New general pore size distribution model by classical thermodynamics application: Activated carbon

A model is developed using classical thermodynamics to characterize pore si ze distributions (PSDs) of materials containing micropores and mesopores. T he thermal equation of equilibrium adsorption (TEEA) is used to provide the rmodynamic properties and relate the relative pore filling pressure of vapo rs to the characteristic pore energies of the adsorbent/adsorbate system fo r micropore sizes. Pore characteristic energies are calculated by averaging of interaction energies between adsorbate molecules and adsorbent pore wal ls as well as considering adsorbate-adsorbate interactions. A modified Kelv in equation is used to characterize mesopore sizes by considering Variation of the adsorbate surface tension and by excluding the adsorbed film layer for the pore size. The modified-Kelvin equation provides similar pore filli ng pressures as predicted by density functional theory. Combination of thes e models provides a complete PSD of the adsorbent for the micropores and me sopores. The resulting PSD is compared with the PSDs from Jaroniec and Chom a and Horvath and Kawazoe models as well as a first-order approximation mod el using Polanyi theory. The major importance of this model is its basis on classical thermodynamic properties, less simplifying assumptions in its de rivation compared to other methods, and ease of use.