Phosphate functionalized silicide for efficient removal of uranium contamination from hypersaline effluents at ultralow dosage

Highly efficient removal of uranium from uranium-containing nuclear wastewater is important both for utilizing the uranium resource and protecting the environment from the hazards of uranium. However, the hypersaline environment of nuclear wastewater makes the removal of uranium a great challenge. Herein, a highly hydrophilic phosphate-functionalized silicide (VTES-PA4) is prepared by a one-step covalent grafting method for highly efficient uranium removal from hypersaline nuclear wastewater. Impressively, the uranium removal of VTES-PA4 reaches up to 97.4% within 7 min at an ultra-low dosage of 0.06 g/L in 12 ppm uranium solution, which outperforms most reported uranium removal materials. More importantly, the VTES-PA4 exhibits excellent removal rates of 86.6% and 76.9% in hypersaline wastewater containing 5 M NaNO3 and NaCl, respectively. Satisfactory uranium removal is due to the full exposure of the functional sites for binding of uranyl, endowing VTES-PA4 with a high uranium uptake capacity of 413.2 mg/g. The adsorption mechanism has been investigated by EXAFS and XPS, which reveals that uranyl is adsorbed by coordinating with six oxygen atoms from the phosphate groups. This work enriches the study on the development of uranium adsorbents from hypersaline nuclear wastewater and can contribute to the sustainable development of the nuclear energy industry.