Iminodiacetic acid-containing polymer brushes grafted onto silica gel for preconcentration and determination of copper(II) in environmental samples

摘要

Silica gel has been modified by silylation with 3- mercaptopropyltrimethoxysilane followed by graft polymerization of dimethylacrylamide and (N,N-bis-carboxymethyl)amino-3-allylglycerol-co- dimethylacrylamide, synthesized via the reaction of allyl glycidyl ether with iminodiacetic acid. The sorbent, poly(AGE/IDA-co-DMAA)-grafted silica gel, has been characterized by FTIR, elemental analysis, thermogravimetric analysis (TGA), FT-Raman, and scanning electron microscopy and studied for the preconcentration and determination of trace amounts of Cu(II) ion in environmental water samples. The optimum pH value for quantitative sorption of Cu(II) in batch mode was 5.5 and desorption was achieved, using 0.5 mol L ~(-1) nitric acid. The sorption capacity of functionalized sorbent is 32.3 mg g ~(-1). The chelating sorbent was reused for 15 sorption-desorption cycles without any significant change in sorption capacity. The profile of copper uptake by the sorbent reflected good accessibility of the chelating sites in the poly(AGE/IDA-co-DMAA)-grafted silica gel. Scatchard analysis demonstrated homogeneous nature of binding sites. The equilibrium adsorption data of Cu(II) on modified sorbent were analyzed by Langmuir, Freundlich, Temkin, and Redlich-Peterson models. Based on equilibrium adsorption data, the Langmuir, Freundlich, and Temkin constants were determined as 0.0665, 4.26, and 8.34, respectively, at pH 5.5 and 20°C. Adsorption isotherms were analyzed at different temperatures to obtain free energy, enthalpy, and entropy of adsorption. The method was applied for Cu(II) determination in sea water samples.