Application of a Chelate Forming Calix[4]arene-o-vanillinthiosemicarbazone Resin to the Separation,Preconcentration and Trace Determination of Cu(II), Cd(II) and Pb(II) in Natural Water Samples

A very stable calixarene-based polymeric chelating resin has been synthesized by covalently linking calix[4]arene-o-vanillinthiosemicarbazone through its lower rim to Merrifield resin. It was characterized by FT IR, ¹H NMR and elemental analysis. The resin was efficiently employed to separate and preconcentrate toxic metal ions such as Cu(II), Cd(II) and Pb(II) in a column prior to their determination by UV-Vis spectrophotometry and atomic absorption spectrophotometry (GFAAS) with a relative standard deviation ranging between 1.0–1.4%. Various physico-chemical parameters such as pH, concentration of eluting agents, flow rate, total sorption capacity, metal-ligand stoichiometry, exchange kinetics, preconcentration factor, distribution coefficient, breakthrough capacity, resin stability, effect of electrolytes and associated metal ions have been studied. Uptake and stripping of these metal ions on the resin were fast, indicating better access of the metal ions to the chelating sites. Detection limits (3_B) of 4.22µgL^–1, 11.89µgL^–1 and 19.61µgL^–1, along with preconcentration factors of 100, 125 and 111 for Cu(II), Cd(II) and Pb(II), respectively, were achieved. The proposed method was successfully applied to the separation and trace determination of Cu(II), Cd(II) and Pb(II) from natural water samples of Ahmedabad city.