Synthesis, characterization and Cr(VI) adsorption properties of modified magnetite nanoparticles

Abstract

In this study, magnetite (Fe3O4) nanoparticles were synthesized by chemical co-precipitation method, coated with silica, and then the surface of silica coated magnetite (Fe3O4@SiO2) nanoparticles was modified with (3-aminopropyl)triethoxysilane (APTES) at first. Secondly, attained nanoparticles were characterized by the Fourier transform infrared, X-ray diffraction, transmission electron microscopy, the Brunauer-Emmett-Teller, vibrating sample magnetometer, and zeta-sizer devices/methods. Finally, detailed adsorption experiments were performed to remove hexavalent chromium (Cr(VI)) from aqueous media by synthesized nanoparticles. Mean size and specific surface area of synthesized nanoparticles were about 15 nm and 89.5 m2/g, respectively. The highest adsorption capacity among used adsorbents (Fe3O4, Fe3O4@SiO2, Fe3O4@SiO2@L) was attained by Fe3O4 nanoparticles and it was determined that adsorption capacity of the other two adsorbents was too low when compared to the Fe3O4 nanoparticles. Optimum conditions for Cr(VI) adsorption by Fe3O4 nanoparticles were: pH, 3; temperature, 55°C; contact time, 90 min; adsorbent concentration, 0.5 g/l and initial Cr(VI) concentration 10 mg/l. Under these conditions, adsorption capacity and removal percentage of Cr(VI) were found to be 33.45 mg/g and 88%, respectively.