MOF-based cotton fabrics with switchable superwettability for oil–water separation

Abstract

• The superhydrophobic cotton fabric could transform into superhydrophilic by wetting with ethanol and could restore after drying. • Whether it is water or oil removal process, the flux and efficiency of the fabric was above 15,300 L·m −2 h −1 and 98.6%. • The superhydrophobic fabric possessed excellent self-cleaning properties. • The fabric wetted with ethanol and water successively had good antifouling properties. • The superhydrophobic fabric had good mechanical durability and chemical stability. Superwettability materials with a single function cannot meet the needs of different oil-bearing wastewater separations. This study proposed a preparation method for the swappable superwettability on cotton fabrics. The superhydrophobic fabric surface that was wetted with ethanol transformed from being superhydrophobic/superoleophilic to being superhydrophilic/underwater superoleophobic, and returned to superhydrophobicity after drying. Regardless of whether it is the oil removal process or the water removal process, the flux of the fabric was above 15,300 L·m −2 h −1 , and the separation efficiency was over 98.6%. Although the continuous separation was conducted 50 times, the flux and separation efficiency did not change significantly. The prepared material could exhibit superhydrophobicity after being immersed in solutions of different pH and actual seawater for some time, even after 50 times of sand impact experiments, indicating excellent mechanical durability and chemical stability. Thus, the preparation strategy of the swappable superwettability materials can develop oil–water separation technology.