Competitive adsorption of phenolic compounds onto activated carbon fibers in fixed bed

For a multicomponent competitive adsorption process, a mathematical model w as built to describe the mass transfer kinetics in a fixed-bed adsorber pac ked with activated carbon fibers (ACFs). The effects of competitive adsorpt ion equilibrium constants, axial dispersion, external mass transfer, and in traparticle diffusion resistances on the breakthrough curves were analyzed for weakly adsorbed and strongly adsorbed components. Experiments were carr ied out to remove phenolic compounds from an aqueous solution. With the equ ilibrium data and the intraparticle (intrafiber) diffusivities obtained fro m separate experiments in a batch adsorber, the axial dispersion coefficien t was evaluated by fitting the experimental data of breakthrough curves wit h the theoretical model. The results show that the effects of intrafiber an d external mass transfer resistances on the breakthrough curves can be negl ected for a fixed-bed adsorber packed with ACFs, and the axial dispersion i s confirmed to be the main parameter that controls the adsorption kinetics. A simpler model, based solely on a liquid phase mass balance and incorpora ting local equilibrium with axial dispersion, provides a good description o f the adsorption process for a fixed-bed adsorber packed with ACFs.