Isotherm and kinetic studies on the adsorption of humic acid onto chitosan-H2SO4 beads

► Chitosan-H2SO4 beads were used to adsorb humic acid in aqueous solution. ► Both heterogeneous and homogeneous adsorption sites existed on the beads. ► Chemical process through the formation of a complex controlled the rate-limiting step. ► Temperature study suggested that the adsorption process was endothermic in nature. ► The highest adsorption capacity attainable by the beads was 342.50 mg/g.