Effect of the drying process on the preparation of porous silica microspheres. (2nd October 2015)

• Record Type: Journal Article
• Authors: Lv, Huisheng; Meng, Fanmei; Zhang, Minhua; Geng, Zhongfeng; Sun, Yanpeng
• Is Part Of: Chemical engineering science. Volume 135(2015)
• Page Start: 285
• Page End: 293
• Publication Date: 2015-10-02
• Subjects: Silica microspheres -- Sol−gel process -- Intermittent Supercritical Fluid drying -- Continuous Supercritical Fluid drying -- Vacuum drying; Chemical engineering -- Periodicals; Génie chimique -- Périodiques; Chemical engineering; Periodicals; Electronic journals; 660
• DOI: 10.1016/j.ces.2015.03.050
• Languages: English
• ISSNs: 0009-2509

Abstract

Abstract: 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 200 r/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 . Highlights: Silica microspheres: silica microspheres are of great interest in several areas. Sol−gel process: four uncertain and important parameters are investigated. Drying process: three drying methods are used and their feasibility are investigated. All experiments led to a successful precipitation of silica microspheres, in the micrometer range.