Adsorption behaviours of copper(II), lead(II), and cadmium(II) ions from aqueous solution by polyethylenimine -modified magnetic hydrogel nanocomposites

A series of novel polyethylenimine (PEI)-modified magnetic hydrogel nanocomposites (PEI-mHNs) for heavy metal ions removal were prepared by copolymerization of acrylamide, acrylic acid and PEI-modified magnetic nanoparticles using polyethylene glycol diacrylate as chemical crosslinker and PEI-modified magnetic nanoparticles as physical crosslinker. FTIR and XRD results preliminarily confirmed the target structure of PEI-mHNs without destroying the structure of magnetic nanoparticles during modification and radical copolymerization. PEI-mHNs have rough and uneven surface with many porous and gap structure, which makes the rapid adsorption rate and high adsorption capacity of heavy metal ions(Cu(II) (150 mg/g), Cd(II) (236.7 mg/g) and Pb(II) (371.4 mg/g). The adsorption capacity of PEI-mHNs could be improved by increasing the pH of the original solution and initial concentration of heavy metal ions. Heavy metal ions adsorption isotherms and kinetics conformed to the Langmuir model and pseudo-second-order kinetic model, respectively. Besides, PEI-mHNs had good magnetic responsiveness, desorption and reusability which made them potential materials to remove heavy metal ions from the aqueous solution.