锕系元素在熔盐体系中的电化学及萃取特性研究进展

摘要
关键词
Abstract
Keyword
1 熔盐概述
2 锕系元素在高温熔盐中的研究进展
2.1 锕系元素在高温熔盐中的电化学行为
2.2 锕系元素在高温熔盐中的热力学和其它物理学特性
表1(Table 1)
3 锕系元素在室温离子液体(RTILs)中的研究进展
3.1 锕系元素在RTILs中的电化学的研究进展
3.2 锕系元素在RTILs中的萃取特性的研究进展
Figure1
Figure2
表2(Table 2)
4 结论与展望
参考文献

引用本文

李瑞瑞, 周彦同, 夏良树, 肖益群, 李广. 锕系元素在熔盐体系中的电化学及萃取特性研究进展. 应用化学, 32(1): 1-9
LI Ruirui, ZHOU Yantong, XIA Liangshu, XIAO Yiqun, LI Guang. Research Progress of Electrochemical and Extractible Characteristics of Actinide Elements in the Molten Salt System. Chinese Journal of Applied Chemistry, 32(1): 1-9 复制到剪切板

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锕系元素在熔盐体系中的电化学及萃取特性研究进展

李瑞瑞, 周彦同, 夏良树^*, 肖益群, 李广

南华大学核科学技术学院湖南衡阳 421001

通讯联系人: 夏良树, 教授; Tel:0734-8282275; Fax:0734-8282251; E-mail:xls1966@hotmail.com; 研究方向:核应用化学

收稿日期:2014-08-14

基金:湖南省自然科学基金与衡阳市自然科学联合基金项目资助(14JJ5019)

摘要

熔融盐是一类非水溶剂,分为高温熔盐、室温熔盐和低温熔盐。作为反应介质和电解介质,因其优良性能,可以溶解很多难溶于水的活泼金属。近年来,该领域的研究热点是将熔盐作为干法后处理的电解质分离和回收锕系元素。本文综述了锕系元素在高温熔盐中的电化学行为、热力学等物理特性,介绍了近几年室温离子液体(RTILs)的研究进展及锕系元素在RTILs中萃取特性的最新研究成果,展望了熔盐体系未来的研究方向。

关键词: 高温熔盐; 室温离子液体; 锕系元素; 电化学; 萃取

中图分类号:O645.4 文献标志码:A 文章编号:1000-0518(2015)01-0001-09

Research Progress of Electrochemical and Extractible Characteristics of Actinide Elements in the Molten Salt System

LI Ruirui, ZHOU Yantong, XIA Liangshu^*, XIAO Yiqun, LI Guang

School of Nuclear Science and Technology,University of South China,Hengyang,Hu'nan 421001,China

Corresponding author:XIA Liangshu, professor; Tel:0734-8282275; Fax:0734-8282251; E-mail:xls1966@hotmail.com; Research interests:nuclear applied chemistry

Fund:Supported by the Hunan Provincial Natural Science Foundation of China(No.14JJ5059)

Abstract

Molten salts are non-aqueous solvents which are divided into high temperature molten salts, low temperature molten salts and room temperature molten salts. Due to their unique physical and chemical properties, they are used as the reaction and electrolytic media to electrodeposit the active metal coatings that can not be obtained in aqueous solution. In recent years, the research hot spot in the field of molten electrochemistry is that it is applicable in non-aqueous reprocessing by substituting caustic molten salts for electro-deposition and separation of actinide metal ions. This article reviews the properties of actinide elements in electrochemistry, thermodynamics and physics in high temperature molten salt. The recent research progress of room temperature ionic liquids and the latest extraction advancement of actinide elements in room temperature ionic liquids are introduced. The future research trend in molten system is also given.

Keyword: high temperature molten salts; room temperature ionic liquids; actinide elements; electrochemistry; extraction

Show Figures

随着世界能源和环境问题的日益凸显, 作为一种安全清洁的能源, 核能在电力供应中所占的比重逐年上升。核燃料的循环利用是保证核能可持续发展的关键, 建立一个独立、完整和先进的核燃料循环工业体系对我国核工业的快速、持续发展至关重要。在这个循环体系中, 乏燃料后处理是确保我国核能可持续发展的关键环节。全世界每年产生的乏燃料约为11000 tHM, 目前乏燃料的累计存量已经超过150000 tHM, 乏燃料中含有大量U、Pu、次锕系元素(MA)和裂变产物(FP), 其中MA和FP对地球生物和环境造成长期的潜在危害, 故乏燃料的处理处置已经成为制约核能可持续发展的关键问题之一。

乏燃料后处理是对核电站卸出的乏燃料元件进行处理、分离并回收未烧尽的铀和新生成的钚, 同时对放射性废物进行处理, 以满足处置要求的一种处理方式^[1]。后处理技术根据使用介质的不同可分为使用水溶液的湿法和不使用水溶液的干法, 湿法主要有溶剂萃取法(液液萃取法)、离子交换法和沉淀法等; 干法主要有熔盐电解法、液态金属还原法和氟化物挥发法等。干法后处理技术具有分离燃耗深、冷却期短、钚含量高(尤其是快堆乏燃料)等优点, 近年来已成为乏燃料后处理领域的研究热点, 世界上的主要核能大国均投入大量人力物力开展干法后处理技术研究, 并将主要精力集中在以熔盐电解法为基础的干法后处理流程的研发上。锕系元素是乏燃料后处理的主要对象, 本文将综述锕系元素在高温熔盐中的电化学行为、热力学等物理特性, 介绍近几年国内外室温离子液体及锕系元素在RTILs中的萃取特性的最新研究成果, 提出熔盐体系未来的研究方向, 为从事乏燃料后处理研究的科技工作者建立基于RTILs的新型后处理技术提供基础理论研究依据。

1 熔盐概述

熔融盐是一类非水溶剂, 作为反应介质和电解介质, 用于冶金、表面处理、电池、能源、合成化工材料、原子能等领域。熔盐又分为低温熔盐、室温熔盐、高温熔盐, 三者之间并无明显的界限^[2]。熔盐电解法分为高温熔盐电解和室温熔盐电解。高温熔盐电解是目前干法回收的重要技术之一, 它是指先将乏燃料溶解到金属氯化物的高温熔盐中, 利用电沉积的方式, 在阴极上分别或者共同沉积出铀和钚。该工艺操作通常要在金属氯化物熔点以上进行, 对设备的要求及能耗极高, 具有耐辐照、低临界风险、放射性废物少、流程简单等优点, 可适用于金属燃料、氮化物燃料及氧化物燃料等多种形态的燃料处理^[3]; 但该工艺存在操作温度高、熔融卤化物及液态金属对材料腐蚀严重、分离性能低等缺点^[4]。

离子液体(RTILs), 也叫室温熔融盐, 由有机阳离子和有机或无机阴离子组成的盐类^[5], 在室温下成液体状态, 它融合了高温熔盐和水溶液的优点:导电性好、不挥发、热稳定性好、电化学窗口宽等^[6], 在室温下就可得到在高温熔盐中电沉积才能得到的金属和合金。因此, 若能用其代替碱金属氯化物熔盐作为熔盐电解技术的介质来分离和回收铀、钚和其它裂变产物, 将从根本上解决其所面临的高温和材料腐蚀问题, 对以熔盐电解为基础的干法后处理具有划时代的意义^[7]。然而, 该技术生产成本高, 很难合成集高电导率、高稳定性、宽电化学窗口等诸多优点为一体的RTILs, 故RTILs在乏燃料后处理技术中的大规模工业化应用尚不成熟^[8]。

2 锕系元素在高温熔盐中的研究进展

自20世纪60年代以来, 各国相继研究过多种干法后处理技术, 比较有发展前景的方法是金属燃料和氧化物燃料的熔盐电解精炼法。锕系元素是乏燃料后处理的主要对象, 对锕系元素尤其是铀和钚的萃取分离是乏燃料后处理的主要任务。目前, 很多研究团队均在进行锕系元素在高温熔盐中的相关性质的研究工作。

2.1 锕系元素在高温熔盐中的电化学行为

近年来, 国内外学者采用循环伏安法和计时电流法研究了U、Pu、Np和Th等锕系元素在氟化物或氯化物熔盐中的电化学行为, 得到了电流密度、电极电势、扩散系数等电化学参数, 探讨了反应机制, 分析了高温熔盐处理乏燃料的可行性。由于钚的强放射性, 关于钚在高温熔盐中的电化学行为研究的文献报道不是很多。 Serp等^[9]采用循环伏安、计时电势等技术研究了钚离子在LiCl-KCl熔盐中的电化学行为, 在733 K时, Pu³⁺扩散系数为D_pu²⁺=2× 10^-5 cm/s, 标准电势为-2.796 V(Cl₂-Cl^-为参比电极), Pu³⁺-Pu反应是简单的一步反应机制, 通过Pu³⁺-Pu形成自由焓估算Pu³⁺离子的活度系数。用类似的方法, Iizuka等^[10]重点研究了电流密度对收集速率的影响, 当阴极电流密度低于4× 10^-2 A/cm²时, 钚的回收率接近100%, 在更高电流密度时, 由于锂和液态镉阴极(LCCs)陶瓷部分反应致使钚的回收率下降, 发现阴极电流密度与熔盐中钚离子的浓度成正比, 由LCCs电极上实验数据外推出Pu的收集速率为324 g/h, 且在LCCs底部钚是以PuCd₆的形式沉淀, 该实验首次推导出Pu的收集速率, 为研究其它锕系元素提供了有益的参考。 Cassayre等^[11]在熔融LiCl-KCl合金中使用循环伏安和计时电流法研究了钍离子的还原机制和扩散系数, 观察到Th在熔盐中只有一个稳定价态, 还原到Th金属是一步反应机制, 在723 K时, Th的扩散系数D_Th=(3.15± 0.15)× 10^-5 cm²/s, 标准电动势 $\begin{matrix} E_{ThC l_{4} / Th}^{0} \end{matrix}$ =-2.582 V(Cl₂-Cl^-为参比电极), 活度系数 $\begin{matrix} γ_{ThC l_{4}}^{(732 K)} \end{matrix}$ =4.6× 10^-4。在该实验的基础上, 王喆等^[12]确定了钍在LiCl-KCl 熔盐中的稳定价态是正四价, Th⁴⁺在阴极是4电子转移的一步电解过程, 发现Th⁴⁺在Mo电极上电解过程受离子扩散控制, 获得了扩散系数随温度变化的经验公式和形式电势的经验公式。因不同电解质和电极对分离和回收锕系元素有很大的影响, 所以很多研究者关心其对钍离子电化学行为的影响。 Chamelot等^[13]研究了氟化物熔盐LiF-CaF₂中, 不同电极(惰性Mo和活性Ni)上Th⁴⁺的电化学行为, 研究表明Th⁴⁺以ThO₂形式沉淀, 形成中间可溶性产物ThOF₂, 在活性电极(Ni和Bi)电解还原Th⁴⁺时, 形成Ni-Th和Bi-Th的化合物。该实验创新性地研究了氟化物熔盐和不同电极对锕系元素电化学行为的影响, 为后来的研究者指出了新的研究方向。

