Methacryloylamidoglutamic acid incorporated porous poly(methyl methacrylate) beads for heavy-metal removal

Poly(methyl methacrylate-methacryloylamidoglutamic acid) beads (average diameter 150-200 mum) were prepared by copolymerizing methyl methacrylate (MMA) with methacryloylamidoglutamic acid (MAGA). Poly(MMA-MAGA) beads were characterized by swelling and surface area studies, scanning electron microscopy, and elemental analysis. These porous beads with a swelling ratio of 36.4% and containing 696 mumol of MAGA/g were used for heavy-metal removal involving cadmium, mercury, and lead. Poly(MMA-MAGA) beads have a specific surface area of about 67.8 m(2)/g. Metal adsorption results were found to be a function of solution properties (i.e., medium pH and metal concentration) and the types of metals to be adsorbed. We have obtained adsorption capacities as 29.9 mg/g (149 mumol/g) for Hg(II), 28.2 mg/g (250 mumol/g) for Cd(II), and 65.2 mg/g (314 mumol/g) for Pb(II). The adsorption capacities on an observed molar basis were in the order of Pb(II) > Cd(II) > Hg(II). Adsorption of heavy-metal ions from synthetic wastewater was also studied. The adsorption capacities are 22.4 mg/g for Hg(II), 24.2 mg/g for Cd(II), and 52.6 mg/g for Pb(II) at 0.5 mmol/L initial metal concentration. Of course, depending on the desired goals, the beads containing metal could be regenerated for appropriate disposal. Our results suggest that poly(MMA-MAGA) beads can be good metal adsorbers and have great potential applications in environmental protection.