Ion pair sites for efficient electrochemical extraction of uranium in real nuclear wastewater

Electrochemical uranium extraction from nuclear wastewater represents an emerging strategy for recycling uranium resources. However, in nuclear fuel production which generates the majority of uranium-containing nuclear wastewater, fluoride ion (F^-) co-exists with uranyl (UO₂²⁺), resulting in the complex species of UO₂F_x and thus decreasing extraction efficiency. Herein, we construct Ti^δ+-PO₄^3- ion pair extraction sites in Ti(OH)PO₄ for efficient electrochemical uranium extraction in wastewater from nuclear fuel production. These sites selectively bind with UO₂F_x through the combined Ti-F and multiple O-U-O bonds. In the uranium extraction, the uranium species undergo a crystalline transition from U₃O₇ to K₃UO₂F₅. In real nuclear wastewater, the uranium is electrochemically extracted with a high efficiency of 99.6% and finally purified as uranium oxide powder, corresponding to an extraction capacity of 6829 mg g^-1 without saturation. This work paves an efficient way for electrochemical uranium recycling in real wastewater of nuclear production.