Selective Sequestration of Palladium(II) Cations Using a Supramolecular Polymer Approach

The selective sequestration of aqueous palladium from waste is an attractive option for metal recovery. However, achieving good metal specificity remains a difficult problem. In this study, we present the synthesis of a metallo-supramolecular system based on a 2-pyridyl-1,2,3-triazole chelating ligand group. Excellent selectivity for Pd(II) ions over Pt(II), Ni(II), Fe(II), Co(II), and Zn(II) from a mixed-metal solution was demonstrated through ESI-MS and ¹H NMR spectroscopic studies of a model ligand system. Following this, a water-soluble copolymer system containing 2-pyridyl-1,2,3-triazole functional groups was prepared. This polymer was shown to exhibit the same specificity for Pd(II) in a mixed-metal solution, quantitatively supported by dialysis and ICP-MS experiments. These findings demonstrate the potential of metallo-supramolecular polymers in selective metal recovery.