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排序方式: 共有226条查询结果,搜索用时 15 毫秒
41.
《分离科学与技术》2012,47(16):2478-2484
We have developed a liquid-liquid countercurrent centrifugal extractor that induces Taylor vortices in the annular fluid region. To demonstrate extraction of multiple species (Nd/Sm/Eu/Gd/Dy) with N,N,N′,N′-tetraoctyl diglycolamide (TODGA), additional chemical agents, such as a surfactant (sodium bis(2-ethylhexyl) sulfosuccinate (AOT)), a synergist (nonanoic acid) and a masking agent (N,N,N′,N′-tetraethyl-3,6-dioxaoctane-1,8-diamide (DOODA(C2))) were employed. When only TODGA was utilized, extraction performance was not effective due to the insufficient dispersion even under a high rotating speed. By combining TODGA and other chemical agents, the separation performance was improved considerably in the countercurrent flow of aqueous and organic phases due to the synergistic effect and improved dispersion. 相似文献
42.
Novel polyfunctional neutral organophosphorus compounds, P(O)-modified N-aryl- carbamoylmethylphosphine oxides, Ph2P(O)CH2C(O)NH-(o-C6H4)(CH2)n-P(O)Ph2 and Ph2P(O)CH2C(O)NH-(m-C6H4)(CH2)n-P(O)Ph2 (n = 1,2), were synthesized and studied as extractants for U(VI), Th(IV) and Ln(III) from HNO3 solutions. The influence of aqueous and organic phases on the extraction efficiency was elucidated and stoichiometry of the complexes extracted was determined. Introduction of an additional phosphoryl group into the phenyl substitutent at the nitrogen atom of diphenyl(N-phenylcarbamoylmethyl)phosphine oxide resulted in an increase of the efficiency of U(VI), Th(IV), Ln(III), and Re(VII) extraction. 相似文献
43.
Yuri A. Ustynyuk Igor P. Gloriozov Stepan N. Kalmykov Artyom A. Mitrofanov Vassily A. Babain Mikhail Yu. Alyapyshev 《溶剂提取与离子交换》2013,31(5):508-528
This article presents a general approach to solving the urgent practical problem of separation of 4f-(lanthanides, Ln3+) and 5f-elements (actinides, An3+) very similar in properties based on the DFT quantum-chemical supercomputer simulation of Ln3+ and An3+ complexes with polydentate nitrogen-containing heterocyclic ligands. The method allows to calculate the geometry parameters of ligands and complexes and the metal to ligand binding energies with accuracy, permitting a direct comparison of calculation results with the experimental data, and estimate selectivity factors for separation of Eu3+/Am3+ model pair cations (SFAm/Eu) in extraction experiments on a semi-quantitative level.The applicability of the method and the approach demonstrated by DFT-modeling (nonempirical PBE functional, extended relativistic full-electron basis set) of a large series of diamides of pyridine-2,6-dicarboxylic (dipicolinic) acid (L) with different substituents at the amide nitrogen atoms and in the pyridine cycle, as well as their complexes [LM]3+, (H2O)nM(NO3)3 (n = 3, 4), and LM(NO3)3 (M = Eu, Am).Based on the theoretical analysis a new model is proposed that describes the mechanism of Ln3+ and An3+ extraction in two-phase system highly acidic water solution-organic solvent, according to which the formation of An3+ and Ln3+ complexes occurs at the water/organic interface as a substitution reaction of hydroxonium ion in a cavity of a protonated ligand for the metal cation.Calculation results confirm the experimentally established higher extraction ability of dipicolinic acid diamides containing one aryl and one alkyl substituent at the amide nitrogen atoms compared to the N,N,N′,N′-tetraalkyl diamides (“effect of anomalous aryl strengthening”). Based on the simulation results the structure of the modified ligand L suggested that it should ensure maximum An3+/Ln3separation selectivity in the series of dipicolinic acid diamides. 相似文献
44.
