Underwater superoleophobic/underoil superhydrophobic corn cob coated meshes for on-demand oil/water separation

Abstract

Abstract The separation of water/oil mixtures is extensively required due to the expanding industrial oily wastewater and frequent oil spill accidents, exciting the development of facile and efficient oil/water separation technologies. In this study, corn cob powders (CCPs) coated meshes with underwater superoleophobicity and underoil superhydrophobicity were successfully fabricated by a facile spraying-coating method, which can be used for on-demand immiscible oil/water mixtures separation without any additional chemical treatment. Thus, both separation modes (oil-blocking or water-blocking) in one single device were achieved for selective oil/water separation regardless of the heavy oil or light oil involved in the mixtures. The oil-blocking mode with underwater superoleophobicity allows water in light oil/water mixtures to permeate, while the water-blocking mode with underoil superhydrophobicity letting heavy oil to permeate. In addition, the high separation efficiencies larger than 99.9% for a series of oil/water mixtures were achieved in the single device with the driving-force only its gravity. Moreover, the coated meshes showed robust environmental stability that could be used for the separation of oil and various corrosive mixtures, such as strong acidic, alkaline and salt aqueous solutions. All these features make the coated mesh become an ideal candidate for on-demand separation of various oil/water mixtures.