NpO_2^+与UO_2^(+2)阳阳离子络合对30%TBP-煤油萃取Np(Ⅴ)性能的影响

Influence of NpO_2^+ and UO_2^(+2) Cation-Cation Complex on Np(Ⅴ)Extraction by 30%TBP-Kerosene

通过分光光度法和液闪计数法研究了Np(Ⅴ)与U(Ⅵ)间的阳阳离子络合作用对Np(Ⅴ)在30%TBP-煤油有机相中的萃取分配行为的影响。结果表明:Np(Ⅴ)-U(Ⅵ)阳阳离子络合物可被萃入TBP有机相中,其萃取分配系数较Np(Ⅴ)提高了数倍。随着U浓度在0.12～0.60mol/L范围内升高,Np(Ⅴ)-U(Ⅵ)阳阳离子络合物萃取分配系数不断增加,当U浓度达到0.72mol/L时,由于有机相铀饱和度原因,Np(Ⅴ)-U(Ⅵ)阳阳离子络合物萃取分配系数下降。在室温下,水相酸度为3mol/L、铀浓度为0.60mol/L、相比(o/a)为2∶1、两相接触时间为1min时,Np(Ⅴ)的总萃取分配系数约为0.1,萃入有机相中的Np约占Np总量的9%。提高酸度有利于Np(Ⅴ)-U(Ⅵ)阳阳离子络合物的萃取,接触时间在1～8min范围内对萃取无影响。

The influence of cation-cation complex between Np（ Ⅴ ） and U（Ⅵ） on the extrac- tion behavior of Np（Ⅴ ） in 30 %TBP-kerosene has been researched by spectrophotometry and liquid scintillation. The results show that Np （Ⅴ）-U （Ⅵ） cation-cation complex can be extracted into TBP organic phase directly and the distribution ratio is several times higher than Np （ Ⅴ ）. The distribution ratio of Np （ Ⅴ）-U （ Ⅵ ） cation-cation increases with the increasing of U concentration within 0.12-0.60 mol/L. The distribution ratio of Np （ Ⅴ ）- U（Ⅵ） cation-cation decreases as the U concentration reaches 0.72 mol/L because of the effect of U saturation degree in organic phase. At room temperature, when the concentration of U（Ⅵ） and HNO3 of solution are 0.6 mol/L and 3 mol/L respectively and the phase ratio （o/a） is 2： 1, the total distribution ratio of Np（Ⅴ） can reaches about 0.1 after 1 min extraction and almost 9% Np is extracted into TBP organic phase. The distribution ratio of Np（ Ⅴ ）-U（Ⅵ） cation-cation complex increases with the increase of HNO3 concentration. The contacting time of two phase has no influence on the extraction of Np（ Ⅴ ）-U（Ⅵ） cation- cation complex.