Preparation Of Magnetite Composites And Their Fenton-like Catalytic Performance

Wastewater containing non-biodegradable organic contaminants shows high toxicity and recalcitrant,which has adverse effects on aquatic life and human health.The heterogeneous Fenton-like process is very attractive for degradation of non-biodegradable organic contaminants from waster water,because of its high activity,simplicity of technology,mild reaction conditions and inexpensive catalyst.However,the rate of heterogeneous Fenton reaction and the stability of catalyst should be further improved.Iron-based compounds are commonly used as heterogeneous Fenton catalyst,Fe₃O₄ has the advantages of earth-abundance,low cost,environmental friendly and excellent magnetic performance,which implicate its role in wastewater treatment field.Adjust the structure and combine with other materials for the Fe₃O₄ catalyst,which can greatly enhance the catalytic activity and stability.The details research contents of this thesis are shown as follows:Fe-Cu composites with different compositions??-Fe2O3/CuO,?-Fe2O3/CuO and Fe₃O₄/C/Cu?and morphologies were synthesized by a hydrothermal method combined with precursor thermal transformation.The Fe₃O₄/C/Cu composite was obtained by calcining under N2 atmosphere at 500 °C,possessed mesoporous structure and large surface area up to 133 m2 g-1.The Fenton catalytic performance of Fe₃O₄/C/Cu composite was closely related to the Fe/Cu molar ratio,and only proper amounts of Fe and Cu exhibited a synergistic enhancement in Fenton catalytic activity.Cu inclusion reduced Fe3+ to Fe2+,which accelerated the Fe3+/Fe2+ cycles and favored H2O₂ decomposition to produce more hydroxyl radicals for methylene blue?MB?oxidation.Due to the photo-reduction of Fe3+ and Cu2+,the Fenton catalytic performance was greatly improved when amending with visible light irradiation in the Fe₃O₄/C/Cu-H2O₂ system,and MB?100 mg L-1?was nearly removed within 60 min.The Fe₃O₄/C/Cu composite showed good recyclability and could be conveniently separated by an applied magnetic field.Magnetic Fe₃O₄/CeO₂ composites with highly ordered mesoporous structure and large surface area were synthesized by impregnation-calcination method,and the mesoporous CeO₂ as support was synthesized via the hard template approach.The mesoporous Fe₃O₄/CeO₂ composite played a dual-function role as both adsorbent and Fenton-like catalyst for removal of organic dye.The methylene blue?MB?removal efficiency of mesoporous Fe₃O₄/CeO₂ was much higher than that of irregular porous Fe₃O₄/CeO₂.The superior adsorption ability was attributed to the abundant oxygen vacancies on the surface of CeO₂,high surface area and ordered mesoporous channels.The good oxidative degradation resulted from high Ce3+ content and the synergistic effect between Fe and Ce.The mesoporous Fe₃O₄/CeO₂ composite presented very low iron leaching?0.22 mg L-1?,which could be ascribed to the strong metal-support interactions for dispersion and stabilization of Fe species.In addition,the composite can be easily separated from reaction solution with an external magnetic field due to its magnetic property.