Synthesis of benzothiazole-based chelating resin for preconcentration of toxic metal ions

Abstract

Polystyrene-divinylbenzene resin (PS-DVB) was functionalized with a benzothiazole group on the surface. PS-DVB with amino group was initially prepared by nitration and reduction reactions and subsequently treated with ethyl 2-benzothiazolyacetate (BA) to obtain the chelating resin with an amide linkage (BA-PS-DVB). On the other hand, the amino-PS-DVB was diazotized and coupled with BA to get the chelating resin with an azolinkage (azo-BA-PS-DVB). The resins were characterized by elemental analysis (EA) and infrared spectroscopy and the evaluated for its extraction of CD(II), Cu(II) and Pb(II) ions in water before their determinations by flame atomic absorption spectrometry (FAAS). Extraction conditions were optimized for batch method such as pH of solution, extraction time, and adsorption isotherm. The optimum pH for the extraction of Cd(II), Cu(II) and Pb(II) are 8.0, 7.0 and 6.0,respectively while the equilibrium time of all three ions were reachedwithin 10-20 minutes. Adsorption behavior of all metal ions followed Langmuir adsorption isotherm. In column method, the optimum flow rates of metal sorption onto BA-PS-DVB and azo-BA-PS-DVB column were 2.5 and 4.0 mL min. Metal ions sorped onto columns were eluted by 0.5 to 2.0 M HNBO[subscript3]. The preconcentratin factors of Cd(II) and Cu(II) on azo-BA-PS-DVB and Cu (II) on BA-PS-DVB were 50, 50 and 20, respectively. The present column method gave good validation results: 71.2 and 74.0% recovery for Cd (II) and Cu(II) and overall % RSD less than 10% (n=15).