The recovery and selective extraction of gold and platinum by novel ionic liquids

Ionic liquids bearing tetrahorylammonium and tetraoctylammonium cations and halide (Br-), dicyanamide (Dca(-)), thiocyanato (SCN-) and bis(trifluoromethysulfonyl)imide (Tf2N-) by liquid-liquid extraction were studied on Au(III), Pt(II) and Pt(IV) extraction. All the system show excellent extractability of Au(III). It is the same for Pt(II) and Pt(W) except for Tf2N- based ionic liquids which do not extract Pt(II) and Pt(IV) and constitute selective system for the separation of Au and Pt from aqueous effluents. The influence of acid concentration on extraction yield is evaluated. The anion-exchange mechanism of Au(III), Pt(II) and Pt(IV) was confirmed. Reductive stripping was used for the recovery of Au(III) and Pt(IV). Tf2N- based ionic liquids show an excellent recovery of Au(III) using thiourea as back-extractant.