羟胺及其衍生物与Pu(Ⅳ)的氧化还原反应定量构效关系

通过Chem3DUltra软件构建羟胺及其衍生物的三维结构,在预优化的基础上,运用gaussian03程序包,采用密度泛函B3LYP方法和6-311+G(3d,3p)基组对6种羟胺及其衍生物进行了几何优化和能量计算,获得了其稳定构型。并利用HyperChem软件包计算优化后的分子的疏水性参数等物理化学参数。运用数学统计软件SPSS对相应的物理化学参数进行相关性分析及逐步回归分析,最终得到具有良好相关性的QSAR方程。方程表明:分子总能量是影响羟胺及其衍生物对Pu(Ⅳ)还原速率的主要因素,且与Pu(Ⅳ)还原速率呈负相关。     

肼及其衍生物与HNO_(2)反应的定量构效关系北大核心CSCD

对肼及其衍生物与HNO_(2)的半反应时间进行了测量,利用Gaussian09中的密度泛函B3LYP方法、6-311+(3d,3p)基组以及HyperChem软件包,选择了肼及其衍生物的部分分子描述符进行了定量计算。将计算得到的量化参数与实验测得的半反应时间结合,利用统计回归的方法建立了肼及其衍生物与HNO_(2)反应的定量构效关系模型。模型显示,分子总能量E是该反应最主要的影响因素,除烯丙基肼外,半反应时间随分子总能量E的增加而增加,也即反应速率随分子总能量E的增加而减小。     

逐步回归法与PLS-Bootstrap法在肼衍生物与Pu(Ⅳ)反应定量构效关系中的应用

钚是一种重要的核材料,在洗锝槽还原试剂的开发过程中,还原试剂与Pu(Ⅳ)的化学反应是关键的影响因素之一,通常要求其与钚几乎不发生反应。为了建立良好的Pu(Ⅳ)与肼衍生物反应的定量构效关系,找到该反应的特征参数,为后续工作提供支撑,采用PLS-Bootstrap法与逐步回归法分别对该反应进行定量构效关系研究,并使用交叉检验和外部检验来对模型进行验证。在疏水性参数作为该反应特征参数的基础上,得到了最高占据轨道能是该反应的又一个特征参数的结果,且疏水性参数与最高占据轨道能的值越大,该反应进行得越慢。     

羟胺乙酸与Pu（Ⅳ）的还原动力学

为了解羟胺乙酸(HAAA)对Pu(Ⅳ)的还原性能,用分光光度法研究了羟胺乙酸与Pu(Ⅳ)的还原动力学,其动力学方程式为:-dc(Pu(Ⅳ))/dt＝kc(Pu(Ⅳ))c1.50(HAAA)c-1.00(H+)c-0.63(NO-3).在15.8 ℃时,k＝(42.1±4.2) (mol/L)-0.13·s-1,活化能为(78.0±1.6) kJ/mol.研究了HAAA浓度、H+浓度、离子强度、Fe3+浓度、UO2+2浓度对HAAA与Pu(Ⅳ)还原反应速率的影响.结果表明:增加HAAA浓度、Fe3+浓度,降低H+浓度、离子强度,Pu(Ⅳ)还原速度增加;UO2+2浓度对Pu(Ⅳ)还原速度基本无影响.HAAA在U-Pu分离中具有良好的应用前景.     

肼衍生物与Pu(Ⅳ)的氧化还原反应定量构效关系研究

钚是最重要的放射性核素之一,Pu(IV)与有机还原的的氧化还原反应一直是核燃料后处理研究的重点之一。通过肼衍生物结构与Pu(IV)还原速率之间构效关系的研究,获得其关键影响因素,为镎钚分离提供关键数据及研究方向指引。采用密度泛函B3LYP方法和6-311+(3d,3p)基组对11种肼衍生物进行了几何优化和能量计算,获得了其最稳定构型。并利用Hyper Chem软件包计算优化后的分子的疏水性参数等结构描述符。运用数学统计软件SPSS对相应的物理化学参数进行相关性分析及逐步回归分析,最终得到具有良好相关性的构效关系(Quantitative structure-activity relationships,QSAR)方程。方程表明,疏水性参数是影响肼衍生物对Pu(IV)还原速率的主要因素,且与Pu(IV)还原速率呈负相关。     

