an increase in the feed flow changes the diffusion of the film without changing the intra-particle diffusion. The movement of the adsorbate from the solution to the region surrounding the adsorbent causes a concentration gradient to develop at this interface, which allows the adsorbate to cross over the film and be adsorbed. An increase in the solution velocity reduces the adhesion of the adsorbate to the adsorbent and consequently reduces the efficiency of the process The P (%) values obtained for flow rates equal to 3.9 and 11.8 mL min 1 were similar; however, the P (%) value for the intermediate flow rate was only 16.4%. This result may be explained by the larger amount of adsorbate fed into the bed (W) to reach bed saturation.