【作者】 郑明芳；

【导师】 陈纪忠；

【作者基本信息】 浙江大学 ， 化学工程， 2008， 硕士

【摘要】 氧化铁红（α-Fe₂O₃）是优质的颜料,具有很高的遮盖力和着色力,廉价,无毒,被广泛用于建材、涂料、塑料、橡胶、陶瓷等领域。目前我国工业合成氧化铁红的方法有很多,其中最常见的是硝酸湿法工艺。相对于其他工艺,硝酸法原料廉价,生产的铁红色相淡雅鲜亮,着色力高,很受欢迎。但目前工业上此法得到的产品颗粒较大,通常在微米级,色相和粒径均不能控,极大的限制了其市场应用,而且在制备过程中产生氮氧化物,造成污染。由于人们对该反应过程及其影响因素的了解不够深入,反应历程不够明确,从而不能有效地解决上述问题。因此,本文通过测定硝酸湿法制备α-Fe₂O₃过程中体系的pH值变化和观测α-Fe₂O₃粒子的形貌变化,从而分析α-Fe₂O₃制备过程的历程。在实验中通过对反应过程的间隔取样、测定体系的pH值,考察α-Fe₂O₃制备过程的pH值变化,并采用透射电镜（TEM）观测粒子的形貌。实验结果表明:α-Fe₂O₃微粒的形成是通过两步相转化过程完成的。第一步是氢氧化铁转化为针状的β-FeOOH粒子;第二步是针状的β-FeOOH粒子溶解再结晶形成α-Fe₂O₃微粒。根据反应历程,实验进一步考察了反应物料比、反应时间、滴酸速度、硝酸浓度和搅拌速率等因素,实验结果显示这些因素均对反应产品有影响。通过对α-Fe₂O₃产品的XRD、TEM和粒度分布等分析,当制备条件为:温度在92～94℃,反应时间6小时,滴酸速度0.2ml/min,搅拌速度300～400r/min时,可制备获得性能优良的纳米α-Fe₂O₃粒子。通过对产品的热处理,得到了结晶度更高的α-Fe₂O₃产品,其各项指标均达到国家标准。更多还原

【Abstract】 Iron oxide red（α-Fe₂O₃）is an excellent pigment with good properties such as covering power,coloring power,innocuity and anti-rust,and is wildly used in the field of coating,plastic,spin,ceramic,rubber and cement.There are many methods to produce iron oxide red in industry.The most common process is HNO₃-method. However,theα-Fe₂O₃ product by HNO₃-method has low grades and poor application performance,and can not meet the need of the market because of inadequate understanding of the production process.Therefore,this work is to study the preparation ofα-Fe₂O₃ particles by HNO₃-method,and to clarify the effect of process parameters.pH of solution and its variation were measured by sampling at given time interval in experiments.TEM was used to observe the mophorlogy of iron oxide particles.The experimental results showed thatα-Fe₂O₃ particles are formed in two-step.The first step is that the ironic hydroxide transforms intoβ-FeOOH.The second step is that the needle-likeβ-FeOOH particles dissolve and recrystallize to formα-Fe₂O₃ particles.Experiments were carried to investigate the effect of factors such as the mass ratio of raw materials,reaction time,the speed of acid-addition,the concentration of nitric acid and the stirring rate.The results showed that these factors have an important influence onα-Fe₂O₃ products.The analysis results of XRD,TEM and particle distribution ofα-Fe₂O₃ products show that nano-sizeα-Fe₂O₃ particles could be prepared at condition of the reaction time of 6h,reaction temperature of 92-94℃, the speed of acid-addition of 0.2ml/min,and the stirring rate of 300～400r/min.After heating treatment ofα-Fe₂O₃ particles,α-Fe₂O₃ particles have higher crystallinity,and can reach the natinoal standards.更多还原