Grafting of poly[1-(N,N- bis-carboxymethyl)amino-3-allylglycerol- co-dimethylacrylamide] copolymer onto siliceous support for preconcentration and determination of lead (II) in human plasma and environmental samples

Abstract

A method is reported for surface grafting of polymer containing a functional monomer for metal chelating, poly[1-(N,N- bis-carboxymethyl)amino-3-allylglycerol- co-dimethylacrylamide] (poly(AGE/IDA- co-DMAA) onto silica modified by silylation with 3-mercaptopropyltrimethoxysilane. Monomer 1-(N,N- bis-carboxymethyl)amino-3-allylglycerol (AGE/IDA) was synthesized by reaction of allyl glycidyl ether with iminodiacetic acid. The resulting sorbent has been characterized using FT-IR, elemental analysis, thermogravimetric analysis (TGA), FT-Raman and scanning electron microscopy (SEM) and evaluated for the preconcentration and determination of trace Pb(II) in human biological fluid and environmental water samples. The optimum pH value for sorption of the metal ion was 5.5. The sorption capacity of functionalized resin was 15.06 mg g −1. The chelating sorbent can be reused for 15 cycles of sorption–desorption without any significant change in sorption capacity. A recovery of 96.2% was obtained for the metal ion with 0.5 M nitric acid as eluting agent. The profile of lead uptake by the sorbent reflects good accessibility of the chelating sites in the poly(AGE/IDA- co-DMAA)-grafted silica gel. Scatchard analysis revealed that the homogeneous binding sites were formed in the polymers. The equilibrium adsorption data of Pb(II) by modified resin were analyzed by Langmuir, Freundlich, Temkin and Redlich–Peterson models. On the basis of equilibrium adsorption data the Langmuir, Freundlich and Temkin constants were determined as 0.70, 1.35 and 2.7, respectively at pH 5.5 and 20 °C. Isotherms have also been used to obtain the thermodynamic parameters such as free energy, enthalpy and entropy of adsorption.