Highly efficient removal of Cu(ii) from aqueous solution using a novel magnetic EDTA functionalized CoFe2O4

Abstract

CoFe₂O₄ exhibits excellent chemical stability and saturation magnetization; consequently, it has been prepared for and applied to contaminant adsorption. However, the material demonstrated a relatively low adsorption capacity due to agglomeration and the lower amount of active sites for pollutants. In this study, we have developed a facile one-pot route to synthesize EDTA functionalized superparamagnetic CoFe₂O₄ nanoparticles (denoted as EDTA-MNP) to adsorb Cu(II) ions from aqueous solution. The physico-chemical properties of the obtained materials were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), vibrating sample magnetometer (VSM) analysis, Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS) and the Brunauer–Emmett–Teller (BET) surface area method. Then, the effects of EDTA mass in EDTA-MNP, adsorbent dosage, initial solution pH, temperature and coexisting cations were measured systematically through batch experiments to evaluate the adsorption performance of Cu(II) ions onto EDTA-MNP nanoparticles. The results indicated that the adsorption efficiency of the CoFe₂O₄ for Cu(II) was negligible, while the value for EDTA-MNP was highly improved, which was due to the special affinity of carboxylic groups on the EDTA-MNP surface for Cu(II) in solution. Kinetic experiments suggested that the pseudo-second-order model showed the best correlation with the adsorption data. Equilibrium data were best described by the Langmuir model, and the estimated maximum adsorption capacity of EDTA-MNP was 73.26 mg g⁻¹ at 323 K, displaying a higher efficiency for Cu(II) removal than previously reported adsorbents. The present work indicated that the EDTA-MNP composite can be an effective and potential adsorbent for removing Cu(II) ions from aqueous solution, and it also provided a very effective way to improve the adsorption affinity of metallic contaminants onto ferrite or other metal oxides.