Glossary: Dubinin-Radushkevich (DR) Analysis

DR Analysis is an approach to analyzing the gas adsorption isotherms of microporous materials based on Polanyi’s potential theory of adsorption. Dubinin showed the defining characteristic of a microporous material is its micropore volume rather than its surface area.

The DR equation is widely used for linearizing the gas adsorption isotherms, and the micropore volumes can be obtained from the intercept of the DR plots.

The DR equation is given by:

W/W0 = exp {− (A / βE0) ²}

where W and W0 are the amount of adsorption at a relative pressure (P/P0) and the saturated amount of adsorption, respectively, E0 is a characteristic adsorption energy, and the parameter A is Polanyi’s adsorption potential, defined as A = RTln(P0/P). The parameter β is the affinity coefficient, and is related to the adsorbate-adsorbent interaction.