Robust, self-healing, superhydrophobic fabric for efficient oil/water emulsion separation

Oil/water emulsion separation to this day is a worldwide problem and the discharge of large amounts of waste oil and oil spills have caused more harm to human health and the environment as a whole. It is therefore important to have the necessary materials in case the need arises to handle such problems. Superhydrophobic coatings have shown promise in dealing with these issues but their poor durability limits their application. To overcome this situation, superhydrophobic coatings endowed with a self-healing ability can work as a potential solution. In this work, a modified fabric is prepared via dip-coating of Polydimethylsiloxane (PDMS), ZIF-90 and fluoroalkyl silane (FAS) on linen fabric. PDMS, a known organosilicon and hydrophobic in nature was first coated on the fabric to serve as the underlying hydrophobic that would migrate to the surface to restore hydrophobicity in case it is lost. ZIF-90 was then coated on the fabric via hydrothermal treatment to provide nanoscale roughness which was then modified with FAS to improve the hydrophobicity. The modified fabric was superhydrophobic with a water contact angle (WCA) of 151 degrees. It also showed good separation capability for several oil/water emulsions, reaching a maximum of 99.5% efficiency and flux of 1213 L m- 2h- 1. The modified fabric exhibited excellent recyclability for 10 cycles and also showed good stability towards mechanical durability and chemical stability tests and could self-heal at room temperature and also by heat treatment. The self-healing mechanism was then explained. The separation efficiency and flux after the tests were also promising, suggesting its potential application in real oil/water emulsion separation.