Stainless Steel Screen Modified with a Self-Healing Hydrogel for Efficient Gravity-Driven Oil–Water Separation

Due to their low oil adhesion and selective oil–water separation, screens with superhydrophilicity and underwater superoleophobicity have attracted significant attention. However, oil–water separation materials with high efficiency and low cost are still urgently in demand. Here, inspired by natural marine mussels, we prepared a self-healing hydrogel-coated screen to achieve highly efficient oil–water separation. Polydopamine (PDA) was incorporated into polyacrylamide (PAM) and uniformly coated on a stainless steel screen to prepare a self-healing hydrogel-coated screen. The results showed that the PDA-PAM hydrogel coating firmly adhered to the stainless steel screen and exhibited superhydrophilicity and underwater superoleophobicity. Regarding the PDA-PAM hydrogel-modified screen with a coating time of 7 min, different types of oil–water mixtures could be driven by gravity to achieve a highly efficient oil–water separation rate of over 97%, and the water flux could reach 91,673 L m−2 h−1. After ten cycles, the separation efficiency did not decrease significantly, suggesting that the self-healing hydrogel-coated screen has excellent stability and recycling performance. This inexpensive novel filter screen with high efficiency has a wide range of potential application in the field of oil–water separation.