在高温熔盐中对铀的电化学行为的研究一直是锕系元素研究的热点。 Iizuka等^[14]使用电化学方法从熔融盐或液态金属镉中回收锕系元素, 验证了从液态镉层电迁移铀和从熔融盐电解质中电解还原铀, 并成功地回收铀, 进一步验证了从高温熔盐中回收锕系元素的可行性。 Reddy等^[15]使用高温熔盐原电池测量方法测出U-Ga合金的吉布斯自由能和电动势, 首次确定了α -U和液态镓组成的合金UGa₃、UGa₂和U₂Ga₃的吉布斯自由能分别为(-44.1± 0.016)T、(-46± 0.017)T和(-46.3± 0.017)T kJ/mol, 并获得铀在液镓中的偏摩尔过剩自由焓和偏摩尔焓, 但并没得出准确的电动势数值。国内学者对铀在高温熔盐中的电化学行为也进行了相关性质的研究, 如高繁星等^[16]研究了LiCl--KCl熔盐中铀的电化学行为; 刘刈等^[17]在1073 K, 采用循环伏安法和计时电流法研究了U在氟化物LiF-NaF-UF₄熔盐中的电化学还原机理, 得出U⁴⁺在氟化物熔盐中的还原分两步即U⁴⁺+e^-=U³⁺, U³⁺+3e^-=U, 这两个还原过程均为扩散控制且可逆, 扩散系数 $\begin{matrix} D_{U^{4 +}} \end{matrix}$ =2.58× 10^-5 cm²/s。

能否成功实现锕系元素的相互分离是高温熔盐电解法用于乏燃料干法后处理的关键, 因此, 很多研究者都进行了深入的研究。 Shirai等^[18]在不同温度下的LiCl-KCl熔盐中, 在W和Mo工作电极下, 通过循环伏安法研究了U和Pu的电沉积和溶解行为, 伏安图表明, U³⁺/U和Pu³⁺/Pu可能是准可逆的, U⁴⁺/U³⁺是可逆的, 且在沉积电势下形成U和Pu的吸收峰和解吸峰。随后Sakamura等^[19]在LiCl-KCl熔盐中通过电解精炼法从稀土金属中分离锕系元素并测量U、Pu、Np和Am的标准电势, 结果表明, Am是最难回收的。镅的伏安图有两个阴极峰表明Am³⁺/Am²⁺, Am²⁺/Am分两步还原, Am²⁺/Am的标准电势为-1.642 V。 Sou $\begin{matrix} \overset{ˇ}{c} \end{matrix}$ ek 等^[20]研究了裂变产物在熔盐LiF-NaF-KF中的电化学分离方法, 分析选择性分离锕系(U, Th)和镧系(Nd, Eu, Gd)的可行性, 根据研究的最新结果讨论不同电化学技术的适用性, 并列出熔盐反应堆燃料循环的基本流程图。

2.2 锕系元素在高温熔盐中的热力学和其它物理学特性

关于锕系元素在高温熔盐中的热力学和其它物理学特性研究的文献报道较少, 研究方法基本相似。 Lambertin 等^[21]采用循环伏安法和计时电流法研究用高温化学法分离钚的热力学的可行性, 得出Pu在液镓中的活度系数是lg (γ _{Pu, Ga})=(-7.3± 0.5), 发现液镓是分离Pu和Ce的理想溶剂。 Van der Meer等^[22]研究氟化物熔盐处理核燃料的热力学和物理学特性, 综述了LiF-BeF₂-ThF₄这个三元系的一些重要特征, 并指出其典型的组成为0.717LiF-0.16BeF₂-0.12ThF₄-0.003UF₄, 蒸汽压是10^-810^-6 bar, 熔合的温度是794.5 K, 与理论值一致, 并且纯氟化物组件的密度和液体混合物的密度呈线性关系。 Rance等^[23]探讨了后处理镎的工艺流程可行性的相关问题并绘制了U、Pu、Am等核素在后处理工艺走向流程图, 分析比较²³⁷Np与其它裂片核素的性质(表1), 发现预期质量的镎与高活性废物转化为陶瓷废料的过程中产生的裂变产物相结合, 但还没有文献报道称镎的分离或转移不会发生, 也没有进行下一步的研究, 但这一发现对研究锕系元素在高温熔盐中的电化学行为提供了新的启发。

表1 ²³⁷Np与其它裂片核素性质的比较^[23] Table 1 Properties of ²³⁷Np compared to other fissile materials^[23]

3 锕系元素在室温离子液体(RTILs)中的研究进展

RTILs具有电导率高、电化学窗口宽、熔点低、辐照稳定性好等优点, 使其可以作为独特溶剂进行电化学研究, 并且在RTILs合成过程中引入特定的官能团, 形成任务专一型的离子液体, 即功能化离子液体(TSIL)^[6], 提高其对目标金属离子的萃取率和选择性。用RTILs代替氯化物熔盐作为熔盐电解质来进行干法后处理, 是解决高温强腐蚀问题的重要方向^[7]。因此, 很多研究者均开展了锕系元素在RTILs中萃取特性的研究。

3.1 锕系元素在RTILs中的电化学的研究进展

近年来, RTILs因其独特的性能成为乏燃料后处理领域的研究热点。国外的Cé line等^[24]使用玻碳电极研究了U⁶⁺的氯化物的氧化还原特性, 在4种新型离子液体中使用循环伏安法揭示了两个主要的氧化还原电对即U⁵⁺C $\begin{matrix} l_{6}^{-} \end{matrix}$ /U⁴⁺C $\begin{matrix} l_{6}^{2 -} \end{matrix}$ 和U⁴⁺C $\begin{matrix} l_{6}^{2 -} \end{matrix}$ /U³⁺C $\begin{matrix} l_{6}^{3 -} \end{matrix}$ , 离子配对的强弱与离子液体阳离子的性质有关, 且遵循U⁵⁺C $\begin{matrix} l_{6}^{-} \end{matrix}$ < U⁴⁺C $\begin{matrix} l_{6}^{2 -} \end{matrix}$ < U³⁺C $\begin{matrix} l_{6}^{3 -} \end{matrix}$ 的顺序。 Joseph等^[25]首次尝试在氯化1-丁基-3-甲基-咪唑盐(C₄mimCl)为稀释剂的RTILs中, 通过氯化反应溶解铀的氧化物UO₂和UO₃, 利用循环伏安法研究U⁶⁺的电化学行为, 结果显示, 因U $\begin{matrix} O_{2}^{2 +} \end{matrix}$ 控制电势电解沉积UO₂, 致使在-1.0 V(vs Pt)循环伏安图有显著的阴极峰, 经UO₃电解后的溶液比UO₂回收的金属铀多。但国内对锕系元素在RTILs中电化学特性的研究开展的实际性工作并不多, 大多是根据国外的研究成果进行一些文献综述或探索性工作。袁立永等^[26]综述了近年来RTILs用于核燃料水法和干法后处理的基础研究成果, 对离子液体辐射效应的研究为室温熔盐电解乏燃料提供了新思路。杨飞龙等^[7]进一步综述了镧系元素和锕系元素在RTILs中电化学方面的研究状况。他们的工作为锕系元素在RTILs中电化学特性的研究提供了有益的参考。张秋月等^[27]使用循环伏安和计时电势等方法研究了镧系元素Eu³⁺和锕系元素U⁶⁺在亲水性离子液体氯化1-丁基-3-甲基咪唑([BMIM]Cl)中的电极过程。观察玻碳电极为工作电极时, [BMIM]Cl的电化学窗口为-1.7~-0.8 V(vs.Ag/AgCl), U $\begin{matrix} O_{2}^{2 +} \end{matrix}$ 通过U $\begin{matrix} O_{2}^{2 +} \end{matrix}$ +2e^-=UO₂的可逆反应还原为UO₂, 并获得U $\begin{matrix} O_{2}^{2 +} \end{matrix}$ 的扩散系数和活化能。

