High adsorption of methylene blue by activated carbon prepared from phosphoric acid treated eucalyptus residue

Activated carbon with large specific surface area (1545 m(2).g(-1)) and total acid density (2.47 mmol.g(-1)) was prepared by thermal activation of phosphoric acid treated eucalyptus residue, and was successfully used for simulated dye wastewater treatment where it showed high methylene blue (MB) adsorption capacity (977 mg.g(-1)). The textural properties and acidic functional groups of the activated carbon could be adjusted and controlled by phosphoric acid/eucalyptus residue mass ratios and activation temperature. Moreover, acidic functional groups could enhance MB adsorption by converting the adsorption pattern from planar to side adsorption with a decrease in activation temperature. The adsorption process was well described by the pseudo-second order kinetics and the Langmuir isotherm model, and it was demonstrated that infra-particle diffusion involved multi-linear stages. These findings provide important insights for the efficient treatment of dye wastewater on an industrial scale using waste eucalyptus residue. (C) 2020 Elsevier B.V. All rights reserved.