A facile one-pot synthesis of monodisperse ring-shaped hollow Fe ₃O₄ nanospheres for waste water treatment

Monodisperse ring-shaped hollow Fe₃O₄ nanospheres with an average diameter of 150 nm were synthesized using a facile one-pot solvothermal method with NH₄Ac as a precipitation agent without any other additives. The results showed that the as-prepared product was composed of aggregated nanoparticles and possessed open holes on the shell; thus, the nanosphere exhibited a hierarchical porous structure. The surface area of the as-prepared product was significantly enhanced compared with that of the solid sample. Moreover, the nanosphere exhibited excellent magnetic properties with high saturation magnetization. When tested as an adsorbent for organic pollutant in waste water treatment, the as-prepared product exhibited rapid adsorption rate, high adsorption efficiency, and quick magnetic separation with the help of an external magnetic field.