Superhydrophobic cellulose nanofibril/silica fiber/Fe3O4 nanocomposite aerogel for magnetically driven selective oil absorption

The development of superabsorbent materials with high absorption capacity, selectivity, and stable performance is needed for oil recovery. Remote-controlled oil absorption is highly favorable for oil absorption in harsh environment. In this study, a novel ultralight superhydrophobic nanocomposite aerogel composed of organic cellulose nanofibrils (CNFs), inorganic silica fiber, and magnetic Fe3O4 nanoparticles was developed through a simple freeze drying and surface modification method as a magnetically driven superabsorbent material. The aerogel has a highly porous and fibrous structure that contains hierarchical micro-nano surface topography. Low surface energy carbon-fluorine chains were grafted on aerogel surface which rendered the aerogel superhydrophobic. The addition of Fe3O4 nanoparticles significantly improved the surface area, compressive property, water contact angle, and the separation efficiency of the aerogel, but reduced the absorption capacity due to the increase of bulk density. The developed nanocomposite aerogel has a high absorption capacity (weight gain of 3420-5837%), separation efficiency similar to 100%, and a water contact angle of 150 degrees. It also demonstrated high elasticity and performance stability in repetitive use. Given its magnetic property, the CNF/silica/Fe3O4 nanocomposite aerogel is a promising candidate for selective oil removal from open water, especially for remotely controlled applications.