Synthesis of Nano - Fe⁰ / PEI Composite and Its Reduction and Chelation Mechanisms for Cr(VI) from Aqueous Solution

In this paper, a nano-Fe0/polyethyleneimine (PEI) composite was synthesized via nano-Fe0 and PEI cross-linked by glutaraldehyde. The removal rate of Cr(VI) by nano-Fe0/PEI composite was investigated and compared with that of Pb(II) and Ni(II). The effects of reacting time, dosage, initial concentration, pH value, and coexisting heavy metal on removal rates of Cr(VI), Pb(II), and Ni(II) are discussed. The characteristics of nano-Fe0/PEI composite and its removal mechanism for Cr(VI) were analyzed by scanning electron microscope (SEM), Fourier transform infrared (FTIR) spectroscopy, and X-ray diffraction (XRD). The results show that the removal rate of Cr(VI) (92.6%) by nano-Fe0/PEI composite is obviously higher than that of Pb(II) (60.2%) and Ni(II) (23.8%). nano-Fe0/PEI composite is effective for Cr(VI) removal. The heavy-metal ions coexisting in the mixture solution have a remarkable effect on the removal of Cr(VI). The paper concludes that Cr(VI) was reduced into Cr(III) by nano-Fe0 before chelating with PEI.