Novel alkaline biochar prepared from woody biomass treated with low-level NaOH via pyrolytic impregnation for efficient removal of Pb(II).

This study addressed Pb(II)-contaminated wastewater pollution by preparing novel alkaline magnetic biochar (MPEC) from plant residues via alkaline activation and magnetic modification. Experiments indicate that when the biomass-to-NaOH mass ratio is 2:1 and the pyrolysis temperature is 600 °C, the biochar achieves its maximum specific surface area (58.6 m2/g), thereby providing abundant active sites for Pb(II) adsorption. The adsorption process of MPEC for Pb(II) ions conforms to pseudo-first-order kinetics and the Langmuir isotherm model. The optimal adsorption capacity (206.8 mg/g) is achieved when the pH is 6, the adsorbent dosage is 0.06 g, and the adsorption time is 90 min. Research into adsorption mechanisms has revealed that MPEC's adsorption of Pb(II) involves multiple interaction pathways, including electrostatic forces, van der Waals forces, surface coordination, and Fe-O-Pb coordination. These interactions collectively facilitate the binding of Pb(II) ions to the biochar surface. In practical aquatic environments, MPEC consistently achieves Pb(II) removal rates exceeding 90%, demonstrating excellent environmental adaptability and application potential.