Extraction and Stripping Behavior of Platinum Group Metals Using an Amic-Acid-Type Extractant

Abstract

The recovery and separation of platinum group metals (PGMs) are of considerable significance for metal sustainability. To establish an efficient extraction process for PGMs, the novel extractant N-[N,N-di(2-ethylhexyl)aminocarbonylmethyl]phenylalanine (D2EHAF), containing a phenylalanine moiety as the metal-affinity group, was synthesized. The extraction of PGMs from aqueous HCl and HNO₃ solutions with D2EHAF, or our previously developed N-[N,N-di(2-ethylhexyl)aminocarbonylmethyl]glycine (D2EHAG), in n-dodecane was investigated. Both D2EHAF and D2EHAG exhibited high extraction affinities for Os⁴⁺, Pt⁴⁺, and Pd²⁺ in aqueous HCl. In a HNO₃ solution, D2EHAF extracted Pd²⁺ more efficiently than D2EHAG, and the extraction of Pd²⁺ from a 1 mol dm⁻³ HNO₃ solution with D2EHAF proceeded quantitatively. The extracted metal ions were stripped from the organic solution using a highly acidic solution, or thiourea.