Liquid–liquid equilibria in the H₂O–HNO₃–Eu(NO₃)₃–Gd(NO₃)₃–tributyl phosphate (TBP) system and in two H₂O–HNO₃–Ln(NO₃)₃–TBP (Ln = Eu, Gd) subsystems have been investigated at 298.15 K in a wide range of nitric acid and rare earth elements (REEs) concentrations. The total compositions of the extraction systems and the content of REEs and nitric acid in equilibrium phases are presented. Densities of solutions in two subsystems have been measured. The distribution coefficients of REEs and nitric acid and the separation factor of REEs in equilibrium phases have been determined. The obtained experimental data can be further used for thermodynamic modeling of systems that are promising for the extraction separation of REEs.

中文翻译：

---

298.15 K时水-硝酸-硝酸Euro-硝酸G-磷酸三丁酯体系中的液-液平衡

H ₂ O–HNO ₃ –Eu（NO ₃）₃ –Gd（NO ₃）₃ –磷酸_三丁酯（TBP）系统和两个H ₂ O–HNO ₃ –Ln（NO ₃）_3中的液-液平衡-TBP（Ln = Eu，Gd）子系统已在298.15 K的硝酸和稀土元素（REE）浓度范围内进行了研究。介绍了萃取系统的总组成以及平衡相中REE和硝酸的含量。已经测量了两个子系统中溶液的密度。确定了稀土元素和硝酸的分布系数以及稀土元素在平衡相中的分离因子。所获得的实验数据可以进一步用于系统的热力学建模，该系统有望实现稀土元素的萃取分离。