POLYDISPERSE MIXTURE ADSORPTION-KINETICS

We present a theoretical study of the adsorption kinetics of particles with a continuous distribution of sizes. If the particles interact wi th short-ranged forces, the diminishing rate of adsorption with increa sing surface coverage can be attributed to a geometrical blocking effe ct of the preadsorbed particles. We exploit the fact that at low cover ages the blocking effects result from isolated adsorbed particles to d evelop an analytic description of the adsorption kinetics using a mome nt expansion approach. We evaluate the time-dependent surface coverage , density and the average size of the adsorbed particles and compare t hese quantities with those of the bulk phase. The effect of desorption is studied by introducing a size-independent desorption constant, and the corresponding adsorption equilibria properties, which are valid a t low coverages, are derived. Simulation results for irreversible adso rption are obtained and compared with the theoretical predictions.