Separation of rhodium and iridium using silicone rubber foam treated with tri-n-octylamine

Abstract

Miligram amounts of rhodium and iridium can be separated from solutions in hydrochloric acid containing free chlorine by batch or column absorption of iridium on to silicone rubber foam loaded with tri-n-octylamine. Under suitable conditions, more than 99% of the rhodium remains in the aqueous phase while 98.5 ± 0.9% of the iridium is retained by the foam. The iridium can be recovered quantitatively from the foam by elution with a small amount of ethanol, and much of the tri-n-octylamine can also be recovered, as can the foam support.