3.2 锕系元素在RTILs中的萃取特性的研究进展

目前, 对锕系元素在RTILs中萃取特性的主要研究工作是合成功能化的离子液体(TSIL), 探索不同的稀释剂和萃取剂对锕系元素的萃取能力, 寻求合成最好的RTILs来分离和回收锕系元素。在RTILs中对Am的研究一直都很活跃, 并为研究其它锕系元素提供理论指导。 Senqupta等^[28]使用RTILs从放射性废物中回收Am, 使用了侧链长度不同的离子液体C_nmim⁺P $\begin{matrix} F_{6}^{-} \end{matrix}$ (n=4, 6, 8)与萃取剂0.01 mol/L二甘醇胺(TODGA)(图1), 结果表明分配系数D_Am分别为102、34和74, Am的萃取能力随3种稀释剂酸度的增加而减小, 在RTILs中, Am³⁺的萃取能力显著提高, 但RTILs较高的粘度系数是萃取动力学较慢的原因, 并指出能从包含U、Pu和Am的放射性废物中选择性分离Am, 实现了Am与体系的分离, 进一步验证了RTILs用于乏燃料分离的可行性。 Pribylovad等^[29]将质量分数为1%5%的1-丁基-3-甲基咪唑双三氟甲基磺酰亚胺([C₄mim]⁺Tf₂N^-)添加到二苯二丁基甲酰甲基磷化氢的氧化物(Ph₂Bu₂), 发现从硝酸中萃取Am的分配系数提高了2个数量级, 实验结果表明, 3个Ph₂Bu₂配体结合在Am的周围, 2个与N $\begin{matrix} O_{3}^{-} \end{matrix}$ 结合, 1个与RTIL阴离子结合。 Panja等^[30]研究了Am³⁺、Pu⁴⁺、U $\begin{matrix} O_{2}^{2 +} \end{matrix}$ 的萃取行为, 确定在RTILs中是阳离子交换机制, 在RTILs中烷基碳链的长度对TODGA的萃取性能方面具有重要作用, 同时也影响分配系数, 虽然在酸度条件下, 反萃很难取得较高分配系数值, 但是具有良好发展前景的是在碳酸胍下使用络合剂乙二胺四乙酸(EDTA)或二乙烯三胺五乙酸(DTPA)进行反萃, 对如何提高反萃能力给予了方向性指导。 Patil等^[31]在硝酸介质中, 将两种二酰胺溶解在RTILs(C_nmimNTf₂)(n=4, 6, 8)中, 研究溶剂萃取锕系离子如Am³⁺、U⁶⁺、Np⁴⁺、Np⁶⁺和Pu⁴⁺, 研究各种参数对萃取金属离子的影响, 对比两种萃取剂的萃取能力和抗辐解退化能力, 并得出二者的降解产物, 1-丁基-3-甲基咪唑双三氟甲基磺酰亚胺([C₄mim][NTf₂])萃取Am³⁺整个过程不到30 min。该实验首次报道了萃取平衡时间, 在探究新的RTILs的过程中, 取得了突破性的成果, 进一步验证了从RTILs中萃取锕系元素的可行性。

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	图1 TODGA和C_nmim⁺的结构式^[28]Fig.1 Structural formula of TODGA and C_nmim^{+ [28]}

在RTILs中对铀的研究一直都是锕系元素的重点, 除了研究它的电化学行为外, 还研究了在功能化离子液体(TSIL)中的氧化物、热力学和氧化还原性质等, 并取得很多创新的实验成果, 为研究其它锕系元素提供新的研究思路。刘浩等^[32]研究磷酸三丁酯/1-辛基-3-甲基咪唑六氟磷酸盐(TBP/[C₈mim][PF₆])和磷酸三丁酯/1-丁基-3-甲基咪唑六氟磷酸盐(TBP/[C₄mim][PF₆])在萃取U $\begin{matrix} O_{2}^{2 +} \end{matrix}$ 中的相关性质。研究表明, 疏水性强的[C₈mim][PF₆]有更好的萃取U $\begin{matrix} O_{2}^{2 +} \end{matrix}$ 的能力, 但当c(HNO₃)_init> 4 mol/L时, 所合成的咪唑类离子液体不稳定, 萃取过程中容易出现第三相, 并伴有白色沉淀析出。因此合成在酸性条件下稳定、疏水性强的RTILs有利于铀酰离子的萃取, 这为后来研究者合成RTILs提供了很好的参考依据。李宏宇等^[33]介绍了近几年RTILs在放射性核素分离中的研究进展, 并首次提出提高反萃取能力是降低成本、实现RTILs循环利用的关键。褚泰伟等^[34]进一步研究了负载有机相为TBP-[C₈mim][PF₆]、TBP-[C₄mim][PF₆] 和季胺类离子液体三辛基甲基氯化铵(TBP-[N₈₈₈₁][Cl])时, 发现季胺类离子液体萃取铀酰离子的分配比高于咪唑类, 碳酸胍能从3种离子液体中定量反萃 U, 从而解决了RTILs萃取铀酰离子的反萃和RTILs循环使用的问题。 Chen等^[35]首次合成了含羧基官能团的磷类离子液体1-羧基-N, N, N-三甲基磷双三氟甲基黄酰亚胺[HCTMP][Tf₂N], 这是一种新型的TSIL, 能使成核作用定向形成单体的或二聚的铀酰化合物, 比其它的铵类似物有更宽的电化学窗口和更低的熔点, 并显示出与U⁶⁺更强的结合力。 Hatchett等^[36]首次把铀和超铀元素溶解在含臭氧组分的溶液中, 从TSIL中回收和萃取乏燃料中的锕系元素, 该实验首次提供了测量RTILs中不同氧化态铀的金属沉积物的热力学特性的方法。

对Pu的分离也是乏燃料后处理的关键步骤, 因其强放射性, 在RTILs中对Pu的研究文献报道较少, Huang等^[37]研究发现, 在RTILs中, 稀释剂为1-己基-3甲基咪唑-双(三氟甲基磺酰)亚胺盐(C₆mimTf₂N), 萃取剂为TODGA, 从水相硝酸中萃取Pu⁴⁺, Pu⁴⁺的萃取百分数超过99%, 在0.1 mol/L TODGA/C₆mimTf₂N中, 遵循阳离子交换机制, Pu⁴⁺被萃取到RTILs相的形式是[Pu(NO₃)(TODGA)]³⁺, 获得了萃取反应方程和热力学平衡常数的参数。随着钍基熔盐堆的发展, 作者认为应更加重视对Th相关性质的研究, Shiri-Yekta等^[38]研究了1-丁基-3-甲基咪唑六氟磷酸盐([C₄mim⁺][P $\begin{matrix} F_{6}^{-} \end{matrix}$ ])为稀释剂的RTILs, 在没有萃取剂时能从硝酸钠溶液中有效萃取Th⁴⁺, 不萃取Eu³⁺, 又以三正锌基氧化磷(TOPO)为萃取剂, 从硝酸介质中萃取Th⁴⁺和Eu³⁺, Eu³⁺通过溶剂化机制形成[Eu(TOPO $\begin{matrix} )_{3}^{3 +} \end{matrix}$ ](N $\begin{matrix} O_{3}^{-} \end{matrix}$ )₃, RTILs能显著提高萃取性能, Th⁴⁺是离子对的交换机制, TOPO不影响Th⁴⁺萃取效果, 通过分析配体结构, 首次报道锕系元素的协同萃取作用。反萃是实现离子液体循环使用的关键, 因此很多研究者重视反萃的研究, 特别是如何提高反萃能力。 Fu等^[39]研究了从水相萃取Th⁴⁺和使用超临界CO₂从RTILs中反萃Th⁴⁺, 在C_nmimNTf₂(n=2, 4, 6, 8)中使用2-噻吩甲酰三氟丙酮(HTTA)从水相高效萃取Th⁴⁺, 且Th⁴⁺形成的中性配合物的组成为HTT^-(Th(TTA)₄), 在Th⁴⁺的萃取和反萃过程中, 不仅提高了工作效率, 而且RTILs的损失可以避免, 只有萃取和反萃相结合, 才能降低成本, 实现离子液体的循环使用。

Iqbal^[40]综合和评估锕系和镧系元素从核废料中萃取时可能形成的配体化合物, 对新形成的配体、配体的特性、亲水性配体的萃取效率、正辛基苯基-N, N'-二异丁基胺甲酰甲基氧化膦(CMPO)功能化离子液体对各种金属离子萃取能力等均做了详细的论证。 Mohapatra等^{[41, 42, 43, 44]}在该领域做了很多研究, 并获得很多创新型实验成果。研究发现, CMPO溶解在C_nmimPF₆中形成的新型功能化溶剂系统L-Ⅰ (CMPO-TSIL-P $\begin{matrix} F_{6}^{-} \end{matrix}$ )具有较高的萃取和分离能力, 萃取遵循离子交换机制, 首次报道合成的新型CMPO-TSIL的L-Ⅰ 和L-Ⅱ (CMPO-TSIL-NT $\begin{matrix} f_{2}^{-} \end{matrix}$ )萃取锕系元素的数据, U $\begin{matrix} O_{2}^{2 +} \end{matrix}$ 离子的萃取顺序为C₄mimNTf₂> C₆mimNTf₂> C₈mimNTf₂, 分配系数非常接近。在室温离子液体1-辛基-3甲基咪唑三氟甲基磺酰胺酸盐(C₈mimNTf₂)中, 溶解不同构成的配合物亚硫基二乙酰胺杯芳烃(C₄DGA)(图2)的L-Ⅰ ~L-Ⅴ 体系(表2)中, 评价锕系离子U $\begin{matrix} O_{2}^{2 +} \end{matrix}$ 、Pu⁴⁺、 Pu $\begin{matrix} O_{2}^{2 +} \end{matrix}$ 、Am³⁺的萃取能力, 发现L-Ⅰ 和L-Ⅳ 是最有发展前景的萃取剂, 首次获得萃取平衡时间为2 h, 在稀释剂为C₈mimNTf₂, 萃取剂为C₄DGAs时, 萃取效率变化趋势为Eu³⁺> Am³⁺> Pu⁴⁺> Pu $\begin{matrix} O_{2}^{2 +} \end{matrix}$ > U $\begin{matrix} O_{2}^{2 +} \end{matrix}$ > Sr²⁺> Cs⁺(表2), 并分析了Am³⁺和Eu³⁺与C₄DGAs的配合物组成, 观察到萃取过程主要是Am³⁺-C₄DGA的配合反应且放热, 他们在RTILs中首次观察到有发生可逆反应的趋势, 从辐射稳定性和反萃研究评估认为该溶剂系统很有希望应用于核废物处理。研究了亚硫基二乙酰胺为官能团的功能化离子液体(DGA-TSILs)从酸性料液中萃取锕系和镧系元素, 观察到DGA-TSILs有异常高的萃取三价锕系离子的能力和很强的辐射稳定性, 使它成为从酸性料液中萃取锕系元素最有效的溶剂系统之一。

