Pyridinedicarboxylic Acid Diamides as Selective Ligands for Extraction and Separation of Trivalent Lanthanides and Actinides: DFT Study

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 (SF_Am/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.     

Heterogenized Phosphinic Acid on UiO-66-NH2: A Bifunctional Catalyst for the Synthesis of Polyhydroquinolines

Catalysis Letters - The preparation and application of UiO-66-NH2-bis(aminomethyl)-phosphinic acid are reported in this study. The supported phosphinic acid is designed via a multi-step...     

Octahedral Chloride Complexes of Trivalent Actinides and Lanthanides in Solution

The preparation of the crystalline octahedral complex tris (triphenylphosphonium) hexachloro-americate (III) is reported. The absorption spectra of the octahedral hexachloro complexes of curium (III), americium (III) and most of the trivalent lanthanides in a nitrile solvent are also reported. The dissociation of the hexachloro americate complex anion in the nitrile solvent and in propylene carbonate has been examined. The stepwise association constant K₆ for its formation from the pentachloro complex was found to be 150 ± 20 and 60 ± 20 in 85% vol succinonitrile 15% acetonitrile solvent and in propylene carbonate respectively.     

Solvent Extraction Separation of Some Actinides and Lanthanides with Sulfoxides

Abstract

Studies have been made on the extraction of some actinides [Th(IV), Pa(V), and U(VI)] and lanthanides [La(III), Ce(III), Pm(III), Eu(III), and Tb(III)] from hydrochloric acid medium by dialkyl sulfoxides. The actinides have extraction maxima at 7.0 M HCl while the lanthanides practically do not get extracted. Thus the extraction separation of these two groups can be effected by the preferential extraction of the actinides by the sulfoxides.     

Solvent Extraction Separation of Some Actinides and Lanthanides with 2-Thenoyltifluoroacetone

Abstract

Solvent extraction behavior of Th(IV) and U(VI) and some lanthanides [Ce(III), Nd(III), Eu(III), Tb(III), and Yb(III)] from thiocyanate medium into sulfoxides and/or 2-thenoyltrifluoroacetone has been studied. The actinides are found to be favorably extracted by both the extractants. The alkyl sulfoxides extract Th(IV) and U(VI) as Th(SCN)₄·3DPSO, Th(SCN)₄·3DOSO, UO₂ (SCN)₂·2DPSO, and UO₂(SCN)₂·3DOSO. The chelate extracts the metals in the following order: U(VI) < Th(IV) < Eu(IV) < Tb(III) < Tb(III) < Ce (III) or Nd(III).     

A Double Liquid Membrane System for the Removal of Actinides and Lanthanides from Acidic Nuclear Wastes

Abstract

Supported liquid membranes (SLM), consisting of an organic solution of n-octyl(phenyl)-N, N-diisobutylcar-bamoylmethylphosphine oxide (CMPO) and tributyl-phos-phate (TBP) in decalin are able to perform selective separation and concentration of actinide and lantha-nide ions from aqueous nitrate feed solutions and synthetic nuclear wastes.

In the membrane process a possible strip solution is a mixture of formic acid and hydroxylammonium formate (HAF). The effectiveness of this strip solution is reduced and eventually nullified by the simultaneous transfer through the SLM of HNOs which accumulates in the strip solution. A possible way to overcome this drawback is to make use of a second SLM consisting of a primary amine which is able to extract only HNO₃ from the strip solution.

In this work the results obtained by experimentally studying the membrane system: synthetic nuclear waste/CMPO-TBP membrane/HCOOH-HAF strip solution/ primary amine membrane/NaOH solution, are reported. They show that the use of a second liquid membrane is effective in controlling the HN0₃ concentration in the strip solution, thus allowing the actinide and lanthanide ions removal from the feed solution to proceed to completion.     

Synergistic Extraction of Trivalent Actinides and Lanthanides Using Htta and an Aza-Crown Ether

Abstract

An aza-crown ether, 4,13-didecyl-1,7,10,16-tetraoxa-4,13-diazacyclooctadecane (K22DD) has been shown to have a synergistic effect on the extraction of trivalent lanthanides and actinides by thenoyltrifluoroacetone (HTTA). The extraction of Am(III), Cm(III), Am(III), Eu(III), Ce(III), and Pm(III) from an aqueous acetate buffer system (pH=4.8) into HTTA/K22DD/chloroform phase was studied at 25[ddot]C. Distribution coefficients were measured as a function of HTTA concentration, K22DD concentration, and pH user radiotracer techniques. The synergistic species was determined from these studies to be M(TTA)3.K22DD. The results show that the presence of K22DD synergizes the extraction of each of the metals studied by factors of approximately lO⁴-1O⁵. Slightly larger organic phase stability constants were measured for the trivalent actinides relative to the trivalent lanthanides.     

Novel Bifunctional Resins in Metal Ion Separations: Ion Exchange/Coordination Resins and Ion Exchange/Precipitation Resins

Abstract

Dual mechanism bifunctional polymers (DMBP's) as metal ion extractants are described within the context of two new examples. The carboxylic acid/pseudocrown resin is a new example of the DMBP class of resins described as ion exchange/ coordination resins. The polyethylene glycol ligand within the resin functions as a coordinating site for metal ions which are brought into the resin via ion exchange with the acid ligand. Initial studies with alkali metal ions are presented. The third general class of DMBP's is also presented. In this case, precipitation is the reaction occurring along with ion exchange thus yielding the ion exchange/precipitation resins. Barium recovery from aqueous solution via barium sulfate precipitation is described.     

