Polyethyleneimine functionalized magnetic nanocluster for removal of heavy metal ions in water

Polyethyleneimine (PEI) functionalized magnetic nanoclusters (MNCs) were fabricated for the removal of heavy metal ions and rapid magnetic separation of absorbent from contaminated water. After the MNCs, composed of aggregates of small primary Fe3O4 nanoparticles with a size of 6.2 nm, were synthesized by one-step hydrothermal method, they were covalently coated with PEI via a simple silane coupling reaction. The resulting PEI-functionalized MNCs (PEI-MNC) had an average diameter of 264.1 nm and showed rapid separation from water by an external magnet. The adsorption behavior of PEI-MNC for heavy metal ions fits well with the Langmuir isotherm models, and their maximum adsorption capacity was 33.11, 11.05, and 9.80 mg/g for Cu2+, Zn2+, and Co2+, respectively. Competitive adsorption among these three metal ions was carried out to investigate the adsorption tendency of PEI-MNC between them. Furthermore, the desorption and stability test of Cu(2+)loaded PEI-MNC in 0.1 M HCl were also investigated to evaluate their reusability for practical application.