Simple Preparation Method for Hydrophilic/Oleophobic Coatings

This work provides a simple method to prepare a hydrophilic/oleophobic coating using polyester filter cloth as the substrate, a mixture of three hydrophilic polymers (poly(aspartic acid), poly(acrylic acid), and poly(vinyl alcohol)); SiO₂ with an average particle size of 30 nm is used to improve the surface roughness of the filter cloth. Then, a long fluorocarbon chain of 1H,1H,2H,2H-perfluorooctyltriethoxysilane is grafted onto the surface by a vacuum silanization coupling reaction to obtain hydrophilic/oleophobic properties. The water and hexadecane contact angles of the treated filter cloth are 3 and 99.8°, respectively. A separation efficiency of 98% was achieved in hexadecane/water separation. The durability test shows that the separation efficiency of toward hexadecane-water mixture remains more than 98% after 20 cycles. The obtained material also presents a strong underwater antipollution property when using hexane, rapeseed oil, mineral oil, and pump oil as model pollutants. For oils with higher viscosity, the separation efficiency remains above 97%. However, the separation efficiency is ∼80% when treating emulsions.

A superhydrophilic and underwater superoleophobic chitosan–TiO2 composite membrane for fast oil-in-water emulsion separation

The CST modified membrane showed an excellent flux and can maintain underwater superoleophobicity in corrosive aqueous media.