Extended X-ray Absorption Fine Structure and Density Functional Theory Studies on the Complexation Mechanism of Amidoximate Ligand to Uranyl Carbonate
Extended X-ray Absorption Fine Structure and Density Functional Theory Studies on the Complexation Mechanism of Amidoximate Ligand to Uranyl Carbonate
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DOI：
10.1021/acs.iecr.5b03217
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发表时间：
2016-04
影响因子：
4.2
通讯作者：
Lin-juan Zhang;Jing Su;Shitong Yang;Xiaojing Guo;Yunpeng Jia;N. Chen;Jing Zhou;Shuo Zhang;Shuao Wang;Jiong Li;Jingye Li;Guozhong Wu;Jianqiang Wang
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文献类型：
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作者：
Lin-juan Zhang;Jing Su;Shitong Yang;Xiaojing Guo;Yunpeng Jia;N. Chen;Jing Zhou;Shuo Zhang;Shuao Wang;Jiong Li;Jingye Li;Guozhong Wu;Jianqiang Wang
为了阐明从碳酸铀酰溶液中萃取胺(AO)配体的机理，我们给出了用扩展X射线吸收精细结构在UL3边上获得的实验数据和理论计算结果。EXAFS数据的模拟结果表明，在赤道平面上，AO配体直接取代CO32-基团形成稳定的[UO2(CO3)3-x(AO)x](4-x)-络合物。密度泛函理论计算表明，虽然它们的静电吸引力略弱于CO32-配体，但由于铀酰-AO络合物中U5f/6d和(N，O)2p之间的轨道杂化作用，它们与铀酰的结合能力更强。这一发现为取代机理提供了强有力的证据，表明阳离子吸附剂在进一步设计高效吸附剂时是首选的，并进一步强调了共价效应在萃取过程中的关键作用。
To shed some light on the uranium extraction mechanism of amidoximate (AO) ligands from uranyl carbonate solution, we present experimental data taken using extended X-ray absorption fine structure at the U L3 edge and theoretical calculation results. The EXAFS data were well simulated and confessedly shows that AO ligands directly substitute the CO32– group in the equatorial plane to form a stable [UO2(CO3)3-x(AO)x](4-x)– complex. Density functional theory calculation indicates that although they have a slightly weaker electrostatic attraction than CO32– ligands, AO ligands display stronger binding capability to uranyl because of the remarkable orbital hybridization between U 5f/6d and (N,O)2p in the uranyl–AO complex. This finding provides strong evidence supporting the substitutional mechanism, which implies that cationic adsorbents are preferred in the further design of higher efficient adsorbents, and furthermore highlights the crucial role of the covalent effect in the extraction process.