Extraction of La(III), Eu(III) and Fe(III) was compared in n-dodecane and two ionic liquids (ILs) (1-ethyl-1-butylpiperidinium bis (trifluoromethylsulfonyl)imide [EBPip⁺] [NTf₂⁻] and 1-ethyl-1-octylpiperidinium bis (trifluoromethylsulfonyl)imide [EOPip⁺] [NTf₂⁻]). Using the extractant N,N′-dimethyl-N,N′-dioctylhexylethoxymalonamide (DMDOHEMA), the effect of pH was investigated in detail to recover extraction mechanisms. The use of ILs as the organic solvent instead of n-dodecane, greatly enhances extraction efficiency, and an ionic liquid with a shorter alkyl chain [EBPip⁺] [NTf₂⁻] provides higher extraction than [EOPip⁺] [NTf₂⁻]. The mechanistic study points out that for low nitric acid concentrations ([HNO₃] ≤ 0.01 M), metal is extracted via a cation of the ionic liquids, while for higher nitric acid concentrations ([HNO₃] ≥ 1.0 M), extraction occurs through pure solvation mechanism of DMDOHEMA as in conventional diluents. This latter case is of high interest for applications, as higher extraction can be obtained without any loss of ILs by ion exchange mechanisms.

中文翻译：

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DMDOHEMA/离子液体系统中硝酸盐介质中稀土元素的溶剂萃取：性能和机理研究

La( III )、Eu( III ) 和 Fe( III ) 在正十二烷和两种离子液体 (ILs) (1-ethyl-1-丁基哌啶双 (三氟甲基磺酰基)亚胺 [EBPip ⁺ ] [NTf ₂ ^- ]和1-乙基-1-辛基哌啶双(三氟甲基磺酰基)亚胺[EOPip ⁺ ] [NTf ₂ ^- ])。使用萃取剂N , N'-二甲基-N , N'-二辛基己基乙氧基丙二酰胺(DMDOHEMA)，详细研究了 pH 的影响以恢复萃取机制。使用 ILs 作为有机溶剂代替n-十二烷，大大提高了萃取效率，并且具有较短烷基链的离子液体[EBPip ⁺ ] [NTf ₂ ^- ]提供比[EOPip ⁺ ] [NTf ₂ ^- ]更高的萃取率。机理研究指出，对于低浓度的硝酸（[HNO ₃ ] ≤ 0.01 M），金属通过离子液体的阳离子被萃取，而对于较高的硝酸浓度（[HNO ₃ ] ≥ 1.0 M），发生萃取与传统稀释剂一样，通过 DMDOHEMA 的纯溶剂化机制。后一种情况对应用具有很高的兴趣，因为可以通过离子交换机制在不损失任何 IL 的情况下获得更高的提取率。