The physical chemistry of uranium (VI) immobilization on manganese oxides
The physical chemistry of uranium (VI) immobilization on manganese oxides
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锰氧化物上固定铀 (VI) 的物理化学
DOI：
10.1016/j.jhazmat.2020.122207
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发表时间：
2020-06-05
影响因子：
13.6
通讯作者：
Wang, Xiangke
中科院分区：
文献类型：
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作者：
Ren, Yiming;Bao, Hongliang;Wang, Xiangke
锰氧化物对铀具有很强的亲和力，在环境保护中的铀固定化方面具有广阔的应用前景。我们成功合成了一系列不同结构的氧化锰材料并研究了它们的U(VI)固定性能。结果表明，所有锰氧化物每单位表面积具有相似的吸附能力，这意味着固定化过程中具有相似的物理化学性质。在这些锰氧化物中，α-MnO2 在铀吸收方面表现出最出色的性能（280 mg/g）。对 U(VI) 在 α-MnO2 上的界面特性进行了更详细的研究，以阐明结合机制。吸收很大程度上受酸度影响，但受离子强度影响较小，表明内球结合模式。对铀的选择性远高于其他选定的金属离子，即Co2+、Ni2+、Eu3+等。ATR-FTIR和EXAFS结果表明，在弱酸性和中性条件下，U(VI)在α-MnO2上形成双齿双核结构，由912 cm(-1)处的v as (0 = U = 0)和U配位壳中Mn的数量证明。在中性条件（pH 7-8）下发现分子水平的UO2(OH)(2)沉淀。研究结果揭示了铀在氧化锰表面固定过程中的物理化学性质，有助于更好地了解铀的环境迁移。此外，它还提供了放射性水净化的替代方法。
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, alpha-MnO2 shows the most outstanding performance for uranium uptake (280 mg/g). More detailed studies on interfacial properties of U(VI) on alpha-MnO2 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. Co2+, Ni2+, Eu3+, etc. ATR-FTIR, and EXAFS results showed that in both mild acidic and neutral conditions, U (VI) formed bidentate binuclear structure on alpha-MnO2, as evidenced by v as (0 = U = 0) at 912 cm(-1) and the number of Mn in U coordination shell. UO2(OH)(2) 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.