The demand for rare earths is expected to keep increasing throughout the following years. Separation of lanthanides in particular is especially challenging because of their chemical similarities. Therefore, improving the separation process is essential. In this work, we present the effect of the counterion nature on the lanthanide extraction by a 1,10-phenanthroline derivative, the N-octyl-N-tolyl-1,10-phenanthroline-2-carboxamide in chloroform. Modification of the counterion yields a drastic change in selectivity, with a shift in the maximum of extraction from the light lanthanides (Pr, Nd, Sm) in the nitrate system to the heavy lanthanides (Dy, Ho) in the perchlorate system. Other salts (NaCl, NaNO₂) showed a gradual increase in extraction along the whole lanthanide series or no effect (Na₂SO₄). This selectivity shift was explained by possible different coordination in the organic phase. The reversed behavior depending on the anion is especially interesting because a cycling extraction/back-extraction of light lanthanides in nitrate/chloride media or a cycling extraction/back-extraction of heavy lanthanides in perchlorate/nitrate media can enhance the separation factors of Nd and Dy/Ho, respectively.

预计在接下来的几年中，对稀土的需求将继续增长。由于镧系元素的化学相似性，特别是镧系元素的分离尤其具有挑战性。因此，改善分离过程至关重要。在这项工作中，我们介绍了在氯仿中由1,10-菲咯啉衍生物，N-辛基-N-甲苯基-1,10-菲咯啉-2-羧酰胺对镧系元素萃取的抗衡离子性质的影响。抗衡离子的修饰会产生极大的选择性变化，最大萃取量从硝酸盐体系中的轻质镧系元素（Pr，Nd，Sm）转移到高氯酸盐体系中的重质镧系元素（Dy，Ho）。其他盐（NaCl，NaNO ₂）显示出沿整个镧系系列的提取逐渐增加或无影响（Na ₂ SO ₄）。通过有机相中可能存在的不同配位来解释这种选择性变化。取决于阴离子的相反行为尤其令人感兴趣，因为在硝酸盐/氯化物介质中循环萃取/反萃取轻质镧系元素或在高氯酸盐/硝酸盐介质中循环萃取/反萃取重质镧系元素可以提高Nd和Nd的分离系数。 Dy / Ho，分别。