Collect. Czech. Chem. Commun. 1988, 53, 3050-3057

A study to the isolation of iridium from platinum metal mixtures

Eliška Kálalová, Marcela Kolářová and Pham Thuy

Department of Inorganic Chemistry, Prague Institute of Chemical Technology, 166 28 Prague 6


Sorption from solution onto a glycidyl methacrylate-ethylene dimethacrylate copolymer modified with ethylenediamine was employed for the isolation of platinum metals. The sorption selectivity coefficients for Rh(III), Ir(IV), Pt(IV) and Pd(II) chloro complexes were determined in the static mode and the values of KRhIr = 10·9, KIrPt = 5·4 and KIrPd = 7·3 were obtained. The dependence of the sorption capacity of the resin on pH of the sorption solution was established; the highest sorption capacity for palladium, 1·7 mmol g-1, was found at pH 3. A procedure for the separation of iridium from palladium is suggested making use of the complexing ability of the sorbent. UV-VIS spectroscopic measurements revealed that Ir(IV) is reduced to Ir(III) on the sorbent and [IrCl6]3- ions are formed. This reduction is caused by aquation of the hydrophilic particles of the sorbent with bonded [IrCl6]2- anions.