Caffeic acid polymer rapidly modified sponge with excellent anti-oil-adhesion property and efficient separation of oil-in-water emulsions

The efficient treatment of high stability emulsion with small diameter and the prevention of oil contamination of materials are serious issues in the process of emulsion separation. In order to address those issues, we reported a fast and versatile hydrophilic surface coating technology that uses oxidants and diamines to synergistically promote the polymerization of caffeic acid (CA). It was found that amino groups can not only accelerate the polymerization of CA, but also promote the deposition of polymers on the sponge surface. Using silica nanoparticles to improve the roughness, superhydrophilic melamine sponge could be prepared, which exhibited excellent superhydrophlic-underwater superolephobic and anti-oil-adhesion properties. DFT simulation was employed to explore the potential mechanism of the anti-oil adhesion ability. In addition, combined with the mechanical compression strategy, the sponge exhibited a high efficiency of 99.10% with a permeation flux of 19080 ± 700 Lm-2 h-1 in emulsion separation just under the action of gravity. Moreover, based on the interaction between the surfactant and the surface of the material, the separation mechanism was discussed. Overall, this work provided an advanced method for the preparation of superhydrophilic sponge with anti-oil-fouling performance, which showed great potential in dealing with practically challenging emulsified wastewater.