Lin Tao,Chen Tao,Jiao Chi,Zhang Haoyu,Hou Kai,Jin Hongxiang,Liu Yan,Zhu Wenkun,He Rong
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 (UO 2 2+ ), resulting in the complex species of UO 2 F x and thus decreasing extraction efficiency. Herein, we construct Ti δ+ -PO 4 3− ion pair extraction sites in Ti(OH)PO 4 for efficient electrochemical uranium extraction in wastewater from nuclear fuel production. These sites selectively bind with UO 2 F x through the combined Ti-F and multiple O-U-O bonds. In the uranium extraction, the uranium species undergo a crystalline transition from U 3 O 7 to K 3 UO 2 F 5 . 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.
Ce-Ti-Zr mixed oxide catalysts prepared by sol-gel method were used in catalytic combustion of CH 2 Cl 2 . The characterization reveals that the incorporation of Ce and Zr into TiO 2 anatase or Ti and Zr into CeO 2 fluorite promotes hydroxyl groups, Lewis acidity and surface oxygen through the formation of Ti-O-Zr, Ti-O-Ce and Ce-O-Zr species. Ce-Ti-Zr catalysts show high activity for CH 2 Cl 2 oxidation with the rate of 5.66 × 10 −3 –6.45 × 10 −3 μmol s −1 m −2 at 250 °C and high stability for 50 h. The substitution of surface oxygen for Cl maintains the availability of Ti-OH and thus promotes Cl removal as HCl, which is verified by a great increase in the stable activity of physically closely contacted mixture of separated CeO 2 and TiO 2 or Ti 9 Zr 1 particles. In situ FT-IR shows that CH 2 Cl 2 interacts with Ti-OH to form -O-CH 2 -O-, which is quickly rearranged into formate. Finally, formate is oxidized with surface oxygen into CO or CO 2 .
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