New hydrophobic eutectic solvents for extraction of a series of trivalent rare earth elements from nitrate solutions, bis(2,4,4-trimethylpentyl)dithiophosphinic acid (DTPA)/menthol and bis(2,4,4-trimethylpentyl)dithiophosphinic acid/trioctylphosphine oxide (TOPO)/menthol, were suggested and studied. The solvents were completely characterized by ³¹P NMR, IR spectroscopy, and differential scanning calorimetry. The physical properties of the eutectic solvents, including density, viscosity and refractive index, were determined. The dependence of viscosity on temperature was described with high accuracy using the Arrhenius and Vogel–Fulcher–Tammann equations. The extraction of rare earth elements (Pr, Nd, Eu) by the suggested eutectic solvents was studied as a function of the medium acidity, concentration of the salting-out agent, composition of the eutectic solvent, initial metal concentration, volume ratio of phases, etc. To detect the synergistic effect, a comparative analysis of the extraction of the rare earth elements by the following three eutectic solvents was carried out: DTPA/menthol, TOPO/menthol, and DTPA/TOPO/menthol. The addition of TOPO to the DTPA/menthol mixture increased the extraction efficiency of the metal ions from nitrate solutions. It has been shown that the application of the suggested extraction systems can be promising in the hydrometallurgical treatment of wastes containing rare-earth metals.

中文翻译：

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基于含磷化合物的疏水共晶溶剂从硝酸盐溶液中提取稀土元素


提出并研究了用于从硝酸盐溶液中提取一系列三价稀土元素的新型疏水性共熔溶剂，即双（2,4,4-三甲基戊基）二硫代膦酸 （DTPA）/薄荷醇和双（2,4,4-三甲基戊基）二硫代膦酸/三辛基膦氧化物 （TOPO）/薄荷醇。通过 ³¹P NMR、IR 光谱和差示扫描量热法对溶剂进行完全表征。测定共熔溶剂的物理性质，包括密度、粘度和折射率。使用 Arrhenius 和 Vogel-Fulcher-Tammann 方程高精度地描述了粘度对温度的依赖性。研究了建议的共晶溶剂萃取稀土元素（Pr、Nd、Eu）与介质酸度、盐析剂浓度、共晶溶剂的组成、初始金属浓度、相的体积比等的函数关系。为了检测协同效应，对以下三种共晶溶剂萃取稀土元素进行了比较分析： DTPA/薄荷醇、TOPO/薄荷醇和 DTPA/TOPO/薄荷醇。在 DTPA/薄荷醇混合物中添加 TOPO 提高了从硝酸盐溶液中提取金属离子的效率。已经表明，建议的提取系统在含稀土金属废物的湿法冶金处理中的应用是有前途的。