Ren Yiming, Bao Hongliang, Wu Qian, Wang Huaisheng, Gai Tao, Shao Lang, Wang Shaofei, Tang Hao, Li Yingru, Wang Xiangke
Institute of Materials, China Academy of Engineering Physics, PO Box 9071-11, Mianyang, China.
Shanghai Institute of Applied Physics, Chinese Academy of Sciences, 2019 JiaLuo Road, Shanghai 201800, China.
J Hazard Mater. 2020 Jun 5;391:122207. doi: 10.1016/j.jhazmat.2020.122207. Epub 2020 Jan 30.
Manganese oxides show strong affinity towards uranium, and have a promising application in uranium immobilization in environmental protection. We successfully synthesized a series of Mn oxide materials of different structures and investigated their U(VI) immobilization performances. The results showed that all Mn oxides share similar sorption capacities per unit surface area, implying similar physical chemistry during immobilization. Among these Mn oxides, α-MnO shows the most outstanding performance for uranium uptake (280 mg/g). More detailed studies on interfacial properties of U(VI) on α-MnO were performed to elucidate the binding mechanism. The uptake was largely influenced by acidity, but less impacted by ionic strength, indicative of an inner-sphere binding mode. The selectivity for uranium is much higher than other selected metal ions, i.e. Co, Ni, Eu, etc. ATR-FTIR, and EXAFS results showed that in both mild acidic and neutral conditions, U(VI) formed bidentate binuclear structure on α-MnO, as evidenced by υ(O = U=O) at 912 cm and the number of Mn in U coordination shell. UO(OH) precipitate was found at the molecular level in neutral condition (pH 7-8). The results reveal the physical chemistry in uranium immobilization process on manganese oxide surfaces and helps to better understand the uranium environmental migration. Furthermore, it provides an alternative approach for radioactive water purification.
氧化锰对铀具有很强的亲和力，在环境保护中铀固定方面有着广阔的应用前景。我们成功合成了一系列不同结构的锰氧化物材料，并研究了它们对U(VI)的固定性能。结果表明，所有锰氧化物单位表面积的吸附容量相似，这意味着在固定过程中具有相似的物理化学性质。在这些锰氧化物中，α-MnO对铀的吸附性能最为突出（280 mg/g）。对α-MnO上U(VI)的界面性质进行了更详细的研究，以阐明其结合机制。吸附受酸度影响较大，但受离子强度影响较小，表明为内球结合模式。对铀的选择性远高于其他选定的金属离子，如Co、Ni、Eu等。ATR-FTIR和EXAFS结果表明，在弱酸性和中性条件下，U(VI)在α-MnO上形成了双齿双核结构，912 cm处的υ(O = U=O)以及U配位壳层中Mn的数量证明了这一点。在中性条件（pH 7-8）下，在分子水平上发现了UO(OH)沉淀。这些结果揭示了氧化锰表面铀固定过程中的物理化学性质，有助于更好地理解铀在环境中的迁移。此外，它为放射性水净化提供了一种替代方法。
