New model for S-shaped isotherm data and its application to process modeling using IAST

Recently S-shaped (sigmoidal-shaped) adsorption isotherms have attracted much attention as having potential for reduced energy use in pressure or temperature swing based separations. Despite a wide variety of such isotherm data reported in the literature, convenient mathematical representations of S-shaped isotherms are not yet available. The absence of such models relating pressure and uptake values hinders the evaluation of many potentially promising adsorbents in separation and storage. Herein, a new mathematical model is proposed that parameterizes S-shaped isotherm data. The model provides a basis for deriving analytical expressions for the spreading pressures, to achieve a dramatic computational cost reduction in the ideal adsorption solution theory (IAST) calculation for multi-component isotherms. Then, the proposed model is generalized for its broader application. To consider the temperature effect based on isotherm data distributed at varying temperatures, a method is suggested to use such distributed data in fitting a single isotherm model. Each of the models and methods is illustrated with their application examples to facilitate the understanding and clarifying the advantages of the proposed model. Among them, a practical example with simulations of breakthrough experiments is provided.

Automated summary

Recent research focuses on S-shaped adsorption isotherms, proposing a new mathematical model to parameterize such data and reduce computational costs while broadening applications. The model also considers the temperature effect on adsorption behavior, with practical examples provided to illustrate its advantages.