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	图2 萃取剂C₄DGAs 的结构式( L-Ⅰ 、L-Ⅱ 和L-Ⅲ 的间隔是2)^[43]Fig.2 Structural formulas of the C₄DGAs extractants(the spacer length(n) is 2 for L-Ⅰ , L-Ⅱ and L-Ⅲ )^[43]

表2 基于萃取剂为C₄DGA-RTIL的溶剂体系L-Ⅰ 、L-Ⅱ 和L-Ⅲ 评估萃取锕系元素和裂片元素^[43] Table 2 Evaluation of C₄DGA-RTIL based solvent systems L-Ⅰ , L-Ⅱ and L-Ⅲ V for the extraction of actinides and fission product elements^[43]

4 结论与展望

乏燃料后处理是核燃料循环的中心环节, 对核能和核安全的可持续发展具有重要意义。在先进核燃料循环系统中, 关键步骤是对这些高燃耗、高钚含量、高辐照的热堆和快堆乏燃料或嬗变靶件的处理, 这使得水法后处理流程无法满足分离要求^[2]。因此, 干法后处理技术重新受到人们的重视, 尤其是高温熔盐电解技术成为乏燃料干法后处理的重要研究方向。该体系存在分离系数低、高温和材料腐蚀等问题, 因此规模还是较小。为了研制更好的乏燃料后处理方法, 国内外的科学家把目光转向离子液体, 因其在室温下就能溶解上千度才能溶解的金属, 若能使RTILs代替高温熔盐用于乏燃料回收, 将对基于熔盐体系电解方法的干法后处理流程做出革命性变革。 RTILs的发展历史较短, 生产成本高, 目前RTILs用于乏燃料后处理的研究还处于起步阶段, 需要加强基础研究, 未来熔盐用于核燃料后处理的研究重点可能包括如下几个方面:

1)高温熔盐方面, 应加强在热力学、动力学和反应机理等方面的基础研究。溶解度和耐高温耐腐蚀材料的问题, 是制约高温熔盐电解用于干法后处理的两大因素。

2)离子液体方面, 应改进对离子液体中杂质的分析检测和去除的方法, 加强动力学、热力学、萃取机理和锕系镧系离子相互分离等方向的基础研究。提高反萃能力、萃取稳定性尤其是辐射稳定性。合成功能化离子液体。增加处理乏燃料后对离子液体回收性质的研究。

3)熔盐体系方面, 应增加对锕系元素及其氧化物和裂变产物在熔盐体系中的基础研究, 以获得实验数据和工艺流程图。这对熔盐体系用于干法后处理, 以及实现工业化至关重要。

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2011

0.67

0.95

Zhongmao

, CHAI

Zhifang.

Some Thinking of Nuclear Fuel Reprocessing/Recycling in China[J]. Prog Chem, 2011, 23(7): 1263-1271(in Chinese).

顾忠茂, 柴之芳. 关于我国核燃料后处理/再循环的一些思考[J]. 化学进展, 2011, 23(7): 1263-1271.

Based on the uranium-plutonium fuel cycle, the once-through fuel cycle, closed fuel cycle for thermal reactors and closed fuel cycle for fast reactors are analyzed and compared from the view point of sustainable development of nuclear fission energy. It is pointed out that both the once-through fuel cycle and the closed fuel cycle of thermal reactor could not meet the strategic needs of sustainable development of nuclear energy and fast reactor with multi-recycling of nuclear fuel is the best option to develop the nuclear fission energy in a sustainable way. The present status and the major trend of reprocessing/recycling technologies in the world are introduced and the gap between China and the major nuclear energy countries is evaluated. Keeping the domestic situation in mind, we try to explore the general considerations of the development of nuclear fuel reprocessing/recycling technologies in China and the technical options to be taken. The key techniques to be solved and the associated supporting measures are also proposed.Contents 1 Introduction 2 Two options of nuclear fuel cycle-once-through fuel cycle and closed fuel cycle 2.1 Concept of nuclear fuel cycle 2.2 Problems of once-through fuel cycle 2.3 Characteristics of closed fuel cycle for thermal reactors 2.4 Advantages of closed fuel cycle for fast reactors 3 Present status and development trends of reprocessing/recycling technologies at home and abroad 3.1 World status and development trends of reprocessing/recycling technologies 3.2 China’s present status of reprocessing/recycling technologies and the gaps from the world advanced level 4 Preliminary considerations of China’s development strategy of reprocessing/recycling technologies 4.1 Recycle plutonium directly in fast reactors is adaptable in China 4.2 Follow the route of “breeder first, burner second” is adaptable in China 5 Key technologies to be developed for reprocessing/recycling in China 5.1 Reprocessing of spent fuel from thermal reactors 5.2 Reprocessing of spent fuel from fast reactors 6 Conclusions

1. China Institute of Atomic Energy, Beijing 102413, China; 2. High Energy Institute of Chinese Academy of Sciences, Beijing 100049, China

本文从核裂变能可持续发展的角度,对基于铀-钚循环的核燃料循环体系中的 “一次通过”循环、热堆闭式循环和快堆闭式循环的特点进行分析和比较,指出“一次通过”循环和热堆闭式循环均不能满足核能可持续发展的战略需要,快堆及核燃料多次循环才是我国核裂变能可持续发展的根本出路;介绍了国际上核燃料后处理/再循环的技术现状和主流发展趋势,指出我国在后处理/再循环技术方面与国际先进水平之间的差距;结合我国国情探讨我国核燃料后处理/再循环技术发展的总体构想和拟采取的技术路线,提出需要突破的关键技术问题和相应的配套措施。

... 乏燃料后处理是对核电站卸出的乏燃料元件进行处理、分离并回收未烧尽的铀和新生成的钚,同时对放射性废物进行处理,以满足处置要求的一种处理方式^[1] ...

2007

0.934

0.0

LIU

Peng

, TONG

Yexiang

, YANG

Qiqin.

Molten Salt Systems and the New Developments for the Application of Molten Salts[J]. Electrochemistry, 2007, 13(4): 351-359(in Chinese).

刘鹏, 童叶翔, 杨绮琴. 熔盐体系及有关应用的新进展[J]. 电化学, 2007, 13(4): 351-359.

介绍近年来熔盐体系的概况,着重室温熔盐的发展.熔盐在电化学制备合金和功能材料、能源、分析和分离、用作反应介质和催化剂、环境保护等方面应用前景良好.

... 熔盐又分为低温熔盐、室温熔盐、高温熔盐,三者之间并无明显的界限^[2] ...

... 在先进核燃料循环系统中,关键步骤是对这些高燃耗、高钚含量、高辐照的热堆和快堆乏燃料或嬗变靶件的处理,这使得水法后处理流程无法满足分离要求^[2] ...

2011

0.67

0.95

Guoan

, ZHANG

Hu.

A Review on the Development of Spent Nuclear Fuel Reprocessing and Its Related Radiochemistry[J]. Prog Chem, 2011, 23(7): 1289-1294(in Chinese).

叶国安, 张虎. 核燃料后处理技术发展及其放射化学问题[J]. 化学进展, 2011, 23(7): 1289-1294.

The development and its corresponding technical features of spent nuclear fuel reprocessing were reviewed systematically according to the changes of its applications to different spent fuels and separation improvements. Aiming at the partition and transmutation (P&T) technologies in future advanced nuclear energy system, the improvements of the Purex process from Generation Ⅱ reprocessing to Generations Ⅲ and Ⅳ reprocessing were highlighted. The key radiochemical issues which should pay much attention in the Purex process and following partition processes as well as the dry reprocessing for spent nuclear fuel of fast reactors were summarized. Contents 1 Introduction 2 Development of reprocessing technologies 3 Reprocessing for P&T 4 Radiochemical issues for further explorations

China Institute of Atomic Energy, Beijing 102413, China

从化学分离手段的改进、后处理的对象变化、与分离功能的拓展等方面较为系统地阐述了核燃料后处理技术发展过程及技术特点;以先进核能系统中分离嬗变为目标,概括总结了从第二代后处理技术向第三代和第四代后处理技术发展过程中Purex流程、后续的分离工艺与处理快堆元件的干法后处理工艺中的主要放射化学问题。

... 该工艺操作通常要在金属氯化物熔点以上进行,对设备的要求及能耗极高,具有耐辐照、低临界风险、放射性废物少、流程简单等优点,可适用于金属燃料、氮化物燃料及氧化物燃料等多种形态的燃料处理^[3] ...

2011

0.67

0.95

WEI

Yuezhou.

Progress and Discussion on Chemical Separation Technologies for Nuclear Fuel Reprocessing Developed Abroad[J]. Prog Chem, 2011, 23(7): 1272-1288(in Chinese).

韦悦周. 国外核燃料后处理化学分离技术的研究进展及考察[J]. 化学进展, 2011, 23(7): 1272-1288.

