Silica Gel Chemically Modified with Ethyl-2-benzothiazolylacetate for Selective Extraction of Pb(II) and Cu(II) from Real Water Samples

A silica-gel chemically modified with ethyl-2-benzothiazolylacetate (SiB) has been synthesized and characterized. The extractions towards Pb(II), Cu(II), Co(II), Cd(II) and Ni(II) were carried out in batch extraction. The maximum extraction was found at pH > 4 within 10 min. The maximum adsorption capacities, evaluated from Langmuir's model were 221, 141, 13, 7 and 5 mu mol g(-1) for Pb(II), Cu(II), Co(II), Cd(II) and Ni(II), respectively. Home-made mini-columns were used in the flow system. The parameters that affected the extraction efficiency were explored. Sample volumes of 100.0 mL and 1% HNO3 of 5.0 mL as the eluent were employed under the optimized conditions. No interfering from Na+, K+, Mg2+, Ca2+, Cl- and SO42- was observed. This modified silica gel was applied to preconcentrate Pb(II) and Cu(II) from spiked pond water, tap water and drinking water, giving high accuracy and precision. The method detection limits obtained from the desorbed metals determined by FAAS after preconcentration with SiB were 22 and 1 mu g L-1 for Pb(II) and Cu(II), respectively.