Advanced TALSPEAK Separations Using a Malonate Buffer System

The extraction behavior of lanthanides and americium has been evaluated under Advanced TALSPEAK (Trivalent Actinide Lanthanide Separation by Phosphorus-reagent Extraction from Aqueous Komplexes) conditions using malonic acid as the aqueous buffering agent. The extractant 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester (HEH[EHP]) was used as an organic phase liquid cation exchanger in n-dodecane diluent, while N-(hydroxyethyl)-ethylenediaminetriacetic acid (HEDTA) served as a selective aqueous holdback reagent. Extractions conducted from malonate media exhibit a pH profile that flattens as the concentration of malonate is increased up to 1.0 M malonate. This relatively flat extraction behavior from pH 2.5–4.0 is reminiscent of previous studies on Advanced TALSPEAK in lactate media. The extraction kinetics with other carboxylic acid buffers as well as the effects of varying HEDTA, HEH[EHP], and malonate concentration are compared.     

Trivalent Lanthanide/Actinide Separation Using Aqueous-Modified TALSPEAK Chemistry

TALSPEAK is a liquid/liquid extraction process designed to separate trivalent lanthanides (Ln³⁺) from the minor actinides (MAs) Am³⁺ and Cm³⁺. Traditional TALSPEAK organic phase is comprised of the monoacidic dialkyl bis(2-ethylhexyl)phosphoric acid extractant (HDEHP) in diisopropyl benzene (DIPB). The aqueous phase contains a soluble aminopolycarboxylate diethylenetriamine-N,N,N’,N”,N”-pentaacetic acid (DTPA) in a concentrated (1.0–2.0 M) lactic acid (HL) buffer with the aqueous acidity typically adjusted to pH 3.0. This process balances the selective complexation of the actinides by DTPA against the electrostatic attraction of the lanthanides by the HDEHP extractant to achieve the desired trivalent lanthanide/actinide group separation. In this study, the aqueous phase has been modified by replacing the lactic acid buffer with a variety of simple and longer-chain amino acid buffers. The results show successful trivalent lanthanide/actinide group separation with the aqueous-modified TALSPEAK process at pH 2. The amino acid buffer concentrations were reduced to 0.5 M (at pH 2), and separations were performed without any effect on phase-transfer kinetics. Successful modeling of the aqueous-modified TALSPEAK process (p[H⁺] 1.6–3.1) using a simplified thermodynamic model and an internally consistent set of thermodynamic data is presented.     

Effect of the Introduction of Amide Oxygen into 1,10-Phenanthroline on the Extraction and Complexation of Trivalent Lanthanide in Acidic Condition

The extractability and complexation properties of lanthanides with N-alkyl-N-phenyl-1,10-phenanthroline-2-carboxamide were investigated. These ligands, which contain two aza-aromatic donors and an oxygen donor in a molecule, are newly developed extractants for actinides and lanthanides. N-Octyl-N-tolyl-1,10-phenanthroline-2-carboxamide exhibited high extractability of Eu³⁺ even under acidic conditions. In addition, strong complexation in acidic media was confirmed by spectroscopic titration experiments. Investigation of the complexation equilibrium revealed that the presence of an oxygen donor promotes ligand coordination with lanthanides over the competing protonation reaction in acidic solution.     

Separation of Americium from Europium using Camphor-BisTriazinyl Pyridine: A Fundamental Study

Among the different components present in spent nuclear fuel, long-lived trivalent actinides are particularly difficult to separate from the shorter-lived lanthanide fission products due to their similar chemical properties. Selective extraction of americium from acidic solution (up to 2M HNO₃) containing tenth molar quantities of lanthanides has been achieved using neutral pyridine-based ligands dissolved in polar diluents. Nitrogen-based Bis Triazinyl Pyridine (BTP) ligands are desirable for both their excellent An/Ln selectivity and incinerability. Results pertaining to ligand solubility, kinetics, hydrolytic stability, and extraction performance in various nitric acid environments are presented.     

Review Article: A Review of the Development and Operational Characteristics of the TALSPEAK Process

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.     

