Green synthesis of a novel Mn-Zn ferrite/biochar composite from waste batteries and pine sawdust for Pb removal.

Magnetic ferrite/biochar composites are a kind of promising adsorbents due to their high adsorption efficiency and facile magnetic separation; however, their synthesis is associated with high cost and secondary environmental impacts. In this study, a novel Mn-Zn ferrite/biochar composite (MZF-BC) is synthesized via a green two-step biocheaching and hydrothermal method using waste batteries and pine sawdust. Characterization results indicate that the introduced Mn-Zn ferrite particles are successfully embedded and coated on biochar (BC), and synthesized MZF-BC with 50% BC content exhibits best performance with a specific surface area of 138.5 m g, the saturation magnetization of 27.5 emu g and CEC value of 53.2 mmol 100 g. The maximum adsorption capacity of Pb is 99.5 mg g based on the Langmuir sorption isotherm study at 298 K, and pseudo-second-order model accurately describes the adsorption process. Regeneration test suggests that MZF-BC can be efficiently reused for 6 cycles. In addition, it exhibits a good selective Pb and Cd removal performance in lead-acid battery wastewater. The results illustrate that this newly developed material has low cost and rapid remediation of Pb as good application potential.