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51.
浊点萃取(cloud point extraction, CPE)是一种安全环保同时兼具高富集系数和低成本的萃取方法,在分析化学中已经被广泛应用于金属离子分析等领域。锕系和镧系金属元素存在环境复杂,自身浓度相对较低,对其进行分离和分析一直是放射化学研究者所关注的问题。经过条件优化,CPE能够有选择性地分离和富集锕系和镧系金属元素。通过与多种技术联用,CPE能实现锕系和镧系元素的高灵敏度分析。本文在介绍浊点萃取机理的基础上,着重描述了不同萃取体系中各类萃取剂(β-二酮类、膦氧类、含氮类、含硫类)对于锕系和镧系元素的萃取效果,全面总结了其中使用的不同联用技术,同时简述了通过构筑超分子识别位点,修饰配体,使用不同表面活性剂及掩蔽剂等改良现有浊点萃取体系的尝试。最后,对浊点萃取在放射化学领域的应用进行了总结和展望。 相似文献
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Fathi Habashi Farouk T. Awadalla Xin-Bao Yao 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1987,38(2):115-126
When phosphate rock is leached with hydrochloric acid, radium can be removed by co-precipitation with Ba0.4Ca0.6SO4 and uranium by extraction with a 5% solution of tributyl phosphate in hexane or Varsol. Phosphoric acid is then separated from calcium chloride solution and other impurities by extraction with undiluted tributyl phosphate. The lanthanides can be precipitated from the raffinate by NH3, and CaSO4.2H2O by H2SO4 to regenerate HCl for recycle. The organic phase containing H3PO4 can be stripped by NH3 to yield ammonium phosphate and to regenerate the tributyl phosphate for recycle. Fluorine can be precipitated from the initial leach solution as Na2SiF6. 相似文献
54.
Anna M. Kaczmarek Ying‐Ya Liu Chunhua Wang Brecht Laforce Laszlo Vincze Pascal Van Der Voort Kristof Van Hecke Rik Van Deun 《Advanced functional materials》2017,27(20)
Hybrid materials displaying multistage security behavior, where a single material shows both wavelength‐ and temperature‐dependent luminescence properties, are reported. The materials consist of mixed‐lanthanide β‐diketonate complexes grafted into the pores of a nanosized 2,2′‐bipyridine‐5,5′‐dicarboxylate‐acid MOF. A very specific choice of lanthanides and their ratios, as well as β‐diketonate ligand, is crucial for obtaining the desired properties. The wavelength‐dependent luminescence properties of the materials are very well matched with the excitation wavelengths of a standard UV lamp, and a clearly visible change in luminescence is observed in a narrow temperature range (slightly below and above room temperature), proving them to be excellent materials for use in anti‐counterfeit technologies, which would be almost impossible to mimic. 相似文献
55.
The extraction of lanthanides(III) from aqueous nitric acid solutions with N,N,N’,N’-tetra(n-octyl)diglycolamide (TODGA) and with mixtures of TODGA and the hydrophobic ionic liquid (IL) [C4mim][Tf2N] into 1,2-dichloroethane (DCE) has been investigated. The extraction efficiency of Ln(III) ions was greatly enhanced by the addition of a small amount of IL to an organic phase containing TODGA. The synergistic effect comes from the higher hydrophobicity of Ln(III) extracted species formed by TODGA and the weakly coordinating Tf2N? anions compared with those formed by TODGA and NO3? ions as the counter-anions. The partition of Tf2N? anions between the organic and aqueous phases is the dominant factor governing the extractability of lanthanides(III) with mixtures of TODGA and [C4mim][Tf2N]. The extraction of Ln(III) from aqueous nitric acid solutions by TODGA alone and its mixtures with [C4mim][Tf2N] into DCE can be described on the basis of the solvation extraction mechanism. However, in the extraction system with added [C4mim][Tf2N], the partition of Tf2N? between two immiscible phases and the interaction between HTf2N and TODGA in the organic phase should be taken into account. Possible reasons of the antagonistic effect in the TODGA–[C4mim][Tf2N] extraction system are discussed. 相似文献
56.
Ytterbium catalysts such as YbCl3/n-BuLi and (Cp2YbCl)2/RLi (R = Me, t-Bu, n-Bu,-CH2SiMe3) have been applied for the C-C-linkage of ethylene. Highly linear oligomers (n-alkanes) and polymers (high molecular weight polyethylene) were obtained. A reaction mechanism based on ytterbium-hydrides is proposed. 相似文献
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58.
《Journal of Nuclear Science and Technology》2013,50(10):937-943
Equilibrium distributions of actinides and fission products were determined in a LiCl-KCl/Cd system at 800–973 K. The redox potential of the system was controlled with the addition of reductant Li. Different distribution behaviors due to different group elements were observed. The group partitioning in this system was thus supported to be feasible. On reduction, however, the actinide and lanthanide elements were found to be less soluble in the Cd phase and to remain at the interface in the form of their solid intermetallics. A group partitioning process in which reductive extraction is combined with filtration was proposed on the basis of the present observations. 相似文献
59.
Extraction behaviour of trivalent americium and europium was investigated with 1-phenyl-3-methyl-4-acetyl-5-pyrazolone (HPMAP) and tri-n-octylphosphine oxide (TOPO) in a room-temperature ionic liquid, 1-methyl-3-octyl-imidazolium bis(trifluoromethylsulphonyl) imide (C8mim·Tf2N). In select cases, comparison was made using xylene, a molecular diluent. For binary extraction studies involving only PMAP, Eu3+ was marginally better extracted than Am3+ and the species extracted into C8mim·Tf2N conformed to species of the type M(PMAP)3 (where M = Am or Eu). On the other hand, cationic species were extracted for the ternary extraction systems involving HPMAP and TOPO. Luminescence spectroscopic studies suggested no inner-sphere water molecules in the extracted species. The luminescence decay lifetime showed mono-exponentials, suggesting the extraction of single species. 相似文献
60.
During treatment of nuclear fuel in the Plutonium/URanium EXtraction (PUREX) process, the extractant tri-n-butyl phosphate (TBP) is known to degrade to dibutylphosphoric acid (HDBP), which increases the extraction of metal ions, thereby inhibiting their stripping from the organic phase. To better understand this phenomenon, we investigated how mixtures of TBP and HDBP influenced the extraction of metal, nitric acid, and water, and correlated the results to aggregated structures in the organic phase. The mole ratios of TBP-HDBP mixtures had a non-linear effect on the extraction of Dy3+ and water from 0.2 M HNO3, indicating synergism. In 2 M HNO3, the TBP:HDBP mole ratio had a more linear relation to Dy3+ and water extraction, so the synergistic effect was less pronounced than in the low acid system. The extraction of nitric acid showed no synergistic effect and follows closely what would be expected in a system using TBP only. The small-angle X-ray scattering (SAXS) data of the 0.2 M acid system showed maximum contrast at a TBP:HDBP mole ratio of 0.25, so that the synergistic mixture is also the most aggregated at 0.2 M acid. The 2 M acid system also showed that the mixed system is more aggregated than the end members, although this does not result in peak extraction. Previous studies of synergistic extraction of metal cations explain the enhanced extraction by increased dehydration of the metal ion. Although our data do not rule out the formation of mixed complexes according to the classical mechanism of synergism, our evidence of increased water extraction and aggregate formation in systems combining TBP and HDBP are complementary to the metal-centric dehydration aspects of the process. The findings in this study give insights into the complex chemistry of solvent extraction, providing a possible link between formation of aggregates in the organic phase and synergistic extraction. 相似文献