Composite polydopamine-based TiO₂ coated mesh with restorable superhydrophobic surfaces for wastewater treatment

Various pollutants in wastewater including water-insoluble oils and water-soluble toxic organic pollutants, have been threatening ecosystems and human health, making wastewater purification difficult. Inspired by the hierarchical structures and chemical compositions of lotus leaf, we combined the usage of polydopamine (PDA) chemistry and photocatalytically active TiO₂ to develop a facile approach toward composite PDA-based TiO₂ coated mesh with restorable superhydrophobicity. In this procedure, PDA assisted loading of TiO₂ nanoparticles onto stainless steel mesh with a result of micro/nanoscale hierarchical surface was achieved via a single-step solvothermal method. After modified with 1H, 1H, 2H, 2H-perfluorodecyltriethoxysilane, this mesh became superhydrophobic. The TiO₂ coated mesh exhibited enhanced superhydrophobicity, excellent environmental stability, robust chemical resistance and high mechanical durability. Moreover, it has been demonstrated the high separation capacity and extraordinary recyclability for various oils collection from water due to its special surface superhydrophobicity. Importantly, such a mesh possessed photocatalytic activity due to the embedded TiO₂, which allowed for the effective degradation of organic pollutants under UV irradiation, representing a plausible way to restore superhydrophobic surface by photocatalytically decomposing the attached contaminants. This investigation suggests a green and facile way to prepare superhydrophobic materials with restored surface wetting property, which will be useful for wastewater purification.