A gas adsorption isotherm equation based on vacancy solution theory

Abstract A new Isotherm equation for pure gas adsorption is developed and tseted. In the new method, the adsorption equilibrium is treated as an osmotic equilibrium between two “vacancy” slutions having different compsoitions. One solutions represents the gas phase and the other the adsorbed phase. The vacancy solution is composed fo adsorbates and vacancies. the latter is an imaginary entity defined as the vacuum space which acts as the solvent for the system. Thermodynamic equations governignt he euilibrium of this system are used to derive the equation of state for the adsorbed phase. The non‐ideality of the adsorbed solution is accounted for in terms of an activity coefficent whose compsotion dependence is decribed by the Wilson equation. The equation of state, together the Gibbs adsorption equation, is then used in the derivaion of the adsorption isotherm equation. The developed correlation has been evalued with the adsorption isotherm data of O 2 , N 2 , and CO on zeolite 10X at 144.3 K, 172.0 K, 227.6 K and 273.2 K, and that of CH 4 , C 2 H 2 , C 2 H 4 , C 2 H 6 , C 3 H 8 , nC 4 H 10 , and CO 2 on Nuxit‐AL activated carbon at 293.2 K, 313.2K, 333.2 K and 363.2 K. For both adsorbents, the correlations are better than those obtained by any other adsorption model which has been extended to gas mixtures. The parametes obtained from the pure component data can be use to predict a priori , gas‐mixture equilibria.