Adsorption and Desorption Kinetics with Systems Having a Concentration-Dependent Coefficient of Diffusion

✍ Scribed by Nadezhda L. Filippova

• Publisher: Elsevier Science
• Year: 1998
• Tongue: English
• Weight: 277 KB
• Volume: 203
• Category: Article
• ISSN: 0021-9797
• DOI: 10.1006/jcis.1998.5556

✦ Synopsis

In many adsorbents, surface diffusion is the governing mechanisms of transport. The coefficient of surface diffusion may be

The calculations are based on a model that considers siconcentration dependent. The model equations for adsorption and multaneous resistance to diffusive-convective mass transfer desorption processes controlling both the diffusive-convective in a film surrounding the adsorbent particle and the surface mass transfer in the bulk and surface diffusion in the adsorbent diffusion within the pores of the solid for arbitrary concentrahave been solved for some cases for a range of parameter values tion-dependent of surface diffusion. The adsorption isotherm which may apply for many adsorption systems. The equations to is allowed to be nonlinear. The rate of mass transfer in a calculate (a) the surface diffusion coefficient, D i , (b) the activation single adsorbent spherical particle is governed by differential energy for surface diffusion, (0DH), (c) the relaxation times equation [1] characterizing the adsorption and desorption processes, and (d) the times needed, t ad G , t des G , to reach the quasiequilibrium state for the adsorption and desorption processes are derived. ᭧ 1998 Academic

ÌG(r, t)

Ìt Å 1 r 2 ͫ D i g i (G)r 2 ÌG(r, t) Ìr ͬ , 0 °r °r0 , [1] Press