Extraction of Gold(III) from Acidic Chloride Media Using Phosphonium-based Ionic Liquid as an Anion Exchanger

The present work addresses Au(III) extraction from chloride media using phosphonium-based ionic liquid (Cyphos IL 109) as a novel anion exchanger diluted in xylene. Gold(III) is extracted into the organic phase as [P 66614 + ][AuCl 4 – ] and can easily be stripped by reduction to Au(I) with CS(NH 2 ) 2 /HCl or Na 2 S 2 O 3 . A series of extraction-stripping cycles show a possible recirculation of used solvent without loss of performance, as far as the extraction of gold(III) from HCl/Cl – media is concerned. Au(III) was quantitatively (99.4%) extracted from 0.1 mol L –1 HCl initially containing 100 mg L –1 Au(III) with 0.8 g L –1 Cyphos IL 109 with two counter-current stages at O/A = 1, whereas total stripping as Au(I) with 0.02 mol L –1 CS(NH 2 ) 2 in 5% HCl or 0.02 mol L –1 Na 2 S 2 O 3 also needed two counter-current stages, at O/A = 3. Simulations of counter-current modes reveal Cyphos IL 109 can be considered a promising new extractant for complete recovery of Au(III) from Cl – media in pilot scale.