Reprocessing technologies can be divided into wet process using aqueous solution and dry process. The wet process includes solvent extraction (liquid-liquid extraction), ion exchange, precipitation, etc. The PUREX process which uses TBP as extractant and can recover about 99.5% of the U and Pu from spent fuel is the only successfully commercialized reprocessing technology nowadays.However, the PUREX process still has some significant drawbacks such as complicated extraction procedures, generation of a great amount of waste and utilization of large scale equipment. In addition, it can not effectively recover the long-lived nuclides such as minor actinides (Np, Am, Cm) and Tc, which will result in a long term radiological effect on the environment. In recent years, many efforts have been devoted to the improvement of the PUREX process and the study of advanced wet reprocessing technologies. Dry process utilizing electro-refining in molten salt, reductive extraction in liquid metal or volatilization of fluorides is attracting wide attention, because it has the advantages of compact equipment, high radiation resistance and critical safety. But relatively low separation factor and corrosion of materials at high temperature are the main problems of the dry process. This article reviews the progress in the chemical separation technologies for nuclear fuel reprocessing abroad. Furthermore, some chemical problems in separation processes are analyzed and discussed. Contents 1 Necessity for the development of advanced reprocessing technologies 2 Progress and discussion on advanced wet reprocessing technologies 2.1 Extraction processes based on the improvement of PUREX 2.2 Separation processes using novel extractants 2.3 Other wet separation processes 2.4 Separation processes for MA and FP 2.5 Summary of wet separation processes 3 Progress and discussion on dry reprocessing technologies 3.1 The principle and characteristics of dry separation processes 3.2 Molten salt electro-refining process for metalic nuclear fuel 3.3 Molten salt electro-reduction process for oxide nuclear fuel 3.4 Hybrid process of dry and wet separation technologies 3.5 Summary of dry separation processes 4 Concluding remarks

School of Nuclear Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China

后处理技术可分为使用水溶液的湿法和不使用水溶液的干法。湿法主要有溶剂萃取法(液液萃取法)、离子交换法和沉淀法等。以TBP(磷酸三丁酯)为萃取剂的PUREX法是当今后处理的主流技术。通过PUREX流程,可回收乏燃料中约99.5%的铀和钚,但由于长寿命次锕系元素(MA: Np、Am、Cm)以及Tc等得不到有效的分离回收,放射性废物的放射毒性仅降低一个量级。并且该技术本身存在萃取工艺流程复杂,设备规模大,产生大量的难处理有机废液等问题。多年来世界核能主要国家都在致力于改良PUREX流程的同时,开展更先进的湿法后处理技术研发。干法后处理采用熔盐或液态金属作为介质,主要有电解精炼法、金属还原萃取法、沉淀分离法和氟化物挥发法等。具有装置规模较小,耐辐照性强,临界安全性高等优点。但分离性能较低,且由于操作温度高(数百摄氏度),材料耐用性以及操作可靠性尚待解决。近年来干法作为金属燃料后处理以及超铀元素嬗变燃料处理的分离技术,重新受到重视。本文概括介绍了国外先进湿法和干法后处理技术的研究动向,并对分离技术中的主要化学问题进行了分析和考察。

... 但该工艺存在操作温度高、熔融卤化物及液态金属对材料腐蚀严重、分离性能低等缺点^[4] ...

2010

0.67

0.95

CHU

Daobao

, ZHOU

Ying

, ZHANG

Xuejiao

, et al. Organic Electrochemical Reactions Based on Ionic Liquid Electrolytes[J]. Prog Chem, 2010, 22(12): 2316-2327(in Chinese).

褚道葆, 周莹, 张雪娇, 等. 基于离子液体电解液的有机电化学反应[J]. 化学进展, 2010, 22(12): 2316-2327.

Room-temperature ionic liquids (RTILs),as a class of novel "green solvents" that exist in the liquid state around room-temperature and possess excellent ionic conductivity, have many promising applications in organic electrochemical reaction. In the review, new type of ionic liquids reported in recent years and the properties of ionic liquid electrolyte are described. The electrochemical experimental methods based on ionic liquid electrolyte are also discussed. Various organic electrochemical reactions in ionic liquid,including electrochemical reduction, electroreduction fixation of CO 2 , electrochemical oxidation, olefin epoxidation, selective fluorination reaction, coupling reaction,the synthesis of functional organic siloxane, electrochemical fluorination desulfurization,electrochemical polymerization reaction, etc, are reviewed specifically, and the development trend is given. Contents 1 Introduction 2 The new ionic liquids 3 Properties of ionic liquid electrolytes 3.1 Viscosity 3.2 Conductivity 3.3 Diffusion of electroactive solutes 3.4 Effects of impurities 3.5 Electrochemical windows 4 The experimental methods based on ionic liquid electrolytes 5 Organic electrochemical reactions in ionic liquids 5.1 Electrochemical reduction 5.2 Fixation of CO 2 in ionic liquids 5.3 Electrochemical oxidation 5.4 Olefin epoxidation 5.5 Selective fluorination reaction 5.6 Coupling reaction 5.7 The synthesis of functional organic siloxane 5.8 Electrochemical fluorination desulfurization 5.9 Electrochemical polymerization reaction 6 Conclusion and perspective

Anhui Key Laboratory of Functional Molecular Solids and Molecular Based Materials, College of Chemistry and Materials Science, Anhui Normal University, Wuhu 241000, China

室温离子液体(RTILs) 作为一类在室温时呈液态且具有良好导电性的新型绿色溶剂, 在有机电化学反应体系中的应用前景广阔。本文介绍了近年报道过的新型离子液体及离子液体电解液的特性,阐述了基于离子液体电解液的电化学实验方法,重点综述了离子液体中的各种有机电化学反应,包括电化学还原反应、CO 2 在离子液体中的电化学固定、电化学氧化反应、烯烃的环氧化、选择性氟化反应、偶联反应、功能化有机硅氧烷的合成、电化学氟化脱硫反应、电化学聚合反应等,并展望了发展趋势。

... 离子液体(RTILs),也叫室温熔融盐,由有机阳离子和有机或无机阴离子组成的盐类^[5],在室温下成液体状态,它融合了高温熔盐和水溶液的优点:导电性好、不挥发、热稳定性好、电化学窗口宽等^[6],在室温下就可得到在高温熔盐中电沉积才能得到的金属和合金 ...

2012

0.0

0.4082

... 3 锕系元素在室温离子液体(RTILs)中的研究进展RTILs具有电导率高、电化学窗口宽、熔点低、辐照稳定性好等优点,使其可以作为独特溶剂进行电化学研究,并且在RTILs合成过程中引入特定的官能团,形成任务专一型的离子液体,即功能化离子液体(TSIL)^[6],提高其对目标金属离子的萃取率和选择性 ...

2013

0.0

0.5042

YANG

Feilong

, CHEN Chang'an, WANG Xiaoying, et al. Electrochemical Behavior of Lanthanides and Actinides in Ionic Liquid[J]. J Nucl Radiochem, 2013, 35(6): 321-327(in Chinese).

杨飞龙, 陈长安, 王小英, 等. 镧系及锕系元素在离子液体中的电化学行为[J]. 核化学与放射化学, 2013, 35(6): 321-327.

The spent fuel reprocessing, as the essential part of nuclear fuel cycle, is of great significance from the point of view of both nuclear safety and sustainable development of nuclear energy. The reprocessing technology can be divided into wet process using aqueous solution and dry process. Molten salt electrolysis technology is one of the important approaches of spent fuel dry reprocessing, but this technique often operates at several hundred degrees with high demands for equipment and energy consumption. Room temperature ionic liquid has many advantages, such as wide electrochemical window, low melting point, insignificant vapor pressure and high thermal stability, which is promising to replace high-temperature molten salt for spent fuel dry reprocessing. This article reviews the electrochemical research status of the actinides and lanthanides in ionic liquids. These results indicate that the ionic liquids can be used for spent fuel dry reprocessing, but more basic research is required.

1.Science and Technology on Surface Physics and Chemistry Laboratory, P. O. Box 718(35), Mianyang 621907, China;2.China Academy of Engineering Physics, Mianyang 621900, China

乏燃料回收是核燃料循环的核心，对核安全和核能可持续发展具有重要的意义，其分为使用水溶液的湿法和不使用水溶液的干法处理。熔盐电解技术是乏燃料干法回收的重要方法之一，但其工艺温度往往在数百摄氏度，对设备和能耗要求都很高。离子液体具有电化学窗口宽、低熔点、低蒸汽压、热稳定性好等优点，有望替代高温熔盐用于乏燃料干法回收。本文概述了镧系元素和锕系元素在离子液体中电化学方面的研究状况，表明离子液体用于乏燃料干法回收是可行的，但需要更多的基础性研究。

... 因此,若能用其代替碱金属氯化物熔盐作为熔盐电解技术的介质来分离和回收铀、钚和其它裂变产物,将从根本上解决其所面临的高温和材料腐蚀问题,对以熔盐电解为基础的干法后处理具有划时代的意义^[7] ...

... 用RTILs代替氯化物熔盐作为熔盐电解质来进行干法后处理,是解决高温强腐蚀问题的重要方向^[7] ...

... 杨飞龙等^[7]进一步综述了镧系元素和锕系元素在RTILs中电化学方面的研究状况 ...

2013

0.0

0.1184

... 然而,该技术生产成本高,很难合成集高电导率、高稳定性、宽电化学窗口等诸多优点为一体的RTILs,故RTILs在乏燃料后处理技术中的大规模工业化应用尚不成熟^[8] ...

2004

2.905

0.0

Serp

, Konings R J M, Malmbeck R, et al. Electrochemical Behaviour of Plutonium Ion in LiCl-KCl Eutectic Melts[J]. J Electroanal Chem, 2004, 561: 143-148.

... Serp等^[9]采用循环伏安、计时电势等技术研究了钚离子在LiCl-KCl熔盐中的电化学行为,在733 K时,Pu³⁺扩散系数为D_pu²⁺=2× ...

2001

1.211

0.0

Iizuka

, Uozumi

, Inoue

, et al. Behavior of Piutonium and Americium at Liquid Cadmium Cathode in Molten LiCl-KCl Electrolyte[J]. J Nucl Mater, 2001, 299(1): 32-42.

... 用类似的方法,Iizuka等^[10]重点研究了电流密度对收集速率的影响,当阴极电流密度低于4× ...

2007

3.777

0.0

Cassayre

, Serp

, Soucek

, et al. Electrochemistry of Thorium in LiCl-KCl Eutectic Melts[J]. Electrochim Acta, 2007, 52(26): 7432-7437.

Abstract This work presents a study of the electrochemical properties of Th chloride ions dissolved in a molten LiCl–KCl eutectic, in a temperature range of 693–823 K. Transient electrochemical techniques such as cyclic voltammetry, chronopotentiommetry and chronoamperometry have been used in order to investigate the reduction mechanism on a tungsten electrode and the diffusion coefficient of dissolved Th ions. All techniques showed that only one valence state was stable in the melt. The reduction into Th metal was found to occur according to a one-step mechanism, through a nucleation-controlled process which requires an overpotential of several 100 mV. At 723 K, the diffusion coefficient is D Th(723 K) = 3.15 ± 0.15 × 10 −5 cm 2 s −1 . EMF measurements indicated that, at 723 K, the standard apparent potential is (723 K) = −2.582 V versus Cl 2 /Cl − , and the activity coefficient γ ThCl 4 (723 K) = 4.6 × 10 −4 on the mole fraction scale (based on a pure liquid reference state).

