Preparation Of Fe₃O₄ Magnetic Nanoparticles As Fenton-like Catalyst And Study On The Degradation Of Malachite Green

Synthetic dyes are widely used in many industries,such as the textile,leather,paper production,food technology and so on.However,the dye wastewater seriously threaten water environment and human health on account of its large emissions,high organic pollutant,deep shade and non-biodegrade.As a new kind of Fenton-like catalyst,the Fe₃O₄ magnetic nanoparticles are easily prepared and modified,have large surface area and can be recycled under magnetic field,which make it has potential application in the field of dye wastewater treatment.Nowadays,ionic liquid has been one of the hot spots of research in inorganic synthesis which as reaction medium.In this thesis,the urea/choline chloride Ionic liquid was used as reactive solvent,and the Fe₃O₄ magnetic nanoparticles were prepared using chemical co-precipitation which have high catalytic activity.The effects of different reaction conditions on the degradation of Malachite Green by Fe₃O₄/H₂O₂ were investigated,and the dynamic analysis were presented by experiments.The effects of common ions on the catalytic degradation reaction were investigated under the condition of fixed reaction conditions,which provides the valuable reference for the application of dye wastewater treatment.In the preparation of Fe₃O₄ magnetic nanoparticles,five different ionic liquids were synthesised,which were urea/zinc chloride,choline chloride/glycerol,urea/choline chloride,[EMIM][HSO4] and [BMIM][HSO4].The solubility of FeCl3.6H2 O,FeCl2.4H2 O and KOH in different ionic liquids were investigated,and the urea/choline chloride Ionic liquid was selected as reactive solvent.The effects of different molar ratio of Fe²⁺ and Fe³⁺ on the final yield of Fe₃O₄ were investigated,while the optimum molar ratio of Fe²⁺ and Fe³⁺ was 1:1.5.The Fe₃O₄ were characterized by XRD,TEM,VSM,and analyzed for iron content.The results show that,the Fe₃O₄ magnetic nanoparticles prepared by ion co-precipitation which average particle size was 16.7 nm,the saturation magnetization was 68.3 emu/g,the iron content was about 71.51%,and had well morphology and distribution.In the research of the effects of different reaction conditions on the degradation of Malachite Green by Fe₃O₄,the initial concentration of Malachite Green,the initialpH,the dosage of Fe₃O₄,the concentrations of H₂O₂ and the reaction temperature were discussed by control variate method.The value of TOC was measured after reaction and the degradation mechanism was investigated.The results showed that under the conditions of 25 oC,0.06 mol/L H₂O₂ concentration,1 g/L catalyst dosage,pH 4,10 mg/L Malachite Green concentration and the reaction time of 30 minutes,the decoloration of Malachite Green was 97.94%,the reaction activation energy was14.05 kJ/mol,the degree of mineralization was 63.75%.The ×OH produced by H₂O₂ played an important role in the catalytic degradation and the degradation reactions followed the first-order kinetics.In the study of the effects of common irons on the catalytic degradation,five common ions(SO₄^2-?Cl^-?Ca²⁺?Mg²⁺and Humic acids)with different concentrations on the degradation of Malachite Green by Fe₃O₄/H₂O₂ were investigated.Meanwhile,the Fe₃O₄ were characterized by power X-ray diffraction?XRD?.The results showed that humic acids enhanced the degradation,Cl^-and SO₄^2-inhibited the degradation in different degrees,Ca²⁺ and Mg²⁺ exhibited negligible effects,and the crystal structure of Fe₃O₄ was not changed because of the common ions.