Underwater superoleophobic palygorskite coated meshes for efficient oil/water separation

Oil/water separation has recently become a global challenging task due to frequent oil spill accidents and increasing industrial oily waste water. Here, we demonstrate for the first time underwater superoleophobic palygorskite coated meshes, which were fabricated by spraying palygorskite and polyurethane mixtures on copper mesh substrates. The underwater superoleophobic meshes were then used to study gravity driven oil/water separation for a series of oil/water mixtures, where only the water from the oil/water mixture is allowed to permeate through the mesh. A separation efficiency of up to 99.6% could be achieved through the coated mesh for the kerosene-water mixture. In addition, the palygorskite coated mesh still maintained a high separation efficiency of over 99.0% and stable recyclability after 50 separation cycles with the surface morphology of the palygorskite coated mesh nearly unchanged. Furthermore, the palygorskite coated meshes exhibit excellent environmental stability under a series of harsh conditions, which are used for the separation of mixtures of oil and various corrosive and active aqueous solutions, including strong acidic, alkaline, or salt aqueous solutions, even hot water. The fabrication approach presented here can be applied for coating large surface areas and to develop a large-scale oil/water separation facility for oil and various corrosive and active aqueous mixtures.