General phenomenological approach for the description of adsorption and absorption equilibria
Rector of Tver State Technical University
Abstract: Up to the present time, the construction of a general theory of the equilibrium adsorption is a very urgent task. In the present paper, a general phenomenological approach is developed to describe both adsorption and absorption equilibria. It was shown that under certain assumptions, the resulting equation transforms into the well-known classical Henry, Langmuir, Brunauer-Emmett-Teller equations with constants having a clear physical meaning. Thus, the constant in the Henry equation is determined by the temperature, the specific surface of the adsorbent, the size of the adsorbate molecules, the molar mass of the adsorbate and the isosteric heat of adsorption (the energy of interaction of the adsorbate molecules with the surface of the adsorbent). In the derived Brunauer-Emmett-Teller partial equation, in contrast to the classical version, a clear dependence of the equation constant on the specific physical characteristics of the adsorption system is indicated for the first time. It is determined by the concentration of adsorbate molecules in the liquid phase at the temperature under consideration, the concentration of adsorbate molecules during the formation of a dense monolayer on the surface of the adsorbent, the energy of interaction of adsorbate molecules with the
surface of the adsorbent and the heat of condensation. The presented approach can serve as a basis for modeling a variety of adsorption and absorption phenomena, including adsorption on microporous adsorbents.
Keywords: adsorption, adsorbent, absorption, thermodynamics of phase equilibria, Henry equation, Langmuir equation, Brunauer–Emmett–Teller equation
- Andrey V. Tvardovskiy – Dr. Sc., Professor, Rector of Tver State Technical University
Tvardovskiy, A.V. General phenomenological approach for the description of adsorption and absorption equilibria / A.V. Tvardovskiy // Physical and chemical aspects of the study of clusters, nanostructures and nanomaterials. — 2022. — I. 14. — P. 321-330. DOI: 10.26456/pcascnn/2022.14.321. (In Russian).
Full article (in Russian): download PDF file
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