ADSORPTION OF ALIPHATIC SPECIES AS A STEPWISE AGGREGATION PROCESS LIKE MICELLIZATION

Micellization is a stepwise process defined by successive equilibrium constants H(s) for monomer bondings whose variations with s are empiri cally derived from the study of micellar solutions. The possibility of aggregation during the adsorption of short-chained aliphatic molecule s due to interactions similar to those prevailing in the case of micel lization is discussed. Transposing to adsorption an empirical law conv enient for micellization allows several kinds of behaviors encountered in the adsorption of aliphatic species to be rediscovered, in particu lar the Frumkin isotherm in the usually explored range of coverage. Th is is found when aggregates grow by stepwise bonding of dissolved mono mers. Computations are carried out assuming that the first step (actua l adsorption) is Langmuirian and that saturation occurs when the adsor bent is covered by compact hemispherical aggregates. Some features of the adsorption behavior are discussed in light of these computations.