A novel magnetic biochar/MgFe-layered double hydroxides composite removing Pb2+ from aqueous solution: Isotherms, kinetics and thermodynamics

An absorbent, magnetic biochar supporting MgFe-Layered double hydroxides (MgFe-LDH) composites was synthesized to remove Pb2+ from the aqueous solution. The results of SEM, EDS, XRD, FT-IR, XPS, VSM and BET determinations showed that MgFe-LDH was successfully loaded on the magnetic biochar by hydrothermal synthesis. These characterizations also indicated that the adsorption of Pb2+ resulted from co-precipitation between interlayer anions, surface hydroxyl groups and Pb2+. The isotherms study revealed that the adsorption of Pb2+ on magnetic biochar/MgFe-LDH was well fitted to Langmuir model. The maximum adsorption capacity was 476.25 mg g(-1) at 25 degrees C. Kinetic and thermodynamic studies indicated that the adsorption process was a spontaneous endothermic reaction and limited by chemisorption. Owing to the simple synthesis, superior adsorption capacity, good magnetic properties and cyclic utilization, the magnetic biochar/MgFe-LDH is a promising adsorbent for removing Pb2+ from aqueous solution.