Preparation of halloysite-based PVDF membrane for effective oil/water separation and dyes removal

The application of materials with selective superwettability to oil/water separation has attracted much attention due to frequent oil spills, large discharges of oily wastewater and many shortcomings of traditional separation methods. Herein, we successfully prepared double-defense membranes by co-precipitating dopamine hydrochloride and polyvinyl polyamine on the original commercial hydrophilic polyvinylidene fluoride (PVDF) membrane and coating the membrane with a halloysite-based hydration layer. Our membranes are highly efficient (>99.6 %) in separating oil-in-water emulsions, have outstanding recycle capacity, good anti-fouling properties (underwater oil contact angle of 156.6 +/- 1.9(degrees), low oil adhesion), and are resistant to acid, alkali, and salt. Besides, our membranes can also remove different dye solutions through simple filtration. With the advantages of double-defense design, excellent underwater oleophobic performance in various environments, oil-water emulsion separation performance, dye removal function, and low cost, our strategy might provide solutions for treating wastewater containing oil or dye, thus expanding the application range of membrane materials.