C. Herry et al., Estimation of the influence of structural elements of activated carbons onthe energetic components of adsorption, CARBON, 39(12), 2001, pp. 1879-1889
The general mechanisms for the adsorption of organic molecules on the surfa
ce of solids are well known for flat/smooth non-porous materials. They depe
nd on low energy dispersive interactions (London-Van der Waals) responsible
for reversible physical adsorption and specific forces of greater energy a
ssociated with dipolar or acid/base interactions. However in the case of ac
tivated carbons (ACs) the study of these mechanisms is considerably hindere
d by their microporosity. The pores increase the surface area considerably
but impede the study of the surface itself. The comparative study of invers
e gas chromatography (IGC) at infinite dilution and a capillary wetting met
hod shows that the dispersive component of the surface energy is greatly in
fluenced by the porosity. The specific adsorption forces liable to interven
e in the adsorption of alkenes do not appear due to steric hindrance. Howev
er alcohols are better adsorbed than alkanes, even more so as the surface o
verlap increases. A method for estimating adsorption energy based on capill
ary wetting shows clearly that porosity is responsible for an increase in t
he dispersive adsorption energies and that the non-specific hydrophobic com
ponent is much more important than acid/base interactions susceptible to in
tervene with the surface functional groups of ACs. (C) 2001 Elsevier Scienc
e Ltd. All rights reserved.