二(2-乙基己基)磷酸酯从硝酸体系中萃取Mo(Ⅵ)

Extraction of Mo(Ⅵ) From Nitric Acid Solution With Bis (2-Ethylhexyl)Hydrogen Phosphate

用低浓缩铀靶代替高浓缩铀靶辐照进行^(99)Mo的生产是一个必然的趋势,但采用低浓缩铀靶辐照后裂变体系的组成可能发生改变,从而影响^(99)Mo的分离提取过程。为此,本工作以低浓缩铀辐照后溶解的模拟溶液为研究对象,在U(Ⅵ)大量存在的情况下,考察了二(2-乙基己基)磷酸酯(P_(204))从硝酸体系中萃取Mo(Ⅵ)的行为,重点研究了不同Mo(Ⅵ)浓度下萃取时间、萃取剂浓度、硝酸浓度、温度、其他主要元素(Cs(Ⅰ),Zr(Ⅳ),Y(Ⅲ),Nd(Ⅲ),Al(Ⅲ))等因素对萃取的影响。实验结果表明,不同Mo(Ⅵ)浓度下,P_(204)-磺化煤油对硝酸体系中Mo(Ⅵ)的萃取行为相似;在相比为1时,φ=10%P_(204)-磺化煤油对Mo(Ⅵ)即有较好的萃取效果;硝酸浓度不大于2mol/L时分配比随着硝酸浓度的增加而减少,但硝酸浓度进一步增大时对萃取无显著影响;萃取反应的ΔH和ΔG均为负值,表明该萃取是一个常温下能自发进行的放热反应;溶液中U(Ⅵ)和本工作考察的其它主要元素存在及其浓度的改变不会显著影响P204对Mo(Ⅵ)的萃取行为,且采用P_(204)可将Mo(Ⅵ)与Y(Ⅲ)、Nd(Ⅲ)、Al(Ⅲ)选择性地分离。

The production of ^99Mo that use low-enriched uranium as irradiation target instead of high-enriched uranium is an inevitable trend.However,the composition of the fission system may be changed with low enriched uranium target,which can affect the separation and extraction process of ^99Mo.In this paper,the extraction behaviors of Mo（Ⅵ）from nitric acid solution by bis（2-ethylhexyl）phosphate in sulfonated kerosene were studied in presentof U（Ⅵ）with high concentration.Especially,the effects of different concentrations of Mo（Ⅵ）,extraction time,extractant concentration,concentration of nitric acid,temperature and the other major elements（included Cs（I）,Zr（Ⅳ）,Y（Ⅲ）,Nd（Ⅲ）,Al（Ⅲ））on extraction were investigated.The results show that the extraction behaviors of Mo（Ⅵ）by bis（2-ethylhexyl）phosphate in sulfonated kerosene are similar in different concentrations.The good extraction efficiency could reach by 10% bis（2-ethylhexyl）phosphate in sulfonated kerosene when the phase ratio is 1.The distribution ratio of Mo（Ⅵ）decrease with the increasing of concentration of nitric acid when the c0（HNO3）≤2mol/L,but it have nearly no effect on extraction of Mo（Ⅵ）by nitric acid when the concentration of HNO3 is more than 2mol/L.The extraction reaction is exothermic and spontaneous at ambient temperature because theΔH andΔGare negative.Additionally,no remarkable influence on the distribution ratio of Mo（Ⅵ）by bis（2-ethylhexyl）phosphate in sulfonated kerosene by U（Ⅵ）and the other major elements could be noted,while,there is a high selectivity for seperation of Mo（Ⅵ）from Y（Ⅲ）,Nd（Ⅲ）,Al（Ⅲ）by using P204.