Theory of adsorption equilibria analysis based on general equilibrium constant expression

Authors: ABDUL SATTAR ALI KHAN

Abstract: Adsorption equilibria were analyzed on the basis of general equilibrium constant expression for the development of fundamental adsorption equations (Freundlich, Langmuir, and BET) in connection with the establishment of a general approach towards physical interpretations of adsorption parameters. Theoretically it was proved that Freundlich plot analysis cannot be used to find useful parameters such as the monolayer adsorption capacity of an adsorbent. The present theory also indicated that the adsorption process with known value of monolayer adsorption capacity can be studied for finding various equilibrium constants on the basis of the Fronaeus equation, which is commonly used in the complexation process. The applications of the Langmuir equation in finding the ligand number of a complex as well as the magnitude of equilibrium constant required for the analysis of the BET equation in the multilayer liquid phase adsorption process was also discussed. It was concluded that the general approach towards exploration and physical interpretation of adsorption parameters can be developed by analyzing the adsorption equilibria on the basis of general equilibrium constant expression in accordance with the law of mass action.

Keywords: Insight, adsorption, complexation, adsorption layer, ligand number, thickness of adsorbed layer, Langmuir, equilibrium constant, law of mass action

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