Freundlich Isotherm The Freundlich isotherm, presented by Freundlich in 1906 (Gaballah et al., 1997), was the first isotherm model proposed for sorption processes. It can be applied for nonideal sorption on heterogeneous surfaces, as well…

Langmuir Isotherm for Solid-liquid Adsorption Classical isotherms of adsorption (Frumkin, Langmuir, Henry) were based on the model of nonpenetrable interface, where an adsorbate can substitute only molecules of one solvent. Langmuir’s theory of unimolecular layer…

Effective Separation by Chromatography An effective separation by chromatography requires a judicious choice of the adsorbing material and the solvent, and they are to be selected on the basis of the properties of the solutes.…

Chromatography An important and useful application of adsorption is in chromatography. Chromatography may be roughly defined as a process by which several constituents in a homogeneous mixture can be separated and identified by preferential and…

Adsorption from Solution When a solid is placed into a solution adsorption takes place on the surface of the solid for the same reasons which cause adsorption in the gas-solid system. The aim of this…

Gibbs’ Adsorption Equation When alcohols, phenol, glycerol, fatty acids etc. are dissolved in water, the surface tension of water is reduced, the extent of reduction depending on the concentration of the solute. In such cases,…

Gas-Liquid Interface: Surface Film and Surface Pressure Mariners in early days used to calm sea waves by spreading oil on the ocean around their boats. It is not known whether they did it knowing the…

BET (Brunauer, Emmet, and Teller) Isotherm BET analysis provides precise specific surface area evaluation of materials by nitrogen multilayer adsorption measured as a function of relative pressure using a fully automated analyzer. This information is…

Deviations from Langmuir Isotherm Deviations from Langmuir isotherm are quite common, particularly when the gas pressure is high. This deviation is thought to be due to the formation of a multimolecular layer on the surface.…

Langmuir Isotherm Measurement Many systems covering a wide range of temperature obey the Langmuir isotherm. As a matter of fact, deviation from linearity was ascribed to various other reasons which were not considered in the…