Consequence of chitosan treating on the adsorption of humic acid by granular activated carbon

► We explore the equilibrium and kinetic adsorption of humic acid onto chitosan treated granular activated carbon (MGAC). ► It was shown that pre-adsorption of chitosan onto the surface of GAC improved the adsorption capacity for HA. ► Monolayer capacities for the adsorption of HA onto MGAC was more than GAC. ► Film diffusion and intra-particle diffusion were simultaneously operating during the adsorption process for MGAC. ► Chitosan provides chemical binding for the adsorption onto the GAC.