Magnetite (Fe₃O₄) nanoparticles as adsorbents for As and Cu removal

The aim of this study consisted to develop novel synthetic magnetite nanoparticles (nFe₃O₄) with preferential reactivity to trace elements (TE) for possible environmental applications as adsorbents. The synthetic magnetite materials obtained through the co-precipitation of both Fe^{3 +} and Fe^{2 +} ions (Fe^{2 +} / Fe^{3 +} = 0.5) were characterized by a set of complementary techniques: X-ray diffraction, transmission and scanning electron microscopy, Fourier transform infrared and Raman spectroscopy, and BET adsorption method. The resulting nFe₃O₄ displayed a wide specific surface area (100 m² g^{− 1}) with particles reaching a size of about 10 nm, smaller than those of the well-crystallized commercial ones (cFe₃O₄) estimated at 80 nm while showing a BET surface area of 6.8 m² g^{− 1}. The adsorption properties of the synthetic nFe₃0₄ magnetite nanoparticles were characterized and compared to the commercial analogous with the adsorption of both As and Cu. The equilibrium adsorption isotherms were properly fitted with Langmuir and Freundlich equation models and suggested that the developed iron oxides nanoparticles display a certain potential for removal and/or immobilization of TE from contaminated waters and/or soils, with an increase of 69.5% of the adsorbed amount compared to that of the commercial ones.