Fabrication of polyethylenimine functionalized magnetic cellulose nanofibers for the sorption of Ni(II), Cu(II) and Cd(II) in single-component and multi-component systems.

Novel polyethyleneimine functionalized cellulose nanofiber magnetic composites (PEI-CNFs@Fe3O4) were prepared using banana peels as the raw materials for the sorption of Ni(II), Cu(II) and Cd(II) in single-component and multi-component systems. The batch experiments, spectral analyses and model fittings were used to reveal the sorption properties. The sorption of Ni(II), Cu(II) and Cd(II) on PEI-CNFs@Fe3O4 all conformed to the Langmuir isotherm and pseudo-second-order kinetic models. And the maximum sorption capacities of PEI-CNFs@Fe3O4 towards Ni(II), Cu(II) and Cd(II) were 134.38, 93.71 and 173.56 mg g-1, respectively. The main sorption mechanism of Ni(II), Cu(II) and Cd(II) on PEI-CNFs@Fe3O4 is the strong surface complexation of the amino, carboxyl and hydroxyl groups with Ni(II), Cu(II) and Cd(II) ions. Especially, the introduction of PEI contributed to the improvement in the sorption capacities of PEI-CNFs@Fe3O4 towards the heavy metals. Besides, the size of the ionic radius and the strength of the surface complexing ability with PEI-CNFs@Fe3O4 are the reasons for the difference in the sorption capacities of Ni(II), Cu(II) and Cd(II) (Cd(II) > Ni(II) > Cu(II)). In conclusion, PEI-CNFs@Fe3O4 has shown the advantages of low cost, simple preparation, easy magnetic separation, environmental friendliness and high sorption capacity, thus having a broad application prospect in the treatment of multi-heavy metals polluted water.