Highly Efficient Uranium Capture via Crystalline Water Coordination Coupling with Cation Exchange and Surface Redox Reaction Mechanisms within an Open-Framework Vanadoborate

Developing highly efficient adsorbents for uranium-contaminated
wastewater treatment has aroused tremendous attention due to the radioactive
feature and environmental hazards. Herein, the 3D vanadoborate framework
SUT-6 constructed from (VO)12O6B18O36(OH)6 clusters bridged by ZnO4(H2O) is evaluated for uranium removal, with a UO22+ adsorption capacity of up to 347.7 mg/g under
the optimal pH of 4.0. It exhibits high selectivity to UO22+ with the existence of various common interfering cations
and anions. In addition, the adsorption efficiency of SUT-6 is above
92% after the third round of the adsorption−desorption process.
Most importantly, SUT-6 retains great UO22+ adsorption
performance in uranium-contaminated environmentally relevant water
sources, including natural river water and groundwater. Comprehensive
characterization techniques were employed to probe the uranium speciation
and accurate atomic-scale position after adsorption, to determine
the adsorption mechanism. Results show that SUT-6 is promising for
UO22+ capture based on the unique crystalline
water coordination coupling with cation exchange and surface redox
chemistry mechanisms under complicated environmental water conditions.
This work provides new insights into designing highly efficient uranium
adsorbents for practical uranium capture.