Fabrication of 3D silica with outstanding organic molecule separation and self-cleaning performance

The existing oil-water separation materials are often limited by their cost, efficiency and environmental implications, so they are difficult to achieve effective utilization in industry. Although silica nanoparticles have excellent environmental-friendly and rich raw materials, their use has been restricted due to poor porous structure or complex preparation process. Herein, we adopt a growth-aggregation-modification-growth strategy to prepare superhydrophobic silica with three-dimensional (3D) structure. Findings show that the as-prepared silica has a 3D network structure of a size of 11 μm, a pore volume of 2.79 cm³/g and an absorption capacity of 2.98 mL/g towards castor oil. Particularly, superhydrophobic silica exhibits an outstanding organic molecule separation performance from series of surfactant stabilized oil-in-water emulsions with size less than 10 μm and dyes in water. In addition, the 3D silica can act as a functional additive in polydimethylsiloxane (PDMS) for enhancing its hydrophobicity. The substrates coated with PDMS/silica composite present outstanding oil/water separation and self-cleaning performance which is due to the silica particles have excellent superhydrophobicity and porous 3D network. In terms of the well available low-cost raw materials and simple preparation method, the superhydrophobic 3D silica could find promising applications in the treatment of oily wastewater or preparation of self-cleaning surfaces.