Influence of the textural characteristics of the support on Au(III) sorption from HCl solutions using Cyphos IL101-impregnated Amberlite resins

Abstract

A series of Amberlite XAD resins (acrylic ester and styrene–divinylbenzene resins) has been impregnated with Cyphos IL101 ionic liquid (IL: trihexyl(tetradecyl)phosphonium chloride) for Au(III) sorption from HCl solution. The textural characteristics (specific surface area, pore size distribution and pore volume) of the extractant impregnated resins (EIRs) have been determined in function of IL loading. The HCl concentration and the IL loading have a significant impact on Au(III) sorption efficiency: acrylic ester resins can weakly bind Au(III) contrary to styrene–divinylbenzene resins that only extract metal ions through the ion exchange of tetrachloro-anionic species with chloride ions from the IL. Uptake kinetics are strongly controlled by both the IL loading, the textural properties of the resin and, in some cases, by the pre-conditioning of the resin. Though a clear correlation exists between pore size/pore volume and apparent intraparticle diffusion coefficients, some resins showed atypical behavior (having lower relative coefficients of intraparticle diffusion than expected from the textural properties of raw resins, while their De fits better the actual textural properties of impregnated materials). Sorption efficiency increases with IL loading while uptake kinetics is slowed down. A good compromise is obtained in terms of both sorption efficiency and uptake kinetics using XAD-1180 resin impregnated with Cyphos IL101 (with IL loading not exceeding 400mgILg−1EIR).