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

Effect of HCl concentration on stripping of Ir(IV) and Rh(III) from Aliquat 336 by the mixture 1M thiourea and HCl. •Ir(IV) was selectively extracted over Rh(III) by amines from HCl solution.•Higher separation factor between Ir and Rh was obtained at low HCl concentration.•Solution aging depressed the extraction of Rh(III).•The mixture of HCl and thiourea stripped selectively Ir from the loaded Aliquat336. 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.