Abstract:

Silica microspheres are of great interest in several areas such as liquid chromatography, medicine, biochemistry, colloidal chemistry and aerosol research. In this work, porous silica microspheres as packing matrix of HPLC were prepared from tetraethoxysilane (TEOS) by Sol-Gel method with carbon dioxide supercritical fluid drying technique. Conventional high-temperature vacuum dying (WO), intermittent supercritical fluid drying (SCF-I) and continuous supercritical fluid drying process (SCF-C) were discussed. Silica microspheres were characterized by BET, TG-DTG, SEM, FT-IR, XRD and zetasizer analysis system. The results showed that the silica particles with spherical morphology were successfully prepared by all of the three processes and agglomeration was avoided. The specific surface area of silica microspheres was 69.04, 268.40 and 513.41 m²·g^-1 prepared by WO, SCF-I and SCF-C, respectively. The specific surface area of porous silica microspheres obtained by supercritical fluid drying was higher than that obtained by vacuum drying. SCF-I process was the optimum selection for the packing matrix of HPLC. Silica microspheres obtained by SCF-I were mostly regular-ball with specific pore volume of 0.5758 m³·g^-1 without particle agglomeration. The mean particle size (D₅₀) was 3 μm and the particle size distribution followed typical Gaussian distribution with a narrow particle size varied from 1 mm to 7 μm.

Key words: chromatography, supercritical fluid, silica, intermittent supercritical fluid drying, continuous supercritical fluid drying, vacuum drying

摘要：

以正硅酸乙酯(TEOS)为硅源, 采用溶胶-凝胶结合超临界CO₂干燥制得高纯度微米级液相色谱填料基质多孔硅球。采用BET, TG-DTG, SEM, FT-IR, XRD和激光粒度仪等表征方法对样品进行分析, 考察真空干燥(WO)、超临界CO₂间歇干燥(SCF-I)和超临界CO₂连续干燥(SCF-C) 3种干燥工艺的可行性, 结果表明, 真空干燥、ScCO₂间歇干燥和ScCO₂连续干燥得到的多孔硅球比表面积分别为69.04、268.40和513.41 m²·g^-1。采用ScCO₂干燥法能够大幅度提高多孔硅球产品的比表面积。参照色谱填料理论最佳比表面积为300 m²·g^-1可知, ScCO₂间歇干燥较ScCO₂连续干燥更适合应用于液相色谱填料基质多孔硅球的制备。ScCO₂间歇干燥法制得硅胶微球球形规则且无团聚现象, 孔体积为0.5758 m³·g^-1, 平均粒径(D₅₀)为3 μm, 呈典型高斯分布, 且分布范围较窄, 为1~7 μm。

关键词: 色谱, 超临界流体, 二氧化硅, 超临界CO₂间歇干燥, 超临界CO₂连续干燥, 真空干燥