Simulation of non-equilibrium physical adsorption taking into account the adatoms interactions

We investigate the gas sorption dynamics in the adsorbate–adsorbent open system of the interacting particles. For the description of the gas transfer dynamics in the adsorptious system we proposed a model in which, unlike the well-known sorption dynamics models, interactions between adatoms and activated complexes are explicitly taken into account. Numerical analysis of the proposed model for the evolution of concentrations ν in the gas phase and θ in the sorbent pores was carried out. It is found that there exists a threshold of the values βε (β=(kBT)−1, ε is the effective adatom–adatom interaction parameter) depending on which the surface coverage reaches the saturation, maximum value θs≡θ→1 very fast. The time τs for reaching such a saturation of the adsorbate concentration decreases essentially with the increase of βε. It is shown that the jumpy behaviour of the concentrations ν and θ in both gas and adsorbate phases exists during the period of t≤τ0. For t>τ0 we have a uniform, equilibrium distribution of the concentrations in the adsorption system. That is, in the system under consideration the characteristic, `chemicalʹ time τchem=τ0 of the interface mass exchange occurs. The estimation of the `chemicalʹ time in the areas of physical adsorption was performed.