Preparation Of Sized-controled And 1d Assemblies Of Fe3O4 Nano-particles And Liquid Conversion In Magnetic Field

Due to the Fe3O4 nano-particles have important practical application values, which posses comprehensive applied foreground in medicine, magnetic recording materials and pigment. In addition, due to size effect of nano-particles, the different size Fe3O4 nano-particles show different characteristic. So the research explore the preparation of the control sized Fe3O4 nano-particles which is important significance.Thanks to their unique photonic, electronic, magnetic and catalytic properties and one dimensional Fe3O4 have configuration characteristic, which have controllability and pertinence in medicine as targeted drug. The Fe3O4 as targeted drug in medicine need exterior magnetic field for draughting. Therefore, preparation of controled size,one dimensional Fe3O4, the effects and mechanisms of 1D assemblies of the Fe3O4 nano-particles are studied in the paper. The aim enhance applicability of the Fe3O4 nano-particles in medicine field.The main research are as follow:(1) The preparation of different nano-sized magnetite particles.The experiment prepares magnetite using oxidation-coprecipitation phase transformation, change the pH value and temperature of the system. Study the effect of the generation and the particle size of Fe3O4 can be prepared when the pH value is in the range of 8-12 by the method of dynamic boiling reflux. Along with the increasing of the pH value, the paticle size of the Fe3O4 will reduce gradually, the particle size is in the range of 20～50nm. The particles are well pure at 20～100℃by the method of static water bath. Along with the increasing of the temperatue, the paticle size will accretion gradually, and the crystallization of the product is getting better, and the particle size is in the range of 10-50nm.(2) The effects of the Fe3O4 nano-particles one-dimensional assembly.Study the effect of the Fe3O4 nano-particles one-dimensional assembly. The result show that the magnetic field and pH values can affect the 1D assembly by dynamic boling reflux method. Under 50 mT, the production present 1D chain structure. Along with the increasing of the magnetic field, the chain structure will disappear gradually; When the pH value is in the range of 9-10, the Fe3O4 nano-particles show 1D chain structure. Simultaneously, under the different intensity of magnetic field, change pH value affect the chain structure of the Fe3O4 . Therefore, the 1D chain stucture is affected by the exterior magnetic field grads and surface charge of the Fe3O4 nano-particles.(3) The liquid phase transformation effect of the Fe3O4 nano-particles in magnetic field. Using preparation of Fe3O4 as precursor for transforming of boiling liquid studies. Discuss the liquid phase transformation effect of the Fe3O4 nano-particles which are different particle size, concentration and aftertreatment fashions, when change the intensity of magnetic field, initialization pH value of reflux liquid, temperature ande the volume of air. The result show that the magnetic field can accelerate the Fe3O4 transformα-Fe2O3; The lower of the pH value(2～7.3), the faster Fe3O4 nano-particles are dissolved; The Fe3O4 nano-particles which are little particle size, low crystallization, washed by deionzed water transformα-Fe2O3 easily in the magnetic field; The Fe3O4 can transformα-FeOOH in the reflux liquid of enrichment air, and the more volume of air, the moreα-FeOOH.Through analyzing the intermediate sampling, we measure solution Fe(III)\Fe(II) concentration and track pH value. We found that the magnetic field could accelerate the dissolution of the Fe3O4, and firstly produceα-FeOOH. As the Fe(II) concentration achieve catalysis, theα-FeOOH transformα-Fe2O3. In addition, explore changing the pH value of reflux liquid in the magnetic field, the more Fe(III) \Fe(II) concentration is dissolved in pH=3.5 than pH=7.3. The Fe(II) of the Fe3O4 dissolution become catalyzer that FeOOH transformα-Fe2O3. In low pH value, the Fe3O4 easily transformα-Fe2O3 .Injetting the air in the solution, the Fe(II) concentration reduce evidently. Because the Fe(II) are oxidized by the oxygen of air ,so the Fe3O4 are difficult to transformingα-Fe2O3. Under the best conditions, the Fe3O4 nano-particles transform pureα-Fe2O3 in 24 hour.