Effect of microbubbles on preparation of precipitated silica by carbonization: physical-chemical structure, kinetic parameters and mass transfer characteristics
Effect of microbubbles on preparation of precipitated silica by carbonization: physical-chemical structure, kinetic parameters and mass transfer characteristics
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DOI：
10.1016/j.ccst.2021.100002
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发表时间：
2021-12-01
期刊：
影响因子：
--
通讯作者：
Qin, Yukun
中科院分区：
文献类型：
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作者：
Zhang, Yu;Zhang, Zijun;Qin, Yukun
二氧化硅因其良好的性能在工业领域得到了广泛的应用，而碳化法制备高质量的二氧化硅是利用二氧化碳的重要途径。在微泡/鼓泡实验装置上进行了实验，根据pH-t曲线分析了其碳化传质动力学。微泡条件下，随着温度升高20℃~ 60℃，二氧化硅的比表面积、吸油值和粒径变化幅度分别为336.80 ~ 231.29 m(2)/g、1.12 ~ 1.81 ml/g和16.49 ~ 14.60 μ m，与气泡条件下相似。在20℃~ 90℃老化时，其老化范围为35.82 ~ 128.76 m(2)/g, 1.59 ~ 2.44 ml/g, 23.15 ~ 14.46 μ m。当溶液总浓度> ~ 0.5 m时，浓度增大，微气泡比表面积和粒径均大于冒泡二氧化硅，吸油值增大至1.81 ~ 2.44 ml/g。动力学分析结果与理论值较为吻合，可判断为二次反应过程。微气泡使CO2利用率和炭化体积传质系数提高2 ~ 4倍，液相传质系数降低。结果表明，微泡传质是通过显著增加比表面积来实现的。
Silica is widely applied in industrial fields due to its good properties, while preparation of high-quality SiO2 by carbonization is an important way to utilize CO2. The experiment was carried out in a microbubble/bubbling experimental device, with its mass transfer kinetics of carbonization analyzed according to the pH-t curves. Under microbubble conditions, with the increasing temperature of 20 similar to 60 degrees C, the specific surface area, oil absorption value and particle size of silica varies at 336.80 similar to 231.29 m(2)/g, 1.12 similar to 1.81 ml/g and 16.49 similar to 14.60 mu m, respectively, which is similar as that with bubble. Aging at 20 similar to 90 degrees C, they involve in the range of 35.82 similar to 128.76 m(2)/g, 1.59 similar to 2.44 ml/g and 23.15 similar to 14.46 mu m. With total concentration of solution > 0.5 M, the concentration increases, the specific surface area and particle size of microbubbles are larger than those of the bubbling silica, and oil absorption value increases at 1.81 similar to 2.44 ml/g. The kinetic analysis shows that it is more consistent with theoretical value, which can be judged as the secondary-reaction process. The microbubbles increase the CO2 utilization rate and volumetric mass transfer coefficient of carbonization by 2-4 times, while the liquid-phase mass transfer coefficient decreases. It indicates that microbubble mass transfer is achieved by significantly increasing the specific surface area.