Production of Porous Silica Microparticles by Membrane Emulsification

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• 作者：Marijana M. Dragosavac ; Goran T. Vladisavljevi膰 ; Richard G. Holdich ; Michael T. Stillwell
• 刊名：Langmuir
• 出版年：2012
• 出版时间：January 10, 2012
• 年：2012
• 卷：28
• 期：1
• 页码：134-143
• 全文大小：1016K
• 年卷期：v.28,no.1(January 10, 2012)
• ISSN：1520-5827

文摘

A method for the production of near-monodispersed spherical silica particles with controllable porosity based on the formation of uniform emulsion droplets using membrane emulsification is described. A hydrophobic metal membrane with a 15 渭m pore size and 200 渭m pore spacing was used to produce near-monodispersed droplets, with a mean size that could be controlled between 65 and 240 渭m containing acidified sodium silicate solution (with 4 and 6 wt % SiO₂) in kerosene. After drying and shrinking, the final silica particles had a mean size in the range between 30 and 70 渭m. The coefficient of variation for both the droplets and the particles did not exceed 35%. The most uniform particles had a mean diameter of 40 渭m and coefficient of variation of 17%. By altering the pH of the sodium silicate solution and aging the gel particles in water or acetone, the internal structure of the silica particles was successfully modified, and both micro- and mesoporous near-monodispersed spherical particles were produced with an average internal pore size between 1 and 6 nm and an average surface area between 360 and 750 m² g^鈥?. A material balance and particle size analysis provided identical values for the internal voidage of the particles, when compared to the voidage as determined by BET analysis.