The sol-gel process and CO 2 supercritical drying technique were used to prepare silica aerogels. The relations of the equilibrium state of the drying system with the solvent extraction efficiency and SiO 2 performance were studied. The samples were characterized by TG/DTA, TEM and XRD techniques. The results show that the solvent extraction efficiency in the drying condition below the critical point of CO 2+C 2H 5OH system increases only slightly with the increase in temperature (40~60、℃) and organic ...