A novel phosphine sulphide functionalized polymer for the selective separation of Pd(II) and Au(III) from base metals

Two new insoluble extractant systems based on a derivated polystyrene have been prepared for the separation and recovery of precious metals. This functional polymer has been obtained by the incorporation of a phosphine sulphide on the Merrifield polymer. This incorporation has been made by either direct attachment to the polymer or through on alkyl chain as spacer between the polymeric backbone and the phosphine sulphide unit. The spacer consists of a tris-ethoxylated chain to provide hydrophilic properties. Adsorption of metals Au(III) or Pd(II) from chloride solutions have been studied for the different polymers prepared and by varying the composition of the metal solution with mixed aqueous-dioxane media. The results obtained include the polymer capacity and the rate of metal adsorption. Capacity for Pd(II) has been observed much higher than for Au(III) in all cases. The capacity as well as the adsorption rate are enhanced by the incorporation of the spacer in the polymer and also by the presence of dioxane in the metal solution. On the other hand, the adsorption process has shown to be selective for Au(III) or Pd(II) in presence of the base metals Pb(II), Ni(II) and Cu(II).