Bioinspired Composite Hydrogel-Coated Stainless Steel Screen for Efficient and Stable Gravity-Driven Oil-Water Separation

The reasonable and efficient treatment of oily wastewater has attracted wide attention. Herein, a composite hydrogel-modified filter screen, inspired by fish scales and marine mussels, is prepared via layer-by-layer modification to separate oil-water mixture even in harsh environments. First, a stainless steel filter screen is coated by a layer of silicon dioxide (SiO2) microspheres by the vapor deposition of polydimethylsiloxane. Then, a SiO2@polydopamine-polyacrylamide composite hydrogel (SiO2@P-PGel)-modified screen is prepared by dipping the screen into a prepolymer solution. Due to the special wettability and micronanostructures, the stable and high efficient water permeation in the air and oil repellency in water are achieved by the screen. A very effective oil-water separation rate of over 99% can be achieved for various types of oil-water mixtures. The separation efficiency and water flux remain stable even after 70 cycles. Another significant feature of the innovative screen is that it displays excellent underwater superoleophobicity in very salty, acidic, and alkaline solutions, suggesting that the screen has excellent oil-water separation performance and stability, even in corrosive aqueous media. This innovative screen is a potentially attractive candidate for the treatment and recovery of oily wastewater due to its high efficiency and stability.