Amberlite XAD-1180 impregnation with Cyphos IL101 for the selective recovery of precious metals from HCl solutions

The impregnation of Amberlite XAD-1180 with Cyphos IL101 (trihexyl(tetradecyl)phosphonium chloride ionic liquid, IL) confers to the resin highly efficient extraction properties for Au(III), Pd(II), and Pt(IV) in highly concentrated HCl solutions. Extraction isotherms (fitted by the Langmuir equation) show maximum extraction capacities proportional to IL loading. Increasing the IL loading has a limiting effect for extraction kinetics, which are controlled by the resistance to intraparticle diffusion: the complete filling of the porous volume of the extractant-impregnated resin (EIR) with the IL considerably hinders mass transfer of target metal ions. The EIRs are selective for precious metals (PGMs) over base metals (BMs), and the selection of appropriate eluents (HCl, HNO3, acidic thiourea) allows recovering almost selectively the three metals in pure or highly enriched proportions.