Preparation Of Porous Silica Microspheres As Packing Matrix Of HPLC With SFD

Porous silica microspheres are the ideal packing matrix of liquidchromatography. At present, there are many problems in the preparation technology. Itis the first time that using supercritical fluid drying in the preparation technology ofporous silica microspheres. Developing the preparation technology of porous silicamicrospheres has great social significance and economic value.In this work, two step sol-gel methods prepare dispersed phase usingtetraethoxysilane (TEOS) as raw material to get high-purity silica microspheres.Castor oil is choosen as continuous phase, using Span80and Tween20as surfactants.The optimum preparation conditions were determined as follows: Span80/Tween20is5/2; stirring speed is200r/min; continuous phase/dispersed phase is2/1; the ratio ofsurfactant is17%; the higher temperature the process is, the smaller particle diameteris obtained.Porous silica microspheres are obtained by vacuum drying, intermittentsupercritical fluid drying and continuous supercritical fluid drying. The specificsurface area of porous silica microspheres is bigger obtained by intermittentsupercritical fluid drying than that obtained by vacuum drying. The specific surfacearea of porous silica microspheres obtained by continuous supercritical fluid drying is513.4m2/g, it’s too much to be packing matrix of liquid chromatography. The porediameter of porous silica microspheres obtained by intermittent supercritical fluiddrying is about4nm, but its range of pore diameter of porous silica microspheresobtained by continuous supercritical fluid is wide. The optimum roasting temperatureis600℃, and the porous silica microspheres is amorphous. The diameter of samplesfrom intermittent supercritical fluid drying is about3μm, the range is between1and7μm.