Theoretical development on the isosteric heat of adsorption and experimental confirmation

Theoretical framework for the isosteric heat of adsorption is developed treating the effects of the non-ideal gas behavior and the adsorbed phase volume. Rigorous thermodynamic treatment for the adsorbed phase volume is presented for multi-layer adsorption from low to high pressures. The proposed model for the isosteric heat of adsorption along with the adsorbed phase volume is validated and verified using experimental data for several, judiciously selected adsorbent + adsorbate (nonpolar molecules) systems. The predictions by the model exhibit excellent agreement with the experimental data for both adsorption isotherms and the isosteric heat of adsorption.