Effect of pH on the removal of copper ions from aqueous solutions using iron oxide nanoparticles and iron oxide/ hydroxyapatite nanocomposites

In this study, iron oxide nanoparticles and iron oxide/hydroxyapatite nanocomposites were synthesized by co-precipitation method. The samples were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), Fourier transform infrared spectroscopy (FT-IR) and vibrating sample magnetometer (VSM). The XRD patterns of the samples confirm the hexagonal structure of hydroxyapatite and tetragonal structure of maghemite. FESEM results showed that both kinds of the prepared samples are almost spherical shape and the average particle sizes are 16±1 nm and 19±2 nm for iron oxide and iron oxide/hydroxyapatite nanocomposite, respectively. FTIR spectroscopy reveals expected bonds formation. Hysteresis curves of the nanoparticles showed that the coercivity of the nanoparticles is almost zero and the nanoparticles exhibit superparamagnetic behavior. The saturation magnetization of the iron oxide nanoparticles was obtained 14.98 emu/g, while the saturation magnetization of the iron oxide/ hydroxyapatite nanocomposites was reduced to 2.83 emu/g. Finally the produced nanoparticles were used as adsorbents for the removal of copper ions from aqueous solutions. In order to compare the ability of iron oxide nanoparticles and iron oxide/ hydroxyapatite nanocomposites to remove copper ions from the aqueous solutions, efficiency and capacity adsorbtion of copper ions by the particles at different pH were determined.