The selective adsorption of gold (III) and palladium (II) on new phosphine sulphide-type chelating polymers bearing different spacer arms -: Equilibrium and kinetic characterisation

New resins, with a functional group based on triisobutyl phosphine sulphide and containing different spacer arms between the polymeric matrix and the functional group, are evaluated in order to determine and characterise the meechansna of the metal adsorption process. These polymers are selective towards gold and palladium from other noble (Pt, Rh and Ir) and base (Fe, Cu, Ni and Zn) metals. Selectivity is higher in the case of gold (2.8 mmol Au/g resin for polymer 3 and 6.5 for polymer 4) than for palladium (0.5 mmol Pd/g resin for polymer 3 and 0.7 for polymer 3). The application of the Langmuir model to the data permits the determination of the adsorption mechanism, which we found to be a chelating process. The result shows that spacer heteroatoms become involved in the adsorption process. The kinetics of the adsorption is faster for palladium than for gold. The elution elf these two metals is accomplished by the use of sodium nitrite and thiourea as eluting compounds. (C) 2001 Published by Elsevier Science B.V.