Preparation of NH₂-Functionalized Fe₂O₃ and Its Chitosan Composites for the Removal of Heavy Metal Ions

NH₂-Fe₂O₃ and NH₂-Fe₂O₃/chitosan (NH₂-Fe₂O₃/CS) with excellent physical properties and high adsorption capacities for several heavy metal ions were synthesized using a one-pot hydrothermal method. The materials were characterized by scanning electron microscopy (SEM), electron dispersive spectroscopy (EDS), transmission electron microscopy (TEM), and X-ray diffraction (XRD). Physicochemical properties were determined by the Fourier transform infrared spectra (FTIR) and nitrogen adsorption analysis (Brunauer-Emmett-Teller (BET) method). The results of the characterization studies show that the material is uniformly dispersed and has good crystallinity and well-defined porous particles. The material is mesoporous, and the particles have a specific surface area of 55.41-233.03m² g^-1, a total pore volume of 0.24-0.54 cm³ g^-1, and a diameter of 3.83-17.56 nm. Additional results demonstrate that NH₂-Fe₂O₃ and NH₂-Fe₂O₃/CS are effective adsorbents for the removal of heavy metal ions from solution. In a ternary system, the order of their selective adsorption was determined to be Pb(II) > Cu(II) > Cd(II), and the adsorption rate of Pb(II) was much higher than that of Cu(II) and Cd (II). The metal ion adsorption capacity of NH₂-Fe₂O₃ and NH₂-Fe₂O₃/CS makes them promising adsorbents for wastewater cleanup.