Application of wave propagation theory to adsorption breakthrough studies of toluene on activated carbon fiber beds

Based on the wave propagation theory, a dynamics model that combines the nonlinear equilibrium isotherm and the linear mass-transfer equation has been developed to predict the breakthrough behaviour of toluene adsorption in a fixed bed packed with activated carbon fibers. The experimental results showed that the constant-pattern wave model using the Langmuir isotherm equation could capture the dynamic behaviour of the adsorption column. Two important parameters, the half breakthrough time (t_1/2) and the volumetric mass-transfer coefficients (k_Gα) in the model were obtained from linear fitting of the model to experimental breakthrough data. k_Gα was found to be insensitive to the initial concentration and increased with the increasing the superficial velocity. It was also observed that t_1/2 decreases with increasing the superficial velocity and the initial concentration, and increases with increasing the bed height. A sensitivity analysis showed that external mass-transfer had a much stronger influence on the breakthrough curve than internal mass-transfer, confirming that the overall mass-transfer for toluene adsorption onto activated carbon fibers in fixed bed is controlled by external mass-transfer.