H. Komiyama is on leave from the University of Tokyo, Japan
Surface diffusion in liquid-filled pores
Article first published online: 17 JUN 2004
Copyright © 1974 American Institute of Chemical Engineers
Volume 20, Issue 6, pages 1110–1117, November 1974
How to Cite
Komiyama, H. and Smith, J. M. (1974), Surface diffusion in liquid-filled pores. AIChE J., 20: 1110–1117. doi: 10.1002/aic.690200608
- Issue published online: 17 JUN 2004
- Article first published online: 17 JUN 2004
- Manuscript Revised: 8 JUL 1974
- Manuscript Accepted: 8 JUL 1974
- Manuscript Received: 9 MAY 1974
Surface diffusivities of benzaldehyde in liquid-filled pores of Amberlite particles (polystyrene) were measured at 25°C using water as a solvent. For particles of different surface areas but chemically similar pore surfaces, the intrinsic surface diffusivity Ds' was about the same, but the relative importance of surface to pore-volume diffusion increased with surface area. For a single type of particle, the adsorption capacity was decreased about twenty-fold by adding up to 19 mole % methanol to the solvent. This was accompanied by an increase in Ds' from 1.2 × 10−8 to 1.2 × 10−7 cm2/s. These results were interpreted in terms of a two-step theory for surface migration: (1) formation of a vacant site on the adsorbent surface followed by (2) movement of the adsorbate molecule into the site by breaking the surface-adsorbate bond. The theory predicts that surface transport will be large when the surface area is high and that the Ds' will be large when the heat of adsorption is low, and when the bond between solvent molecules and the surface is weak.
In our studies the surface contribution to intraparticle transport was as much as 20 times the contribution due to pore-volume diffusion. This ratio increases as the concentration of adsorbate in the liquid decreases.