Synthesis and characterization of poly(hydroxyethyl methacrylate-N-methacryloyl-(l)-glutamic acid) copolymer beads for removal of lead ions

N-methacryloyl-(l)-glutamic acid (MAGA) was synthesized using methacryloyl chloride and l-glutamic acid methyl ester as a metal-complexing ligand and/or comonomer. MAGA was characterized by FTIR and NMR. Spherical beads with an average diameter of 150-200 μm were obtained by suspension polymerization of MAGA and 2-hydroxyethyl methacrylate (HEMA) performed in an aqueous dispersion medium. Poly(HEMA-MAGA) beads were characterized by swelling studies, surface area measurements and elemental analysis. Poly(HEMA-MAGA) beads have a specific surface area of 56.7 m2/g. Poly(HEMA-MAGA) beads were used in the removal studies of Pb2+ ions. Adsorption equilibrium was achieved in about 60 min. The adsorption of Pb2+ ions onto PHEMA beads was negligible (0.38 mg/g). The MAGA incorporation into the polymer structure significantly increased the lead adsorption capacity (348 mg/g). The adsorption of Pb2+ ions increased with increasing pH and reached a plateau value at around pH 5.0. Competitive adsorption of heavy metal ions from synthetic wastewater was also studied. The adsorption capacities are 42.5 mg/g for Pb2+, 26.8 mg/g for Hg2+ and 17.6 mg/g for Cd2+ at 0.5 mmol/l metal concentration. Consecutive adsorption and elution operations showed the feasibility of repeated use for poly(HEMA-MAGA) chelating beads.