result of these fittings, there have be
en obtained the parameters characterizing both the geometric and energetic
heterogeneities of these two gas/solid systems.