PREDICTIONS OF MULTILAYER ADSORPTION USING LATTICE THEORY

Multilayer adsorption is calculated for a one-component vapor using id eas based on the Ono-Kondo lattice model. It is shown that this model predicts the common types of adsorption behavior: the Henry, Langmuir, and Frumkin equations as particular cases; multilayer isotherms inclu ding steps due to two-dimensional condensation; changes in the isother m that occur when the temperature is varied from subcritical to superc ritical conditions. In this paper, we investigate the adsorption isoth erm as the concentration approaches saturation conditions. The analysi s shows that at conditions near saturation the Gibbs adsorption has a weak divergence which can be described by either a logarithmic singula rity or an exponential singularity with small exponent (less than 0.05 ). (C) 1997 Academic Press.