无卤阻燃剂二乙基次膦酸铝的表面改性

硅烷偶联剂KH550,KH560和KH570被用于对二乙基次膦酸铝粉体阻燃剂的表面改性。经该法改性的二乙基次膦酸铝粉体的吸水率被明显降低,在PBT中的相容性被提高,并且在PBT中的分散度也得到提高。该改性方法有效地解决了利用化学沉淀法制备该阻燃剂时粉体易团聚的问题。     

Theory for the XPS of Actinides

Two aspects of the electronic structure of actinide oxides that significantly affect the X-ray photoelectron spectroscopy (XPS) spectra are described; these aspects are also important for the materials properties of the oxides. The two aspects considered are: (1) The spin–orbit coupling of the open 5f shell electrons in actinide cations and how this coupling affects the electronic structure. And, (2) the covalent character of the metal oxygen interaction in actinide compounds. Because of this covalent character, there are strong departures from the nominal oxidation states that are significantly larger in core–hole states than in the ground state. The consequences of this covalent character for the XPS are examined. A proper understanding of the way in which they influence the XPS makes it possible to use the XPS to correctly characterize the electronic structure of the oxides.     

核黄素与氨基酸的络合研究

介绍了核黄素的一些药理作用及应用前景。根据配位原理研究核黄素与氨基酸如色氨酸的二元体系的络合情况。利用紫外可见光谱在室温条件下,采用相同的给体体积配比、不同的浓度配比,随着给体的浓度不断增大,通过测定其吸光度找出吸光度与浓度配比的规律。对紫外光谱图进行比较,在实验中找到了核黄素与氨基酸络合的一些规律。     

Extraction of Lanthanides with Diamides of Dipicolinic Acid from Nitric Acid Solutions. I

Abstract

Three ortho-, meta-, and para-derivates of ethyl(tolyl)diamides of dipicolinic acid were synthesized and tested on their extraction performance from nitric acids solutions. Extraction of americium and lanthanides (Ln) by these compounds as a function of nitric acid concentration was studied. Distribution ratios of studied metals were determined using ICP-OES method and radiotracer ²⁴¹Am. Am/Ln separation differs among studied diamides, and the best separation was found for N,N′-diethyl-N,N′-di(ortho)tolyl-diamide.     

衣康酸光固化树脂的研究进展

被誉为"绿色技术"的光固化技术,不仅节能环保而且经济高效,已在众多领域得以应用.利用天然可再生资源制备光固化树脂对光固化技术的可持续发展具有重要意义.衣康酸作为一种来源广泛的天然可再生资源,其分子结构中同时含有不饱和双键和两个羧基,可替代丙烯酸、己二酸等石化资源合成各种光固化不饱和树脂,所得树脂综合性能优良.本文综述了...     

极性后交联吸附树脂的制备及其对水杨酸的吸附

将GMA与DVB悬浮聚合得到了初始共聚物PDG,再通过悬挂双键后交联反应制备出极性后交联树脂PDGpc,并研究了合成树脂对水杨酸的吸附性能。结果表明,后交联后,树脂的BET比表面积和孔容都显著增加,且对水杨酸拥有更高的吸附量。     

一种氨基膦酸螯合树脂的合成及其表征

以丙烯酰胺为单体,N,N'-亚甲基双丙烯酰胺为交联剂,通过自由基反应合成交联聚丙烯酰胺;然后通过Mannich反应,对交联聚丙烯酰胺进行膦酸基功能化修饰,合成一种氨基膦酸螯合树脂(简称APAR).通过对交联度、亚磷酸用量、反应温度和回流时间的探讨,确定了制备APAR的最佳工艺条件.通过傅里叶变换红外光谱仪(FTIR)和热重分析仪对树脂的结构和热性能进行表征.结果表明:该树脂具有较好的热稳定性.     

柠檬酸稀溶液的络合萃取研究

利用磷酸三丁酯（TBP）、三烷基胺（7301）为络合剂,分别采用甲苯、正辛醇、煤油作为稀释剂萃取柠檬酸稀溶液。实验结果表明,用混合型络合剂对柠檬酸稀溶液进行萃取,具有相当高的分配系数。考察了柠檬酸溶液初始浓度、有机相中络合剂浓度、温度对络合萃取相平衡分配 系数的影响,获得了萃取工艺过程较佳的操作条件;并对三烷基胺萃取柠檬酸稀溶液的机理进行了探讨,证实了三烷基胺对柠檬酸的萃取时同时存在离子缔合成盐和氢键缔合溶剂化两种历程。     

丙烯酸类树脂脱色性能的研究

利用胺解法对丙烯酸类树脂进行脱色性能的研究,结果发现,树脂的交换容量对丙烯酰胺阴离子交换树脂的脱色性能有较大影响,因此要想得到较好的脱色效果,必须保证树脂具有较高的交换容量.在4种功能基类型中,以四乙烯五胺的树脂脱色效果最好.     

离子交换树脂法吸附醋酸工艺

采用离子交换树脂法吸附醋酸溶液,并对该过程进行系统的研究. 通过树脂选型确定大孔弱碱性阴离子交换树脂D311,其对醋酸吸附容量较大,且膨胀收缩率较小. 用D311树脂对醋酸含量为1.5%(w)的醋酸溶液进行了吸附和脱附工艺优化研究,考察了体系温度、进料流量等对吸附和脱附过程的影响,在优化条件为温度30.0℃、进料流量4.0 mL/min时,吸附率达93.97%;温度50.0℃、洗脱剂3.98 mol/L NaOH、流量1.0 mL/min时,脱附率达100%. 树脂再生循环结果表明,D311重现性及机械强度较好.