Analysis Of Supercritical Adsorption Equilibrium Data For Active Carbons
ANALYSIS OF SUPERCRITICAL ADSORPTION EQUILIBRIUM DATA FOR ACTIVE CARBONS
L. Czepirski and B. Laciak
University of Mining and Metallurgy, Faculty of Fuels and Energy,
al. Mickiewicza 30, 30-059 Cracow, Poland
The adsorption under equilibrium conditions when both pressure and temperature are higher than the critical has received big attention in the published literature. Research interest in this area has been promoted by projects developed for many important separations of gaseous mixtures (in PSA processes), as well as, adsorption storage of gases. The proper design and optimization of these processes requires detailed knowledge of the adsorption isotherm, which are required for capacity, selectivity and breakthrough curves calculations.
The objective of this study is to correlate adsorption isotherms for some gases on active carbons by an idea based on the Polanyi and Dubinin potential theory of adsorption.
Methods of treatment of equilibrium data at temperature above the critical where the concept of saturation vapor pressure is meaningless are presented.
Temperature - independent characteristic curves as well as generalized curve of adsorbate volume in the adsorbed state versus the reduced adsorption potential were obtained. This successful correlation gives the possibility to predict adsorption isotherm points for a given adsorbate at any temperature and pressure.
Modification of Dubinin – Astakhov equation is given and discussed. The form of D-A equation is preserved and physical background of its parameters is modified in accordance with the behavior of the adsorbate at supercritical temperature.
The results can be used for the design of adsorption systems and for predicting adsorption equilibrium behavior of binary and/or multicomponent gaseous mixtures on active carbon under wide range of conditions, without time consuming and expensive experimental determination.
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