共查询到20条相似文献,搜索用时 46 毫秒
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《Journal of Nuclear Science and Technology》2013,50(9):724-729
The kinetics of the reaction between Np (V) and hydroxylammonium chloride in perchloric acid solution was studied at 70°c. In perchloric acid solutions from 1.0 to 1.5 mol·dm?3, the reaction rate is described by ?d[Np(V)]/dt = k{Np(V)][NH3OHCl]1.0[H+]2.1 where the rate constant k = (6.7 ± 0.3) × 10?2 mol?3.7dm11.1min?1. Detailed studies of the dependence of the rate on the concentrations of hydroxylammonium ion and chloride ion showed that the reaction is much accelerated by chloride ion. 相似文献
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Np(Ⅳ)的溶解行为研究 总被引:3,自引:2,他引:1
在低氧条件下以Na2S2O4或铁粉作还原剂,测定了Np(Ⅳ)在模拟地下水和重蒸水中的溶解度,讨论了溶液pH值和放置时间对Np(Ⅳ)的形态及在两种水样中溶解度的影响。实验结果表明:放置时间对溶解度的影响不大;随着溶液pH值(6-12)的变化,Np(Ⅳ)在模拟地下水和重蒸水中的溶解度不变,Np(Ⅳ)主要以Np(OH)4,Np(OH)5^-两种形态存在。 相似文献
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《Journal of Nuclear Science and Technology》2013,50(10):1024-1029
Abstract A spectroscopic study of Np(VI) was performed in carbonate solutions. The characteristic absorption bands were observed at 625, 670 and 703 nm and examined for the dependence on pH and carbonate concentration. The absorbances showed no dependence on pH but proportionally increased with the increasing carbonate concentration. From the observations, the result was analyzed by considering the reaction of NpO2(OH)2(s)+CO3 2-=NpO2 (OH)2CO3 2-. By measuring the solubility, the equilibrium reaction constant was calculated to be log K=- 2.49±0.15. The stability constant of NpO2(OH)2CO2 2- was predicted to be log β= 20.21±0.15 by taking the literature value of solubility product of NpO2 (OH) 2(s). 相似文献
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237Np(Ⅴ)在膨润土上的吸附行为研究 总被引:1,自引:1,他引:1
以甘肃红泉膨润土为预选的缓冲、回填材料,研究了核素237Np在该材料中的吸附行为.在大气和低氧(氧含量低于5×10-6 mol/mol的Ar气气氛)两种条件下,分别测定了237Np在混合型、Mg-型、Ca-型三种膨润土上的吸附分配比Kd值;并以混合型膨润土为例,研究了pH值和CO2-3浓度对Kd值的影响.得到如下主要结果(1)大气条件下,237Np在混合型、Mg-型、Ca-型膨润土上的吸附分配比Kd分别为47.3,52.0,42.4 mL/g;低氧条件下分别为89.3,38.8,29.0 mL/g;(2)低氧条件下,混合型膨润土在最终pH<9.2时,随着pH的升高,Kd值增大,在pH=9.2时,出现最大值;(3)在大气和低氧两种条件下,在Np(V)的浓度低于NaNpO2CO3的溶解度时,随着CO2-3浓度增加Kd值减小.结果表明,混合型膨润土对Np(V)有较好的吸附能力. 相似文献
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用分光光度法研究了硝酸体系中特丁基肼还原Np(Ⅵ )的动力学。考察了特丁基肼浓度、酸度、NO-3 浓度、UO2 + 2 浓度、Fe3 + 浓度以及温度等对反应速率的影响。求出了反应动力学方程 :-dc(Np(VI) ) /dt =kc(Np(Ⅵ) )c0 .9(TBH) /c0 .75(H+ )。 2 5℃时的速率常数 :k=5 .4 4 (mol/L) -0 .15·min-1。反应的表观活化能 :Ea=6 1.2kJ/mol。在所研究的浓度范围内 ,NO-3 ,UO2 + 2 ,Fe3 + 对反应速率影响较小 ;而升高温度能显著提高反应速率 相似文献
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一、绪言关于镎的分析方法,国内外都进行了大量的工作,报道的文献也很多[1—3],而经常采用的有:(1)放化测量法,这是最常用的一种方法,尽管~(237)Np的比放比较低(1.56×10~3衰变/μg·min),但计数法还是比化学法,化学光谱法灵敏。(2)分光光度法,此法虽然比放化测量灵敏度稍低,但是在含镎的样品中,往往总是伴随有其它α放射性元素,而这些杂质元素比放经常比镎要强得多,因此采用α计数法测量镎时,对其它杂质要求有很 相似文献
