Efficient incorporation of highly migratory thallium into struvite structure: Unraveling the stabilization mechanisms from a mineralogical perspective.

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 NH 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 (NH/K) within the structure and Tl. Ultimately, Tl is incorporated in the form of a (NH,Tl)MgPO 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.