U(Ⅵ)在N_(1113)NTf_2离子液体中的电化学行为

研究了U(Ⅵ)在疏水性离子液体双三氟甲基磺酰亚胺化三甲基丙基季铵盐(N1113NTf2)中的电化学氧化还原过程。利用循环伏安法,确定了U(Ⅵ)在离子液体中的如下还原过程:大量U(Ⅵ)直接在电极表面还原为U(Ⅳ),电极反应受电荷迁移和物质扩散共同控制。随后,U(Ⅳ)在离子液体中继续被还原生成U(Ⅲ)。在低浓度下电极反应U(Ⅵ)→U(Ⅲ)的过程是准可逆过程,但随着U(Ⅵ)浓度增大,此反应转变为不可逆过程。利用恒电位沉积方法,实验得到了具有不同形貌的沉积产物,X射线衍射(XRD)分析表明此沉积产物为UO2。     

铀(Ⅵ)与某些β-二酮配合物的制备及红外光谱研究

制备了分子式为UO_2A_2·HA的四种铀酰β-二酮配合物,式中HA代表乙酰丙酮、苯甲酰丙酮、二苯甲酰甲烷及2-噻吩甲酰三氟丙酮等四种β-二酮配体,A为相应的β-二酮阴离子。 研究了这些配合物在4000-150cm~(-1)范围的红外光谱,对一些特征吸收带作了指认,并讨论了它们与配合物结构之间的相互关系。     

铀在离子液体中的物种及电化学行为研究进展

总结了近年来离子液体用于铀的水法及干法后处理相关的基础研究成果,主要内容包括铀在离子液体中的存在物种及电化学行为研究,归纳和分析了其中关键的科学问题。同时,基于当前的研究现状展望了离子液体在铀的净化分离方面的应用研究前景。     

铀(Ⅵ)在氯化1-丁基-3-甲基咪唑中的电化学性质

通过循环伏安和计时电位等电化学测量方法研究了硝酸铀酰在亲水性离子液体--氯化1-丁基-3-甲基咪唑([BMIM]C1)中的电化学过程.结果表明,UO2+2在离子液体[BMIM]Cl中转移2个电子,一步还原为UO2.当扫描速率为10～100 mV/s、体系温度为353 K、UO2+2浓度为13.27 mmol/L时,电极...     

铀的离子交换反应——Ⅱ.硫酸和盐酸介质中铀(Ⅵ)在阳离子交换树脂上的化学状态

本文用红外光谱法和当量计算法研究了在硫酸、盐酸介质中铀(Ⅵ)在阳离子交换树脂上的化学状态及其含量。结果表明,在阳离子交换树脂上,铀(Ⅵ)除了以UO_2~(2 )外,还可以(UO_2HSO_4)~ 和(UO_2Cl)~ 存在,但当酸的浓度低于 0.5N时,其量可忽略不计。即使在酸浓度相当大(2—3N)时,(UO_2HSO_4)~ 和(UO_2Cl)~ 也只占树脂交换容量的很小一部分。因此,在通常用的阳离子交换色层法富集铀同位素的工作中,可以按照阳离子交换树脂上只有 UO_2~(2 )来考虑同位素效应及计算分离因数。     

铀(Ⅵ)、钍(Ⅳ)与N,N′-二(邻羟基苯亚甲基)对苯二胺配合物的合成与表征

合成了Ｕ（Ⅵ）和Ｔｈ（Ⅳ）与双希夫碱Ｎ，Ｎ′－二（邻羟基苯亚甲基）对苯二胺（以Ｌ表示）的两种新固体配合物。采用元素分析、红外光谱、紫外光谱、差热－热重及摩尔电导分析等方法，确定配合物的组成分别为［ＵＯ２Ｌ（ＮＯ３）］ＮＯ３、［ＴｈＬ（ＮＯ３）２］（ＮＯ３）２，并对它们的配位方式和某些性质进行了研究。     

用三辛基氧膦和联苯与萘的熔融混合物通过溶剂萃取分光光度法测定铀(Ⅵ)

在三辛基氧(?)进入到联苯和萘的熔融混合物中萃取之后,用分光光度法测定矿石中的铀,把盐析剂如硝酸钠加入到水相中并冷却,在水相表面可得到固体块的有机相,简单地把有机相收集起来,然后用1-(2-吡啶偶氮)-2-萘酚或2-(5-溴-2-吡啶偶氮)-5-二乙基氨基苯酚可在有机相中直接测定铀.     

