Preparation of Extractant-Impregnated Fiber for Recovery of Palladium from Hydrochloric Acid Solution

For recovery of palladium (Pd) from a hydrochloric acid medium, dioctyl sulfide (DOS), a neutral extractant capable of specifically capturing Pd anionic species, was impregnated onto a hydrophobic ligand-containing polymer chain grafted onto 6-nylon fiber, using radiation-induced graft polymerization. The hydrophobic ligand was the dodecanethiol (C12S) moiety, which functions both in the impregnation of DOS via hydrophobic interaction and in the direct uptake of Pd species by a similar mechanism as DOS. The C12S group was immobilized at a density of 2.0 mmol/g through its reaction of C12S with the epoxy group of the poly-glycidyl methacrylate (GMA) chain grafted onto the nylon fiber, and DOS was impregnated onto the resulting fiber at a density of 0.40-1.1 mmol/g. For example, fiber impregnated with DOS at a density of 0.40 mmol/g possessed a saturation capacity of 0.70 mmol-Pd/g in 1 mol/L HCl. The molar binding ratios of Pd to impregnated DOS and immobilized C12S were calculated as 0.50 and 0.27, respectively. In addition, the DOS-impregnated fiber specifically captured Pd species from a mixture solution of Pd and platinum (Pt) species in 1-4 mol/L HCl.