Lecture 7: Adsorption and the Langmuir and Freundlich Models

In this final lecture of Chapter 3, we take up the topic of adsorption. For adsorption, a critical characteristic of the solid phase is its surface area. Solid-phase concentrations are limited with solutes restricted to the surface or interface, resulting in competition between solutes (and often solvent molecules) for sorption sites. As a result, isotherms for such processes demonstrate decreasing slopes as solute molecules saturate surfaces. Here, the most common models for fitting adsorption isotherms, the Langmuir and Freundlich equations, will be reviewed.