Background: Extraction and separation of neptunium is one of the focused research topics in the field of reprocessing. As an organic salting-free reductant, because of its reduction rate differences between Np(Ⅵ) and Pu(Ⅳ), methyl hydrazine (MMH) has the potential to separate Np/Pu.Purpose: In this study, the feasibility of applying MMH to reductive stripping separate Np/Pu was evaluated.Methods: The reductive back-extraction dynamics of Np(Ⅵ) and Pu(Ⅳ) by MMH were investigated using a single-stage extraction device.Results: By investigating the effects of the concentration for nitric acid and methyl hydrazine nitrate, as well as reaction temperature on the reductive stripping process, the Np(Ⅵ) and Pu(Ⅳ) stripping kinetics equation and their apparent activation energy were determined.Conclusion: Further, the half reaction time of reductive stripping Np(Ⅵ) and Pu(Ⅳ) with hydrazine nitrate can be obtained by means of kinetics equation, and a preliminary exploration for Np(Ⅵ)/Pu(Ⅳ) separation was carried out.%镎的提取和分离是后处理领域重点关注的研究课题之一.甲基肼作为一种有机无盐试剂,其还原Np(Ⅵ)的速率快于还原Pu(Ⅳ)的速率,理论上可以利用其反应速率上的差异来实现镎与钚的分离.为了探索甲基肼还原反萃分离镎、钚的可行性,本文采用单级萃取池研究了甲基肼还原反萃Np(Ⅵ)和Pu(Ⅳ)的过程.通过考察还原剂浓度、硝酸浓度以及反应温度和搅拌速率等条件对甲基肼还原反萃Np(Ⅵ)和Pu(Ⅳ)过程的影响,确定了Np(Ⅵ)和Pu(Ⅳ)反萃动力学方程和表观活化能.通过所得的动力学方程得出甲基肼还原反萃Np(Ⅵ)和Pu(Ⅳ)的半反应时间,并对Np(Ⅵ)和Pu(Ⅳ)分离过程的工艺进行了初步探索.
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