Kinetics of gas adsorption in activated carbons, studied by applying the Statistical Rate Theory of Interfacial Transport

The Statistical Rate Theory of Interfacial Transport (SRTIT) is an approach that makes it possible to deduce the basic features of adsorption kinetics from the behavior of the system at equilibrium. In the case of activated c arbons, the Dubinin-Astakhov (DA) isotherm has been known as the simplest a nd very efficient formula to correlate equilibrium adsorption isotherms, an d their temperature dependence. Thus, using the SRTIT approach, we have dev eloped the rate equation corresponding to the DA isotherm equation. The new kinetic equation has successfully been used to correlate experimental data for the kinetics of sorption of benzene by an activated carbon. That succe ssful attempt has brought us to postulate another form of sorption kinetics , than those already recognized, i.e., "molecular", "Knudsen", and "surface ". Namely, that in the case of some adsorption systems, the Knudsen's diffu sion may be fast, and the rate-determining step is the exchange of mass bet ween the pore walls and the interior of the pores.