Cation and anion selectivity of zwitterionic salicylaldoxime metal salt extractants

Forgan, R.S. , Davidson, J.E., Fabbiani, F.P.A., Galbraith, S.G., Henderson, D.K., Moggach, S.A., Parsons, S., Tasker, P.A. and White, F.J. (2010) Cation and anion selectivity of zwitterionic salicylaldoxime metal salt extractants. Dalton Transactions, 39(7), pp. 1763-1770. (doi:10.1039/B916877J)

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Abstract

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 CuCl(2). 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.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Forgan, Dr Ross
Authors: Forgan, R.S., Davidson, J.E., Fabbiani, F.P.A., Galbraith, S.G., Henderson, D.K., Moggach, S.A., Parsons, S., Tasker, P.A., and White, F.J.
Subjects:Q Science > QD Chemistry
College/School:College of Science and Engineering > School of Chemistry
Journal Name:Dalton Transactions
ISSN:1477-9226
Published Online:07 January 2010

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