Green Nanocellulose/PEI‐Grafted Magnetic Nanoparticles for Effective Removal of Heavy Metal Ions

Abstract

In response to the pressing issue of water pollution caused by heavy metal ions, there is a growing demand for green adsorbents that can effectively remove these contaminants while being easy to separate and regenerate. A novel magnetic composite was synthesized by bonding amino‐functionalized Fe3O4−SiO2 magnetic particles (MNP‐NH2) to polyethyleneimine (PEI)‐grafted cellulose nanofibers (CNF). The modification of CNF with PEI through a peptidic coupling reaction resulted in the uniform dispersion and strong attachment of MNP‐NH2 particles (286.7 nm) onto the PEI‐CNF surface. This composite exhibited exceptional adsorption capabilities for heavy metals, achieving 16.73 mg/g for Pb, 16.12 mg/g for Cu, and 12.53 mg/g for Co. These remarkable adsorption capacities are attributed to the complex interactions between the metal ions and the amino, carboxyl, and hydroxyl groups on the surface of PEI‐CNF‐MNP. The introduction of PEI significantly enhanced the adsorption capacities, and the adsorption sequence (Pb(II)>Cu(II)>Co(II)) can be explained by differences in ionic radius and surface complexation strength. Langmuir isotherm and pseudo‐second‐order kinetic models described the adsorption process, while Na2EDTA was proved effective for desorption with high recovery rates. This magnetic composite holds promise for treating heavy metal‐contaminated wastewater due to its impressive performance.