Mutual separation of platinum group metals via seed-mediated growth on a polymer with metal-coordination unit

Abstract

• Mutual separation of platinum group metals (PGMs) • Seed-mediated growth of platinum or palladium atoms on a polymer with a metal-coordination unit. • Selective separation of platinum from PGM mixture. • Selective separation of palladium from PGM mixture. • Various target platinum group metals are able to be selectively separated by selection of nucleation site. Platinum group metals (PGMs) are extremely difficult to separate from each other because of the similarity in their chemical and physical properties. We report here the effective mutual separation of PGMs utilizing a seed-mediated growth approach on a polymer with a metal-coordination unit (PMCU). Nucleation of Pt 4+ ions by sodium borohydride produced Pt 0 seeds on the metal-coordination unit (thiocarbonyl group) of PMCU. The Pt seeds-attached polymer was added into a solution containing Pt 4+ and other PGM ions, and reduction with L-ascorbic acid selectively assembled Pt atoms around the Pt seeds. The resulting polymer was removed from the mixture and washed to remove Pt and other PGMs that were only physically adsorbed, achieving selective separation of Pt. By changing the nucleation site from Pt to Pd, the immersion of Pd seeds-attached polymer in the mixed solution containing Pd 2+ and other PGM ions and reduction with L-ascorbic acid selectively separated Pd. Therefore, this approach is applicable to selective separation of various target PGMs by the selection of nucleation sites on PMCU.