Equilibrium, kinetic, and thermodynamic studies of the adsorption of Fe(III) metal ions and 2,4-dichlorophenoxyacetic acid onto biomass-based activated carbon by ZnCl2 activation

This study investigated the preparation of activated carbon from low-cost biomass as precursor and the using of obtained activated carbon for the removal of Fe(III) and 2,4-D pollutants from model solution. The different parameters affecting the adsorption were examined. Equilibrium data were fitted into Langmuir, Freundlich, D-R and Temkin isotherm models for four different examined temperatures (from 20 to 50 °C). Adsorption of 2,4-D was well described by Freundlich isotherm as a physical adsorption, whereas Langmuir model well described the adsorption of Fe(III) at four different temperatures from 20 to 50 °C. Pseudo-first-order, pseudo-second-order, intra-particle diffusion and Elovich models were used to analyse kinetic data. The adsorption kinetics for both pollutants were found to match pseudo-second-order kinetic model with high correlation (between 0.975-0.999 for Fe(III), between 0.995-0.999 for 2,4-D) than the other models. In addition, the thermodynamic parameters were evaluated and discussed for the thermodynamically modeling of the adsorption processes.