A simple determination method of the absolute adsorbed amount for high pressure gas adsorption

A new determination method of the absolute adsorbed amount is proposed. The present method, which is called the buoyancy-mediated (BM) method, is simpler than the adsorbed volume mapping (AVM) method [Chem. Phys. Lett., 321 (2000) 342]. If there are data of the experimental surface excess mass up to the high pressure region, the BM method coincides with the AVM method. In the case of methane adsorption on pitch-based activated carbon fiber (ACF: P-5), the obtained volume of the adsorbed layer is from 0.84 to 20 ml/g. The isosteric heat of adsorption from the absolute adsorption isotherms is in the range of 19 to 25 kJ/mol, which almost coincides with the value calculated from grand canonical Monte-Carlo simulation.