(513dz) A Green Process for Facile One-Pot Synthesis of Nickel Ferrite Anchored on Reduced Graphene Oxide for Water Treatment

Spinel ferrite nanocomposites have captivated the interest of researchers owing to their unique physicochemical properties allowing the magnetic nanocomposites to be utilized for adsorbents and photocatalysts in water remediation. More recently, magnetic ferrite nanoparticles are incorporated with graphene-related materials such as graphene oxides (GOs) and reduced graphene oxides (rGOs), not only to support the nanoparticles, but to strengthen the ability to adsorb both inorganic/heavy metal and organic contaminants due to their high oxygen containing surface functionalities, large theoretical surface areas, and relatively high hydrophilicities. The magnetic characteristics and catalytic activity of anchored ferrite nanoparticles are also likely to be enhanced in favor of GO/rGO. As per the synthetic route, co-precipitation and solvothermal techniques have been the majority so far. The drawbacks of these conventional techniques are in need of vast improvement including the usage of organic solvents/toxic chemicals, which does not fit for its future use in water treatment, and long preparation time (>12 hrs).

In this research, a green process for facile one-pot synthesis of nickel ferrite anchored on reduced graphene oxide (rGONF) using supercritical water was proposed. A mixed aqueous solution of Ni(NO₃)₂, Fe(NO₃)₃ and GO was used as the starting materials. The reaction was initiated by immersing a lab-scale batch reactor into the molten salt bath. After a predefined time, the reactor was quenched to stop the reaction. The characterization of synthesized rGONF was conducted by XRD, TEM-EDX, FT-IR, TG and MPMS.

The results have clearly indicated the in-situ formation of uniform and highly crystalline NiFe₂O₄ nanoparticles on the basal plane surface of rGO with in an extremely short time (15 min). MPMS results illustrated a typical superparamagnetic property with the saturation magnetization of 34 emu/g. Lastly, the synthesized rGONF showed satisfactory methyl orange removal ability for the water treatment test, while retaining its magnetic property.