... Cassayre等^[11]在熔融LiCl-KCl合金中使用循环伏安和计时电流法研究了钍离子的还原机制和扩散系数,观察到Th在熔盐中只有一个稳定价态,还原到Th金属是一步反应机制,在723 K时,Th的扩散系数D_Th=(3 ...

2012

0.0

0.392

WANG

Zhe

, OUYANG

Yinggen

, WANG

Changshui

, et al. Research of Electrochemical Behavior of Thorium in LiCl-KCl Melts[J]. Atom Energy Sci Technol, 2012, 46(supp): 180-183(in Chinese).

王喆, 欧阳应根, 王长水, 等. LiCl-KCl熔盐中钍的电极过程研究[J]. 原子能科学技术, 2012, 46(增刊): 180-183.

The electrochemical process on the Mo cathode of Th 4+ ion in the LiCl-KCl melts was studied by the cyclic voltammetry and chronopotentiometry. The results of research show that the electrode process is controlled by diffusion and the temperature dependence of diffusion coefficient D can be described by ln D ＝ 33.94-2.879 × 10 4 / T . The apparent potential is E vsCl- 0 /Cl 2 ＝ -3.45+7.5 × 10 -4 T .

1.Nuclear and Radiation Safety Center, Ministry of Environmental Protection, Beijing 100082, China;2.China Institute of Atomic Energy, Beijing 102413, China

通过循环伏安法和计时电位法，研究 LiCl-KCl 熔盐中 Th 4+ 在 723 ～ 803 K 内在 Mo 电极上的电极过程。结果表明， Th 4+ 在 Mo 电极上的电极过程受离子扩散步骤控制，扩散系数 D 随温度 T 变化的经验公式为 ln D ＝ 33.94-2.879 × 10 4 / T ，形式电位的经验公式为 E vsCl- 0 ′ /Cl 2 ＝ -3.45+7.5 × 10 -4 T 。

... 在该实验的基础上,王喆等^[12]确定了钍在LiCl-KCl 熔盐中的稳定价态是正四价,Th⁴⁺在阴极是4电子转移的一步电解过程,发现Th⁴⁺在Mo电极上电解过程受离子扩散控制,获得了扩散系数随温度变化的经验公式和形式电势的经验公式 ...

2010

3.777

0.0

Chamelot

, Massot

, Cassayre

, et al. Electrochemical Behaviour of Thorium(Ⅳ) in Molten LiF-CaF₂ Medium on Inert and Reactive Electrodes[J]. Electrochim Acta, 2010, 55(16): 4758-4764.

Abstract The electrochemical behaviour of the Th(IV)/Th system was examined in molten LiF–CaF 2 medium on inert (molybdenum), reactive (nickel) and liquid (bismuth) electrodes in the 810–920 °C temperature range by several electrochemical techniques. Experimental results showed that (i) thorium fluoride was reduced in a single step exchanging 4 electrons and limited by thorium ions diffusion in the solution, (ii) the oxide ions induce the precipitation of Th(IV) in the form of thorium oxide (ThO 2 ), in a process involving as intermediate compound a soluble oxifluoride (ThOF 2 ), (iii) the reduction of thorium ions on reactive (Ni and liquid Bi) electrodes yields compounds Ni–Th and Bi–Th with a potential shift of around 0.7 V (for Ni and Bi) more anodic than the reduction of Th(IV) on inert substrate.

... Chamelot等^[13]研究了氟化物熔盐LiF-CaF₂中,不同电极(惰性Mo和活性Ni)上Th⁴⁺的电化学行为,研究表明Th⁴⁺以ThO₂形式沉淀,形成中间可溶性产物ThOF₂,在活性电极(Ni和Bi)电解还原Th⁴⁺时,形成Ni-Th和Bi-Th的化合物 ...

1997

1.211

0.0

Iizuka

, Koyama

, Kondo

, et al. Actinides Recovery from Molten Salt/Liquid Metal System by Electrochemical Methods[J]. J Nucl Mater, 1997, 247: 183-190.

... Iizuka等^[14]使用电化学方法从熔融盐或液态金属镉中回收锕系元素,验证了从液态镉层电迁移铀和从熔融盐电解质中电解还原铀,并成功地回收铀,进一步验证了从高温熔盐中回收锕系元素的可行性 ...

2001

1.989

0.0

Prabhakara Reddy

, Kand an

, Nagarajan

, et al. Molten Salt EMF Cell Measurements on U Ga Alloys[J]. Thermochim Acta, 2001, 366(1): 37-45.

... Reddy等^[15]使用高温熔盐原电池测量方法测出U-Ga合金的吉布斯自由能和电动势,首次确定了α ...

2008

0.0

... 国内学者对铀在高温熔盐中的电化学行为也进行了相关性质的研究,如高繁星等^[16]研究了LiCl--KCl熔盐中铀的电化学行为 ...

2013

0.0

... 刘刈等^[17]在1073 K,采用循环伏安法和计时电流法研究了U在氟化物LiF-NaF-UF₄熔盐中的电化学还原机理,得出U⁴⁺在氟化物熔盐中的还原分两步即U⁴⁺+e^-=U³⁺,U³⁺+3e^-=U,这两个还原过程均为扩散控制且可逆,扩散系数 DU4+=2 ...

1998

0.0

... Shirai等^[18]在不同温度下的LiCl-KCl熔盐中,在W和Mo工作电极下,通过循环伏安法研究了U和Pu的电沉积和溶解行为,伏安图表明,U³⁺/U和Pu³⁺/Pu可能是准可逆的,U⁴⁺/U³⁺是可逆的,且在沉积电势下形成U和Pu的吸收峰和解吸峰 ...

0.0

... 随后Sakamura等^[19]在LiCl-KCl熔盐中通过电解精炼法从稀土金属中分离锕系元素并测量U、Pu、Np和Am的标准电势,结果表明,Am是最难回收的 ...

2005

0.0

... Sou cˇek 等^[20]研究了裂变产物在熔盐LiF-NaF-KF中的电化学分离方法,分析选择性分离锕系(U,Th)和镧系(Nd,Eu,Gd)的可行性,根据研究的最新结果讨论不同电化学技术的适用性,并列出熔盐反应堆燃料循环的基本流程图 ...

2005

0.0

Lambertin

, Ched`homme S, Bourges G, et al. Activity Coefficients of Plutonium and Cerium in Liquid Gallium at 1073 K: Application to a Molten Salt/Solvent Metal Separation Concept[J]. J Nucl Mater, 2005, 341(2/3): 131-140.

... Lambertin 等^[21]采用循环伏安法和计时电流法研究用高温化学法分离钚的热力学的可行性,得出Pu在液镓中的活度系数是lg (γ ...

2007

1.211

0.0

Van der Meer J P M, Konings R J

. Thermal and Physical Properties of Molten Fluorides for Nuclear Applications[J]. J Nucl Mater, 2007, 360(1): 16-24.

... Van der Meer等^[22]研究氟化物熔盐处理核燃料的热力学和物理学特性,综述了LiF-BeF₂-ThF₄这个三元系的一些重要特征,并指出其典型的组成为0 ...

2007

0.0

... Rance等^[23]探讨了后处理镎的工艺流程可行性的相关问题并绘制了U、Pu、Am等核素在后处理工艺走向流程图,分析比较²³⁷Np与其它裂片核素的性质(表1),发现预期质量的镎与高活性废物转化为陶瓷废料的过程中产生的裂变产物相结合,但还没有文献报道称镎的分离或转移不会发生,也没有进行下一步的研究,但这一发现对研究锕系元素在高温熔盐中的电化学行为提供了新的启发 ...

2013

4.593

0.0

Céline

, Naour C

, Moisy

, et al. Specific Interaction between Uranium Anionic Complexes and the Cations of Bis(trifluoromethylsulfonyl)imide Based Ionic Liquids[J]. Inorg Chem, 2013, 52: 11218-11227.

† Institut de Physique Nucléaire, CNRS, Univ. Paris-Sud 11 , 91406 Orsay Cedex, France ‡ CEA , Nuclear Energy Division, Radiochemistry & Processes Department, 30207 Bagnols sur Cèze, France *Tel.: +33 169157152 . Fax: +33 169157150 . E-mail address: cannes@ipno.in2p3.fr .

The redox properties of uranium(IV) hexachloro complex have been investigated with a glassy carbon electrode in four bis(trifluoromethylsulfonyl)imide (Tf 2 N – ) based ionic liquids (ILs): the 1-butyl-3-methylimidazolium ([BuMeIm] + ), the 1-butyl-2,3-dimethylimidazolium ([BuMe 2 Im] + ), the N -butylmethylpyrrolidinium ([BuMePyr] + ), and the tributyl-methylammonium ([MeBu 3 N] + ). The cyclic voltammetric analysis has revealed two main redox systems: U V Cl 6 – /U IV Cl 6 2– around 0.2 V and U IV Cl 6 2– /U III Cl 6 3– around −2 V. The formation of U V Cl 6 – , a non-dioxo uranium(V) species, can then be observed at the electrode in [Tf 2 N] − based ILs. This work also provides evidence of a specific interaction between the uranium anionic species and the IL cations because the standard potentials of both redox couples depend on the IL. The interaction extent has been evaluated by comparison of the IL cation number associated with the uranium anionic complex. For that purpose, the standard potentials of both systems have been measured in the less interacting medium [MeBu 3 N][Tf 2 N] as a function of the [BuMeIm] + , [BuMe 2 Im] + , and [BuMePyr] + concentration. Predominance diagrams for uranium hexachloro complexes, analogous to the Pourbaix diagram, have then been built in [MeBu 3 N][Tf 2 N] depending on the IL cations concentration. The exploitation of these diagrams leads to the conclusion that the interaction is function of the charge of the uranium hexachloro complex (U V Cl 6 – IV Cl 6 2– III Cl 6 3– ) and the IL cation ([BuMe 2 Im] + + + ). The influence of the IL cation could be correlated to the size and the electropositivity of the IL cation. The association would occur by H-bonding and electrostatic interaction. Ab initio calculations were also carried out to evaluate the strength of the interaction between the anionic uranium(IV) chloro complex and the IL cations. The results show that [BuMeIm] + interacts the most and [MeBu 3 N] + the least with U IV Cl 6 2– , and the magnitude of the interaction is comparable for [BuMe 2 Im] + and [BuMePyr] + .

