Characteristic adsorption isotherm for adsorption of vapors on heterogeneous adsorbents

The dimensionless group [(mRT/ΔG) ln(P/P°)] is a universal function of θ (fractional filling of micropores) for different vapors adsorbed on a heterogeneous adsorbent. Adsorptive parameters are the saturation capacity (m) and the free energy of immersion of the solid in bulk liquid adsorbate (ΔG). The heat of immersion of the adsorbent determines the temperature dependence of ΔG according to the Gibbs-Helmholtz equation ΔH = ∂(ΔG/T)/∂(1/T).