阳离子交换法分离147Pm与Nd的条件研究

Investigation on Separation of 147Pm from Nd by Cation Exchange Chromatography

  • 摘要: 反应堆辐照富集146Nd靶件是制备147Pm的重要途径,其难点在于从常量Nd基体中高效分离微量147Pm。为建立可行的147Pm/Nd分离工艺流程,本研究系统考察AG 50W×8强酸型阳离子交换树脂对Nd及147Pm的吸附与分离行为,其中以Sm作为147Pm的替代元素用于工艺参数优化。静态吸附结果表明,在0.0001~0.1 mol/L HCl的稀酸体系中,Nd和147Pm在10 min内达到吸附平衡,过程符合准二级动力学模型,吸附等温线符合Langmuir模型,其对Nd(Ⅲ)和Sm(Ⅲ)的饱和吸附容量分别为236.9 mg/g和210.9 mg/g,据此可推断147Pm 的吸附容量介于两者之间。基于静态吸附结果,采用Sm替代147Pm,系统开展柱分离条件研究,确定最佳工艺条件为:以0.4 mol/L α-羟基异丁酸(pH=4.1)为淋洗剂,流速1.0 BV/h,温度75 ℃。在该条件下,以147Pm为示踪剂,进行Nd与147Pm的分离实验。结果显示,147Pm/Nd分离度达到1.21,147Pm回收率为88.1%以上。本研究建立了一种基于阳离子交换-络合淋洗的147Pm/Nd分离工艺,可为从辐照146Nd靶件中提取147Pm提供实验依据和技术支撑。

     

    Abstract: Reactor irradiation of enriched 146Nd targets represents an important route for the production of 147Pm, where the major challenge lies in the efficient separation of trace 147Pm from a bulk Nd matrix. To establish a feasible separation process of 147Pm/Nd, the adsorption and separation behaviors of Nd and 147Pm on AG 50W×8 strong-acid cation-exchange resin were systematically investigated. Samarium was employed as a chemical surrogate for 147Pm during the optimization of process parameters.Batch adsorption results demonstrated that, in dilute hydrochloric acid media (0.0001-0.1 mol/L HCl), Nd and 147Pm reached adsorption equilibrium within 10 min. The adsorption kinetics followed a pseudo-second-order model, and the adsorption isotherms were well described by the Langmuir model. The maximum adsorption capacities of the resin for Nd(Ⅲ) and Sm(Ⅲ) were determined to be 236.9 mg/g和210.9 mg/g, respectively, from which the adsorption capacity of 147Pm can be reasonably inferred to lie between those of Nd and Sm. Based on the batch adsorption results, systematic column separation studies were carried out using Sm as a surrogate for 147Pm. The optimal chromatographic conditions were determined to be 0.4 mol/L α-hydroxyisobutyric acid (α-HIBA) as the eluent at pH 4.1, a flow rate of 1.0 BV/h, and a temperature of 75 ℃. Under these conditions, separation experiments using 147Pm as a tracer demonstrated that 147Pm was preferentially eluted prior to Nd, achieving a resolution of 1.21 and a recovery yield exceeding 88.1%.This study establishes a cation-exchange chromatographic process coupled with complexing elution for the separation of 147Pm from Nd, providing a practical experimental basis for the purification of 147Pm from irradiated 146Nd targets.

     

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