SEPARATION OF RHODIUM FROM RUTHENIUM AND IRIDIUM BY FAST SOLVENT-EXTRACTION WITH HDEHP

Solvent extraction of rhodium, ruthenium and iridium with di(2-ethylhe xyl)phosphoric acid (HDEHP) has been investigated. Under the condition s {Cl-} = 0.20 M, [(HDEHP)(2)] = 0.30 M, pH 4.05, phase contact time 1 minutes, Rh(III) is extracted 90.7%, Ru(III) and Ir(III) 20.0% and 11 .5%, respectively, at phase ratio 1:1. The distribution ratio of rhodi um is proportional to [(HDEHP)(2)](3) for a freshly prepared aqueous p hase with low chloride concentration but might drop to [(HDEHP)(2)](1t o2) for an aqueous phase high in chloride concentration and after stan ding. The spectroscopic studies indicate that the extracted compound o f rhodium is Rh(H2O)(6-x)Cl-x[H(DEHP)(2)](3-x) (x = 0, 1, 2).