Fabrication of superhydrophobic copper stearate@Fe3O4 coating on stainless steel meshes by dip-coating for oil/water separation

A robust superhydrophobic surface coated with copper stearate (CS) and Fe3O4 nanoparticles was prepared on stainless steel mesh (SSM) by dip-coating method for oil/water separation. The superhydrophobicity of CS@Fe3O4 SSM was found to be superior to that of SSM coated with bare CS because of the enhanced surface roughness by Fe3O4 nanoparticles. The CS@Fe3O4 SSM shows good performance in water repellency, self-cleaning property, long-term storage, mechanical and chemical stability. And it is capable of separating various immiscible oil/water mixtures even in extreme environments (such as highly acidic, alkaline, and salty solutions) with the separation efficiency > 98% and excellent recyclability. Furthermore, various surfactant-stabilized water-in-oil emulsions were successfully separated by the CS@Fe3O4 SSM due to its good superhydrophobic and superoleophilic properties as well as dense hierarchical micro/nanostructure. The preparing approach of CS@Fe3O4 SSM presented in this work is facile, inexpensive and environment-friendly, which enables the CS@Fe3O4 SSM to be applied in actual oil/water separation.