Recovery of palladium from acidic nitrate media with triazole type extractants in ionic liquid

A series of ligands with triazole ring were synthesized via a facile, safe, high yielding Cu(I)-catalysed click reaction, which was used for the first time to recovery Pd(II) from HNO3 medium, wherein ligands 2-[1-(Pyridin-2-ylmethyl)-1H-1,2,3-triazol-4-yl]pyridine (Tz1) and 1,1′-Bis(pyridin-2-ylmethyl)-1H,1′H-4,4′-bi-1,2,3-triazole (Tz2) had excellent extraction efficiency and selectivity. Extraction performance of such two ligands in ionic liquid vs. a classical solvent (chloroform) was compared. Their extraction ability in ionic liquid was four times better than that in chloroform. The mechanism of extraction was investigated by exploring the effects of different parameters such as HNO3, NaNO3 and ligand concentrations on extraction efficiency. It revealed the nature of the extracted species was [Pd(NO3)2·Tz)] confirmed by Electrospray Ionization Mass Spectrometry data. The coordination properties between palladium and the ligand were examined by the structure-activity relationship and the Fourier transform infrared spectra. More than 95% of palladium could be obtained after three times stripping. The Tz/ionic liquid system showed remarkable separation efficiency towards palladium in a simulated mixed metal solution. •The ligands with triazole ring were synthesized and used to recover Pd(II).•The ligands in ionic liquids extract palladium high efficiently.•The structure-activity relationship was determined.•The extracted species was found to be [Pd(NO3)2·Tz)]