Atomic layer deposition of γ-Fe2O3 nanoparticles on modified MWCNT for efficient adsorption of Cr(VI) ions from aqueous solution

gamma-Fe2O3 nanoparticles were deposited on the surface of multiwalled carbon nanotubes (MWCNT) by atomic layer deposition, followed by polyethyleneimine (PEI) surface modification, and the amine groups on the MWCNT were confirmed by Fourier transform infrared spectroscopy. MWCNT/gamma-Fe2O3 samples both with and without PEI surface decoration were used to remove Cr(VI) in water by adsorption. The adsorption results indicate that PEI-decorated MWCNT/gamma-Fe2O3 has 42.8% higher adsorption efficiency than MWCNT/gamma-Fe2O3 without surface modification, which was attributed to the chelation and complexation of amine groups with Cr(VI). The magnetization from gamma-Fe2O3 also contributed to efficient separation of the nanocomposite from solution. Moreover, the adsorption behaviors were also studied by Langmuir and Freundlich isotherm models.