Bioinspired superoleophobic/superhydrophilic functionalized cotton for efficient separation of immiscible oil-water mixtures and oil-water emulsions.

Oil contamination is pressing environmental and natural resource issues. Oil-water separation technology can be used for water purification. Traditional methods are either time consuming or energy intensive. Bioinspired materials with combination of affinity and/or repellence towards oil and water in mesh-based methods have attracted widespread attention in the oil-water separation. Among existing materials, superhydrophobic/superoleophilic materials are prone to contamination by oil. Superhydrophilic/underwater superoleophobic materials can only operate underwater which restricts the practical use. In contrast, superoleophobic/superhydrophilic materials are desirable for oil-water separation. However, traditional mesh-based method cannot be used for separation of emulsions since the dispersed microdroplets can easily pass through the mesh pores. Superhydrophobic/superoleophilic cotton has been used for separation of water-in-oil emulsions. In this study, a facile method to fabricate bioinspired superoleophobic/superhydrophilic cotton was developed. The functionalized cotton exhibits an oil-repellent and water-wetting behavior and is capable of separating both immiscible oil-water mixtures and also oil-in-water emulsions without oil contamination. This developed cotton is of interest for various applications.