【作者】 宋珊珊；

【导师】 陈汝芬；

【作者基本信息】 河北师范大学 ， 无机化学， 2010， 硕士

【摘要】 纳米Fe3O4具有重要的实际应用价值,在医学、磁记录材料和颜料等领域有着极广泛的的应用前景。另外,由于纳米粒子的尺寸效应,不同尺寸的纳米Fe3O4颗粒常表现出不同的特性。因此,探究低成本制备可控粒径纳米Fe3O4具有重要的意义。纳米Fe3O4具有独特的光、电、磁和催化性质,而一维纳米Fe3O4由于其结构的特点,在医药领域的应用中更具可控性、针对性等特点,具有更高的效率。另外,纳米Fe3O4在医药领域作为靶向药物使用时,往往借助外界磁场对纳米Fe3O4的牵引而实现。因此,本文进行了可控粒径、一维纳米Fe3O4的制备,并研究了磁场作用下纳米Fe3O4液相转化的影响因素及机理,以增强纳米Fe3O4在医药领域等的应用性。本论文的研究内容包括:(1)不同粒径纳米Fe3O4的制备。利用氧化-共沉淀相转化法制备纳米Fe3O4,改变反应体系的pH值和反应温度,研究各种条件对纳米Fe3O4粒径的影响。结果表明:在动态沸腾回流加热的条件下,pH值在8～12范围内可生成纯纳米Fe3O4,随着pH值的升高,纳米Fe3O4的粒径逐渐减小,粒径范围在20～50nm之间。在静态水浴加热的条件下制备纳米Fe3O4,温度在20～100℃之间均能得到纯净的纳米Fe3O4粒子,随着温度的升高,产物粒径逐渐增大,晶化性变好,产物粒径在10～50nm。(2)纳米Fe3O4一维成链的影响因素。研究了四氧化三铁一维成链的影响因素。结果表明:在沸腾回流加热条件下,外加磁场对四氧化三铁一维成链有影响。当磁场强度在50mT以下时,产物一维成链趋势明显,而磁场再进一步加强其一维结构减弱;同时发现,回流液初始pH值对产物一维成链也有明显的影响,当pH值在9～10范围内,四氧化三铁呈一维链状结构。同时,在不同磁场强度下改变pH值对四氧化三铁的链状结构有较大的影响。纳米四氧化三铁粒子的成链结构是由外界磁场梯度和其表面电荷的协同效应所影响的。(3)磁场作用下Fe3O4液相转化的研究以制备的Fe3O4为前驱物,进行沸腾回流相转化的研究。探究了改变磁场强度及在磁场作用下回流液初始pH值、反应温度及空气用量等条件对不同粒径、不同后处理方式及不同浓度的纳米Fe3O4液相转化的影响。结果表明:外加磁场能够促进Fe3O4向α-Fe2O3的转化;体系的pH(2～7.3)值越低越有利于纳米Fe3O4在磁场作用下的溶解;小粒径、晶化性差且经过水洗等后处理的纳米Fe3O4更易于在磁场作用下转化成α-Fe2O3;通入空气,能够使纳米Fe3O4转化成α-FeOOH,空气量越大转化出α-FeOOH的量就越多。通过对转化液进行取样,测量溶液中Fe(Ⅲ)、Fe(Ⅱ)离子的浓度及pH跟踪。发现:磁场有利于Fe3O4快速溶解出Fe(Ⅲ)、Fe(Ⅱ) ,说明磁场的加入有利于Fe3O4的溶解,而Fe3O4的快速溶解,首先产生α-FeOOH,而Fe(Ⅱ)的存在会促进α-FeOOH向α-Fe2O3的转化。另外,在外加磁场作用下改变回流液pH值,跟踪发现: pH值在3.5的条件下比pH值为7.3时较快的溶解出更多的Fe(III),Fe(Ⅱ) ,Fe3O4溶解产生的Fe(Ⅱ),会促使FeOOH向α-Fe2O3的转化,低pH更易于转化成α-Fe2O3;通入空气后溶液中的Fe2+浓度显著降低,说明空气的通入,使Fe(Ⅱ)被空气中的氧气氧化为Fe(III)而降低,造成α-FeOOH难以向α-Fe2O3转化。在Fe3O4向α-Fe2O3转化的最佳条件下,液相回流24h ,Fe3O4可转化为纯α-Fe2O3。更多还原

【Abstract】 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.更多还原