ABSORPTION OF GASES INTO ACTIVATED CARBON WATER SLURRIES IN A STIRRED CELL

A surface-aerated stirred cell with a flat liquid surface was used to investigate the absorption of propane and ethene gas into slurries of activated carbon and water. Slurries with a solids concentration up to 4% by weight and particle diameters up to 565-mu-m were used. The experimental mass transfer data were interpreted using a three-resistance model (gas-liquid, liquid-solid and intraparticle resistance). The gas-liquid mass transfer coefficient was found to be enhanced by the presence of small carbon particles in the slurry, the maximum enhancement factor being 3.5. This enhancement was not influenced by the addition of 0.6% by weight of large particles (d(p) = 565-mu-m) to the liquid phase. Intraparticle resistance to mass transfer is low, which can be explained by assuming surface diffusion of the adsorbed molecules on the porous carbon

THE ENHANCEMENT OF THE PHYSICAL ABSORPTION OF GASES IN AQUEOUS ACTIVATED CARBON SLURRIES

The enhancement of the gas-liquid mass transfer rates in aqueous slurries containing small activated carbon particles was studied in a semi-batchwise operated stirred cell absorber with a plane interface. The maximum observed enhancement factors for absorption of propane, ethene and hydrogen in the aqueous slurries were 3.6, 3.3 and 2.0, respectively. It was shown that for our results and those reported in the literature the maximum enhancement factor, E(max), decreases with increasing liquid side gas-liquid mass transfer coefficient, k(l). From all the experimental data the following relationship is found: (E(max) - 1) = 0.0019 (k(l)/[m s(-1)])(-0.71) although different types of activated carbon particles and differences in sizes were used by the various research groups. To describe these results a simple theory is presented