Theoretical Aspects of Multicomponent Adsorption Equilibria. Part II: Limitationsin the Application of the Adsorbed Solution Theory

摘要

Theoretical aspects of multicomponent adsorption equilibria are investigated witha focus on the thermodynamically based Adsorbed Solution Theory (AST). A previously published NRL Memorandum Report 6116-97.7946 detailed the development of a computationally fast, heterogeneous, binary adsorption relation using the Langmuir isotherm with the Ideal AST (IAST) as the local, single component and mixture adsorption models. This report outlines the limitations in the AST when applied to systems which contain components demonstrating unfavorable adsorption isotherms. Investigation of organic/water mixture data on activated carbon produces erroneous excess areas of mixing as calculated by the AST. Theoretical studies involving both the Freundlich and constant separation factor isotherms reinforce the calculations from the organic/water mixture AST work-up. The combination of these results indicate that care should be taken when applying the AST to systems that contain one or more unfavorably adsorbed components.