Stepwise grafting polyethyleneimine onto silica surface for Cu(II) removal

Polyethyleneimine (PEI) is a novel polymer that contains multiple amine groups that are suitable for chelation with many heavy metal ions (HMI). Anchoring PEI onto the surface of a solid substrate has been widely adopted to develop adsorbent materials with the hope of combining the HMI chelating ability of PEI with the heterogeneity of the substrate. Herein, the preparation of PEI grafted SiO2 (PEI/SiO2) has been demonstrated by a stepwise method in which SiO2 nanoparticles were functionalized with 3-glycidoxypropyltrimethoxysilane (KH560) followed by refluxing with PEI. The method could provide PEI/SiO2 material with 23.4% of PEI by weight. Studying the adsorption properties of PEI/SiO2 with Cu(II) revealed that the adsorption of Cu(II) ions on PEI/SiO2 followed Langmuir and Dubinin-Radushkevich models and included both chemisorption and physisorption. The adsorption capacity was about 25.3-27.3 mg/g. The stepwise method demonstrated in this study may be adopted to fabricated PEI based materials for HMI removal.