Separations of the Platinum Metals by Ion Exchange

Abstract

Distribution coefficients for the chlorides of ruthenium, rhodium, palladium, iridi~un(II1 and IV), and platinu~n have been deternli~led between the anion exchanger Amberlite IRA-400 and hydrochloric acid solutions of various molarities. Separations of various combinations'of rhodium, iridium, palladiu~ll, and platinum in amounts of 0.5 mg. or less are described. When, in the course of these separations, the four metals are present together, special procedures are required to ensure conlplete recovery of platinu~l~.There have been several attempts to employ ion exchange in the separation of the platinum metals, but only a limited degree of success has been achieved. MacNevin and Cruinmett (1) suggested that a separation of rhodium, iridium, palladium, and platiilum might be possible owing to the graded stabilities of the chloride and ammine complexes of these metals, but presented no experimental data. Another report by the same authors (2) elaborated on a separation of iridium from palladium achieved by converting the palladium to a cationic diammine, leaving the iridium as an anion, and separating the two on this basis. Stevenson et al. (3) submitted a note on the separation of the four metals on the cation exchanger Dowex-50, based on the formation of perchlorates of these metals by fuming their solutioils with perchloric acid. No data were given, but this separation is of questionable value because of the inability to keep even milligram quantities of platinum and iridium from precipitating in this medium. Blasius and Wachtel (4) achieved separations of from the other three metals by adsorbing the platinum complex on the anion exchanger Permutit-ES in the hydroxide form. The other three metals were eluted by a solution of sodium hydroxide, and the platinum recovered by elution with nitric acid. WIacNevin and McI<ay ( 5 ) have prepared spectrographically pure rhodium through the formation of a cationic rhodium species, the other metals being left as anions. This separation is not quantitative. The separations of rhodium and iridium have been discussed in a previous paper (G).The only equilibrium data recorded co~lcer~li~lg the behavior of platinum metal complexes toward ion exchangers are those of Kraus et al. (7). These worlters measured the distribution coefficients of chloroplatinate (IV) and chloropalladate (11) relative to the anion exchanger Dowex-1 in hydrochloric acid solutions. In the followi~lg report the measurement of the distribution coefficients of ruthenium, rhodium, iridium, palladium, and platinum in hydrochloric acid solutions relative t o the anion exchanger Amberlite IRA-400 is described, as well as a series of separations of these metals. Standard SolutionsPal1adiunz.-A stock solution was prepared by dissolving pure palladium sponge in aqua regia, evaporating several times to dryness with hydrochloric acid, and then dissolving the residue and diluting with 0.1 M hydrochloric acid. This solution was standardized gravimetrically by precipitation with salicylaldoxime (8). Analyses f...

Quantitative Radiochemical Analysis by Ion Exchange. Calcium, Strontium, and Barium

“…Reduction of uranium by means of stannous chloride in the presence of iron and orthophosphoric acid as "catalysts," proposed by Main (12), allows both high precision and reproducibility in the volumetric determination of uranium, as was shown recently by Byrne, Larsen, and Pflug (2). Several elements interfere in this reduction method.…”

Separation of platinum group metal ions by Donnan dialysis

“…The distribution coefficients of these species between anion-exchange resins and solutions containing high concentrations of chloride or bromide indicate that a chromato-Ions by Donnan Dialysis graphic procedure should be simple (10,11); however, for several reasons, this does not turn out to be the case. Chemical equilibria involving these species are very complicated (12), stable compounds seem to be formed on the anion exchanger (10, 11), and elution of some of the platinum-group metal complexes is highly asymmetric (11).…”

The Spallation of Iridium With Protons of Energies 9–87 Mev

“…Therefore the Re(VI1) was further purified by distilling rhenium heptoxide from a perchloric acid medium and trapping it in ice-cold 6 N sodium hydroxide. Since Pt(1V) is adsorbed very strongly a t all hydrochloric acid concentrations (13), about 20 ml of 35% perchloric acid was used a s eluant (15).…”