Oil/water mixtures and emulsions separation of stearic acid-functionalized sponge fabricated via a facile one-step coating method

Superhydrophobic and superoleophilic sponge was prepared by facile dip coating in a stearic acid (SA) solution and subsequent heat treatment. The obtained sponge exhibits excellent superhydrophobic stability and selectively sorption ability for oil pollutants on water surface. Also, the sponge is capable of separating huge amounts of oils from water continuously via a vacuum system and oil droplets in oil-in -water emulsions. After the separation by the coated sponge, the transparency for the emulsions (n-Hexane in-water and toluene-in-water) can increase to over 80% from below 14.7%. The oil sorption capacity of as-prepared sponge for various types of oils and organic solvents can reach 17.4-41.6 times of its own weight, and the absorbed oils are easy to be recovered by a simple squeezing process. Moreover, the recovered sponge can repeatedly absorb/desorb the oils for at least 100 times, demonstrating slightly decrease in sorption capacities and hydrophobicity. The proposed approach for fabricating superhydrophobic sponges is simple and inexpensive so that the as-prepared sponge has great potential as an efficient sorbent in oily wastewater filtration and oil spill clean-up. (C) 2017 Published by Elsevier B.V.