Fabrication of novel superhydrophilic and underwater superoleophobic hierarchically structured ceramic membrane and its separation performance of oily wastewater

Hierarchically engineered asymmetric ceramic membrane is successfully fabricated, and special wettability is endowed to the membrane by introducing superhydrophilic and underwater superoleophobic silica nanoparticles through dip-coating technology onto the active separation layer. Effect of reaction temperature on the wettability of the silica nanoparticles is discussed. It has been found that the hydrophilicity of the silica increases with increasing the temperature and superhydrophilicity can be obtained when the temperature reaches to 60   °C. Underwater oil contact measurements are performed using a series of oils and it turns out the as-prepared material bear excellent oil repellency towards various oil droplets. Separation performance of the membrane for oily wastewater treatment was investigated. It has been revealed that the as-prepared membrane can successfully separate the oil contaminated wastewater within one step under a small applied pressure (0.1   MPa) with oil rejection coefficient R >99.95%, indicating an extremely high separation efficiency.