乙醇超临界技术制备疏水性白炭黑粉体

Preparation of hydrophobic nano-silica powders by supercritical ethanol drying

以硅酸钠为硅源,浓硫酸为酸化剂,在超重力旋转床中制备出二氧化硅,经处理后置于高压釜内,在分别改变溶液体积与高压釜容积比值、滤饼质量或氮气预加压条件下进行乙醇超临界干燥,制得白炭黑粉体。用接触角测定仪、透射电镜、FT-IR红外光谱、氮气吸附容量法、DBP吸油值来表征所得样品。结果表明:所得样品具有极强的疏水性,接触角大都在130°以上,当溶液体积与高压釜容积比值增大时,接触角大体呈增大趋势;当滤饼质量增加时,接触角亦增大;当氮气预加压力增大时,接触角变化规律不明显;所得样品除粒径变化不大外,分散性、比表面积、吸油值等均有规律变化。

SiO2 has been prepared in a high-gravity rotating packed bed using sodium silicate as the silica source and sulfuric acid as proton source. The silica was washed with water and ethanol, filtered, and then placed in a high-pressure autoclave. Supercritical ethanol drying was carried out under different conditions by varying the volume of ethanol in the reactor tank, the mass of filter cake, and N2 pre-pressurization pressure. The resulting products were characterized by TEM, FT-IR, and low temperature N2 adsorption studies, and by determination of DBP oil factor and contact angle. The contact angles of the powders obtained by supercritical ethanol drying were almost all above 130~, indicative of strong hydrophobicity. Larger volumes of ethanol or larger masses of filter cake resulted in larger contact angles whilst increasing the N2 pre-pressurization pressure gave an irregular variation in the contact angle.