Selective adsorption and recovery of precious metal ions from geological samples by 1,5,9,13-tetrathiacyclohexadecane-3,11-diol anchored poly(p-CMS-DVB) microbeads

Poly(p-chloromethylstyrene-divinylbenzene) polymeric microbeads, poly(p-CMS-DVB), were synthesized and 1,5,9,13-tetrathiacyclohexadecane-3,11-diol was attached chemically to the polymeric microbeads. Characterizations of all microbeads were carried out using FT-IR, TGA, DSC and an elemental analyzer. The amount of 1,5,9,13-tetrathiacyclohexadecane-3,11-diol attached to the polymer was found to be 2.76 mmol/g polymer. These microbeads were used for recovery, preconcentration and the selective adsorption of precious metal ions by changing the pH and the initial metal ion concentrations. Au(III), Ag(I), Pt(II) and Pd(II) from single and competitive solutions were recovered and preconcentrated. High levels of metal ion adsorption were found below pH = 2, even when the pH fell as low as pH = 0.5. Preconcentration factors for the precious metal ions studied were found to be more than 1000-fold and recovery was between 96% and 102%. Selectivity of the modified microbeads followed the order Au(III) > Ag(I) > Pd(II) > Pt(II). In the geological samples and in some samples from water-lands, the ultra-trace precious metal ion concentration was determined easily by using modified microbeads after preconcentration. For the desorption of the precious metal ions, HCl (3 M) containing thiourea (0.8 M) was used and desorption ratio obtained was more than 96%. (c) 2005 Elsevier B.V. All rights reserved.