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Citric acid modifiedmixed hardwoods powder (CMH) was preparedas a biosorbent to remove copper ions and methylene blue (MB) fromaqueous solution by batch techniques. FT-IR and XRD were used to characterizethe biosorbent. The effects of initial pH value, biosorption temperature,contact time, and initial adsorbate concentration on the biosorptioncapacities and adsorptivity of Cu2+and MB onto CMH wereinvestigated. The results showed that CMH exhibited excellent biosorptioncharacteristics for Cu2+and MB. The maximal biosorptioncapacity of Cu2+and MB onto CMH was 165.0 and 237.4 mg/gat 20 °C, respectively. The biosorption kinetics studies indicatedthat Cu2+and MB biosorption followed the pseudo-second-ordermodel. The biosorption may be controlled by external intraparticlediffusion mass transfer during the whole biosorption process. Furthermore,the biosorption-equilibrium can be well described by Langmuir andFreundlich isotherm models. [ABSTRACT FROM AUTHOR]