New applications of azamacrocyclic ligands in ion recognition, transport and preconcentration of palladium

Abstract

This work deals with the evaluation of a synthesized 15-membered triolefinic azamacrocycle containing a NH group, ( E, E, E)-1,6-bis( p-tolylsulfonyl)-1,6,11-triazacyclopentadeca-3,8,13-triene (R 2NH), for the selective extraction of palladium and platinum from aqueous chloride matrices prior their analysis by ICP-AES. The optimal conditions for liquid–liquid experiments have been evaluated, with special emphasis given to the selection of the organic solvent and the optimal aqueous chloride concentration for the extraction of PdCl 4 2− and PtCl 6 2−. The selective transport and separation of palladium(II) from a mixture of Pd(II) and Pt(IV) was accomplished by means of a supported liquid membrane system containing the macrocycle as carrier dissolved in anethol and 0.5 M thyocianate solution as stripping solution. A C18 cartridge has been activated with the reagent R 2NH in order to test the feasibility of achieving the preconcentration of palladium solutions. Enrichment factors close to the theoretical ones were obtained with the designed system and using thiourea as eluting solution.