Effective Removal of Pb²⁺ from Aqueous Solution Using Magnetic Mesoporous Silica Prepared by Rubidium-Containing Biotite Leaching Residues and Wastewater

The rubidium leaching process from biotite generates a large amount of waste materials that should ideally be reused for heavy metal ion adsorption so as not to create environmental problems. Ferric oxide/mesoporous silica (FO/MS) is a novel adsorbent used for heavy metal ion removal with a high removal capacity of Pb2+ (143.47 mg/g within 60 min) that was prepared for the first time by comprehensively utilizing both rubidium-containing biotite leaching residues and wastewater. The incorporation of mesoporous silica prepared by leaching residues could provide a porous framework and channel for depositing ferric oxide. Mesoporous channels have a high specific surface area that improves the adsorption activity and capacity of the material. Additionally, in a pH study, the adsorptive thermodynamic and dynamic analyses, as well as XPS and FTIR analyses, verified the adsorption properties involved in surface complexing and electrostatic binding. The surface complexation process mainly was the interaction of Pb2+ with surface hydroxyl groups. This work provided a novel and effective strategy for preparing waste solid-based heavy metal ion adsorption and expanded technologies for treating acid leaching wastewater. The adsorbents of FO/MS with a high Pb2+ adsorption capacity suggested that, compared with other materials, it is a suitable remediation material for Pb2+ contaminated water