钍(Ⅳ)和铀酰离子与水杨醛缩邻氨基苯甲酸配合物的合成与表征

合成了硝酸钍、硝酸铀酰分别与水杨醛缩邻氨基苯甲酸（以Ｈ２Ｌ表示）配合的２种固体配合物,通过元素分析、差热－热重、红外光谱、紫外光谱、摩尔电导分析等手段,确定配合物的组成分别为［Ｔｈ（ＨＬ）（ＮＯ３）２］ＮＯ３、［ＵＯ２（ＬＨ）ＮＯ３］。并对它们的某些性质进行了研究     

呋喃甲酰基吡唑啉酮双席夫碱与铀(Ⅵ)、钍(Ⅳ)配合物的合成、表征及生物活性

合成了U(Ⅵ)和Th(Ⅳ)与双席夫碱N,N′-双[(1-苯基-3-甲基-5-氧-4-吡唑啉基)α-呋喃次甲基]乙二亚胺(HPMαFP)2en形成的新配合物.通过元素分析、红外光谱、紫外光谱、核磁共振谱、摩尔电导率等方法测试,确定其组成为:[UO2(PMαFP)2en]、[Th(PMαFP)2en(NO3)]NO3.并对新配合物的结构与性质进行了表征.抗菌实验表明,配合物具有一定的生物活性.     

用三烷基(C_6-C_8)氧膦(TRPO)萃取-液体闪烁计数法测定水溶液中微量α核素的研究

用三烷基氧膦(TRPO)作萃取剂,二甲苯为溶剂,2.5-二苯基噁唑为闪烁体研究了TRPO及杂质元素的猝灭效应,结果表明萃取-液体闪烁计数法用于测量大量杂质元素及氨羧络合剂中的~(233)U,~(239)Pu,~(241)Am微量α核素具有简便、迅速,灵敏高度等优点。     

镧系及锕系元素在离子液体中的电化学行为

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。     

Structural and Electrochemical Studies on Uranium(VI) Nitrato Complex with n-Octyl(phenyl)-N,N-Diisobutylcarbamoylmethylphosphine Oxide in Non-aqueous Solvents

The structure of uranyl nitrato complex with CMPO [n-Octyl(phenyl)-N,N-diisobutylcarbamoylmethylphosphine oxide] in solid state and in non-aqueous solvents without containing free CR/IPO has been studied by using IR spectrophotometer, ¹³C- and ³¹P-NMR. The carbonyl(vcO) and phosphoryl(vpO) stretching bands of coordinated CMPO were observed at lower wavenumber than the corresponding bands of free CMPO in both the states. The ¹³C and ³¹P peaks assigned to the carbonyl carbon and phosphoryl phosphine of coordinated CMPO was detected in the lower field than that of free CMPO. From these results, it was concluded that the uranyl nitrato complex with CMPO in both the states has the structure with two nitrate and one CMPO coordinated as bidentate in the equatorial plane of uranyl ion, i.e., UO₂(NO₃)₂·CMPO. Furthermore, the electrochemical studies of UO₂(NO₃)₂·CMPO complex in CH₃CN have been carried out using cyclic and normal pulse voltammetric methods. It was found that the UO₂(NO₃)₂·CMPO complex is reduced to U(V) complex at around ?1.22V vs. Fc/Fc⁺ (ferrocene/ferrocenium) and that the resulting reductant is oxidized to U(VI) at around +0.04V vs. Fc/Fc⁺.     

聚丙烯酰胺-咪唑类聚离子液体凝胶的辐射合成及其对铀和碘的吸附

采用γ射线辐射引发技术制备了一类聚丙烯酰胺-咪唑类聚离子液体凝胶(PAm-C_nvim_2Br_2)。当吸收剂量为5kGy时,得到了凝胶分数超过95%的聚离子液体凝胶,其溶胀度可由吸收剂量控制。合成的PAmC_nvim_2Br_2可以从碳酸盐溶液中吸附铀最大吸附量约130mg/g,或从碘化钠溶液中吸附碘离子最大吸附量约160mg/g,吸附过程符合Langmuir模型。红外与XPS分析表明,吸附过程遵循离子交换的反应机理。PAmC_nvim_2Br_2凝胶对铀及碘有很好的吸附、解吸性能,有望用于含有铀和碘的放射性废水处理。     

HBMPPT/TOPO/甲苯体系从硝酸介质中分离三价镅和镧系元素的研究

HBMPPT（4－苯甲酰基－2，4二氢－5－甲基－2－苯基－3H－吡唑硫酮－3）或TOPO（三正辛基氧化膦）的甲苯溶液，在HNO3介质中对三价镅 和镧系元素在所研究的pH范围内无明显的萃取能力，但当两者混合时，其协同效应可使该体系从镧系锕系混合溶液中有选择地萃取三价镅（pH3.5-4.5)，两者的分离系数达10－156，实验结果还显示，代表三价锕系元素的镅和各镧系元素与该体系的化学反应机理也有所不同。     

Internal-Shear Mode Instabilities on High-Speed Liquid Jet, (I) Characteristics of Linear Solutions

The instabilities on a high-speed liquid jet, induced by amplification of perturbations in the initially-laminar shear layer underneath the free surface (internal-shear mode instabilities), are investigated theoretically and experimentally. Part I of the present paper describes the characteristics of temporally and spatially unstable modes predicted by a linear perturbation equation where the shear layer velocity profile is represented by a single straight line. The analysis focuses on simulated liquid-metal beam target flow conditions characterized by high Froude numbers Fr _Δ and moderate Weber numbers We _Δ, both based on the velocity difference and the thickness of the shear layer. Temporally and spatially unstable modes are predicted for We _Δ >1.8, for a certain range of wave number. For these spatiotemporal modes, the temporal growth rate tends to decrease with an increase in the spatial growth rate. The instabilities predicted by the present theory are all convective, and not absolute, for We _Δ ranging up to 20.     

