Research On The Preparation And Mechanism Of Modified Fenton-Like Catalyst

With the development of industrialization,various organic wastewater pollutants have been discharged to our environment,which has endangered human health and the environment.Until now,many traditional and advanced approaches have been applied for the remediation of organic contaminated effluents or sites.In spite of this,these approaches still need to be upgraded for more cost-effective and environmental compatibility.In addition,further studies are still required to inspect the reaction mechanisms of many remediation technologiesIn regard to these problems,this study fabricated Fe-Ce/ZSM-5 and Fe-Ce/MCM-41catalysts via equivalent-volume impregnation method using ferric nitrate and cerium nitrate as precursors that were simultaneously immobilized on ZSM-5 and MCM-41 zeolites surface and employed as heterogeneous Fenton-like catalysts for the oxidation of methyl orange?MO?.The optimal preparation condition of obtained materials were evaluated based on the degradation of MO.In addition,Fe-Ce/ZSM-5 and Fe-Ce/MCM-41 catalysts were characterized by XRD,N₂ adsorption/desorption,FT-IR,XPS,and TEM methods.The experimental results indicated that the best preparation condition of Fe-Ce/ZSM-5 was obtained at impregnation concentration 20%,the mole ratio of Fe and Ce 3:1 and the calcination temperature 200°C;the best preparation condition of Fe-Ce/MCM-41 was obtained at impregnation concentration 10%,the mole ratio of Fe and Ce 3:1 and the calcination temperature 200°C.XRD,FT-IR?TEM results indicated that Fe-Ce/ZSM-5and Fe-Ce/MCM-41 catalysts retained the framework of zeolites as well as properties of iron oxides and cerium oxides.N₂ adsorption/desorption results indicated that Fe-Ce/ZSM-5and Fe-Ce/MCM-41 catalysts possess relative large surface areas.XPS results indicated that the element composition of Fe-Ce/ZSM-5 and Fe-Ce/MCM-41 catalysts are mainly Fe,Ce,O,and C,and Fe and Ce on the surface of ZSM-5 and MCM-41 catalyst are in the form of Fe₂O₃,Fe₃O₄,and CeO₂.In addition,the activity of the Fe-Ce/ZSM-5 and Fe-Ce/MCM-41catalysts were evaluated based on the degradation of MO,and the effects of operation conditions?i.e.,pH value,catalyst addition,hydrogen peroxide?H₂O₂?concentration and MO concentration?on degradation performance were investigated.The kinetic results indicated that MO removal followed the pseudo-first order.The Fe-Ce/ZSM-5 and Fe-Ce/MCM-41 catalysts with removal efficiencies of 87%and 99%were achieved after120 min with the following reaction conditions:pH 5.0,20 mmol/L H₂O₂,2.0 g/L catalyst,temperature 30°C and 100 mg/L MO solution.Furthermore,the leaching of total iron ions of Fe-Ce/ZSM-5 and Fe-Ce/MCM-41 catalysts catalyst were 0.03 and 0.73 mg/L,respectively.For inspecting of Fe-Ce/MCM-41 catalyst,a possible mechanism was proposed based on the detected·OH,X-ray photoelectron spectroscopy results,and metal leaching.MO in the bulk solution was primarily oxidized by surface-bound·OH,which were generated by the reaction of the Fe²⁺and Ce³⁺species with H₂O₂ on the catalyst surface.Finally,the mineralization ability and reusability of the catalyst was evaluated...