Water adsorption in active carbons described by the Dubinin–Astakhov equation

Abstract

It is shown that the adsorption of water by a variety of active carbons can be described within the framework of Dubinin's theory. Owing to the low values of the characteristic energy, E(0.8–2.5 kJ mol–1), the Dubinin–Astakhov equation becomes S-shaped in the range 0.3 < p/po <0.7 and provides a good basis for the fit of the adsorption branch of type V isotherms near room temperature. The parameters of the equation are almost temperature invariant and consequently a good agreement is also found in many cases for the enthalpies of immersion into water, as predicted by the extension of Dubinin's theory.