... line等^[24]使用玻碳电极研究了U⁶⁺的氯化物的氧化还原特性,在4种新型离子液体中使用循环伏安法揭示了两个主要的氧化还原电对即U⁵⁺C l6-/U⁴⁺C l62-和U⁴⁺C l62-/U³⁺C l63-,离子配对的强弱与离子液体阳离子的性质有关,且遵循U⁵⁺C l6-< ...

2013

1.164

0.0

... Joseph等^[25]首次尝试在氯化1-丁基-3-甲基-咪唑盐(C₄mimCl)为稀释剂的RTILs中,通过氯化反应溶解铀的氧化物UO₂和UO₃,利用循环伏安法研究U⁶⁺的电化学行为,结果显示,因U O22+控制电势电解沉积UO₂,致使在-1 ...

2012

0.0

0.95

YUAN

Liyong

, SHI

Weiqun

, LAN

Jianhui

, et al. Application of Ionic Liquids in Nuclear Fuel Reprocessing[J]. Chinese Sci Bull, 2012, 57(8): 581-593(in Chinese).

袁立永, 石伟群, 蓝建慧, 等. 离子液体在核燃料后处理中的应用[J]. 科学通报, 2012, 57(8): 581-593.

The nuclear fuel reprocessing, as the essential part of nuclear fuel cycle, is of great significance from the point of view of both nuclear safety and sustainable development of nuclear energy. Room temperature ionic liquids (RTILs) regarded as “new generation green solvents” have recently received an ever-increasing amount of interest in nuclear fuel reprocessing due to their unique physical and chemical properties. They can be used in aqueous reprocessing as environmentally benign alternatives to volatile organic solvents for traditional liquid-liquid extraction of high level radioactive nuclides. They are also applicable in non-aqueous reprocessing by substituting caustic molten salts for electro-deposition of metal ions. Herein, we reviewed the recent basic researches on the utility of RTILs in nuclear fuel reprocessing, from which the key scientific issues on their practical application were summarized. In addition, it is well known that nuclear fuel reprocessing involves high-level radioactive matter, and full realization of the potential application of RTILs in nuclear fuel reprocessing requires a comprehensive knowledge of stability and properties of RTILs under radiation. Therefore, the recent investigations of radiation effects on RTILs were also selectively described in this paper, and the feasibility of RTILs as alternative media for separations of highly radioactive nuclides from spent nuclear fuel was assessed from the radiation chemistry aspect. Finally, further basic studies on the application of RTILs in the nuclear fuel reprocessing were prospected.

Key Laboratory of Nuclear Analytical Techniques, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China

核燃料后处理是核燃料循环的核心, 对于核环境安全和核能的可持续发展意义重大.离子液体作为“新一代绿色溶剂”在核燃料后处理中具有广阔的潜在应用前景. 离子液体可以替代易挥发的有机溶剂用于水法后处理萃取分离放射性核素, 也可以替代强腐蚀性的高温熔盐用于干法后处理电解回收金属离子. 本文在作者工作基础上总结了近年来离子液体用于核燃料水法和干法后处理的基础研究成果, 归纳和分析了其中的关键科学问题. 此外, 由于核燃料后处理涉及强辐射应用环境, 离子液体的辐射稳定性是其实际应用的前提和关键, 因此本文还综述了国内外有关离子液体辐射效应的研究进展, 评估了离子液体用于核燃料后处理的辐射化学可行性. 最后, 基于当前的研究现状和研究水平展望了离子液体在核燃料后处理应用方面的研究前景.

... 袁立永等^[26]综述了近年来RTILs用于核燃料水法和干法后处理的基础研究成果,对离子液体辐射效应的研究为室温熔盐电解乏燃料提供了新思路 ...

2009

0.0

... 张秋月等^[27]使用循环伏安和计时电势等方法研究了镧系元素Eu³⁺和锕系元素U⁶⁺在亲水性离子液体氯化1-丁基-3-甲基咪唑([BMIM]Cl)中的电极过程 ...

2012

0.0

... Senqupta等^[28]使用RTILs从放射性废物中回收Am,使用了侧链长度不同的离子液体C_nmim⁺P F6-(n=4,6,8)与萃取剂0 ...

2013

0.0

Pribylova G

, Smirnov I

, Novikov A

, et al. Effect of Ionic Liquids on the Extraction of Americium by Diphenyl(dibutyl) carbamoylmethyl Phosphine Oxide in Dichloroethane from Nitric Acid Solutions[J]. J Radioanal Nucl Chem, 2013, 295(1): 83-87.

1. Vernadsky Institute of Geochemistry and Analytical Chemistry, Russian Academy of Sciences, Kosygin Str. 19, 119991, Moscow, Russia 2. Khlopin Radium Institute, 2nd Murinskii Avenue, 28, 194021, St. Petersburg, Russia

The present paper demonstrates that room temperature ionic liquids (RTIL) added at 1–5 wt% to a diphenyl (dibutyl) carbamoylmethylphosphine oxide (Ph 2 Bu 2 ) solution increase the extraction coefficients of americium from nitric acid by more than two orders of magnitude. Moreover, the use of the RTIL—1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide makes the extraction possible even from 8 M HNO 3 . This is an important attribute of such extraction system from the point of its possible application for radiochemical analysis of technological samples and environmental solutions, since many methods are based on transferring the solid samples into an 8 M HNO 3 solution. The extraction data obtained revealed that three Ph 2 Bu 2 ligands are included into the coordination sphere of americium, two of which represent a compound with the nitrate anion and one with the RTIL anion.

... Pribylovad等^[29]将质量分数为1%5%的1-丁基-3-甲基咪唑双三氟甲基磺酰亚胺([C₄mim]⁺Tf₂N^-)添加到二苯二丁基甲酰甲基磷化氢的氧化物(Ph₂Bu₂),发现从硝酸中萃取Am的分配系数提高了2个数量级,实验结果表明,3个Ph₂Bu₂配体结合在Am的周围,2个与N O3-结合,1个与RTIL阴离子结合 ...

2012

2.894

0.0

Panja

, Mohapatra P

, Tripathi S

, et al. A Highly Efficient Solvent System Containing TODGA in Room Temperature Ionic Liquids for Actinide Extraction[J]. Sep Purif Technol, 2012, 96: 289-295.

... Panja等^[30]研究了Am³⁺、Pu⁴⁺、U O22+的萃取行为,确定在RTILs中是阳离子交换机制,在RTILs中烷基碳链的长度对TODGA的萃取性能方面具有重要作用,同时也影响分配系数,虽然在酸度条件下,反萃很难取得较高分配系数值,但是具有良好发展前景的是在碳酸胍下使用络合剂乙二胺四乙酸(EDTA)或二乙烯三胺五乙酸(DTPA)进行反萃,对如何提高反萃能力给予了方向性指导 ...

2013

0.0

... Patil等^[31]在硝酸介质中,将两种二酰胺溶解在RTILs(C_nmimNTf₂)(n=4,6,8)中,研究溶剂萃取锕系离子如Am³⁺、U⁶⁺、Np⁴⁺、Np⁶⁺和Pu⁴⁺,研究各种参数对萃取金属离子的影响,对比两种萃取剂的萃取能力和抗辐解退化能力,并得出二者的降解产物,1-丁基-3-甲基咪唑双三氟甲基磺酰亚胺([C₄mim][NTf₂])萃取Am³⁺整个过程不到30 min ...

2009

0.0

0.2913

... 刘浩等^[32]研究磷酸三丁酯/1-辛基-3-甲基咪唑六氟磷酸盐(TBP/[C₈mim][PF₆])和磷酸三丁酯/1-丁基-3-甲基咪唑六氟磷酸盐(TBP/[C₄mim][PF₆])在萃取U O22+中的相关性质 ...

2008

0.0

0.2913

... 李宏宇等^[33]介绍了近几年RTILs在放射性核素分离中的研究进展,并首次提出提高反萃取能力是降低成本、实现RTILs循环利用的关键 ...

2007

0.0

0.5042

CHU

Taiwei

, QIN

, LIU

Xinqi

, et al . Extraction of Uranium from Nitric Acid Medium by TBP in Room-Temperature Ionic Liquids[J]. J Nucl Radiochem, 2007, 29(3): 146-150(in Chinese).

褚泰伟, 秦丽, 刘新起, 等. 离子液体用于溶剂萃取铀酰离子的初步研究[J]. 核化学与放射化学, 2007, 29(3): 146-150.

The extraction of&nb

Beijing National Lab

初步研究了以咪唑类离子液体1-辛

... 褚泰伟等^[34]进一步研究了负载有机相为TBP-[C₈mim][PF₆]、TBP-[C₄mim][PF₆] 和季胺类离子液体三辛基甲基氯化铵(TBP-[N₈₈₈₁][Cl])时,发现季胺类离子液体萃取铀酰离子的分配比高于咪唑类,碳酸胍能从3种离子液体中定量反萃 U,从而解决了RTILs萃取铀酰离子的反萃和RTILs循环使用的问题 ...

2013

6.378

0.0

... Chen等^[35]首次合成了含羧基官能团的磷类离子液体1-羧基-N,N,N-三甲基磷双三氟甲基黄酰亚胺[HCTMP][Tf₂N],这是一种新型的TSIL,能使成核作用定向形成单体的或二聚的铀酰化合物,比其它的铵类似物有更宽的电化学窗口和更低的熔点,并显示出与U⁶⁺更强的结合力 ...

0.0

... Hatchett等^[36]首次把铀和超铀元素溶解在含臭氧组分的溶液中,从TSIL中回收和萃取乏燃料中的锕系元素,该实验首次提供了测量RTILs中不同氧化态铀的金属沉积物的热力学特性的方法 ...

