硅气凝胶对苯系物和醇的吸附性能及微观结构变化

Adsorption Performances of the Pure Liquid of Benzenes and Alcohols onto Silica Aerogel and the Microstructure Changes

摘要: 硅气凝胶不仅是优良的绝热保温材料，也广泛用于苯、醇等挥发性有机物(VOCs)的吸附，实现分离或污染控制。未有研究考虑纯物质液体的循环吸附性能及微观结构变化，本文对此进行考察研究。结果表明，硅气凝胶对苯系物(苯、甲苯、乙苯、对二甲苯、苯乙烯)纯溶液的首次吸附容量可达到14.8、12.8、14.0、14.7和14.3 g/g，是活性炭的8~11.5倍；对丙酮、丁醇和乙醇纯溶液的首次吸附容量为10.6，11.0，11.3 g/g。然而，随着循环次数增加吸附容量降低，循环吸附苯纯溶液5次、循环吸附丁醇纯溶液6次后，硅气凝胶的孔容和孔径均大幅降低，比表面积从618.2变为690 m²/g左右，平均孔径从23.6降到14 nm左右，孔容从3.6降到2.4 mL/g左右。该研究对VOCs污染控制及硅气凝胶应用研究具有重要意义。

Abstract: Silica aerogel is not only excellent thermal insulator, but also used widely for VOCs (volatile organic compounds) adsorption to realize separation or pollution control. No report focused on the microstructure change of silica aerogel after the cyclic adsorption of pure VOC liquid. And this is the study of this paper. The results indicated that the first-cycle adsorption capacity of pure liquid benzenes, i.e. benzene, toluene, ethyl benzene, p-xylene, styrene onto silica aerogel could reach at 14.8, 12.8, 14.0, 14.7, 14.3 g/g, respectively, which are 8 - 11.5 times of those onto activated carbon. The first-cycle adsorption capacity of acetone, butanol, ethanol was 10.6, 11.0, 11.3 g/g, respectively. However, the adsorption capacity decreased with the increase of cycle number. After 5-cycle benzene adsorption or 6-cycle butanol adsorption, the surface area of the silica aerogel increased from 618.2 to about ~690 m²/g, average pore size decreased from 23.6 to about 14 nm, and pore volume decreased from 3.6 to about 2.4 mL/g. This study is helpful for the researches of VOCs control and silica aerogel application.