Study on Intelligent Bionic Superhydrophobic Material and its Oil-Water Separation Mechanism

Abstract

Marine oil spills and improper disposal of daily oil usage have posed significant threat to ecological environments and human health due to rapid industrial development. In this study, an environmentally friendly, simple process and high-performance Fe₃O₄@SiO₂@Polymethyl methacrylate (PMMA)-based smart bionic superhydrophobic oil-absorbing material was developed for effectively collecting and removing oil pollutants from water. By studying the effects of Fe₃O₄ particle size, polydimethylsiloxane (PDMS) concentration, and heating time on the superhydrophobicity of the materials, the directional regulation of superhydrophobicity and oil-water separation performance of Fe₃O₄@SiO₂@PMMA@PDMS materials was realized. The results showed that the material exhibited optimal performance when the Fe₃O₄ particle size combination was 20/500 nm/1 μm, the mass ratio of PDMS to Fe₃O₄@SiO₂@PMMA was 7 : 1, and it was heated at 350°C for 1 minute. The coating achieved an apparent contact angle (APCA) of 158.7° and a rolling angle as low as 4.9°. This coating not only remained superhydrophobic after a 21 m abrasion test and 288 h immersion in acid, alkali, salt, and high-temperature solutions, but also efficiently separated oil-water mixtures and water-in-oil emulsions, and the separation efficiency for oil-water mixtures of trichloromethane, dichloromethane and bromomethane was over 99.78 %, and that for water-in-oil emulsions was over 98.34 %. Furthermore, the superhydrophobic magnetic polyurethane (SFPU) sponge prepared using Fe₃O₄@SiO₂@PMMA not only exhibited excellent oil-absorbing capacity (11–28 g/g), but also realized precise oil absorption at multiple sites by magnetic conduction. In the actual oily wastewater test, the oil-water separation efficiency of the sponge reached 90.58 % and the oil absorption capacity reached 17.03 g/g. This efficient oil-water separation performance as well as oil adsorption capacity comes from the fact that the nonpolar molecules (e. g., −CH₃) generated by the hydrolysis of PDMS can produce van der Waals adsorption with oil substances, while the excellent micro-nanostructure of the coating surface greatly increases the contact area between oil droplets and the coating, which can make them adsorb or pass through quickly. This multifunctional coating and sponge had immense application potential in fields like offshore oil spill treatment, organic pollution control in water bodies.