Magnetite nanoparticles are an exceptional adsorbent materials due to their magnetic properties and good adsorption capacity. The aim of this work is to investigate the suitability of magnetite nanoparticles for adsorption of heavy metal cation and its efficiency. Magnetic iron oxide nanoparticles were successfully prepared by a coprecipitation method followed by modification with 3-aminopropyl triethoxysilane (APTES) and acryloyl chloride (AC) subsequently. Then the surface of modified nanoparticles was modified by graft polymerization with acrylic acid. The grafted magnetite nanoparticles were next used for separation of heavy metal cations. The adsorption of heavy metal cations from aqueous solution by polyacrylic acid grafted onto magnetite nanoparticles was studied too. The ability of heavy metal adsorption of these nanoparticies for removal from aqueous solutions was measured with atomic absorption technique and they showed their potential for the separation of heavy metal cations such as Cd2+, Pb2+, Ni2+ and Cu2+. The obtained nanoparticles were characterized by X-ray diffraction (XRD). scanning electron microscopy (SEM). vibrating sample magnetometer (VSM), Fourier transform infrared (FT-IR), thermogravimetric analysis (TGA) and DSC analyses with the size ranging from 10 to 23 nm. The magnetite nanoparticles exhibited superparamagnetism above 300 K and the saturation magnetization was 57.1 emu/g at 300 K. (C) 2010 Elsevier B.V. All rights reserved.