Superhydrophobic silica aerogels reinforced with polyacrylonitrile fibers for adsorbing oil from water and oil mixtures

Abstract

Silica aerogels are unique solids with extremely high porosity, transparency and low density. They make excellent adsorbing materials due to their high surface area and three-dimensional reticular structures. However, their fine structures and hydrophilic surfaces make them fragile and impractical for adsorbing oil from water and oil mixtures. To improve their mechanical properties, we incorporate small amounts of polyacrylonitrile fiber into the aerogels, prepared at relatively mild temperatures. Electron microscopy images and pore size distributions of the modified aerogels show that the silica aerogel had a co-continuous porous structure. The aerogels were modified to be superhydrophobic, and the surface hydroxyl or alkoxy groups were converted to stable –CH₃ groups with a contact angle as high as 169°. The oil adsorption capacity of the silica aerogels was calculated as 9.56 g/g. The sorption and desorption process could be repeated at least 100 times, indicating that silica aerogels are promising oil-absorbing materials.