【作者】 严会娟；

【导师】 魏雨；

【作者基本信息】 河北师范大学 ， 物理化学， 2002， 硕士

【摘要】 均分散超细α-Fe₂O₃胶粒在精细陶瓷、催化、滤光、光吸收、医药、防腐、颜料、感光材料和磁记录材料等领域都已被广泛应用。目前，国内外科技工作者对纳米级均匀α-Fe₂O₃胶粒的制备已有广泛研究。本研究所以Fe（OH）₃凝胶为反应前驱物，采用液相催化相转化法制得α-Fe₂O₃均匀胶粒。该方法具有操作简单，反应物浓度高，转化速度快等特点。 本论文在本研究所前期工作的基础上，做了以下工作： （1）Fe₂（SO₄）₃溶液的制备 本试验采用H₂SO₄酸化低碳铁皮制得FeSO₄，再用HNO₃进行氧化制得Fe₂（SO₄）₃，对此过程进行了详细研究，制得了浓度适合使用、未水解的Fe₂（SO₄）₃。 （2）Fe（Ⅱ）对Fe（OH）₃凝胶相转化的影响 研究了Fe（Ⅱ）对Fe（OH）₃凝胶催化相转化制备的α-Fe₂O₃胶粒的粒度的影响。结果表明随着Fe（Ⅱ）含量的增大，粒径明显减小；阐明了Fe（Ⅱ）对α-Fe₂O₃粒径的影响要大于Fe（Ⅲ）浓度变化的影响，并提出了不通浓度下的Fe（OH）₃凝胶中，制备α-Fe₂O₃时，Fe（Ⅱ）能达到的最大含量。 （3）有机羧酸对Fe（OH）₃凝胶相转化的影响 研究了新生成硫酸铁盐为初始物，不同有机羧酸对Fe（OH）₃凝胶相转化速度和颗粒形貌的影响，表明还原性有机羧酸如甲酸、乙酸、丙酸、 草酸和柠檬酸对 FepH)／疑胶相转化过程有一定的促进作用。其作用机 理与无机还原性物质类似，均遵循还原，电于转移催化溶解，聚集再结 晶机理。还原性较强的有机羟酸配体交换机制的影响较大。 p中间物FeOOH的转变历程及对a－Fe。O。生成的影响令 详细研究了不同温度时，以硫酸铁软为初始物制备a－Fe。Os过程中， 中］’。J物5－厂eOOH的生成条件，说明了动态及静态情况下各种铁黄的转化 过程，进一步证明了硫酸铁软为初始物时的反应瞩巳 同时阐明只有迅 速升温至 100”C，i有利于完全转化为a－Fe心。。更多还原

【Abstract】 Monodispersed a-Fe2O3 nanoparticles have been widely applied in fine ceramics, catalysis, light filter, light adsorption, medicine, anticorrosion, pigment, photosensitive materials and magnetic recording media, etc. The preparation of monodispersed a-Fe2O3 nanoparticles has been studied extensively. In our laboratory, a new method of preparing nanosized hematite by catalytic phase transformation in solution was successfully developed. In this method, FeCb. Fe(NO3)3 or Fe2(SO4)3 are main raw materials and Fe(OH)3 gel is firstly prepared, then a-Fe2O3, is obtained by the catalytic dissolution of Fe(OH)3in aqueous solution. It was considered that the new-method is with such outstanding characteristics as simple equipment, high initial concentration, fast rate of phase transformation, and gentle reaction conditions etc.On the basis of the former work of our laboratory, in this paper the main research aspects are as follows:(1)The preparation of Fe2(SO4)3 solutionFirst, pure iron with low carbon is acidized by FSO and then we can obtain FeSO4 solution. Second, Fe2(SO4)3 solution is prepared through the oxidization of the FeSO4 solution with HNO3. the obtained Fe2(SO4)3 solution haven’t hydrolysis and is fit for the preparation of a-Fe2O3.(2) The effect of Fe(II) on the phase transformation of Fe(OH)3This research shows that when more Fe(II) is added, the diameters of a-Fe2O3 nanoparticles are smaller, but that there is a limit in the increasing of Fe(II) content. Moreover, a-Fe2O3 nanoparticles are more affected by the content of Fe(II) than the concentration of reactant Fe(III).(3) The effect of carboxylic acid on the phase transformation of Fe(OH)3In this paper, a small amount of carboxylic acid was added to the Fe(OH)3 gel under neutral condition, a-FeO with different morphology was produced after a certain period of reaction time. The effect of different carboxylic acid on the phase transformation rate and a-Fe203 morphologies was studied in this paper. The reaction mechanism was discussed.(4) The formation of intermediate product FeOOH and the effect on the preparation of a-The intermediate products FeOOH play an important role in the preparation of a-Fe2O3 In this particle, the reaction is studied under the dynamic and static condition. The research of three temperature 80 60 , 40 explains the proceeding of the transition of intermediate product a-FeOOH, (3-FeOOH and y-FeOOH during the the preparation of oc-Fe2O3, and their effects on the occurrence of a-Fe2O3.更多还原