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. (C) 2011 Elsevier B.V. All rights reserved.