Facile preparation of hybrid microspheres for super-hydrophobic coating and oil-water separation

Super-hydrophobic materials have recently attracted great interest from both academia and industry, due to their promising applications in self-cleaning, oil-water separation, etc. Here, we developed a facile one step method to prepare the hybrid polyvinylidene fluoride (PVDF)/SiO2 microspheres based on electro-spraying for super-hydrophobic coating. By controlling nanoparticle concentration, the SiO2 could be uniformly distributed on PVDF microsphere surface, forming a hierarchical micro/nano structure. The contact angle (CA) of the super-hydrophobic coating could reach as high as 162°, and the sliding angle (SA) could be close to zero degree. The super-hydrophobic coating possessed a good self-cleaning performance, water jet stability and corrosion resistance. It was found that gravity driven oil-water separation was achieved by using the filter paper coated with the super-hydrophobic hybrid microspheres. More importantly, the coated filter paper could not only separate the oil with the pure water but also the corrosive solution including the salt, acid and alkali solution. With the increase of the solution concentration, the free-standing membrane composed of the hybrid microspheres and ultrathin threads were obtained, and the membrane showed a high flux and efficiency for oil-water separation. In addition, the flexible membrane could be used for adsorption of different kinds of oil.