A Method For The Preparation Of Ultra Purity Silica Spheres As Packing Materials

In this paper, we presented a method for preparing mesoporous silicaspheres as high performance liquid chromatography （HPLC） packingmaterials via two steps. In the first step, the high purity and dispersed nanosilica particles had been prepared by the hydrolysis of silicon powders. Weused aqueous ammonia and ionic polymer with big cores as catalytic. Theoptimal reaction conditions we got were that the proportion of the dosage ofSi/NH4OH/resin was31.89g/320mL/20g, the temperature was75℃, the stirspeed was1000r/min and the reaction time was9h. Under these conditionswe got the dispersed silica with the productivity of95.0%, the averagediameter of29nm and the SiO₂%by weight of30³5%. In the second step,the multiple emulsion solvent evaporation method, in which the silica solwas coated by polystyrene, was used to synthesis the high purity silicaspheres. In this reaction, the silicon resource was the silica sol with theSiO₂%by weight of30%prepared in the first step, the volume ratio of thesystem of silica sol and oil phase was1:20, the weight ratio of polystyreneand deionized water in the water loving protective colloid solution was 1:300, the stir speed was800r/min, the solvent was removed at80℃, thesample was dehydrated by distillation by being solvent removed, washed,distiled and high temperature treated. The obtained mesoporous silicaspheres were characterized by inductively coupled plasma massspectrumetry （ICP MS）, scanning electron microscopy （SEM） and BETanalysis. The silica spheres with the diameter of3m, specific surface areaof168.44m²/g, average pore size of10.19nm and average volume of0.42cm³/g were demonstrated to be excellent packing materials for HPLCdue to its high purity, equal size distribution, high mechanical strength andstrong separating power.