SIMULATION OF NONEQUILIBRIUM PHYSICAL ADSORPTION TAKING INTO ACCOUNT THE ADATOMS INTERACTIONS

We investigate the gas sorption dynamics in the adsorbate-adsorbent op en system of the interacting particles. For the description of the gas transfer dynamics in the adsorptious system we proposed a model in wh ich, unlike the well-known sorption dynamics models, interactions betw een adatoms and activated complexes are explicitly taken into account. Numerical analysis of the proposed model for the evolution of concent rations v in the gas phase and theta in the sorbent pores was carried out. It is found that there exists a threshold of the values beta epsi lon (beta = (k(B)T)(-1), epsilon is the effective adatom-adatom intera ction parameter) depending on which the surface coverage reaches the s aturation, maximum value theta(S) equivalent to theta --> 1 very fast. The time tau(S) for reaching such a saturation of the adsorbate conce ntration decreases essentially with the increase of beta epsilon. It i s shown that the jumpy behaviour of the concentrations v and theta in both gas and adsorbate phases exists during the period of t less than or equal to tau 0. For t > tau(0) we have a uniform, equilibrium distr ibution of the concentrations in the adsorption system. That is, in th e system under consideration the characteristic, 'chemical' time tau(c hem) = tau(0) Of the interface mass exchange occurs. The estimation of the 'chemical' time in the areas of physical adsorption was performed . (C) 1997 Elsevier Science B.V.