乙醇超临界技术制备疏水性白炭黑粉体

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。

Preparation of hydrophobic nano-silica powders by supercritical ethanol drying

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. 