Kinetics of Adsorption on Activated Carbon: I. Single‐Solute Systems

Abstract

Adsorption kinetics of a variety of single substances on activated carbon is investigated at low liquid‐phase concentrations. Experimental data obtained by the minicolumn method show the influence of dissociation and molecular weight of the adsorbates on their external mass transfer behavior. Modeling of minicolumn breakthrough curves proves that internal mass transport resistances have to be taken into account at low concentrations as well as high. A differential fixed‐bed reactor technique was used to determine intraparticle mass transport parameters. For strongly adsorbable substances, diffusion in the adsorbed phase proves to be prevailing, whereas for weakly adsorbable or high molecular weight adsorbates, pore diffusion also contributes to the internal mass transport. However, the surface diffusivities depend on the carbon loading in an adsorbate‐specific manner.