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

Abstract

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.