Development of CO2/H2O activated biochar derived from pine pyrolysis: application in methylene blue adsorption

Abstract BACKGROUND The interaction mechanism between adsorbent and adsorbate is of great significance in the adsorption process. Activated biochar, prepared from pine sawdust using CO 2 and H 2 O as activator, was employed to adsorb methylene blue in printing and dyeing pollutants. The pore structure, carbon structure of the aromatic ring system and functional groups were investigated though characterization analysis, and the adsorption kinetics and possible adsorption mechanism were also studied. RESULTS The activated biochar prepared using CO 2 activation had greater specific surface area, pore structure and surface oxygen‐containing functional groups than that prepared using H 2 O, which was more conductive to improving its adsorption capacity. The electrostatic interaction between the surface oxygen‐containing functional groups and the π – π interaction formed in the aromatic rings enhanced the adsorption capacity of activated biochar for methylene blue. CONCLUSIONS The adsorption process of methylene blue by activated biochar was spontaneous, and it conformed to pseudo‐second‐order kinetic characteristics and the Langmuir adsorption isotherm equation. It was a monolayer adsorption and the maximum adsorption capacity was about 160 mg g −1 . Activated biochar as an adsorbent for wastewater treatment has promise for application and development prospects. © 2021 Society of Chemical Industry (SCI).