Sugaring-out three-liquid-phase extraction and one-step separation of Pt(IV), Pd(II) and Rh(III)

This paper proposed a novel sugaring-out assisted three-liquid-phase system (TLPS) of diisopentyl sulfide (S201)–acetonitrile–glucose–water to extract and separate platinum, palladium and rhodium from their hydrochloric acid solution. Experimental results demonstrated that Pd(II), Pt(IV) and Rh(III) could be separated in one-step extraction process, respectively into the S201 organic top phase, sugaring-out acetonitrile-rich middle phase and aqueous bottom phase of the TLPS. The influences of different phase-forming agents, glucose concentration, HCl concentration in equilibrating aqueous phase and the initial volume ratio of added acetonitrile to aqueous glucose solution on partitions of platinum-group metal (PGM) ions were discussed. It was found that the three-liquid-phase partition behaviors of Pd(II), Pt(IV) and Rh(III) had a close relation with the phase-forming behavior of TLPS. The recovery of Pt and Pd were investigated. Sugaring-out assisted TLPS exhibited obvious advantages over the traditional salting-out systems.

► A sugaring-out assisted three-liquid-phase system for separation of Pt, Pd and Rh.
► Three-liquid-phase partitions of Pt, Pd and Rh have a close relation with the phase-forming behavior.
► Sugaring-out induced three-liquid-phase extraction exhibits obvious advantages over the salting-out systems.