Chemically modified silica gel with aminothioamidoanthraquinone for solid phase extraction and preconcentration of Pb(II), Cu(II), Ni(II), Co(II) and Cd(II).

Silica gel chemically bonded with aminothioamidoanthraquinone was synthesized and characterized. The metal sorption properties of modified silica were studied towards Pb(II), Cu(II), Ni(II), Co(II) and Cd(II). The determination of metal ions was carried out on FAAS. For batch method, the optimum pH ranges for Pb(II), Cu(II) and Cd(II) extraction were >/=3 but for Ni(II) and Co(II) extraction were >/=4. The contact times to reach the equilibrium were less than 10min. The adsorption isotherm fitted the Langmuir's model showed the maximum sorption capacities of 0.56, 0.30, 0.15, 0.12 and 0.067mmol/g for Pb(II), Cu(II), Ni(II), Co(II) and Cd(II), respectively. In the flow system, a column packed modified silica at 20mg for Pb(II) and Cu(II), 50mg for Cd(II), 60mg for Co(II), Ni(II) was studied at a flow rate of 4 and 2.5mL/min for Ni(II). The sorbed metals were quantitatively eluted by 1% HNO(3). No interference from Na(+), K(+), Mg(2+), Ca(2+), Cl(-) and SO(4)(2-) at 10, 100 and 1000mg/L was observed. The application of this modified silica gel to preconcentration of pond water, tap water and drinking water gave high accuracy and precision (%R.S.D.</=9). The method detection limits were 22.5, 1.0, 2.9, 0.95, 1.1mug/L for Pb(II), Cu(II), Ni(II), Co(II) and Cd(II), respectively.