Extraction of iridium(III) by ion-pair formation with 2-octylaminopyridine in weak organic acid media

ABSTRACT

To extract iridium(III), various physicochemical parameters were studied. 2-Octylaminopyridine was used for the extraction of iridium(III) from acetate medium at 8.5 pH. Quantitative extraction of iridium(III) was achieved via ion-pair formation of cation [2-OAPH⁺] and anion [Ir(CH₃COO)₄]⁻. The stripping of iridium(III)-laden organic phase was carried out 2 M HCl (3 × 10 mL) . The stoichiometry of the extracted ion–pair complex was found to be 1:4:1 (metal: acetate: extractant). The extracted species [2-OAPH⁺. Ir(CH₃COO)₄⁻] is assumed to be an ion association product of [Ir(CH₃COO)₄] ⁻ and [2-OAPH]⁺. The proposed method was successfully used in the separation of iridium(III) from binary and ternary mixtures. Analysis of various alloy samples was also carried out.

KEYWORDS:

• Alloy analysis
• iridium(III)
• sodium acetate
• solvent extraction
• 2-Octylamiopyridine