Abstract The recovery and purification of rare earth metals from electronic waste is an attractive alternative to environmentally damaging virgin mining of these metals, as the concentrations of rare earth metals are significantly higher in electronic waste than can be found naturally. It is therefore prudent to develop recycling and purification processes for these metals from electronic waste. Solvent extraction is the most commonly used technique for the purification of rare earth metals, as solvent extraction is capable of handling large volumes while maintaining high product purities. Since there is a scarcity of thermodynamic phase equilibrium data that can assist in developing such recycling processes, this study begins a series of investigations to address this gap. The distribution coefficients of Y3+ and Eu3+ ions between an organic phase and an aqueous nitric acid solution, as a function of the nitric acid concentration, were measured at approximately 298 K. These are reported for systems containing an organic phase of di-(2-ethylhexyl) phosphoric acid (HDEHP) in a diluent; varying either the diluent or the concentration of the HDEHP. The two diluents investigated were n-nonane and n-dodecane. Measurements were conducted in a liquid-liquid equilibrium cell, with the concentration of the rare earth metals determined by ICP-OES analysis. The distribution coefficients for Y3+ and Eu3+ were shown to be inversely proportional to the aqueous acid concentration, and dependent upon both the concentration of the HDEHP in the organic phase and the diluent used. The data were used for the optimisation of a rare earth metal extraction column.

中文翻译：

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Y3+和Eu3+在HNO3和HDEHP之间的分配系数

摘要 从电子垃圾中回收和提纯稀土金属是对这些金属的环境破坏性原始开采的一种有吸引力的替代方法，因为电子垃圾中稀土金属的浓度明显高于自然中的浓度。因此，谨慎地从电子废物中开发这些金属的回收和净化工艺。溶剂萃取是纯化稀土金属最常用的技术，因为溶剂萃取能够处理大量样品，同时保持产品的高纯度。由于缺乏可以帮助开发此类回收过程的热力学相平衡数据，因此本研究开始了一系列调查以解决这一差距。Y3+ 和 Eu3+ 离子在有机相和硝酸水溶液之间的分布系数，作为硝酸浓度的函数，在大约 298 K 下测量。这些是针对含有 di-(2-乙基己基）磷酸（HDEHP）在稀释剂中；改变稀释剂或 HDEHP 的浓度。研究的两种稀释剂是正壬烷和正十二烷。测量在液-液平衡池中进行，稀土金属的浓度通过 ICP-OES 分析确定。Y3+ 和 Eu3+ 的分配系数显示与酸水溶液浓度成反比，并取决于有机相中 HDEHP 的浓度和所用稀释剂。