Synthesis and characterization
Nano-Fe3O4, is produced as previously described [2] by the combination of Fe(II) and Fe(III) in an alkaline solution to form the hydroxide precipitate forms of Fe(OH)2 and Fe(OH)3, respectively. Simultaneous precipitation and adsorption of these two hydroxides occur for the formation of Fe3O4 with the loss of water molecule. The produced nano-Fe3O4 particles can be collected and separated from the aqueous solution by the action of an external magnetic field. The second synthesized sorbent, in this work, is based on the addition and surface encapsulation of nano-Fe3O4 by DOP to form the nano-Fe3O4-DOP sorbent. Finally, the third modified magnetic nano-sorbent was based on the direct reaction of triethylentetramine (TETA), as a nitrogen containing sequestering agent, with nano-Fe3O4-DOP for the formation of a newly synthesized nano-Fe3O4-DOP-TETA sorbent. The three magnetic nano-sorbents were characterized by several instrumental and surface techniques such as thermal gravimetric analysis (TGA), Fourier transform-infrared (FT-IR), scanning electron microscopy (SEM) and high resolution transmission electron microscopy (HR-TEM).