High‐Flux Steady‐State Demulsification of Oil‐In‐Water Emulsions by Superhydrophilic‐Oleophobic Copper Foams with Ultra‐Small Pores Under Pressure

Abstract 3D superwetting materials struggle to maintain high‐flux steady‐state demulsification for oil‐in‐water emulsions because the accumulated oil within the material is difficult to discharge rapidly. The water flow shear force can swiftly remove the oil from the anti‐fouling surface. In this study, by introducing nanofibers and carbon nanotubes and chemical modification, a superhydrophilic‐oleophobic copper foam with pores of several micrometers is prepared, which can achieve a continuous demulsification process with steady‐state flux over 57000 L m −2 h −1 for oil‐in‐water emulsions and rapid hydraulic‐driven oil release under an additional pressure of 5 kPa. Thanks to the ultra‐small pores of the copper foam, the steady‐state demulsification efficiency can be still maintained at over 97.5%. During the demulsification process, the accumulation of oil and surfactants within the copper foam can be maintained at low levels, achieving dynamic equilibrium. With the aid of second‐stage superhydrophilic copper mesh, the demulsified oil‐water mixtures can be rapidly separated. This high‐flux, steady‐state, and efficient demulsification process shows great potential for industrial applications.