Recovery of Platinum and Palladium from Spent Automobile Catalyst by Solvent-Impregnated Resins

ABSTRACT

Separation of platinum and palladium, using solvent-impregnated resin (SIR) impregnating di-hexylamine (DHA), di-n-octylamine (DOA), or di-hexyl sulfide (DHS), coated by polyvinyl alcohol crosslinked by glutaraldehyde, was investigated. Coating of the SIR successfully suppressed leakage of the extractant during adsorption. The coated SIR was applied to chromatographic recovery of the two metals and quantitative adsorption–elution was performed via the frontal analysis mode. The adsorption of Pt and Pd was achieved, while adsorption of the co-existing metals in the leaching solution was suppressed. Separation of Pt and Pd was achieved by employing sequential chromatography system together with the quantitative elution of Pt from DHA-SIR with the mixture of 0.5 mol/L thiourea and 0.5 mol/L HCl and that of Pd from DHS-SIR with the mixture of 0.1 mol/L thiourea and 0.5 mol/L HCl solution. Finally, elementary Pt was then obtained from the eluent of sequential chromatography system by simultaneous precipitation and reduction of Pt with sodium borohydride with 99.2% purity.