Statistical Rate Theory Approach to Kinetics of Competitive Adsorption at the Solid/ Solution Interface

Abstract

Removal of pollutants from aqueous solution is an important process, and adsorption is one of the most popular methods for this. Wastewater usually contains several solutes, and therefore the adsorption process in some systems is competitive. The lack of an adequate model for kinetics of competitive adsorption and also difficulties in modeling led only to the reporting of experimental data in most publications. Here we propose the first description of the competitive adsorption kinetics at the solid/solution interface based on the statistical rate theory (SRT) approach. For derivation of rate equations based on the SRT approach, at first we derived the chemical potential of adspecies for a competitive adsorption based on statistical thermodynamics from the partition function of a canonical ensemble. The derived kinetic equations for competitive adsorption are able to describe quantitatively the kinetics of some experimental data. Since the analytical solution of the derived rate equations led to complex expressions, we used stochastic numerical simulation for modeling of experimental data by the derived SRT equations. The present study shows that the stochastic numerical simulation is a powerful technique for modeling adsorption kinetics based on statistical rate theory.