Abstract: Using microfluidic technology to prepare silica microspheres with a bimodal pore structure can easily control pore structure and morphology.The silica microspheres with a bimodal pore structure were prepared by adjusting pH and temperature to improve gelation rate in the co-axial micro-channel.The effects of oil phase properties, flow rate of oil phase and gelation temperature on morphology and microstructure of the microspheres were investigated.Experimental results showed that the diameter of silica microspheres could be controlled between 300—600 μm, the specific surface area was about 1000 m²·g^-1, the pore diameter of mesopores was about 4—10 nm, and the pore diameter of macropores was about 400—1500 nm.Increase of flow rate of oil phase decreased particle size, accelerated rate of extraction of trioctylamine to hydrochloric acid, and then sped up the process of silica particle gel, making it easier to generate a loose mesh macroporous structure.High gelation temperature increased pore volume and pore size of the mesoporous pores.

Key words: bimodal pore structure, silica microsphere, micro-channel, mass transfer

摘要： 利用微流控技术制备双重孔结构SiO₂微球具有微观结构和宏观形貌可控的优点。在同轴环管微通道中,通过pH和温度变化引发快速凝胶过程制备得到了具有双重孔结构的SiO₂微球,考察了有机相溶剂性质、有机相流速以及凝胶温度等因素对微球宏观形貌以及微观结构的影响规律。实验结果表明,制备得到的SiO₂微球粒径在300～600 μm可调,比表面积可以达到1000 m²·g^-1,介孔孔径在4～10 nm之间,大孔孔径在400～1500 nm之间。实验发现有机相流速的增大会导致微球粒径的减小,提高三辛胺对盐酸的萃取速率,加快二氧化硅溶胶粒子的凝胶过程,更易生成松散的网状大孔结构。较高的凝胶温度会增大SiO₂微球介孔的孔容和孔径。

关键词: 双重孔结构, 二氧化硅微球, 微通道, 质量传递