S, n-containg-silica for nobel metal analysis in natural and wastewater

Abstract

Selective pre-concsntration of a trace amount of heavy and noble metal ions is usually performed with the use of compisxing sorbents, including organo-silicas. The wide variety of modified S,N-containing silicas are known. They show great affinity to the several heavy metal ions. However, most of them are unstable, sines having easily oxidized SH-groupi. The purpose of current research is application of stabile S.N>containlng orgsno-slllca with covalently immobilized propylthloethyleamlne (SN-Si02) for pre-concentration and analysis of some heavy and noble metal ions. It was demonstrated that SN-SI02 effectively binds some metal ions, such as Au, Pd, Hg, Pb, Cd, Ou etc. Adsorption properties of SN-SI02 at different conditions, such as solution pH (ranging from 0 to 8), metal concentrations (ranging from 50 mkmol to 1 mmol) and contact time (ranging from 5 minutes to 30 minutes) was studied. Peversibility of the process was also controlled. The results presented, demonstrate that SN-SI02 is an efficient adsorbent for selective pre-concentration of lead, copper, zinc, cadmium, palladium, silver and gold from wastewater. The Cu, Pb, Cd and Zn ions can be completely removed from water at pH 6-7, followed by acid elution and finally analysed by atomic-absorption technique. The Au, Ag and Pd ions can be selectively remover at pH 1-3, followed by 10% thiourea desorption and further determination by atomic-absorption technique. The developed method 1$ successfully applied for the analysis of natural and drinking water ^or Cu, Zn, Cd, Pb and Ag with detection limits of0.0021pg ml-1,2.19 10-4pg ml-1, S.69-10-4pg ml-1, 0.0076pg ml-1, 0.OOSpg ml-1 respectively) and wastewater (for Au and Pd with detection limit 0.01 pg ml-1, 0.OSpg ml-1 respectively).