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 Pb. 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. 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 Pb removal. Finally, XRD and XPS analyses confirmed the occurrence of Pb (OH) 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.