Analytical Sciences

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

Wanlapa AEUNGMAITREPIROM, Wittaya NGEONTAE, and Thawatchai TUNTULANI

Department of Chemistry, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand

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 μmol 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 μg L⁻¹ for Pb(II) and Cu(II), respectively.

J-STAGE: View this article in J-STAGE