KINETICS OF ADSORPTION OF PHENOLIC-COMPOUNDS FROM WASTE-WATER ONTO ACTIVATED CARBON

The adsorption kinetics of phenol and p-nitrophenol in aqueous solutio n using activated carbon as adsorbent has been studied, providing new experimental data at 25-degrees-C obtained in a glass agitated batch a dsorber. Three kinetic models are compared: a simple external resistan ce model; a linear model assuming linear isotherm and external mass tr ansfer resistance negligible, and a pore diffusion model assuming non- linear isotherm and significant mass transfer resistance. Diffusion co efficients are considered constant in these two last models. Best repr oduction of adsorption decay curves is given by the pore diffusion mod el for both adsorbates, requiring a numerical solution for solving the equations. The linear model, in spite of its simplicity, provides goo d reproduction too, particularly for phenol. Since it only requires an alytical solution. it could give a good balance between accuracy and p ractical needs for preliminary design.