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Luminescence spectroscopic investigations of europium complexes formed in the kaolinite-humic acid/citric acid systems
Radiochimica Acta ( IF 1.4 ) Pub Date : 2020-11-26 , DOI: 10.1515/ract-2019-3148
Parveen Kumar Verma 1 , Prasanta Kumar Mohapatra 1
Affiliation  

Abstract In the present study, the nature of Eu(III) complexes (Eu(III) was used as a surrogate for Am(III)) formed in kaolinite–humic acid (HA)/citric acid (CA) system was investigated by luminescence spectroscopy. In addition to the ternary system (kaolinite + Eu + L(CA/HA)), the binary system (Eu-L) was also looked at for a better understanding of the complexes formed at the kaolinite surface. The lifetime and emission spectra of Eu-L complexes on the kaolinite surface differ considerably as compared to the same in the aqueous phase. The Eu-HA aqueous complexation shows differences in the excitation spectra with similar decay lifetimes with increasing aqueous HA concentrations. The ligand-to-metal charger transfer (LMCT) in the Eu-HA excitation spectra suggests the complexation of Eu(III) with HA at pH ∼ 4. Although the mode of Eu(III) binding to the kaolinite surface in the presence of CA/HA was the same i.e. metal-bridged ternary complex formation, the local surroundings around the sorbed Eu(III) differ in the two cases. The loading of HA in the Eu-HA-kaolinite system does not have a large effect on the local structure around the sorbed Eu(III) ion, but enhances the percentage of Eu(III) uptake onto the kaolinite surface. The number of H2O molecules in the primary hydration sphere of sorbed Eu(III) differs in the Eu-HA-kaolinite and Eu-CA-kaolinite systems. In addition, Eu(III) assisted precipitation of HA was also seen using a radiometric method.

中文翻译:

高岭石-腐殖酸/柠檬酸体系中形成的铕配合物的发光光谱研究

摘要 在本研究中,高岭石-腐植酸 (HA)/柠檬酸 (CA) 体系中形成的 Eu(III) 配合物 (Eu(III) 用作 Am(III) 的替代物) 的性质通过发光研究。光谱学。除了三元系统(高岭石 + Eu + L(CA/HA)),二元系统 (Eu-L) 也被用来更好地理解在高岭石表面形成的配合物。与水相中的相同,高岭石表面上的 Eu-L 配合物的寿命和发射光谱有很大不同。随着含水 HA 浓度的增加,Eu-HA 水络合显示出具有相似衰减寿命的激发光谱的差异。Eu-HA 激发光谱中的配体到金属电荷转移 (LMCT) 表明 Eu(III) 与 HA 在 pH ~ 4 时发生络合。尽管在 CA/HA 存在下 Eu(III) 与高岭石表面结合的模式是相同的,即金属桥连的三元络合物形成,但在两种情况下吸附的 Eu(III) 周围的局部环境不同。Eu-HA-高岭石体系中HA的负载对吸附的Eu(III)离子周围的局部结构没有很大影响,但提高了Eu(III)在高岭石表面的吸收百分比。在 Eu-HA-高岭石和 Eu-CA-高岭石系统中,吸附的 Eu(III) 的初级水合球中的 H2O 分子数量不同。此外,Eu(III) 辅助 HA 的沉淀也被发现使用辐射测量方法。Eu-HA-高岭石体系中HA的负载对吸附的Eu(III)离子周围的局部结构没有很大影响,但提高了Eu(III)在高岭石表面的吸收百分比。在 Eu-HA-高岭石和 Eu-CA-高岭石系统中,吸附的 Eu(III) 的初级水合球中的 H2O 分子数量不同。此外,Eu(III) 辅助 HA 的沉淀也被发现使用辐射测量方法。Eu-HA-高岭石体系中HA的负载对吸附的Eu(III)离子周围的局部结构没有很大影响,但提高了Eu(III)在高岭石表面的吸收百分比。在 Eu-HA-高岭石和 Eu-CA-高岭石系统中,吸附的 Eu(III) 的初级水合球中的 H2O 分子数量不同。此外,Eu(III) 辅助 HA 的沉淀也被发现使用辐射测量方法。
更新日期:2020-11-26
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