Solvent Extraction of Strontium from Nitric Acid Medium by Di-Tert-butyl Cyclohexano-18-crown-6 in N-Octanol: Extraction Behavior and Flowsheet Demonstration

The extraction of strontium from nitric acid medium by di-tert-butyl cyclohexano-18-crown-6 (DtBuCH18C6) in n-octanol was studied. The thermodynamic parameters were determined under different acidities, and the extraction was found to be driven by exothermic enthalpy and opposed by unfavorable entropy. Based on the results from batch experiments, a strontium extraction flowsheet (10, 2, and 4 stages for extraction, scrubbing, and stripping, respectively) was designed and tested on an array of 10-mm centrifugal contactors to treat a simulated acidic High Level Liquid Waste (HLLW). Strontium was found to be well separated from the simulant, and a decontamination factor of ?4000 was achieved. The results indicate that this process is promising in actual HLLW treatment. Supplementary materials are available for this article. Go to the publisher's online edition of Solvent Extraction and Ion Exchange to view the supplementary file.     

Evaluation of Novel Solvent Systems Containing Calix-crown-6 Ligands in A Fluorinated Solvent for Cesium Extraction from Nitric Acidic Feeds

Several commercial calix-crown-6 ligands such as: calix[4]arene-bis-crown-6 (CC), calix[4]arene-bis-benzo-crown-6 (CBC), calix[4]arene-bis-naphtho-crown-6 (CNC), and bis-(octyloxy)calix[4]arene-mono-crown-6 (CMC) have been evaluated for their Cs uptake ability from nitric acid feed solutions in a novel solvent system. The calix-crown-6 ligands were made soluble in phenyl trifluoromethyl sulphone (PTMS) and 1 × 10^?3 M solutions were used for metal ion extraction from nitric acid feed solutions. The extraction efficiency of the calix-crown-6 ligands was found out to be: CBC > CNC > CMC ? CC, which was attributed to trends of their partition coefficients. CNC was considered to be the most suitable extractant in view of its better organophilicity. The effects of concentrations of nitric acid and Cs carrier in feed were also investigated. Studies carried out using variation of ligand concentration yielded an extracted species of the type [CsL⁺][NO₃^?]_org. Stripping of Cs(I) from the loaded organic phase was found to be possible when the organic phase contained minute quantities of Alamine 336. Co-current extraction and stripping studies were also carried out using CNC as the extractant.     

Combined Extraction of Cesium and Strontium from Alkaline Nitrate Solutions

Abstract

The combined extraction of cesium and strontium from caustic wastes can be achieved by adding a crown ether and a carboxylic acid to the Caustic‐Side Solvent Extraction (CSSX) solvent. The ligand 4,4′(5′)‐di(tert‐butyl)cyclohexano‐18‐crown‐6 and one of four different carboxylic acids were combined with the components of the CSSX solvent optimized for the extraction of cesium, allowing for the simultaneous extraction of cesium and strontium from alkaline nitrate media simulating alkaline high level wastes present at the U.S. Department of Energy Savannah River Site. Extraction and stripping experiments were conducted independently and exhibited adequate results for mimicking waste simulant processing through batch contacts. The promising results of these batch tests showed that the system could reasonably be tested on actual waste.     

Scale-up of Caustic-Side Solvent Extraction Process for Removal of Cesium at Savannah River Site

Abstract

The caustic-side solvent extraction process to remove radioactive cesium from Department of Energy salt waste was developed using small-scale annular centrifugal contactors. A scale-up factor of 750X is required. Testing with commercially available centrifugal contactors identified key design and operational parameters. Air flow is significant and the rotor bottom must remain covered to prevent surging flow. The Clean-in-Place feature was modified to allow hands-on maintenance. Flow rates and rotor speeds were optimized to reduce other-phase carryover. Startup, operation, and recovery methods were confirmed. Testing validated a Decontamination Factor > 12 and a strip Concentration Factor of 12 to 15.     

