The Relation between Immersion Calorimetry and the Parameters of the Water Adsorption Isotherm on Active Carbons

It is shown that for active carbons with a single type of hydrophilic adsorption sites, the enthalpy of immersion into water is related to the number of sites, a0, and to a parameter, c, both of which appear in the Dubinin–Serpinskii equation for the water adsorption isotherm. The correlation was established on the basis of data for 13 different active carbons whose sites were either acidic or of the carbonyl type. It follows that the adsorption branch of the water isotherm can be calculated from data based on the enthalpy of immersion and the micropore volume.