Reconsideration of theoretical basis of freundlich adsorption isotherm equation: I. The problem

Abstract

I discussed the problem we face if attempts are made to derive the Freundlich isotherm equation as an electrostatic adsorption model like the surface complexation models. To derive this equation we need the following electrostatic energy: (Formula Presented), where n is the number of ions adsorbed, and C, D, and E are constants with a positive value. This equation requires that when the number of ions adsorbed is relatively small, there must be attractive forces among adsorbed ions on the surface. The partial derivative of this equation: (Formula Presented), diverges to minus infinite at the limit n→0. This divergence requires that the attractive forces among adsorbed ions diverge to infinite at the limit n→0. To derive the Freundlich isotherm equation, we need to reveal the mechanism that leads to the requirements described above. © 1996, Taylor and Francis Group, LLC.