Observation of Wall Effects in Activated Carbon Filters by X-ray μCT

A. Léonard1, H. Wullens2, S. Blacher1, P. Marchot1, D. Toye1, M. Crine1, P. Lodewyckx3

1University of Liège – Department of Applied Chemistry, Laboratory of Chemical Engineering Sart Tilman B6c, 4000 Liège, Belgium, Email: A.Leonard@ulg.ac.be

2DLD Defence Laboratoria Department – NBC Protection – Martelarenstraat 181, B-1800 Vilvoorde - Belgium

3Royal Military Academy – Dept. of Chemistry – Renaissancelaan 30, 1000 Brussel - Belgium

ABSTRACT

X-ray microtomography has been recently used to follow adsorption dynamics in activated carbon beds. In the present work, this technique allows the detection of wall effects during the dynamic adsorption of methyl iodide. The analysis of transversal cross sections clearly shows the existence of radial concentration profiles within the filters. The adsorption profiles are directly linked to velocity profiles due to a higher permeability at the wall. It is essential to take into account this phenomenon to model adsorption and to predict precisely breakthrough times.

Keywords X-ray microtomography, activated carbon, adsorption, wall effect