What's wrong with Lagergreen pseudo first order model for adsorption kinetics?

Abstract

Adsorption processes can be modeled on the basis of phenomenological principles using conservation, equilibrium and transport kinetics equations. However many times an empirical approach is followed using pseudo first order and pseudo second order models to describe adsorption kinetics. In this short communication we discuss the use of Lagergreen model (pseudo first order kinetic model) and compare it with the linear driving force model of Glueckauf for a linear adsorption equilibrium isotherm. A relation between the kinetic constants of both models is derived, being possible to disclose they exhibit very distinct dependency with temperature whatever the porous structure of the adsorbent particle. In conclusion, care must be taken when using the short-cut approach of pseudo first order expressions, taking into account their theoretically inconsistent trends.