甲醛肟与Pu(Ⅳ)的还原动力学

研究了甲醛肟(FO)与Pu(Ⅳ)的还原反应动力学,其动力学方程式为-dc(Pu(Ⅳ))/dt=kc(Pu(Ⅳ))c1.61(FO)c-0.88(H+),在18.7℃时,反应速率常数k=(110.39±7.70)(mol/L)-0.73/s,活化能为(68.82±3.00)kJ/mol。研究了甲醛肟浓度、H+浓度、硝酸根浓度、Fe3+浓度、UO22+浓度以及温度对甲醛肟与Pu(Ⅳ)还原反应速率的影响。结果表明:增加甲醛肟浓度、降低UO22+和H+浓度、增加Fe3+浓度以及升高温度,均使Pu(Ⅳ)还原速度增加;硝酸根浓度对甲醛肟还原Pu(Ⅳ)的速率基本无影响。     

氨基羟基脲与Pu(Ⅳ)的还原动力学研究

研究了氨基羟基脲(HSC)与Pu(Ⅳ)的还原反应动力学,其动力学方程式为：-d_c（Pu(Ⅳ)）/d_t=kc（Pu(Ⅳ））c^1.06（HSC）c^-0.43（H⁺）c^-0.58（NO₃^-）,在22.1℃时反应速率常数k＝(11.8±1.1)（mol/L）^-0.046•s^-1,活化能为(71.0±1.0)kJ/mol。研究了氨基羟基脲浓度、H⁺浓度、硝酸根浓度、Fe³⁺浓度、UO₂²⁺浓度对氨基羟基脲与Pu(Ⅳ)还原反应速率的影响,增加氨基羟基脲浓度,降低H⁺浓度、硝酸根浓度,Pu(Ⅳ)还原速度增加;UO₂²⁺浓度和Fe³⁺浓度对Pu(Ⅳ)还原速度基本无影响。     

偏二甲基肼还原Np（Ⅵ）的动力学研究

报道了用分光光度法研究硝酸体系中偏二甲基肼还原Ｎｐ（Ⅵ）的动力学。研究了偏二甲基肼浓度、酸度、温度、离子强度、ＵＯ２２＋浓度等因素对反应速率的影响，求出了反应的动力学方程。实验结果表明：偏二甲基肼还原Ｎｐ（Ⅵ）—→Ｎｐ（Ⅴ）的速度较快，但不能进一步还原Ｎｐ（Ⅴ）—→Ｎｐ（Ⅳ），提高偏二甲基肼浓度、降低酸度、升高温度均有利于加快反应速率。离子强度和ＵＯ２２＋浓度对反应速率的影响很小     

Aβ显像剂2-苯基苯并噻唑衍生物的定量构效关系

11C或123I标记的含有给电子基团的2-苯基苯并噻唑衍生物一般具有较高的Aβ斑块亲和性,是一类潜在的Aβ显像剂。本工作以Aβ亲和性参数lgKi为因变量,一些通过G98W结构优化得到的分子结构参数为自变量,对28个2-苯基苯并噻唑衍生物进行了定量构效关系研究,结果表明,Aβ亲和性与化合物的lgP、Vm、lgVm、He和EHOMO呈线性相关,其中脂溶性参数lgP是影响Aβ亲和性的主要因素。     

U(Ⅳ)用作Purex过程中Pu(Ⅳ)还原剂的研究

研究了U(Ⅳ)在分离的有机相(30％TBP-煤油)中、在两相振荡混合和逆流萃取过程中的稳定性。通过单级反萃实验研究了有机相中钚浓度、铀浓度,反萃剂的酸度和肼浓度,U(Ⅳ)用量(M_(u(Ⅳ))/M_(Pu)对钚反萃率的影响。通过串级实验研究了在1B槽工艺条件下,M_(u(Ⅳ))/M_(Pu)和U(Ⅳ)加入位置,反萃剂酸度和相比等条件的变化对铀钚分离的影响。给出了铀和钚的净化系数。     

Application of N,N-di(2-ethylhexyl)butanamide for mutual separation of U(VI) and Pu(IV) by continuous counter-current extraction with mixer-settler extractors

Continuous counter-current extraction using N,N-di(2-ethylhexyl)butanamide (DEHBA) as an extractant was performed with mixer-settler type extractors consisting of U–Pu extraction, scrub, U recovery, Pu back-extraction, and U back-extraction steps. The feed solution used in the continuous counter-current extraction was 3 mol/dm³ (M) nitric acid containing U, Pu, and simulated fission products of Sr, Ba, Zr, Mo, Ru, Rh, Pd, and Nd. More than 99.9% of U and Pu in the feed was extracted by 1.9 M DEHBA at the U–Pu extraction step with negligible extraction of Sr, Ba, Mo, Ru, Rh, and Nd. The extracted Pu was back-extracted via contact with 0.3 M nitric acid in the Pu back-extraction step, and the ratio of Pu distributed to the Pu fraction stream was ～ 82%. It was confirmed that 1.9 M DEHBA effectively recovered U in the U recovery step, and the ratio of U in the Pu fraction stream was less than 1%. The extracted U was back-extracted in the U back-extraction step, and more than 98% of U was recovered in the U fraction stream.     