Nuclear Magnetic Resonance Study of Ligand Exchange Reaction in Lanthanum Nitrate Complex with n-Octyl(phenyl)-N,N-Diisohutylcarbamoylmethylphophine Oxide

The Molten Salt Reactor (MSR) concept has recently been considered as one of the candidates for the generation IV nuclear power systems. MSRs have many advantages such as improved safety, proliferation resistance, resource sustainability and waste reduction. But MSR developmental activities have lagged and there are few data available to support detailed analyses. However, the authors believe that additional investigations are merited for future study. From this point of view, the authors have analyzed the depressurization accident of the MSR “Fuji-12” using a newly developed MSR transient analysis code. In Fuji-12, a small amount of helium gas bubbles are circulated in the primary loop for stripping out gaseous fission products. A depressurization of the primary system would cause these bubbles to expand, resulting in a positive reactivity insertion. We have attempted to determine the severity of such an accident. Although the analysis is still preliminary and the assumptions are crude, it can be expected that the depressurization would not result in a severe accident in Fuji-12.     

Electrochemical Properties of Uranyl Ion in Ionic Liquids as Media for Pyrochemical Reprocessing

We have proposed a new reprocessing process by using ionic liquids (ILs) instead of molten salts of alkali chlorides in pyrochemical process. In the proposed process, spent nuclear fuels are dissolved in ILs by using Cl₂ as an oxidant, and UO₂ ²⁺ and PuO₂ ²⁺ ions in ILs are recovered as UO₂ and PuO₂ by electrochemical reduction. In order to examine applicability of ILs as media for reprocessing, we have studied electrochemical behavior of UO₂ ²⁺ in 1-butyl-3-methylimidazolium chloride (BMICl), 1-butyl-3-methylimidazolium tetrafluoroborate (BMIBF₄), and 1-butyl-3-methylimidazolium nonafluorobutanesulfonate (BMINfO). Electrochemical properties of uranyl chloride dissolved into ILs were examined by cyclic voltammetry. In BMICl, an almost reversible redox couple was observed, and the formal potential and the diffusion coefficient were evaluated as _0:758V vs. Ag/AgCl and 4:8 × 10^?8 cm²s^?1, respectively. On the other hand, the electrochemical reactions of UO₂ ²⁺ in BMIBF₄ and BMINfO were irreversible. In BMINfO, some reduction peaks and one sharp oxidation peak were observed in the range of ?0:6～–0:2V and around 0.85V vs. Ag/AgCl, respectively. The reduction and oxidation peaks were assigned to multi step reduction of UO₂ ²⁺ to U(IV) via U(V) and/or direct reduction of UO₂ ²⁺ to U(IV), and the oxidative dissolution of the resulting U(IV) compounds, respectively. The electrochemical reduction of UO₂ ²⁺ in BMINfO at ?1:0V vs. Ag/AgCl produced the deposits on a carbon electrode as a cathode. Analyses of the deposits with the scanning electron microscope and the energy dispersive X-ray spectrometer indicated that the deposits are compounds containing uranium, oxygen, and chlorine. As a result, it is expected that the UO₂ ²⁺ in IL can be recovered electrolytically as uranium compounds such as UO₂ and uranium oxychlorides.     

离子液体体系的萃取行为及其在乏燃料后处理中的应用前景

离子液体由于其特有的性质,在乏燃料后处理中的应用已受到广泛关注。本文综述了不同种类离子液体中多种萃取剂对乏燃料所含若干锕系元素及放射性裂片元素的萃取,重点分析了不同萃取体系的萃取效率、萃取选择性、萃取机理和反萃等关键问题。综合目前的研究成果,可发现:离子液体-萃取剂体系由于其独特的萃取机理,通常比传统萃取体系具有更高的萃取效率;一些萃取体系具有高选择性使其在乏燃料后处理中有很好的应用前景。在简要介绍阳离子交换机理、阴离子交换机理和中性复合物机理三种离子液体体系萃取机理的同时,重点总结了萃取中三相问题和协同萃取效应。本文还总结了液-液反萃、超临界CO2反萃和电化学反萃三种常见的反萃方法,讨论了各自的优缺点。本文最后对离子液体在乏燃料中的应用进行了总结与前景展望。