
84 Green Chemical Engineering
adsorbed molecules are not necessarily tightly packed with identical orientation. Other
complications include the presence of solvent molecules and the formation of micelles from
adsorbed molecules. Various isotherm equations such as those of Freundlich, Langmuir,
Temkin, Dubinin–Radushkevich (D–R) and Redlich–Peterson (R–P) have been reported
in the literature to describe the equilibrium characteristics of adsorption. Adsorption iso-
therms are mostly empirical expressions for representing experimental data within lim-
ited concentration ranges.
2A.2.1.1 Langmuir Isotherm
The Langmuir isotherm best describes the chem ...