Precipitation ability to U(IV) and stability of 1,3-dimethyl-2-imidazolidone for selective precipitation of U(VI) in nitric acid media

As a part of the investigation of precipitants with selectivity to U(VI) in nitric acid media, a preliminary study on the precipitation ability of 1,3-dimethyl-2-imidazolidone (DMI) to U(IV), a simulant of Pu(IV), was performed. DMI is a ring compound like N-n-butyl-2-pyrrolidone (NBP) which is one of the pyrrolidone derivatives (NRPs) and a promising precipitant for U(VI). While DMI is known to precipitate U(VI) from 3 mol dm⁻³ (=M) HNO₃, no precipitate was observed in the solution containing 0.15 M U(IV) and 3 M HNO₃ by adding DMI at the ratio of [DMI]/[U(IV)] = 5. This indicates that the selectivity of DMI to U(VI) than U(IV) is much higher compared with that of NBP.On the other hand, the stability of DMI under γ-ray irradiation and heating in HNO₃ solutions (≤4 M) was also examined to evaluate the applicability of DMI to the practical process, because gradual acid hydrolysis of DMI is inevitable due to the nature of the chemical structure. As a result, it was found that the stability is strongly affected by the concentration of HNO₃. Namely, very few DMI in 2 M HNO₃ underwent the ring-opening by the irradiation up to 220 kGy and heating at 50 °C up to 5 h, respectively, indicating that these treated samples may still hold the precipitation ability to U(VI). On the contrary, the cleavage of the ring of DMI in 4 M HNO₃ was found to proceed easily. From the above results, it was concluded that DMI may be a candidate as a selective precipitant for U(VI) in HNO₃ solutions up to ca. 2 M.     

DFT study on the bonding properties of Pu(III) and Pu(IV) chloro complexes

Understanding of chemical bonding is a fundamentally important topic. Given the importance of bonding studies, we performed quantum calculations on plutonium chloro complexes (PuClx(III) and PuClx(IV)) that are believed to form as molten chloride salts during nuclear waste treatment. The result of these calculations was verified by comparing them to experimental data on a similar actinide chloro complex. Charge and bond order analyses of the complexes provide insight into the electronic properties, bonding, and nuclear magnetic resonance characteristics of the plutonium chloro complexes. The chemical shift of the Pu(III) complexes are found to be negative while those of Pu(IV) are positive.     

Solvent extraction of nitric acid,uranium（VI） and thorium（IV） by N,N,N‘,N’—tetrahexylsuccinylamide

A new kind of diamide N,N,N‘,N‘-tetrahexylsuccinylamide(THSA) was synthesized,characterized and used for the extraction of HNO3,U(VI)and Th(IV) in a diluent composed of 0.5 volume fraction 1,2,4-trimethy benzene(TMB) and 0.5 volume fraction kerosene(OK),Extraction distribution coefficients of U(VI) and Th(IV) as functions of aqueous nitric acid concentation,extractant concentration.temperature and salting-out agent (LiNO3) have been studied,and it is found that THSA as an extractant is superior to TBP for extraction of U(VI) and Th(IV),Back Extraction was also studied.At low acidity,the main adduct of THSA and NHO3 is HNO3 is HNO3.THSA,THSA.(HNO3)2 and THSA.(HNO3)3 are also found at high acidity.The compositions of extracted species.apparent equilibrium constants and enthalpies of extraction reactions have also been calculated.     

