Isothermal adsorption data for many gases and vapors on charcoal and other adsorbents have been shown by various investigators (1), (2), (3), (4), to agree satisfactorily with the Langmuir adsorption isotherm, except for deviations, possibly due to multilayer adsorption, as the pressure of the saturated vapor is approached. The Langmuir equation is derived on the hypothesis of a unimolecular adsorbed layer. The rate of adsorption, assumed proportional to the pressure p and the fraction of the surface unoccupied, (1 - ϑ), is equated to the rate of desorption which is assumed proportional to the fraction of the surface covered, ϑ, giving the equation below.
Proceedings of the Iowa Academy of Science
© Copyright 1940 by the Iowa Academy of Science, Inc.
Rowley, H. H. and Innes, W. B.
"Application of the Van't Hoff Equation to Adsorption Equilibria,"
Proceedings of the Iowa Academy of Science: Vol. 47:
, Article 28.
Available at: https://scholarworks.uni.edu/pias/vol47/iss1/28