Cation and anion selectivity of zwitterionic salicylaldoxime metal salt extractants
Cation and anion selectivity of zwitterionic salicylaldoxime metal salt extractants
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DOI：
10.1039/b916877j
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发表时间：
2010-01-01
影响因子：
4
通讯作者：
White, Fraser J.
中科院分区：
文献类型：
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作者：
Forgan, Ross S.;Davidson, James E.;White, Fraser J.
3-二烷基氨基甲基取代的水杨醛肟是有效的金属盐萃取剂，并且与相关的“salen”基试剂相比，其对酸水解足够稳定，以允许在贱金属回收中进行商业应用。晶体结构表明，金属盐与试剂的两性离子形式结合，硝酸铜(II)、四氟硼酸铜和三氟乙酸铜以三元排列形成[Cu(L)(2)X-2]组件，阴离子在配位球外进行反式排列。氯化铜 (II)、溴化物和氯化锌 (II) 与金属内配位层中的卤化物形成 1:1 组装体 [Cu(L)X-2]，从而实现高氯化物选择性和非常好的 CuCl2 传质效率。将阴离子结合位点引入水杨醛肟萃取剂中会改变其阳离子选择性；配体从混合金属水溶液中共同提取少量 Fe-III 和 Cu-II，这是在工业应用之前需要解决的问题。
3-Dialkylaminomethyl substituted salicylaldoximes are efficient metal salt extractants, and, in contrast to related "salen"-based reagents, are sufficiently stable to acid hydrolysis to allow commercial application in base metal recovery. Crystal structures show that metal salts are bound by a zwitterionic form of the reagents, with copper(II) nitrate, tetrafluoroborate and trifluoroacetate forming [Cu(L)(2)X-2] assemblies in a tritopic arrangement with a trans-disposition of the anions outwith the coordination sphere. Copper(II) chloride, bromide and zinc(II) chloride form 1:1 assemblies, [Cu(L)X-2], with the halides in the inner coordination sphere of the metal, leading to high chloride selectivity and very good mass transport efficiencies of CuCl2. Introduction of the anion-binding sites into the salicylaldoxime extractants changes their cation selectivities; the ligands co-extract small amounts of Fe-III along with Cu-II from mixed metal aqueous feed solutions, an issue which will need to be addressed prior to industrial application.