A new kinetic equation suitable for three different adsorption systems

Inspired by reaction molecular dynamics together with chain reaction theory, physical adsorption process is proposed to be determined by two successively coupling steps, such as a transport of adsorbate molecules into adsorption system in a free convection velocity and a formation of collision-complex between surface and activated adsorbate molecule in a surface complexing velocity. This leads to establish a new kinetic equation by a product of exponential monotonic and logistic growth functions equal to adsorption extent ratio, which can be quite well validated experimentally by both uptake curves in vacuum or dynamic basket and breakthrough curves from fixed bed for adsorption of benzene vapor by micro-porous carbon. Molecular transport step is an ideal flow with a rate constant of the free convection velocity over the system size; whereas, surface complexing step depends not only on a rate constant of the surface complexing velocity over the apparent free path basically around carbon granular size, but also on its initial surface complex density distribution. The activated adsorbate growth probability is less than unity and equal to the ratio of surface complexing over free convection velocity, both of which are almost nearly proportional to the adsorbate concentration relative to adsorption capacity.