Preparation Of Nanosized Iron-based Materials And Their Catalytic Degradation Performance Of Harmful Pollutants

With the development of industry,environmental pollution has become increasingly serious,and the safety of water resources has also been seriously threatened.The control and treatment of pollution have become a hot research topic.The advanced oxidation technology based on reactive radical reactions is widely used in water treatment.Because of the good,stability,low-cost and aboundance,iron-based materials have been widely used in water treatment.Iron oxides with five different morphologies were prepared by a precipitation method,and the process and mechanism of catalytic degradation of tetracycline hydrochloride were studied.Three-dimensional Fe@GNS/GF monoliths were prepared by chemical vapor deposition,the structural properties of the resulting Fe@GNS/GF monolith are characterized.The adsorption and catalytic performance of the samples were studied using Congo red and methyl violet as target pollutants.In this thesis,the preparation of iron-based materials and their application in the degradation of organic pollutants are studied.The main contents are listed as follows:?1?Iron oxides with five different morphologies were prepared by a precipitation method.The samples were characterized by scanning electron microscopy,X-ray diffraction and N₂adsorption-desorption isotherms.Five kinds of nanosized iron oxide show uniform sizes and similar surface areas.The catalytic activity was studied used tetracycline hydrochloride as the target pollutant.It was demonstrated that the morphology of iron oxide was one of the key factors affecting the catalytic activity.?2?Fe₂O₃ was used as a heterogeneous Fenton catalyst to degrade tetracycline hydrochloride.The effects of hydrogen peroxide concentration,catalyst dosage,pH and reaction temperature on the degradation process were systematically investigated.The degradation reaction rate well described by the second-order kinetic model,and the activation energy was determined to be 53.37 kJ/mol.Free radical scavenging experiments and ESR tests showed that both hydroxyl radicals and superoxide radicals played an important role for the degradation of tetracycline hydrochloride.The catalyst was recycles for three times and show limited activity decay and ion leaching,indicating that the catalyst had excellent stability.?3?The photocatalytic activity of the five types iron oxides was studied by using tetracycline tetracycline as the target pollutant.Results,showed that the morphology also greatly affected the catalytic activity.The effects of substrate concentration and pH on the photocatalytic process were investigated.The activity of the catalyst was decreased after three cycles.Free radical scavenging experiments and ESR tests showed that besides the hole electrons,hydroxyl radicals and superoxide radicals also played an important role in the photocatalytic reaction.?4?Three-dimensional Fe@GNS/GF monoliths were prepared by chemical vapor deposition.The structural properties of the resulting Fe@GNS/GF monolith are characterized by X-ray diffraction,field emission scanning electron microscopy,transmission electron microscopy,X-ray photoelectron spectroscopy and N₂ adsorption-desorption isotherms.The adsorption and catalytic performance of the samples were studied using Congo red and methyl violet as target pollutants.The Fe@GNS/GF monolith possesses maximum sorption capacities of 177 and 142 mg/g for the sorption of CR and MV-2B,respectively.It exhibited rate constants of 0.0563 and 0.0464 min^-1 for the catalytic degradation of CR and MV-2B,respectively.The samples were recyclable and exhibited outstanding stability.The Fe@GNS/GF monolith was utilized to treat simulated organic waste water by the combination of sorption and catalytic degradation processes.It was found that the chemical oxygen demand of the wastewater was reduced from 590 mg/L to 12 mg/L.