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食品中~(237)Np 和~(239)Pu 的同时测定 总被引:1,自引:0,他引:1
本文给出了食品中~(237)Np 和~(239)pu 的同时分析方法,该方法用草酸钙浓集,用三正辛胺(TOA)从8N 盐酸体系中萃取,然后电沉积制源,在低本底α谱仪上测定。本方法对~(237)7Np 和~(239)Pu 的全程回收率分别为(80.1±9.6)%、(75.2±7.8)%;灵敏度分别为6.0×10~(-16)、6.1×10~(-16)Ci/g(灰)。本文还给出了五种食品中~(237)Np 和~(239)Pu 的分析结果。 相似文献
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本文为从复杂的多种锕系元素共存体系中准确测定超微量~(235)Np(10~(-15)-10~(-14)g/g)的含量,建立了一个特殊的中子活化分析流程。样品经阴离子交换柱浓集和PMBP萃淋树脂柱分离纯化,共存的~(237)Np作内标,高注量堆中子活化后,测定~(235)Np活化产物子体~(236)Pu而获得~(235)Np的含量。 相似文献
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《Journal of Nuclear Science and Technology》2013,50(11):1100-1107
The extraction of Np(V) in the presence of U(VI) or Nd(III) was studied with 0.2 M CMPO- decalin and with 0.2 M CMPO-1.4 M TBP-n-dodecane. Distribution ratios of Np(V) decreased with increasing the concentration of Nd(III), which was considered to be explained by the decrease in the concentration of free CMPO. On the other hand, distribution ratios increased as the concentration of U(VI) increased. The absorption spectrum of Np(V) in organic solution showed a new absorption peak which was probably attributable to the formation of cation-cation complexes of Np(V) and U(VI). Assuming the formation of cation-cation complexes, the dependence of distribution ratio of Np(V) on the concentration of U(VI) was found to be semi-quantitatively explained. 相似文献
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研究了肼的衍生物与Fe^3 的反应对Np(Ⅵ)还原反应速率的影响。单甲基肼,偏二甲基肼和2-羟基乙基肼均以较慢的速率将Fe^3 还原为Fe^2 ,在温度为293K时,其反应速率常数分别为0.023,0.11和0.45min^-1。生成Fe^2 能以较快的速率将Np(Ⅵ)还原为Np(Ⅴ)。导出了Fe^3 影响Np(Ⅵ)还原速率的关系式。 相似文献
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《Journal of Nuclear Science and Technology》2013,50(6):560-566
Abstract Sorption of Np(IV) on bentonite in the presence of carbonate was studied by a batch method. The sorption was considered mainly due to Np(OH)2(CO3)2 2- and Np(OH)4(CO3)2 4- The distribution coefficient (Kd of Np(OH)2(CO3)2 2- and Np(OH)4 (CO3)2 4- was determined to be 104.01±0.24 ml/g and 103.93±0.37 ml/g respectively. The increasing Kd at high pH was attributed to the sorption of NpO2(OH)-2 with the Kd of 105.82±0.39 ml/g The formation of colloidal species was observed under a reducing condition. By assuming Np(OH)4 as the colloidal species, the formation constant was evaluated to be βc≤1053.85 Under an oxidizing condition, the formation of the colloidal species was less observed possibly due to the transformation of Np(OH)4 to NpO2OH. 相似文献
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用连续提取法研究了2 37Np在破碎凝灰岩和凝灰质砂上的吸附。研究结果表明 ,4 8h以后 ,2种介质对2 37Np的吸附百分数相近 ,而且吸附的2 37Np在各相间的分布均以离子交换态为主。凝灰岩和凝灰质砂的阳离子交换容量差异显著 ,说明离子交换作用仅发生在粘土矿物的表面 ,凝灰岩中蒙脱石的层间没有发生阳离子交换。在 2 8d的实验时间内 ,2 37Np在介质中的Fe Mn氧化物 氢氧化物上的吸附百分数几乎不随时间变化。这可能是因为该吸附过程为瞬时即可完成的表面化学反应。介质内离子交换相和残余相上的吸附则显示为缓慢的吸附过程 相似文献