Synergistic Solvent Extraction Is Driven by Entropy.
Synergistic Solvent Extraction Is Driven by Entropy.
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DOI：
10.1021/acsnano.9b07605
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发表时间：
2019-11
期刊：
影响因子：
17.1
通讯作者：
M. Špadina;K. Bohinc;T. Zemb;J. Dufrêche
中科院分区：
文献类型：
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作者：
M. Špadina;K. Bohinc;T. Zemb;J. Dufrêche
在溶剂萃取中，两亲性分子自组装成有组织的结构是负责将金属离子从水相转移到有机溶剂的现象。尽管它们对化学工程和分离科学具有重要意义，但驱动溶质转移的力尚未完全了解。而不是假设简单的络合反应与预定义的化学计量，我们模型协同萃取系统的胶体方法，明确考虑到自组装所产生的两亲性的萃取剂。与液-液萃取背后的简单化学计量的当前范例相反，存在严重的聚集体的多分散性，其组成完全不同，但自由能相似。纳米尺度上的这种多样性结构是离子向有机相的协同转移的原因。协同作用可以理解为螯合作用的相互作用：它增强了提取，因为它增加了提取离子的构型熵。协同混合物的复杂性质的全局概述显示了自组装的不同机制，因此在提取效率方面可以相对于绿色化学方面进行调整。
In solvent extraction, the self-assembly of amphiphilic molecules into an organized structure is the phenomenon responsible for the transfer of the metal ion from the aqueous phase to the organic solvent. Despite their significance for chemical engineering and separation science, the forces driving the solute transfer are not fully understood. Instead of assuming the simple complexation reaction with predefined stoichiometry, we model synergistic extraction systems by a colloidal approach that explicitly takes into account the self-assembly resulting from the amphiphilic nature of the extractants. Contrary to the current paradigm of simple stoichiometry behind liquid-liquid extraction, there is a severe polydispersity of aggregates completely different in compositions, but similar in the free energy. This variety of structures on the nanoscale is responsible for the synergistic transfer of ion to the organic phase. Synergy can be understood as a reciprocal effect of chelation: it enhances extraction because it increases the configurational entropy of an extracted ion. The global overview of the complex nature of synergistic mixture shows different regimes in self-assembly, and thus in the extraction efficiency which can be tuned with respect to the green chemistry aspect.