Iordache Andreea Maria, Zgavarogea Ramona, Nasture Ana Maria, Feizula Erdin, Ionete Roxana Elena, Santos Rui, Nechita Constantin
ICSI Analytics Department, National Research and Development Institute for Cryogenics and Isotopic Technologies-ICSI, 4 Uzinei Street, 240050 Râmnicu Vâlcea, Romania.
ICSI Energy Department, National Research and Development Institute for Cryogenics and Isotopic Technologies-ICSI, 4 Uzinei Street, 240050 Râmnicu Vâlcea, Romania.
Materials (Basel). 2025 May 27;18(11):2519. doi: 10.3390/ma18112519.
The growing energy demand has emphasized the importance of developing nuclear technologies and high-purity lithium isotopes (Li and Li) as raw materials. This study investigates how voltage and migration time affect two types of low-density polyethylene membranes-one impregnated with ionic liquids and the other non-impregnated-for lithium isotope separation via electromigration from a lithium-loaded organic phase to an aqueous solution. We developed a laboratory-made setup for high-precision lithium isotope measurements (2RSD = ±0.30‱) of natural carbonate samples (LSVEC) and an optimized protocol for isotope ratio measurements using quadrupole ICP-MS with the sample-standard bracketing method (SSB). The results document that both impregnated and non-impregnated membranes can achieve promising Li enrichment under different environmental conditions, including ionic liquids and organic solutions in the cathode chamber. Lithium-ion mobility is influenced by voltage in an environment assisted by 0.1 mol/L tetrabutylammonium perchlorate and increases quasi-linearly from 5 to 15 V. Between 20 and 25 h, the lithium-ion concentration had the maximum value, after which the trend declined. In the BayesGLM model, we incorporated all data and systematically eliminated those with a low enrichment factor, either individually or in groups. Our findings indicated that the model was not significantly affected by the exclusion of measurements with low α. This suggests that voltage and migration time are crucial, and achieving a better enrichment factor depends on applying the optimal ratio of ionic liquids, crown ethers, and organic solvents. Ionic liquids used for impregnation sustain enrichment in the first hours, particularly for Li; however, after 25 h, Li demonstrated a higher enrichment capacity. The maximum single-stage separation factor for Li/Li was achieved at 24 and 48 h for an impregnated membrane M2 (α = 1.021/1.029) and a non-impregnated membrane M5 (α = 1.031/1.038).
不断增长的能源需求凸显了开发核技术以及将高纯度锂同位素（锂-6和锂-7）作为原材料的重要性。本研究调查了电压和迁移时间如何影响两种类型的低密度聚乙烯膜（一种浸渍有离子液体，另一种未浸渍），用于通过电迁移将负载锂的有机相中的锂同位素分离到水溶液中。我们开发了一种实验室自制装置，用于对天然碳酸盐样品（LSVEC）进行高精度锂同位素测量（2RSD = ±0.30‱），并制定了一种优化方案，用于使用四极杆电感耦合等离子体质谱仪和样品-标准品括弧法（SSB）进行同位素比率测量。结果表明，浸渍和未浸渍的膜在不同环境条件下（包括阴极室中的离子液体和有机溶液）都能实现有前景的锂富集。在0.1 mol/L高氯酸四丁铵辅助的环境中，锂离子迁移率受电压影响，并在5至15 V之间近似线性增加。在20至25小时之间，锂离子浓度达到最大值，之后呈下降趋势。在BayesGLM模型中，我们纳入了所有数据，并系统地单独或分组剔除了富集因子低的数据。我们的研究结果表明，排除低α测量值对模型没有显著影响。这表明电压和迁移时间至关重要，实现更好的富集因子取决于应用离子液体、冠醚和有机溶剂的最佳比例。用于浸渍的离子液体在最初几个小时维持富集，特别是对于锂-6；然而，在25小时后，锂-7表现出更高的富集能力。浸渍膜M2（α = 1.021/1.029）和未浸渍膜M5（α = 1.031/1.038）在24小时和48小时时实现了锂-7/锂-6的最大单级分离因子。
