Separation of Ir(IV) and Rh(III) from strong hydrochloric acid solutions by solvent extraction with amines

Abstract

The separation of Ir(IV) and Rh(III) from chloride solution by extraction with amines (TOA, TEHA, Alamine 308, and Aliquat 336) was investigated. Ir(IV) was selectively extracted over Rh(III) by these extractants. HCl concentration affected little the extraction of metals. The highest separation factor of 82.5 between the two metals was obtained from 1M HCl solution by extraction with Aliquat 336. Solution aging until 2 weeks depressed the extraction of Rh(III). The mixture of HCl and thiourea stripped Ir(IV) selectively from the loaded amines and thus promoted the separation.