Preparation of magnetic MgO/Fe3O4 via the green method for competitive removal of Pb and Cd from aqueous solution

The current work focused on the development of magnesium oxide – based adsorbent for heavy metal removal. Magnetic MgO/Fe3O4 composite was prepared using lysine as a binding agent. The as-prepared adsorbents were characterized using Fourier transform infrared (FTIR) spectroscopy, Transmission electron microscopy (TEM), zeta potential, x-ray diffraction (XRD), Vibrating sample magnetometer (VSM), and specific surface measurement. The adsorption efficiency of MgO, Lysine-modified MgO and magnetic MgO /Fe3O4 composite were determined through Pb(II) and Cd(II) removal from aqueous solution. The effect of pH (2–12), adsorbent dosage (0.3–1.5 g/l) and contact time on adsorption efficiency were investigated. The results showed that maximum efficiency was obtained in the presence of 0.5 g/l of the adsorbent. Additionally, it was found that the pseudo second-order model interpreted the kinetic of adsorption on as-prepared adsorbents. Competitive adsorption of Pb(II)-Cd(II) multi-component solution were studied at different feed concentration. Compared to single-component systems, the adsorption efficiency of Cd(II) was reduced by 33, 19, and 4 % for MgO, lysine modified MgO and magnetic MgO/Fe3O4 composite, respectively. For adsorption of Pb(II) ion, Cd(II) showed inhibition effect only on lysine-modified MgO. The experimental competitive adsorption data were adequately fitted on extended Langmuir isotherm.