Triazole Diglycolamide Cavitand for lanthanide extraction

Click chemistry, which relies on the efficiency of the copper (I)-catalyzed azide-alkyne cycloaddition, was used to link four diglycolamide (DGA) moieties to a resorcinarene platform leading to a specific tetra-DGA-resorcinarene ligand (c-methylcalix(4)methylresorcinarene-4-triazole-dioctyldiglycolamide denoted CR4-Tz-DODGA). The extraction ability of this ligand was studied in a mixture of toluene/iso-octanol (90/10, v/v) toward rare earth elements (REE) at different nitric acid concentrations, ranging from 1 to 5 M. The results show the efficient extractability of and selectivity towards heavy REEs. The stoichiometry of the extraction was established by the slope analysis method and an extraction mechanism was proposed based on estimates of the thermodynamic parameters. From the extraction behavior of the tetra-DGA-resorcinarene ligand, we present the possibility for the extraction and separation of dysprosium from used permanent magnets. (C) 2016 Elsevier B.V. All rights reserved.