Thesis (M.Sc. )--Chulalongkorn University, 2008

The anion exchange resin was successfully loaded with piperazinedithio- carbamate via anion exchange mechanism. The new synthesized complexing resin was characterized by IR spectroscopy. The loading capacity of complexing ligand onto resin at pH 5 during loading times of 8 min was found to be 3.5 µmol g-1. The separation of the metal ions as Ag(I), Cu(II), Pb(II) and Au(III) was studied in batch method. The optimum pHs for the sorption of Ag(I) and Cu(II) were found to be 7 and 2, respectively. The optimum pH of Pb(II) and and Au(III) of 5 was obtained. The suitable contact time of Ag(I) and Pb(II) were found to be at 15 and 20 min, respectively. While Cu(II) and Au(III) showed long sorption kinetic within 60 min. The sorption behaviors of all metal ions fit well to the Langmuir’s model and the sorption capacities in the order of Pb(II) > Ag(I) > Cu(II) > Au(III) were observed with the maximum sorption capacities of 81.1, 74.2, 43.5 and 21.9 µmol g-1, respectively. For the flow system, the separation and preconcentration of Ag(I) and Pb(II) were studied. The optimum sample flow rates of Ag(I) and Pb(II) were obtained at 3.0 and 4.0 mL min-1, respectively. The elution of Ag(I) was achieved by using 5.0 mL of 0.5 mol L-1 thiourea in 1 mol L-1 HCl at the flow rate of 0.25 mL min-1 and the Pb(II) was desorbed by 5.0 mL of 0.2 mol L-1 EDTA in 0.1 mol L-1 HCl at the flow rate of 1.0 mL min-1. The preconcentration factor of 10 and 50 for Ag(I) and Pb(II) were obtained, respectively. Coexisting cations such as Na+, K+ and Ca2+ did not affect the recoveries of metal ions in comparison with cation exchange resin. The proposed method can be applied to preconcentrate Ag(I) and Pb(II) from tap water and sea water with spiked sample method before determination of Ag(I) and Pb(II) with FAAS resulting in high accuracy and precision.