Adsorption from Binary Gas Mixtures and its Theoretical Description

Abstract

The experimental and theoretical investigation of adsorption of a number of binary gas mixtures on graphitized thermal black (GTB), on black TG-10 and on silochrome S-80 was carried out to discover the thermodynamic characteristics of the adsorbed substance, when the surface concentration of component 1 was very small and the concentration of component 2 was varied over rather wide limits. The adsorption was measured by the gas chromatographic method. The dependence of the Henry constant, K 1 , of the component 1 on the degree of coverage, θ 2 , of the adsorbent surface by the adsorbed component 2 was determined. For the theoretical description of the adsorption data obtained on the homogeneous GTB surface three models were used: (a) two-dimensional lattice model of adsrption from gas mixture in the Bragg–Williams approximation; (b) the well-known model of non-localized (mobile) adsorption on the basis of two-dimensional van der Waals' equation of state; (c) unidimensional lattice model of adsorbing surface which takes into account the interaction between the neighbouring adsorbed molecules. For the last model the exact solution was obtained by the matrix method. The numerical calculations with the suitably chosen parameters were carried out using the limiting forms of the isotherm equations for the dependence of K 1 on θ 2 . The results of calculations were compared with experimental data.