Durable tetra-scale superhydrophobic coatings with virus-like nanoparticles for oil–water separations

Abstract

For highly efficient water–oil separation, superhydrophobic surfaces were prepared by coating the virus-like silica nanoparticles (VLSNs) on a substrate in scalable manner and subsequent fluoroalkyl silane through the sol–gel process. On the VLSN-coated glass substrate, the contact angle of the water droplet increased from 100.8° (plain silica nanoparticles) to 178.9° in the air as the areal density of coated nanoparticles increased up to 8,170 nanoparticles per µm2. Furthermore, fabric membrane and stainless-steel mesh were coated with VLSNs and subsequently functionalized with fluoroalkyl silane, which was utilized for continuous oil–water separation with a high separation efficiency (>99%), high flux (>2,000 L/m2⋅h) and high washing durability (>500 cycles). Additionally, these superhydrophobic fabrics were applied for removing oil contaminants on water by absorption within ten seconds.