N，N-乙基，羟乙基羟胺在PUREX流程铀钚分离中的应用

为了解N，N-乙基，羟乙基羟胺（EHEH）在PUREX流程铀钚分离中的作用，研究了EHEH对Pu(Ⅳ)的单级反萃取行为及其影响因素。结果表明，EHEH能够迅速地将有机相中的Pu(Ⅳ)还原反萃入水相，相比（o/a）为1∶1，接触时间5s时，钚的反萃取率接近99%；相比（o/a）为4∶1时，5s内钚的反萃取率可达到80%，相比增大，Pu的反萃取率降低。低酸、升温和提高EHEH浓度有利于钚的还原反萃取。采用14级逆流串级反萃取实验（还原反萃段8级，补充萃取段6级），模拟PUREX流程1B槽U/Pu分离工艺，在相比(1BX∶1BF∶1BS)为1∶4∶1的条件下，铀的收率大于99.999%，Pu的收率大于99.99%;铀中去钚的分离因数α(Pu/U)=1.1×104；钚中去铀的分离因数α(U/Pu)=3.2×105。EHEH作为还原反萃取剂，可以有效实现铀钚分离。     

A study on selective precipitation ability of cyclic urea to U(VI) for developing reprocessing system based on precipitation method

We have proposed a new reprocessing system based on precipitation method. In order to find out precipitants with high selectivity to U(VI) and to investigate factors controlling precipitation ability to U(VI) and U(IV), properties of 3,4,5,6-tetrahydro-1,3-dimethyl-2(1H)-pyrimidinone (DMPU) as a precipitant have been examined by using U(VI), U(IV) as a simulant of Pu(IV), and simulated fission products (FPs). We have evaluated precipitation ratios (P.R.) for U(VI) and U(IV), solubility of U(VI) precipitates to 3.0 mol dm^?3 (M) HNO₃ solution, melting points (MPs) of U(VI) precipitates, log P (distribution ratio of a substance in 1-octanol/water biphasic system, a measure of hydrophobicity) of precipitants, and decontamination factors (DFs) of FPs. The properties of DMPU were compared with those in systems using N-n-butyl-2-pyrrolidone (NBP), N-cyclohexyl-2-pyrrolidone (NCP), and other pyrrolidone derivatives as the precipitant. The P.R. values of DMPU to U(VI) and U(IV) in 3.0 M HNO₃ solutions were around 99% at [DMPU]/[U(VI)] = 2.0 and 0% at [DMPU]/[U(IV)] = 5.0, respectively. In DMPU system, the DF values of the most of simulated FPs [Rb(I), Cs(I), Sr(II), Ba(II), Ru(III), Rh(III), La(III), Ce(III), Pr(III), Nd(III), and Sm(III)] used in the present study were found to be more than 100. Even in U(VI)–U(IV) coexisting system, the selectivity of DMPU to U(VI) was higher than those of NBP and NCP. This selective precipitation ability of DMPU to U(VI) was evaluated by the solubility of U(VI) precipitates on the basis of their MPs and the log P values of precipitants. As a result, it was found that the precipitants having low hydrophobicity and forming the U(VI) precipitates with high MPs have highly selective precipitation ability to U(VI).     

Extraction of Th(IV) from nitric acid with 4-benzoyl-2,4-dihydro-5-methyl-2-phenyl-3H-pyrazol-3-thione

1IntroductionTheextractionofActinide(ill)andLanthanide(ill)fromaqueoussolutionwithBMPPTandTOPOinbenzenehasbeenstudiedbysomeautho...[1-5]Tosomeextent,BMPPTisaveryusefulextractionagentforseparationofAm(lll)andEu(lll).TheextractionofTh4+fromaqueoussolutionhasnotbeenstudiedever,soweherereporttheextractionbehaviorofTh4+innitricacidmediawithBMPPTinbenzene.2Experimental2.1SynthesisofBMPPTCompoundBMPPTwassynthesizedfromBMPP(4-benzoyL2,4-dihydro-5-methyl--2phenyl-3H~pyrazoL3-one).25gB…     

N,N,N,,N,-四己基丁二酰胺萃取铀、钍及硝酸的机理

合成了 N,N,N?N?四己基丁二酰胺(THSA)。以正十二烷为稀释剂研究了THSA萃取硝酸的平衡,认为在低酸度下主要形成THSA·HNO3加合物,在高酸度下主要形成加合物THSA·HNO3和THSA·(HNO3)2;还研究了THSA从硝酸介质中萃取铀、钍的机理,通过考察 HNO3浓度、THSA浓度及温度对铀和钍分配比的影响,得出了萃合物的组成为UO2(NO3)2·THSA和Th(NO3)4·2THSA,并计算出萃取反应的表观平衡常数及热焓。实验结果表明THSA具有较强的对铀、钍萃取能力,并有望实现铀、钍分离。