Thermal Degradation of the Solvent Employed in the Next-Generation Caustic-Side Solvent Extraction Process and its Effect on the Extraction,Scrubbing, and Stripping of Cesium

As part of the ongoing development of the Next-Generation Caustic-Side Solvent Extraction (NG-CSSX) process, the thermal stability of its process solvent, the Next-Generation Caustic-Side Solvent (NGS) was investigated and shown to be adequate for industrial application. The solvent was thermally treated at 35°C over a period of 13 months whilst in dynamic contact with each of the aqueous phases of the current NG-CSSX process, namely SRS?15 (a highly caustic waste simulant), sodium hydroxide scrub solution (0.025 M), and boric acid strip solution (0.01 M). The effect of thermal treatment was evaluated by assessing batch extract/scrub/strip performance as a function of time, by monitoring the sodium extraction capacity of the solvent, and by analysis of the solvent using electrospray mass spectrometry. Current studies indicate that the NGS should be thermally robust without replenishment for a period of 7 months in the Modular Caustic-Side Solvent Extraction Unit (MCU), which has been treating waste using NG-CSSX since early 2014 at the Savannah River Site. The guanidine suppressor appears to be the solvent component most significantly impacted by thermal treatment of the solvent, showing significant degradation over extended operation.     

碱土金属溶剂萃取分离的新进展

本文就碱土金属离子萃取分离的进展情况,按萃取剂的分类进行了综述。     

Decomposition of Solvent Extraction Media during Nuclear Reprocessing: Literature Review

Abstract

Reprocessing spent nuclear fuel is indispensable for the economical use of uranium in nuclear energy production, and has been used industrially for more than 40 years. These processes involve the use of an extractant/diluent (solvent) for separation of the reusable actinides from unwanted fission products. The most widely used processes employ tributyl phosphate (TBP) diluted with normal-paraffin hydrocarbon. However, on repeated use, the solvent becomes degraded due to thermal, radiolytic, and chemical attacks, resulting in chemical as well as physical damage. In view of the considerable expansion in the knowledge and understanding regarding the chemical and radiolytical decomposition of both TBP and the hydrocarbon diluent, an up-to-date review seemed appropriate. This review is concerned mainly with the mechanisms of the degradation of the solvent system. Schemes of TBP and diluent radiation-chemical transformations occurring on decomposition of the solvent system are presented.     

锶特效固相萃取片分析技术研究进展

用于放射性锶测量的锶固相萃取片技术是最近几年开发的新技术,它比常规的放射化学分析方法简便快速,溶液能够以较高流速（50 mL/min）通过膜片,这使得该技术更适用于大体积水样品的分析,并可以节省大量的样品分析费用.总结了近年来锶特效固相萃取片分析水样中锶-90的研究进展,重点阐述了样品体积、流速、酸度和干扰离子对锶化学回收率的影响以及在环境水样监测中的应用,旨在为此项研究进展提供一个阶段性的总结,希望能够为我国锶特效固相萃取片分析技术的发展起到一定的作用.     

溶剂萃取分离铁锌

氯化物溶液中，铁（Ⅱ）、铁（Ⅲ）、锌（Ⅱ）与氯离子配位，形成不同的络合物，具有可萃性差异。对ＴＢＰ、叔胺、季铵进行分离性能比较后发现，季铵对铁（Ⅱ）、锌表现出优良的分离性能和较大的负载容量。机理研究表明，季铵萃锌是阴离子交换反应。模拟实验证实，经两级萃取能使铁（Ⅱ）、锌几乎完全分离。     

Feasibility of Using Di-Dodecyl-Di-Octyl Diglycolamide for Partitioning of Minor Actinides from Fast Reactor High-Level Liquid Waste

