Durable superhydrophobic/superoleophilic epoxy/attapulgite nanocomposite coatings for oil/water separation

To improve the durability of oil/water separation materials, the superhydrophobic/superoleophilic epoxy/attapulgite nanocomposite coatings on the stainless steel meshes for oil/water separation were fabricated via a facile spray-coating method. The surface microstructure and wettability of the coated mesh were closely related to the attapulgite content. At the attapulgite content of 44.4 wt%, the coated mesh exhibited superhydrophobicity with the water contact angle of 160 ± 1° and superoleophilicity with the oil contact angle of 0°, which caused water to run off the mesh while allowing oil to permeate through. Various oil/water mixtures, such as hexadecane/water mixture, lubrication oil/water mixture, and paroline/water mixture, can be successfully separated by a simple filtering method using the coated mesh with the separation efficiency above 98%. This gravity-driven oil/water separation using the coated mesh was simple, time saving, and repeatable for at least 30 times. Most importantly, after being treated in various harsh conditions, including mechanical scratch, high temperature, humid atmospheres, and corrosive substance, the coated mesh still maintained highly efficiency for oil/water separation. The advantages of scalable production, high efficiency, and excellent durability for the epoxy/attapulgite coating make it to be a good candidate for oil/water separation in practical applications.