The separation of Platinum Group Metals (PGMs) is critical across various fields, including industrial metal recovery and nuclear waste management. This study rigorously examines the separation mechanisms of PGMs using Aluminum Hexacyanoferrate (AlHCF) and employs multiple analytical techniques. The mechanism involves not only simple adsorption but also the dissolution of AlHCF, leading to PGM ion precipitation and elution of components, as well as adsorption onto the AlHCF surface. We conducted X-ray diffraction (XRD), scanning electron microscopy (SEM), Energy-Dispersive X-ray Spectroscopy (EDS), X-ray Absorption Fine Structure (XAFS), and Pair Distribution Function (PDF) analyses to thoroughly investigate the structural and chemical changes in AlHCF before and after PGM adsorption. Our findings reveal that Pd 2+ ions in solution replace Fe 2+ site in AlHCF, preserving the ferrocyanide framework and the adsorption of Ru and Rh. In contrast, Ru and Rh adsorption result in a broadened XRD pattern that lacks the initial AlHCF structure, suggesting the formation of amorphous precipitates via complexation with dissolved ions. By detailing these mechanisms, this study highlights the efficacy of AlHCF as a PGM separation agent and offers valuable insights to improve metal recovery processes.
Nakase et al. (Thu,) studied this question.