Underwater superoleophobic GO-PEI-SiO2-Hal quaternary sphere-rod nacre-inspired mesh by LBL self-assembly for high-efficiency oil-water separation

The easy preparation of robust superwetting materials for oily wastewater disposal still remains a challenge. Inspired by the self-cleaning and mechanical properties of natural nacre underwater, herein, we have successfully developed sphere-rod quaternary artificial nacre-inspired meshes (named GO-PEI-SiO 2 -Hal) via interfacial self-assembly using 2D graphene oxide nanosheets , hyperbranched polyethyleneimine, SiO 2 nanospheres , and hollow halloysite nanotubes (Hal) as the building blocks. The nacre-like “brick-and-mortar” layered microstructure was successfully formed and tightly coated to the mesh, showing excellent mechanical properties with Young's modulus up to 19.7 ± 2.6 GPa. Compared to the ternary structures, the quaternary sphere-rod morphology improved the surface roughness , and these four organic/inorganic building blocks are all hydrophilic , which together resulted in the superhydrophilic and underwater superoleophobic characteristics. The effects of building block concentration, dipping number, and mesh size on wettability and oil-water separation performance were studied in detail. The optimal (GO-PEI-SiO 2 -Hal-1) 15 @Fe 300 mesh showed an underwater oil contact angle of 159 o for 1,2-dichloroethane, low oil adhesion, and excellent separation efficiency up to 99.8% at an ultrahigh flux up to 195,038 L m −2  h −1 . This nacre-like mesh exhibited excellent salt tolerance, acid-alkali resistance, recycling ability, and mechanical properties for practical oily wastewater treatment .