Copper-selective chelating resins. I: Batch extractions

Abstract Eleven novel metal ion-chelating resins based upon porous poly(glycidyl methacrylate-co-ethylene glycol dimethacrylate) have been prepared by direct reaction of the polymer with ligands containing an amino group. Those species involving a 2-pyridyl-2-imidazole and a 2-aminomethylpyridine proved to be the most interesting and, for comparison, polystyrene resin analogues of these were also produced. As expected from the literature, the above pyridine-containing ligands remained effective for the extraction of Cu 2+ down to pH 2. Despite having superficially similar overall physical characteristics (particle size, surface area, porosity) the glycidyl methacrylate-based resins showed remarkably enhanced kinetic behaviour in the batch extraction of base metal ions such as Cu 2+ , with an extraction half life as low as ∼ 8 minutes, four times faster than a polystyrene-based analogue. In addition the glycidyl methacrylate-based resins displayed superior selectivity in the extraction of particular metal ions from feed liquors containing a mixture of metal ions. The most remarkable separation discovered was that of Cu 2+ from Zn 2+ where the glycidyl methacrylate-based species with the above ligands achieved essentially quantitative separation of Cu 2+ , even with Zn 2+ present in 250 times excess. Extracted metal ions were rapidly and quantitatively eluted from these resins with 2 M H 2 SO 4 , and in the case of Cu 2+ an acid strength of only 0.25 M was adequate.