Facile preparation of hybrid coating-decorated cotton cloth with superoleophobicity in air for efficient light oil/water separation

Superwetting materials have attracted broad attention in oil-water separation application in the last few years. In our work, a kind of modified cotton cloth with superoleophobicity/superhydrophilicity in air is obtained by using polydopamine and nano silica powder to construct micro-nanostructure on cotton cloth and subsequent sodium perfluornonanoate decoration to reduce the surface energy. The results show that the modified cotton cloth has high contact angle (CA) to various oils, and the CAs to canola oil, flaxseed oil, corn oil, and sesame oil are 164.5°, 153°, 152.5°, 144.5°, respectively. The constructed cloth has high oil-water separation efficiency to the mixtures of corn oil, linseed oil, rapeseed oil and water. Even after 25 cycles, the efficiency is still higher than 97%. Besides, the modified cloth can resist severe friction damage and the CA to oil is still greater than 135° after 18 cycles of friction on sandpaper. Especially, the separation efficiencies to rapeseed oil in pH 2 solution, pH 12 solution, 3.5% NaCl solution, hot water, ice water are above 96%, implying the applicability of the cloth in harsh water environments.