Extraction Theory and Form of the Extraction Complex for the Metals Dysprosium,Holmium, Thulium,and Curium in the Synergistic System Kerosene/HTTA/TBP/Dilute HNO3

Abstract

Data were taken for the distribution of HTTA and the metals Dy, Ho, Tm, and Cm in the system kerosene/thenoyltrifluoroacetone (HTTA)/tributylphosphate (TBP)/dilute HNO₃. The theory first proposed by Tournier (1) and Tournier and Davis (2) for the HTTA distribution was modified and new values of the equilibrium constants resulting from the theory were determined by a least squares fit of the HTTA distribution data. The new values are K ₁ = 14 and K ₂ = 3.45.

An analysis of the HTTA distribution data indicates that one molecule of TBP associates with one molecule of (HTTA·H₂O) to form a complex. Analysis of distribution data for the metals, Dy, Ho, Tm. and Cm using the modified theory indicates that the form of the metal complex is M⁺³(TTA)₃(TBP)₂ reported by most investigators.

A log-log plot of q o/a as a function of [H⁺] under conditions of constant free TBP and HTTA and constant ionic strength indicates an inverse squared effect of [H⁺] on the metal distribution ration, q o/a. This in turn supports the indications that two (TTA) molecules are associated with the metal complex. No experimental data to verify the presence of (NO₃ ^?) in the complex have as yet been obtained.     

Influence of an Alkoxy Group on Bis-Triazinyl-Pyridines for Selective Extraction of Americium(III)

The extraction of americium(III), curium(III), and lanthanides(III) from nitric acid by 2,6-bis-(5,6-dimethyl-[1,2,4]-triazin-3-yl)-pyridine and 2,6-bis-(5,6-dimethyl-[1,2,4]-triazin-3-yl)-4-methoxypyridine was studied. The physico-chemical properties of these ligands, such as the protonation and complexation constants, were also determined to describe the influence of different substituent groups. The selectivity of substituted-BTP was confirmed both in complexation and in solvent extraction experiments. The presence of an alkoxy-group in position 4 of the pyridine decreases the BTP selectivity. Influence of a long alkyl chain on protonation and complexation constants was also studied with 2,6-bis-(5,6-dimethyl-[1,2,4]-triazin-3-yl)-4-dodecyloxypyridine.     

纳滤膜用于给水深度处理的研究进展

纳滤可以脱除各种有机物和有害化学物质,同时保留人体所必须的无机离子,因此其在给水深度处理方面具有不可比拟的优越性。作者综述了纳滤膜的分离机理、纳滤膜在给水深度处理中的典型应用以及影响纳滤处理效果的几个因素,展望了纳滤膜的发展前景,并提出了需要进一步完善的研究内容。     

高级氧化与生物联用技术处理制药废水的研究

制药工业废水成分复杂,有机污染物种类多,难于降解,毒性大。高级氧化技术处理制药废水尚处于实验研究阶段,然而将其与生物法联合具有良好的应用前景。重点介绍了各类高级氧化技术的原理和特点,讨论了高级氧化及生物联用技术运用于制药废水的处理现状、存在的问题及未来发展方向。     

石化废水深度处理用于回用的研究进展

为了解决石化用水量大,水资源短缺的问题,本文叙述了对石化污水进行深度处理已达到回用标准的方法,主要有：活性炭吸附法,高级氧化法,膜分离法,其它方法如生物回用技术也是有效的方法。经深度处理后的废水可进行回用。     

无机盐水溶液体系的纳滤膜分离实验研究

选择了NF45和SU200两种纳滤膜对1－1型（KC1、NaCl、LiCl)、2－1型MgCl2)、1－2型（K2SO4）及2－2型（MgSO4)等6种无机盐水溶液体系进行分离实验;考察了纳滤膜分离性能随操作压力、料液浓度及电解质种类等因素的变化所受到的影响。实验结果表明,纳滤膜对盐的截留率随操作压力的增加而增大,并趋向于定值（即膜的最大截留率,又称为膜的反射系数）;纳滤膜对盐的截留率随电解质种类的不同而改变,随盐浓度的增大而下降,但当盐浓度很高时,截留率趋向于一定值,该值并不等于0,说明与纳滤膜的孔径相比,不可忽视电解质离子大小的影响。     

