Synergism by coassembly at the origin of ion selectivity in liquid-liquid extraction.
Synergism by coassembly at the origin of ion selectivity in liquid-liquid extraction.
复制标题
液-液萃取中离子选择性起源的共组装协同作用。
DOI：
10.1021/la301733r
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发表时间：
2012
期刊：
影响因子：
--
通讯作者：
T. Zemb
中科院分区：
文献类型：
--
作者：
S. Dourdain;I. Hofmeister;O. Pecheur;J. Dufrêche;R. Turgis;A. Leydier;J. Jestin;F. Testard;S. Pellet;T. Zemb
在液液萃取中，当溶剂相的特定配方中，混合物中某些阳离子的分配系数增加时，就会出现协同作用。为了描述协同机制，我们确定了聚集体中混合共聚的自由能。相图中任何一点的聚集不仅在结构上可以被SANS， SAXS和SLS跟踪，而且在热力学上可以通过确定与反向聚集共存的单体的浓度来跟踪。利用工业上常用的HDEHP/TOPO偶对形成的混合反向聚集体，以及具有代表性的U/Fe偶对，我们发现在协同作用最大时，聚集体的微观结构没有特异性。然而，根据协同选择峰，形成包含萃取离子的极性核心混合聚集体所需的聚集自由能与目标离子和非目标离子之间的转移自由能差相当。
In liquid-liquid extraction, synergism emerges when for a defined formulation of the solvent phase, there is an increase of distribution coefficients for some cations in a mixture. To characterize the synergistic mechanisms, we determine the free energy of mixed coassembly in aggregates. Aggregation in any point of a phase diagram can be followed not only structurally by SANS, SAXS, and SLS, but also thermodynamically by determining the concentration of monomers coexisting with reverse aggregates. Using the industrially used couple HDEHP/TOPO forming mixed reverse aggregates, and the representative couple U/Fe, we show that there is no peculiarity in the aggregates microstructure at the maximum of synergism. Nevertheless, the free energy of aggregation necessary to form mixed aggregates containing extracted ions in their polar core is comparable to the transfer free energy difference between target and nontarget ions, as deduced from the synergistic selectivity peak.