Undescribed Hitherto Universal Properties of Isotherms of Excess Adsorption of Liquids and Gases. Connection of Peculiar Points of an Isotherm with Extremums of Its Curvature

Abstract

In the proposed paper, a new result is presented, which is as follows: the point on the equilibrium excess adsorption isotherm at which the rate of increase of concentration of a component in the adsorption phase reaches its mean value is the point at which the curvature of the isotherm takes its extreme value. This regularity also holds in the case of the adsorption of gases. This result is confirmed and valid for isotherms of various types. This in turn allows us to directly find the limiting adsorption of the pure component and then the partial isotherm of absolute adsorption. Thus, this result demonstrates that the curvature of the excess adsorption isotherm holds crucial information about the adsorption system, enabling the calculation of absolute adsorption isotherms and several specific characteristics such as the volume of the adsorption space.