Adsorption on heterogeneous surfaces: site energy distribution functions from Fritz-Schlüender isotherms.

Different site energy distribution functions based on the condensation approximation method are proposed for the liquid-phase or gas-phase adsorption equilibrium data following the Fritz-Schlüender isotherm. Energy distribution functions for the four limiting cases of the Fritz-Schlüender isotherm are also discussed. The proposed models are successfully applied to the experimental equilibrium data of nitrogen molecules at 77 K on a pitch-based activated carbon (PA) and a pitch-based activated carbon containing boron (PBA).