The unsymmetrical diglycolamide, di-dodecyl-di-octyl diglycolamide (D³DODGA) is a modifier-free extractant proposed for partitioning of trivalent actinides from nitric acid medium. D³DODGA has been evaluated for the feasibility of using it in the absence of a phase modifier, for the partitioning of minor actinides from fast reactor high-level liquid waste (FR-HLLW). The extraction behavior of various metal ions present in the simulated FR-HLLW was studied in a solution of 0.1 M D³DODGA/n-dodecane from nitric acid medium. The distribution ratio of about 20 metal ions was measured as a function of concentration of nitric acid and other interfering ion. The extraction was found to be strongly dependent on the oxidation state of the metal ion. The extraction of Am(III) from 3–4 M nitric acid medium was quantitative in a single contact. However, it was accompanied by the quantitative extraction of fission products such as trivalent lanthanides (Ln(III)), Y(III), and Zr(IV). The extraction of Sr(II), Pd(II), and Ru(III) in 0.1 M D³DODGA/n-dodecane was not insignificant, but quite low. The extraction of Ba(II), Ni(II), Mo(VI), and Fe(III) was marginal and the extraction of Co(II), Sb(III), Mn(II), and Cs(I) in 0.1 M D³DODGA/n-dodecane was negligible. Our results indicated that 0.1 M D³DODGA/n-dodecane is a promising candidate for the separation of trivalent actinides from fast reactor high-level liquid waste containing significant quantities of trivalent lanthanides and actinides.     

Development of Steam Reforming for the Solidification of the Cesium and Strontium Separations Product from Advanced Aqueous Reprocessing of Spent Nuclear Fuel

Abstract

Steam reforming is one option currently being investigated for stabilization of the cesium/strontium strip products from spent fuel reprocessing solvent extraction processes because it can potentially destroy the nitrates and organics present in these aqueous, nitrate‐bearing solutions, while converting the cesium and strontium into leach resistant aluminosilicate minerals, such as pollucite. To produce pollucite and other mineral analogs of the alkaline metals, the feeds must be mixed with aluminosilicate compounds and thermally sintered or calcined to activate solid‐state crystal formation. Scoping tests completed indicated that the cesium/strontium in these organic and acid solutions can be converted into aluminosilicate materials using steam reforming.     

溶剂萃取法回收废弃含能材料的研究现状

废弃含能材料主要来源于退役武器和超过存储期弹药,是特殊性质的危险品,必须妥善处理。综述了废弃含能材料组分的提取技术,并介绍了改善方法（即加速溶剂萃取法和超临界流体萃取法）。当设计合理时溶剂萃取法可以做到处理过程安全、操作简单,所用溶剂可回收再利用,无三废排放,是一种处理和利用废弃含能材料的较优途径。     

The Radiation Chemistry of the Cs-7SB Modifier used in Cs and Sr Solvent Extraction

Abstract

The compound 1-(2,2,3,3,-tetrafluoropropoxy)-3-(4-sec-butylphenoxy)-2-propanol, also called Cs-7SB, is used as a solvent modifier in formulations containing calixarenes and crown ethers for cesium and strontium extraction from nuclear waste solutions. The compound solvates complexes of both metals and decreases in its concentration result in lowered extraction efficiency for both. The use of Cs-7SB in nuclear-solvent extraction ensures that it will be exposed to high-radiation doses, and thus its radiation-chemical robustness is a matter of interest in the design of extraction systems employing it. The behavior of the compound in irradiated solution, both in the presence and absence of a nitric acid aqueous phase was investigated here using steady state- and pulsed-radiolysis techniques. The rate constants for the aqueous reactions of Cs-7SB with ^?H, ^?OH, ^?NO₃, and ^?NO₂ radicals are reported. UPLC-UV-MS results were used to identify major products of the radiolysis of Cs-7SB in contact with nitric acid, and revealed the production of hydroxylated nitro-derivatives. Reaction mechanisms are proposed and it was concluded that the aryl-ether configuration of this molecule makes it especially susceptible to nitration in the presence of radiolytically-produced nitrous acid. Fluoride yields are also given under various conditions.     

Solvent Extraction Studies of Holmium with Acidic Extractants

Abstract

Liquid-liquid extraction studies of holmium with 2-ethylhexyl phosphoric acid mono-2-ethylhexyl ester, naphthenic, and Versatic 10 acids have been carried out. The nature of the extracted species and the extraction equilibrium constants of these systems have been determined from aqueous nitrate solution. The extraction mechanism and complexation models have been proposed.     

