Abstract: A mathematical model was built to describe the mass transfer processes and competitive adsorption in a fixed bed packed with activated carbon fibers (ACFs).The orthogonal collocation method was used to simulate the mathematical model in order to predict the breakthrough curves.The effects of competitive equilibrium constants, axial dispersion,intrafiber diffusion and external mass transfer resistance on the breakthrough curves were investigated for weakly-adsorbed and strongly-adsorbed components.The experiments were carried out to remove the phenolic compounds from water.With the equilibrium data and the intrafiber diffusivities obtained from separate experiments in a batch adsorber, axial dispersion coefficient was obtained by fitting the experimental data of breakthrough curves with the theoretical model.The effects of intraparticle and external mass transfer resistances can be negligible for the fixed bed packed with ACFs,and the axial dispersion is confirmed to be the main parameter that controls the adsorption kinetics.A simpler model, based solely on liquid phase mass balance and incorporating local equilibrium with axial dispersion, provides a good description of the process.