Novel coating can contribute to wastewater purification

Superhydrophobic surfaces with reversible switchable wettability have great application value in the treatment of oily wastewater. However, the advancement of switchable wettability surfaces is limited by the complexity of the manufacturing process and the excessive use of environmentally unfriendly solvents. Now an all-water-based reversible wettability coating was fabricated by simply spraying a water suspension consisting of N-[3-(trimethoxysilyl) propyl] ethylenediamine (AS)-, 3-(trimethoxysilyl) propyl methacrylate (KH-570)-, and 1H,1H,2H,2H-perfluorodecyltrimethoxysilane (FAS)-modified titanium dioxide (TiO₂) nanoparticles and cellulose.

High efficiency

The coating possesses good adhesion with various substrates and exhibits stable mechanical and chemical stability as well as good resistance to harsh environments such as various organic solvents, strongly corrosive environments and extreme temperature environments. The coating can be switched between having superhydrophobicity (160°) and superhydrophilicity under UV irradiation and heating treatment. Coated cotton fabric can separate heavy/light oil-water mixtures and water-in-oil/oil-in-water emulsions with a high efficiency of greater than 95%. Due to the photocatalytic properties of TiO₂, the coating can degrade soluble pollutants in water during UV irradiation. The degradation efficiency is over 97%. As the researchers point out, their study provides a green industrial route for designing a simple, switchable wettability coating, which is expected to promote the large-scale industrial production and application of functional smart surfaces.

The study has been published in Progress in Organic Coatings, Volume 165, April 2022.