Advanced modelling of adsorption process on activated carbon

Abstract

To gain a deeper insight into the adsorption kinetics mechanism, the adsorption of p-chlorophenol (PCP) from water, cyclohexane, and heptane on surface chemistry modified activated carbons was modeled by the general rate (GR) differential mass transport model, which takes into account external and internal mass transfer resistance. Due to the fact that the particles of AC are characterized by a wide particle size distribution (PSD) and pore diameter distribution (PDD), which are usually not considered for the simulation, our experimental dates were modeled with the GR model, in which PSD and PDD were included. It was found that, for organic phases, mainly the slow surface adsorption–desorption process controls mass transfer. In the case of water, the mass transfer was controlled by molecular diffusion in pores or by slow surface adsorption depending on AC. It was also shown that neglecting the PSD can lead to errors in the evaluation of the values of the adsorption model parameters, whereas, on the other hand, the pore diameter distribution can be successively approximated by average pore diameter.