Remediation of Pb2+ and Cd2+ using rice husk biochar produced at low temperatures

Abstract In this study, biochar was obtained under mild conditions by pyrolysis treatment (350 oC) of rice husk, providing energy-efficient and low-carbon footprint synthesis. The pyrolyzed biochar was selected as the basis for solvothermal reaction to combine with ferrite in which the abundant functional groups would facilitate the removal of lead (Pb2+) and cadmium (Cd2+). Biochar/Ferrite (MBC) has special physicochemical properties and characterized by XRD, FT-IR, SEM, TEM, and BET. The sorption possessions of the magnetic biochar (MBC) towards the heavy metals Pb2+ and Cd2+ were validated by the batch sorption process. The findings of the batch sorption kinetics propose the mechanism of sorption follows a pseudo-second-order model. The Langmuir and Freundlich isotherm models applied to the sorption equilibrium data for assessment of sorption potential and related mechanism. These findings showed that the sorption occurred through physical and chemical connections among Pb2+ and Cd2+ through MBC functional groups. Pb2+ and Cd2+ had a sorption potential of 147 mg/g, 104 mg/g at pH 5.5, and 300 k. The synthesized MBC was tested for recovery of heavy metal from industrial effluent, and successfully recovered 80% of heavy metals Pb2+ and Cd2+. Finally, the findings obtained showed the MBC adsorbent's ability for extracting trace heavy metals from industrial effluent.