Recovery of Boric Acid from Wastewater by Solvent Extraction

Abstract

An extraction system for the recovery of boric acid using 2-butyl-2-ethyl-1,3-propanediol (BEPD) as an extractant was studied. Loss of the extractant to the aqueous solution was lowered by using 2-ethylhexanol as a diluent. The extraction equilibrium of boric acid with BEPD was clarified, and the equilibrium constants for various diluents were determined. Furthermore, continuous operation for the recovery of boric acid using mixer-settlers for extraction and stripping was successfully conducted during 100 hours.     

Review Article: The Effects of Radiation Chemistry on Solvent Extraction 3: A Review of Actinide and Lanthanide Extraction

The partitioning of the long‐lived α‐emitters and the high‐yield fission products from dissolved used nuclear fuel is a key component of processes envisioned for the safe recycling of used nuclear fuel and the disposition of high‐level waste. These future processes will likely be based on aqueous solvent‐extraction technologies for light‐water reactor fuel and consist of four main components for the sequential separation of uranium, fission products, group trivalent actinides, and lanthanides, and then trivalent actinides from lanthanides. Since the solvent systems will be in contact with highly radioactive solutions, they must be robust toward radiolytic degradation in an irradiated mixed organic/aqueous acidic environment, with the formation of only benign degradation products. Therefore, an understanding of their radiation chemistry is important to the design of a practical system. In the first paper in this series, we reviewed the radiation chemistry of irradiated aqueous nitric acid and the tributyl phosphate ligand for uranium extraction in the first step of these extractions. In the second, we reviewed the radiation chemistry of the ligands proposed for use in the extraction of cesium and strontium fission products. Here, we review the radiation chemistry of the ligands that might be used for the group extraction of the lanthanides and actinides. This includes traditional organophosphorus reagents such as CMPO and HDEHP, as well as novel reagents such as the amides and diamides currently being investigated.     

溶剂萃取法制取硝酸钾综述

综述了溶剂萃取法制取硝酸钾各种工艺路线,对各种工艺的原理和优缺点进行了探讨,提出了萃取法制取硝酸钾技术工业化所需解决的课题。     

溶剂抽提法分离印尼油砂的实验研究

利用溶剂抽提法对印尼油砂进行萃取分离实验,综合考察了剂砂比、抽提温度、抽提时间、抽提次数等操作条件对油砂沥青提取的影响,确定较佳的油砂分离条件。结果表明,印尼油砂更适合采用溶剂抽提法分离,从油砂沥青提取率、操作成本和环保多角度考虑,在超声波的作用下,剂砂比为2．5,抽提温度40℃,抽提时间30min,抽提3次的条件下,油砂沥青的提取率较高,达到20．31％。     

Deep Eutectic Solvent as Green Solvent in Extraction of Biological Macromolecules: A Review

Greater awareness of environmental sustainability has driven many industries to transition from using synthetic organic solvents to greener solvents in their manufacturing. Deep eutectic solvents (DESs) have emerged as a highly promising category of green solvents with well-demonstrated and wide-ranging applications, including their use as a solvent in extraction of small-molecule bioactive compounds for food and pharmaceutical applications. The use of DES as an extraction solvent of biological macromolecules, on the other hand, has not been as extensively studied. Thereby, the feasibility of employing DES for biomacromolecule extraction has not been well elucidated. To bridge this gap, this review provides an overview of DES with an emphasis on its unique physicochemical properties that make it an attractive green solvent (e.g., non-toxicity, biodegradability, ease of preparation, renewable, tailorable properties). Recent advances in DES extraction of three classes of biomacromolecules—i.e., proteins, carbohydrates, and lipids—were discussed and future research needs were identified. The importance of DES’s properties—particularly its viscosity, polarity, molar ratio of DES components, and water addition—on the DES extraction’s performance were discussed. Not unlike the findings from DES extraction of bioactive small molecules, DES extraction of biomacromolecules was concluded to be generally superior to extraction using synthetic organic solvents.     

医药化工中溶剂萃取技术进展

本文讨论了医药化工中８０年代以来特别是近１０年来溶剂萑取技术的研究进展，包括化学反应萃取、液膜技术、在线萃取中化反应过程，异构体的分离和预分散萃取等新工艺的发展趋向和应用前景。