Facile fabrication of a robust superhydrophobic/superoleophilic sponge for selective oil absorption from oily water

Abstract

Superhydrophobic/superoleophilic sponges with good stability, high absorption capacity and excellent recyclability have attracted intense interest due to their potential applications in oil removal. In this paper, a superhydrophobic/superoleophilic sponge was successfully fabricated through the facile functionalization of the polyamide sponge with a core–shell fluorinated-polyacrylate (PFA) latex and hydrophobic SiO₂ particle composite coating. Owing to the outstanding corrosion resistance of PFA and high adhesion between the PFA/SiO₂ composite coating and polyamide sponge, the as-prepared sponge showed excellent resistance to corrosive aqueous solutions of acid, base and salt, and could maintain good hydrophobicity even after being immersed in toluene for 12 h or abraded by sandpaper for more than 10 cycles. Compared to the pristine sponge, the PFA/SiO_2-coated sponge had a faster oil absorption rate and higher oil and lower water absorption. Moreover, the superhydrophobic/superoleophilic sponge could selectively and effectively absorb oil from water with an absorption capacity over 25 times its own weight. More importantly, the absorbed oil was easily collected by a simple squeezing process, and the sponge could be reused for many cycles while still maintaining a high absorption capacity, excellent separation efficiency and good hydrophobicity. Together, these data indicate that the as-prepared sponge is a promising candidate for the separation of water and oil.