Mikael Nilsson 《溶剂提取与离子交换》2013,31(6):665-701
Abstract The separation of trivalent transplutonium actinides from fission product lanthanide ions represents arguably the most challenging aspect of advanced nuclear fuel partitioning schemes. A considerable amount of effort has been dedicated to the development of effective methods for accomplishing this separation, essential for transmutation of the actinides heavier than Pu. Among the methods currently considered to be ready for technological deployment is the TALSPEAK (Trivalent Actinide ‐ Lanthanide Separation by Phosphorus reagent Extraction from Aqueous Komplexes) Process, developed in the late 1960s at Oak Ridge National Laboratory. This process is based on the partitioning of lanthanides and actinides between an acidic organophosphorus extractant ((RO)2PO2H) solution and an aqueous phase containing a high concentration of a carboxylic acid buffer and a polyaminopolycarboxylate complexant. The latter reagent is principally responsible for holding back the trivalent actinides, allowing the selective transfer of the lanthanides into the organic phase. Several combinations of different extractants and aqueous complexants have been investigated, as have the effect of diluent, temperature and p[H+] on separation efficiency. In this report, the prior literature is examined to help provide guidance for potential deployment of the technology in advanced nuclear fuel cycles and to identify opportunities for fine‐tuning the process. 相似文献
45.
Ryo Ishihara Shiho Asai Shigeyoshi Otosaka Shinsuke Yamada Hideyuki Hirota Kazuyoshi Miyoshi 《溶剂提取与离子交换》2013,31(2):171-180
An octadecylamino-group-introduced polymer chain grafted onto a porous sheet was impregnated with bis(2-ethylhexyl)hydrogen phosphate (HDEHP). A mixture of HDEHP and ethanol of various HDEHP concentrations was used for the impregnation. The porous sheet into which a C18H37NH group was introduced was immersed in HDEHP/ethanol solution before ethanol evaporation. The liquid permeability of a cartridge charged with the HDEHP-impregnated porous sheet in disk form prepared in 50 (v/v)% HDEHP/ethanol solution was 96% that of the starting-porous-disk-packed cartridge. The equilibrium binding capacity of the HDEHP-impregnated porous disk for yttrium ions was 0.32 mol per kg of the disk. In addition, the HDEHP-impregnated-porous-disc-packed cartridge was found to be applicable to the preconcentration of trace amounts of lanthanides in a multielement solution prior to their measurement by inductively coupled plasma mass spectrometry. 相似文献
46.
Tom Vander Hoogerstraete Bieke Onghena Koen Binnemans 《International journal of molecular sciences》2013,14(11):21353-21377
Several fundamental extraction parameters such as the kinetics and loading were studied for a new type of metal solvent extraction system with ionic liquids. The binary mixture of the ionic liquid betainium bis(trifluoromethylsulfonyl)imide and water shows thermomorphic behavior with an upper critical solution temperature (UCST), which can be used to avoid the slower mass transfer due to the generally higher viscosity of ionic liquids. A less viscous homogeneous phase and mixing on a molecular scale are obtained when the mixture is heated up above 55 °C. The influence of the temperature, the heating and cooling times, were studied for the extraction of neodymium(III) with betaine. A plausible and equal extraction mechanism is proposed in bis(trifluoromethylsulfonyl)imide, nitrate, and chloride media. After stripping of the metals from the ionic liquid phase, a higher recovery of the ionic liquid was obtained by salting-out of the ionic liquid fraction lost by dissolution in the aqueous phase. The change of the upper critical solution temperature by the addition of HCl or betaine was investigated. In addition, the viscosity was measured below and above the UCST as a function of the temperature. 相似文献
47.
48.
研究了二氯苯基二硫代膦酸 (DCPDTPI)对示踪量Am3+ 和Eu3+ 的萃取。实验结果表明 ,此萃取剂优先萃取Am3+ ,当萃取剂浓度为 0 1mol/L ,pH =2 73时 ,最大的分离因数β(Am3+ /Eu3+ ) max=8。用ICP MS法同时测定了DCPDTPI对除钷以外的所有镧系元素的萃取分配比 ,并计算了Am3+ 与这些元素的分离因数 相似文献
49.
Ananda S. Amarasekara Onome S. Owereh Sukesh K. Aghara 《中国稀土学报(英文版)》2009,27(5):870-874
The Schiff base form of the 4-acylpyrazoione ligand was immobilized on the silica surface by reaction of 3-aminopropyl silica with 4-acetyl-5-methyl-2-phenyl-2,4-dihydro-pyrazol-3-one in 97% yield, producing grafted silica with 0.77 mmol/g ligand loading. This surface modified silica was shown to be selective in the adsorption of Yb3+ ions from dilute aqueous solutions, for which 98% adsorption was observed from a 1.0×10-5 mol/L aq. solution at pH 6.7, after 24 h at room temperature. Six other lanthanides studied Eu3+, Gd3+, Nd3+, Tb3+,Sm3+ and La3+ showed moderate to weaker adsorptions of 39%, 28%, 16%, 12%, 11% and 5% respectively under similar conditions. 相似文献
50.
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