High-Performance Magnetic Biochar Prepared via Acid and Mg/Fe Co-Modification for Ultraefficient Pb (II) Adsorption

In this study, MgO-containing magnetic composite biochar (MBC) was prepared from activated corn stover for the efficient removal of Pb2+. Through the introduction of magnesium and iron ions, the surface and pore structures of the acid-treated corn stover biochar adsorbent were optimized, with its adsorption capacity being enhanced to 253.6 mg g-1. MBC showed excellent adsorption performance and monolayer chemisorption, as evidenced by its pseudo-second-order kinetics and conformance with the Langmuir isotherm model. Moreover, it could maintain >85% efficiency even after five regeneration cycles. Mechanistic studies revealed that physical adsorption, electrostatic attraction, hydrogen bonding, and ion exchange were the key pathways of MBC-mediated Pb2+ removal. Finally, XRD and XPS analyses confirmed the occurrence of Pb (OH)2 precipitation and Pb-O coordination during removal. This study represents an advance in sustainable remediation technologies, providing an eco-friendly solution for managing water pollution and agricultural waste.