The law proposed in this paper to the adsorbate-adsorbent interaction potential, as a function of the dimensions of the pores, based on a simple and obvious hypothesis: the amount of material adsorbed per unit time is proportional to the variation of the potential.

This law is purely experimental. The experimental study of the flux allowed us to determine the expression of the variation of the potential, and by integration, to specify the expression of the latter.

Experience shows that the adsorption potential is constant and highest for micropores and that it decreases linearly in the case of mesopores and macropores, finally it is low for side surface interactions of the adsorbent when saturation is almost reached. The tangent intersects the curve in the part relating to the adsorption of mesopores and macropores, which implies a change in the type of adsorbate-adsorbent interaction forces. This physically implies the existence of two types of interaction forces: one type of force is active in the case of adsorption in micropores and mesopores and the other is active during adsorption in macropores and on the lateral surface of Zeolite13X. These findings justify the existence of the two most commonly used models, Dubinin-Astakov and BET.