Separation Study of Am(III) and Eu(III) Using a Synergistic System of Cyanex-301 and 4,7-di-Phenyl-1,10-Phenanthroline

Separation of Am(III) and Eu(III) was attempted employing a mixture of Cyanex-301 and several O- and N- donor neutral ligands from low pH solutions. Out of these, the O-donor ligands displayed poor separation behavior at pH 2.0 as compared to those reported earlier at pH 3.5 which was ascribed to a change in the extraction mechanism. Out of the N-donor phenanthroline derivatives employed for the separation studies, 4,7-diphenyl-1,10-phenanthroline (Ph₂Phen) displayed superior extraction behavior for Am(III) while not significantly extracting Eu(III). This resulted in a separation factor (S.F., defined as D_Am/D_Eu) value of ～9000 at pH 2.0 which is about four times lower that the S.F. value reported earlier at pH 3.5 using Phen as the neutral donor ligand. The methyl derivative, Me₂Phen, showed remarkable poor extraction and separation behavior. Molecular modeling using ab initio calculations was used for explaining the unusual extraction behavior. The effect of sodium nitrate concentration on the separation behavior was also investigated.     

基于木质素的先进材料

综述基于木质素的先进材料及其制备方法和特性,展望了木质素的未来发展。     

膜分离技术研究与应用

石油化工生产过程中产生的炼油污水,含有多种污染物,对生态环境造成严重污染。膜分离作为一种工艺流程简单,处理效率高以及能耗低的技术,正日益受到广泛的关注。文章介绍了膜分离技术及其研究进展,分析了影响炼油污水处理效果的各种因素以及产生膜污染的主要原因及其处理措施,并展望了膜分离技术的发展趋势。     

多变量预测控制技术在重芳烃分离塔控制中的应用

针对扬子石化公司某二甲苯分离装置中重芳烃分离塔进料波动大、操作变量多、关联性强、容量滞后大等特点,使用多变量预测控制软件APC-Hiecon,实现对重芳烃分离塔的平稳控制并提高分离效果,取得了很好的控制效果和显著的经济效益.     

改性环糊精手性毛细管柱的研制及拆分机理

合成了四种改性 β 环糊精手性固定相 ,对几类手性化合物和芳香异构体进行了拆分 ,并研究了其可能的拆分机理 ,同时对毛细管柱的色谱性能进行了考察。     

络合吸收分离丙烯的初步研究

络合吸附分离作为新兴的分离工艺,关键是络合分离吸附剂(包括活性组分和载体)的开发;在活性组分相对固定的情况下,载体是重点的研究对象.本文提出采用壳聚糖作为新的探索载体,实验表明壳聚糖作载体的络合吸收分离剂的吸收性能显著,可以作更深一步的研究.     

Investigation of Ionic Liquids for the Separation of Butanol and Water

Abstract

With the continual rise in the cost of fossil fuel based energy, research into economic and sustainable alternatives is of increasing importance. One significant source of increased cost and demand is the consumption of fossil fuels for automotive fuels. While ethanol has received the most attention as a fuel additive; butanol could be a better direct fuel alternative owing to its physical properties and energy value when compared to ethanol. Commercial butanol is nearly exclusively produced from petroleum feedstocks currently; however, some recent interest has begun to refocus on its generation via fermentation. Unfortunately, this production is limited due to the nature of the process and the use of energy-intensive separation techniques. Ionic liquids are novel green solvents that have the potential to be employed as an extraction agent to remove butanol from the aqueous fermentation media. A hurdle to this potential is the limited availability of solubility data for ionic liquids. This research investigates the phase behavior of two ionic liquids, butanol, and water. Additionally, issues related to the implementation of the investigated ionic liquids are discussed.     

分子筛在空气分离中的新进展

展示了多种分子筛在对空气中的主要成分O2、N2、CO2、H2O等气体进行分离时表现出的不同性能,以及对有害气体NOx和SO2消除作用;展望了分子筛作为空分吸附剂的进一步发展,以及在石油化工等方面应用的前景。