Scientists have always been seeking more efficient extractants for rare earths extraction and separation, especially for heavy rare earths. In this paper, a novel extractant (2,4-dimethylheptyl)(2,4,4′-trimethylpentyl)phosphinic acid (USTB-2) was synthesized. The structures of the intermediate and USTB-2 were characterized by ³¹P NMR, ¹H NMR, FT-IR and ESI-MS. Its pK_a was 5.62. Its extraction ability was between Cyanex 272 and P507. Its extraction mechanism was cation exchange. Its extraction capacity was larger than that of Cyanex 272 and lower than that of P507. Its solubility in 3 mol/L HCl and deionized water was 11.2 mg/L and 19.0 mg/L, respectively. The Lu(III) loaded in USTB-2 solution can be easily stripped by HCl, HNO₃ and H₂SO₄. It has good separation performance for heavy rare earths. Its average separation factor ($\overline{\beta }$) for adjacent heavy REs from Gd to Lu was 2.18. For some heavy RE couples like Er/Ho, Yb/Tm and Lu/Yb (especially for Lu/Yb), USTB-2 possesses even better separation performance than Cyanex 272. Its extraction efficiency for nonferrous metal ions was in the order Al > Gd > Zn > Nd > La > Co > Cu. The separation factors of Al/Gd, Gd/Zn, Zn/Nd, La/Co by USTB-2 were 2.67, 5.39, 3.35 and 26.67, respectively.

科学家一直在寻找更有效的稀土萃取和分离剂，特别是重稀土萃取剂。本文合成了一种新型的萃取剂（2,4-二甲基庚基）（2,4,4'-三甲基戊基）次膦酸（USTB-2）。中间体和USTB-2的结构通过³¹ P NMR，¹ H NMR，FT-IR和ESI-MS进行表征。其p K _a为5.62。它的提取能力介于Cyanex 272和P507之间。其提取机理为阳离子交换。它的提取容量大于Cyanex 272，但低于P507。它在3 mol / L HCl和去离子水中的溶解度分别为11.2 mg / L和19.0 mg / L。负载在USTB-2溶液中的Lu（III）可以很容易用HCl，HNO ₃汽提和H ₂ SO ₄。对重稀土具有良好的分离性能。其平均分离系数（$\overline{\beta }$），从Gd到Lu的相邻重RE均为2.18。对于某些重稀土离子对，例如Er / Ho，Yb / Tm和Lu / Yb（尤其是Lu / Yb），USTB-2的分离性能比Cyanex 272更好。其对有色金属离子的萃取效率约为Al> Gd> Zn> Nd> La> Co> Cu。USTB-2对Al / Gd，Gd / Zn，Zn / Nd，La / Co的分离系数分别为2.67、5.39、3.35和26.67。