Digital light processing technique aided 3D printing hierarchical super-wetting mesh coated with hydrophobic SiO2 for highly efficient oil-water separation

Abstract

Gravity-driven filtration using super-wetting mesh surfaces holds significant promise in addressing oil pollution resulting from human activities. However, conventional techniques need help fabricating efficient separation mesh structures due to their limited stability in oily-water solutions. To overcome this, we employed a Digital Light Processing (DLP) 3D printing technique to fabricate a mesh with a micro-patterned surface using a UV light-curable polyurethane (PU). A post-UV curing step was implemented to transform the soft segments of PU into a solid state. To enhance the super-wetting properties, hydrophobic modified silica (m-SiO2)/UV curable polydimethylsiloxane (PDMS) solution was applied through dip coating, resulting in a hierarchical structure with high surface roughness and superhydrophobic characteristics. In oil–water separation tests, the hierarchical superhydrophobic mesh, featuring a pore size of 300 µm, demonstrated exceptional performance, achieving a remarkable flow flux of 37,410 L/m2 h with a separation efficiency of 97.46 %. Furthermore, the separation efficiency remained consistently above 97.0 % under varying pH conditions and oil mixtures, highlighting the excellent water-repellence capacity of the hierarchical mesh developed in this study.