A new isotherm for multisite occupancy adsorption of binary gaseous mixtures

Langmuir. 2009 Feb 17;25(4):2309-12. doi: 10.1021/la803675h.

Abstract

Adsorption is one of the most popular methods for reducing pollutants or separation of gases. Therefore it is important to introduce new and extended isotherm equations for binary systems. In the previous adsorption isotherms for binary systems, it is assumed that an adsorbate occupies one site in lattice sites. However, the adspecies may occupy more than one site in the lattice. Here we propose an adsorption isotherm for binary systems where the adsorbates occupy more than one site. The new isotherm equation for multisite occupancy of binary mixtures was derived based on statistical thermodynamics. The present new adsorption isotherm provides information about the structure of molecules in adsorbed form. Finally, the results of the present theoretical study were confirmed by analysis of two experimental systems.