✦ LIBER ✦

Extraction separation of Ir(III) and Rh(III) with Cyanex 923 from chloride media: a possible recovery from spent autocatalysts

✍ Scribed by Devendra V Chavan; Purushottam M Dhadke

Publisher: Wiley (John Wiley & Sons)
Year: 2002
Tongue: English
Weight: 126 KB
Volume: 77
Category: Article
ISSN: 0268-2575
DOI: 10.1002/jctb.652

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✦ Synopsis

Abstract

Liquid–liquid extraction of Ir(III) and Rh(III) with Cyanex 923 from aqueous hydrochloric acid media has been studied. Quantitative extraction of Ir(III) was observed in the range of 5.0–8.0 mol dm^−3^ HCl with 0.1 mol dm^−3^ Cyanex 923, while Rh(III) was extracted quantitatively in the range of 1.0–2.0 mol dm^−3^ HCl with 0.05 mol dm^−3^ Cyanex 923 in toluene along with 0.2 mol dm^−3^ SnCl~2~. The Ir(III) was back extracted with 4.0 mol dm^−3^ HNO~3~ quantitatively from the organic phase while Rh(III) was stripped with 3.0 mol dm^−3^ HNO~3~. The extraction of Rh(III) with Cyanex 923 was not quantitative without use of SnCl~2~. However in the extraction of Ir(III) a negative trend was observed in the presence of SnCl~2~. Varying the temperature of extraction showed that the extraction reactions of both the metal ions are exothermic in nature, and the stoichiometric ratio of Ir(III)/Rh(III) to Cyanex 923 in organic phase was found to be 1:3. The methods developed were applied to the recovery of these metal ions from a synthetic solution of similar composition to that from leaching of spent autocatalysts in 6.0 mol dm^−3^ HCl.