title: A method for the calculation of the adsorbed phase volume and pseudo-saturation pressure from adsorption isotherm data on activated carbon.
abstract: We propose a new method for evaluating the adsorbed phase volume during physisorption of several gases on activated carbon specimens. We treat the adsorbed phase as another equilibrium phase which satisfies the Gibbs equation and hence assume that the law of rectilinear diameters is applicable. Since invariably the bulk gas phase densities are known along measured isotherms, the constants of the adsorbed phase volume can be regressed from the experimental data. We take the Dubinin-Astakhov isotherm as the model for verifying our hypothesis since it is one of the few equations that accounts for adsorbed phase volume changes. In addition, the pseudo-saturation pressure in the supercritical region is calculated by letting the index of the temperature term in Dubinin's equation to be temperature dependent. Based on over 50 combinations of activated carbons and adsorbates (nitrogen, oxygen, argon, carbon dioxide, hydrocarbons and halocarbon refrigerants) it is observed that the proposed changes fit experimental data quite well.
authors.affiliation: Department of Mechanical Engineering, National University of Singapore, Singapore117576. mecks@hotmail.com
authors.forename: Kandadai
authors.initials: K
authors.lastname: Srinivasan
authors.forename: Bidyut Baran
authors.initials: BB
authors.lastname: Saha
authors.forename: Kim Choon
authors.initials: KC
authors.lastname: Ng
authors.forename: Pradip
authors.initials: P
authors.lastname: Dutta
authors.forename: Madhu
authors.initials: M
authors.lastname: Prasad