Separation of platinum (IV) and rhodium (III) from hydrochloric acid solutions using diaion resins

Abstract

Pt and Rh in HCl solutions were separated by adsorption with strong basic resins (Diaion SA10A, Diaion SA20A, and Diaion PA308) in the HCl concentration range 0.15 mol/dm3. The molar ratio of Pt to Rh in the feed solution was fixed at 5: 1, based on the composition of spent automobile catalysts. The resins used had selectivity for Pt over Rh, and the adsorptions of both metals were clearly affected by the acid concentration. Batch experiments indicated that it is possible to separate Pt from Rh at low acid concentrations with these resins; Diaion SA10A was the most effective. The feasibility of separation of Pt and Rh with Diaion SA10A was verified using continuous column experiments. The loaded Diaion SA10A resin was regenerated by elution with a mixture of HCl and thiourea.