Highly efficient capture of uranium (VI) from wastewater by urchin-like W18O49: insights to performance-dependence on active sites

Urchin-like W 18 O 49 , with a large specific surface area (113.738 m 2 ·g −1 ) and abundant oxygen vacancies (OVs), was prepared using an active sites tuning and microstructure engineering method. This material was applied for U(VI) adsorption for the first time, demonstrating a high adsorption capacity of 567.55 mg·g −1 , which exceeds that of most inorganic adsorbents. Characterization via active site masking experiments and theoretical calculations, etc., indicated that the excellent adsorption performance toward U(VI) was due to strong complexation between UO 2 2+ and W–O bond of W 18 O 49 , facile oxygen vacancy adsorption, and interface electron transfer from W 5+ to UO 2 2+ , which acted as a reducing agent, partially converting U(VI) to U(IV). Furthermore, W 18 O 49 exhibited practical applicability with a removal rate exceeding 82% after 5 cycles, a 92.79% removal rate for real uranium-containing wastewater, and a high uranium recovery rate of 75.96%. Additionally, the synergistic adsorption-photocatalytic effect significantly enhanced U(VI) extraction, reaching an extraction capacity of 988.0 mg·g −1 . This work provides a promising strategy for developing highly efficient U(VI) WO 3 -based adsorbents. Graphical abstract