2013

0.0

Huang X

, Zhang Q

, Liu J

, et al. Solvent Extraction of Pu(Ⅳ) with TODGA in C₆mimTf₂N[J]. J Radioanal Nucl Chem, 2013, 298(1): 41-46.

1. Department of Radiochemistry, China Institute of Atomic Energy, Beijing, 102413, People’s Republic of China

Studies on the solvent extraction of Plutonium(Pu(IV)) from aqueous nitric acid by N , N , N ′, N ′-tetraoctyl-diglycolamide (TODGA) in 1-hexyl-3-methylimidazolium-bis(trifluoromethylsulfonyl) imide (C 6 mimTf 2 N) room temperature ionic liquid (RTIL) were carried out. It was found that Pu(IV) is extracted into RTIL phase as [Pu(NO 3 )(TODGA)] 3+ through cation exchange mechanism. Extraction reaction equation is obtained by the influence of acidity and extractant concentration, and the parameters of thermodynamic equilibrium constant was calculated.

... 对Pu的分离也是乏燃料后处理的关键步骤,因其强放射性,在RTILs中对Pu的研究文献报道较少,Huang等^[37]研究发现,在RTILs中,稀释剂为1-己基-3甲基咪唑-双(三氟甲基磺酰)亚胺盐(C₆mimTf₂N),萃取剂为TODGA,从水相硝酸中萃取Pu⁴⁺,Pu⁴⁺的萃取百分数超过99%,在0 ...

2013

1.467

0.0

Shiri-Yekta

, Yaftian M

, Nilchi

Extraction-Separation of Eu(Ⅲ) and Th(Ⅳ) Ions from Nitrate Media into a Room-Temperature Ionic Liquid[J]. J Iranian Chem Soc, 2013, 10(2): 221-227.

Abstract Application of a room-temperature ionic liquid (RTIL), 1-butyl-3-methylimidazolium hexafluorophosphate ([C 4 mim + ][PF 6 − ]), in the extraction of Eu(III) and Th(IV) ions from nitrate media using tri- n -octylphosphine oxide (TOPO) as extractant is investigated. The results are compared with those obtained in dichloromethane. It is shown that the europium ions are extracted via a solvation mechanism by formation of [Eu(TOPO) 3 3+ ](NO 3 − ) 3 species in both [C 4 mim + ][PF 6 − ] and dichloromethane. Nevertheless, application of the studied RTIL makes a significant improvement in the extraction efficiency of europium ions. A different attitude was observed for the extraction of thorium ions. In fact, although the analysis of the extraction data of these ions from sodium nitrate solutions confirms the formation of [Th(TOPO) 3 4+ ](NO 3 − ) 4 species in dichloromethane, the extraction of these ions into the ionic liquid was not affected by the presence of TOPO. This latter outcome states the process takes place by a cation-exchange mechanism. It is found that the extraction of thorium ions diminishes in the presence of nitric acid. Interestingly, in contrast to the results observed in the extraction of thorium ions from sodium nitrate solutions, TOPO shows a co-operative effect on the extraction of these ions from nitric acid media. This allows considering the mechanism of the extraction of Th 4+ ions from nitric acid media as a mixed ion exchange-solvation mechanisms by formation of [Th(TOPO) 4+ ](NO 3 − )(PF 6 − ) 3 species.

1. Phase Equilibria Research Laboratory, Department of Chemistry, Faculty of Science, University of Zanjan, 4537138791, Zanjan, Iran 2. N. S. T. R. I., P.O. Box 11365-8486, Tehran, Iran

... 随着钍基熔盐堆的发展,作者认为应更加重视对Th相关性质的研究,Shiri-Yekta等^[38]研究了1-丁基-3-甲基咪唑六氟磷酸盐([C₄mim⁺][P F6-])为稀释剂的RTILs,在没有萃取剂时能从硝酸钠溶液中有效萃取Th⁴⁺,不萃取Eu³⁺,又以三正锌基氧化磷(TOPO)为萃取剂,从硝酸介质中萃取Th⁴⁺和Eu³⁺,Eu³⁺通过溶剂化机制形成[Eu(TOPO )33+](N O3-)₃,RTILs能显著提高萃取性能,Th⁴⁺是离子对的交换机制,TOPO不影响Th⁴⁺萃取效果,通过分析配体结构,首次报道锕系元素的协同萃取作用 ...

2013

2.894

0.0

, Chen Q

, Sun T

, et al. Extraction of Th(Ⅳ) from Aqueous Solution by Room-Temperature Ionic Liquids and Coupled with Supercritical Carbon Dioxide Stripping[J]. Sep Purif Technol, 2013, 119: 66-71.

... Fu等^[39]研究了从水相萃取Th⁴⁺和使用超临界CO₂从RTILs中反萃Th⁴⁺,在C_nmimNTf₂(n=2,4,6,8)中使用2-噻吩甲酰三氟丙酮(HTTA)从水相高效萃取Th⁴⁺,且Th⁴⁺形成的中性配合物的组成为HTT^-(Th(TTA)₄),在Th⁴⁺的萃取和反萃过程中,不仅提高了工作效率,而且RTILs的损失可以避免,只有萃取和反萃相结合,才能降低成本,实现离子液体的循环使用 ...

2012

0.0

... Iqbal^[40]综合和评估锕系和镧系元素从核废料中萃取时可能形成的配体化合物,对新形成的配体、配体的特性、亲水性配体的萃取效率、正辛基苯基-N,N'-二异丁基胺甲酰甲基氧化膦(CMPO)功能化离子液体对各种金属离子萃取能力等均做了详细的论证 ...

2013

0.0

... Mohapatra等^{[41,42,43,44]}在该领域做了很多研究,并获得很多创新型实验成果 ...

2013

0.0

... Mohapatra等^{[41,42,43,44]}在该领域做了很多研究,并获得很多创新型实验成果 ...

2013

4.593

0.0

Mohapatra P

, Sengupta

, Iqbal

, et al. Diglycolamide-Functionalized Calix[4]arenes Showing Unusual Complexation of Actinide Ions in Room Temperature Ionic Liquids: Role of Ligand Structure, Radiolytic Stability, Emission Spectroscopy, and Thermodynamic Studies[J]. Inorg Chem, 2013, 52(5): 2533-2541 .

† Radiochemistry Division, Bhabha Atomic Research Centre , Trombay, Mumbai-400085, India ‡ Laboratory of Molecular Nanofabrication, MESA+ Institute for Nanotechnology, University of Twente , P.O. Box 217, 7500 AE Enschede, The Netherlands *Fax: +91-22-25505151 . E-mail: mpatra@barc.gov.in .

Diglycolamide-functionalized calix[4]arenes (C4DGAs) with varying structural modifications were evaluated for actinide complexation from their extraction behavior toward actinide ions such as UO 2 2+ , Pu 4+ , PuO 2 2+ , and Am 3+ in the room temperature ionic liquid (RTIL) 1- n -octyl-3-methylimidazolium bis(trifluoromethane)sulfonamide (C 8 mimNTf 2 ). The formation constants were calculated for Am 3+ which showed a significant role of ligand structure, nature of substituents, and spacer length. Although the alkyl substituents on the amidic nitrogen increase the extraction efficiency of americium at lower acidity because of the inductive effect of the alkyl groups, at higher acidity the steric crowding around the ligating site determines the extraction efficiency. All C4DGAs formed 1:1 complexes with Am 3+ while for the analogous Eu 3+ complexes no inner sphere water molecules were detected and the asymmetry of the metal ligand complex differed from one another as proved by time-resolved laser induced fluorescence spectroscopy (TRLIFS). Thermodynamic studies indicated that the extraction process, predominant by the Am 3+ -C4DGA complexation reaction, is exothermic. The unique role of the medium on Am 3+ complexation with the C4DGA molecules with varying spacer length, L-IV and L-V , was noticed for the first time with a reversal in the trend observed in the RTIL compared to that seen in a nonpolar molecular diluent like n -dodecane. Various factors leading to a more preorganized structure were responsible for favorable metal ion complexation. The solvent systems show promise to be employed for nuclear waste remediation, and sustainability options were evaluated from radiolytic stability as well as stripping studies.

... Mohapatra等^{[41,42,43,44]}在该领域做了很多研究,并获得很多创新型实验成果 ...

2013

3.499

0.0

Mohapatra P

, Sengupta

, Iqbal

, et al. Highly Efficient Diglycolamide-Based Task-Specific Ionic Liquids: Synthesis, Unusual Extraction Behaviour, Irradiation, and Fluorescence Studies[J]. Chem Eur J, 2013, 19(9): 3230-3238.

1 Radiochemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai-400085 (India), Fax: (+91) 22-25505151 2 Laboratory of Molecular Nanofabrication, MESA+Institute for Nanotechnology, University of Twente, PO Box 217, 7500 AE Enschede (The Netherlands) * Radiochemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai-400085 (India), Fax: (+91) 22-25505151

> Two new diglycolamide-based task-specific ionic liquids (DGA TSILs) were evaluated for the extraction of actinides and lanthanides from acidic feed solutions. These DGA TSILs were capable of exceptionally high extraction of trivalent actinide ions, such as Am 3+ , and even higher extraction of the lanthanide ion, Eu 3+ (about 5–10 fold). Dilution of the DGA TSILs in an ionic liquid, C 4 mim + ⋅ NTf 2 − , afforded reasonably high extraction ability, faster mass transfer, and more efficient stripping of the metal ion. The nature of the extracted species was studied by slope analysis, which showed that the extracted species contained one NO 3 − anion, along with the participation of two DGA TSIL molecules. Time-resolved laser fluorescence spectroscopy (TRLFS) analysis showed a strong complexation with no inner-sphere water molecule in the Eu III DGA TSIL complexes in the presence and absence of C 4 mim + ⋅ NTf 2 − as the diluent. The very high radiolytic stability of DGA TSIL 6 makes it one of the most-efficient solvent systems for the extraction of actinides under acidic feed conditions.

... Mohapatra等^{[41,42,43,44]}在该领域做了很多研究,并获得很多创新型实验成果 ...