Adsorption of gas mixtures on homogeneous surfaces Extension of Jovanovic equation on adsorption from gaseous mixtures

I n th,e development of the theory of physical adsorption of gases a very important p a r t is played by an extension of studies on multicomponent systems, i.e., extension of pure-gas equations on the adsorption from gaseous mixtures. Then t h e multicomponent adsorption isotherms are derived in terms of parameters of the pure-gas isotherms. As a typical example the mixed-gas Langmuir equation of Markharn and Benton [1] may be considered. Recently Jovanovic [2] reexamined the Langmuir adsorption model, and proved t h a t a more rigorous t rea tment of this model leads t o new isotherm equation for monolayer adsorption of pure gas on homogeneous surfaces. Jovanovic [3] demonstrated on numerous adsorption systems t h a t his equation fits exp3rimental data better t h a n the Langmuir equation. Since, t h e Jovanovic equation has been adopted by Misra [4], Rudzinski and Jaroniec [5] for developing t h e description formalism for adsorption on heterogeneous surfaces. The statistical interpretation of Jovanovic equation was discussed by Jaroniec [6]. The adsorption model considered by Jovanovic is essentially the same as t h a t of Langmuir, except for two new types of collisions taken into account. I n addition to the two types of surface-molecule collisions considered by Langmuir, two new types of collisions between bulk and adsorbed molecules are considered by Jovanovic. In the language of statistical mechanics it means t h a t the considerations of Jovanovic take into account the mechanical contact between adsorbed and bulk phase [5—7]. The adsorption mechanism assumed by Jovanovic leads (after some complicated kinetic derivation) to t h e following isotherm equation [2]