Heavy metal removal from synthetic solutions with magnetic beads under magnetic field

The aim of this study is to prepare magnetic beads which can be used for the removal of heavy metal ions from synthetic solutions. Magnetic poly(ethylene glycol dimethacrylate-vinyl imidazole) [m-poly(EGDMA-VIM)] beads were produced by suspension polymerization in the presence of magnetite Fe3O4 nano-powder. The specific surface area of the m-poly(EGDMA-VIM) beads was found to be 63.1 m(2)/g with a size range of 150-200 m in diameter and the swelling ratio was 85%. The average Fe3O4 content of the resulting m-poly(EGDMA-VIM) beads was 12.4%. The maximum binding capacities of the m-poly(EGDMA-VIM) beads were 32.4 mg/g for Cu2+, 45.8mg/g for Zn2+, 84.2 mg/g for Cd2+ and 134.5 mg/g for Pb2+. The affinity order on mass basis is Pb2+ > Cd2+ > Zn2+ > Cu2+. Equilibrium data agreed well with the Langmuir model. pH significantly affected the binding capacity of the magnetic beads. Binding of heavy metal ions from synthetic wastewater was also studied. The binding capacities were 26.2 mg/g for Cu2+, 33.7 mg/g for Zn2+, 54.7 mg/g for Cd2+ and 108.4 mg/g for Pb2+. The magnetic beads could be regenerated up to about 97% by treating with 0.1 M HNO3. These features make m-poly(EGDMA-VIM) beads a potential candidate for support of heavy metal removal under magnetic field.