Reduction kinetics of iron oxide in metatitanic acid by organic reductant
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摘要: 研究了一种有机还原剂对偏钛酸中氧化铁的还原过程动力学，以探讨过程机理，指导实际生产。结果表明，该还原反应有机还原剂的反应分级数为1，氧化铁的反应分级数为2。在有机还原剂过量的情况下，氧化铁的还原过程速率大小与反应温度、搅拌强度和体系酸度有关。还原速率随温度的增加而增加，表观反应活化能为51.73 kJ/mol。还原速率随搅拌强度的增加先增加而后变化不大，表明在一定的搅拌强度下，扩散步骤不是过程的控制环节。还原速率随酸度的增加先增加后减小，这与偏钛酸中氧化铁的溶解和有机还原剂的分解有关。推断在有机还原剂过量及一定的搅拌强度下，还原反应步骤是有机还原剂对偏钛酸中氧化铁的还原过程的控制环节。Abstract: The reduction kinetics of iron oxide in metatitanic acid by organic reductant was investigated in the paper to explore the process mechanism and guide the actual production. The results show that the step reaction order is one for the organic reductant and two for iron oxide. Under the condition of excessive reductant, the reduction rate of iron oxide is affected by reaction temperature, stirring strength and acidity of metatitanic acid. The reduction rate increases with increasing temperature, and the apparent activation energy in the reaction is 51.73 kJ/mol. The reduction rate first increases and then changes slowly with increasing stirring strength, which shows that the reduction rate is not controlled by diffusion step under higher stirring strength. The reduction rate first increases and then decreases with increasing acidity of metatitanic acid, which was relevant to the dissolution of iron oxide and the resolution of organic reductant. Therefore, it can be inferred that the reduction rate of iron oxide in metatinic acid by organic reductant is controlled by reduction reaction step under the conditions of excessive organic reductant dosage and certain stirring intensity.
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Key words:
- metatitanic acid /
- iron oxide /
- reduction /
- organic reductant /
- kinetics
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图 3 不同温度下 1/[Fe3+]与 t 的关系
Figure 3. The relation graph of 1/[Fe3+] and t under different temperatures
图 5 不同搅拌强度下 1/[Fe3+]与t的关系
Figure 5. The relation graph of 1/[Fe3+] and t under different stirring strength
图 6 不同酸度下 1/[Fe3+]与 t 的关系
Figure 6. The relation graph of 1/[Fe3+] and t under different acidity
表 1 不同温度下的反应速率常数
Table 1. The reaction rate constants under different temperatures
T/℃ k /(m3·mol−1·s−1) 40 9.01×10−4 45 15.0×10−4 50 18.9×10−4 55 25.6×10−4 60 30.5×10−4 
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表 2 不同搅拌强度下的反应速率常数
Table 2. The reaction rate constants under different stirring strength
搅拌强度/(r·min−1) k /(m3·mol−1·s−1) 100 8.71×10−4 200 8.92×10−4 300 8.97×10−4 400 9.01×10−4
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表 3 不同酸度下的反应速率常数
Table 3. The reaction rate constants under different acidity
cH2 SO4/(g.dm−3) k /(m3·mol−1·s−1) 0.5 9.01×10−4 1 9.65×10−4 2 9.81×10−4 5 9.41×10−4
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