Lv H.,Tianjin University of Technology |
Lv H.,nter for Petrochemical Technology |
Meng F.,Tianjin University of Technology |
Meng F.,nter for Petrochemical Technology |
And 6 more authors.
Chemical Engineering Science | Year: 2015
Silica microspheres are of much interest in several areas, such as liquid chromatography, medicine, biochemistry, colloidal chemistry and aerosol research. In this study, the sol-gel method was used to prepare these microparticles followed by three different drying processes. The first process involved intermittent supercritical fluid drying (SCF-I) using intermittent supercritical carbon dioxide (scCO2) at a low temperature. The second approach involved continuous supercritical fluid drying (SCF-C) using continuous scCO2 at low temperature, as well. The third approach involved vacuum drying (WO), which is a high temperature process. All of the experiments led to the successful precipitation of silica microparticles in the micrometre range. In all of the cases, a spherical morphology and no agglomeration were observed. The optimum preparation conditions were determined as follows: stirring speed is 200r/min; continuous phase/dispersed phase is 2/1; Span® 80/ Tween® 20 is 5/2; the ratio of surfactant is 17%. In addition, the primary textural characteristics of these microspheres were investigated by nitrogen physisorption experiments. The results indicated that the size of the pore volume is as follows: V SCF-C>V SCF-I>V WO. The BET data indicate that the specific surface area of the porous silica microspheres is as follows: S SCF-C>S SCF-I>S WO. © 2015 Elsevier Ltd. Source