Efficient incorporation of highly migratory thallium into struvite structure: Unraveling the stabilization mechanisms...

The remediation of high-concentration thallium (Tl⁺) contaminated wastewater is a critical environmental concern. Current research emphasizes the effectiveness of adsorption and oxidation methods for Tl⁺ treatment, yet challenges persist in enhancing their performance. This study explores the feasibility of emergency Tl⁺ wastewater treatment and elucidates the mechanisms of Tl⁺ incorporation into mineral structures, with a focus on the struvite mineral as a framework for Tl⁺ integration via NH₄⁺ ion exchange. To assess the efficacy and mechanisms of Tl⁺ immobilization, we utilized comprehensive analytical techniques, including X-ray Diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), Fourier-Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy with Energy-Dispersive X-ray Spectroscopy (SEM-EDS), Thermogravimetric Analysis (TG), and Density Functional Theory (DFT) calculations. The findings reveal that struvite adsorbs Tl⁺ onto its surface, followed by an ion exchange process between monovalent cations (NH₄⁺/K⁺) within the structure and Tl⁺. Ultimately, Tl⁺ is incorporated in the form of a (NH₄,Tl)MgPO₄ solid solution within the structure, achieving a remarkable maximum incorporation capacity of 320.56 mg/g, which significantly surpasses the capacity of typical adsorbents. The findings demonstrate significant Tl⁺ incorporation, validating the approach for emergency wastewater treatment and suggesting the potential of mineralogy in environmental remediation. This research contributes to advancing heavy metal wastewater treatment strategies, offering a foundation for further investigation.