Superhydrophobic composite coatings with thermal stability for oil/ water separation

The superhydrophobic coating, due to its excellent water-repellent properties, is commonly utilized in the treatment of oily wastewater, oil spill cleanup and fuel purification. However, in practical industrial applications, oil/water mixtures often exist at elevated temperatures, thus, the thermal stability of superhydrophobic surfaces is a critical concern. In this study, we employed a combination of sol-gel method and impregnation technique to fabricate superhydrophobic coatings. This process is straightforward and cost-effective, making it suitable for large-scale production. The resulting superhydrophobic filter paper demonstrates the ability to separate various types of oils with universal applicability, after ten cycles of oil/water separation, the efficiency remains at 98.2 %. Furthermore, the coating demonstrates exceptional mechanical durability, withstanding 11 cycles of sandpaper abrasion and impacts from 60 g of gravel. It also exhibits remarkable chemical stability after exposure to outdoor sunlight for seven weeks, ultraviolet radiation for ten days and acid-base testing, maintaining a water contact angle (WCA) above 150 & ring;. After treatment at 400 & ring;C, the material still retained its superhydrophobic properties, the measured the WCA to be 157 & ring;and the water sliding angle (WSA) to be 2 & ring;. This characteristic was crucial for practical applications, particularly in high-temperature environments.