Preparation Of Nano-size Iron Oxide Red

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.