Environment-Friendly superhydrophobic sponge for highly efficient Oil/Water separation and microplastic removal

The pollution of water resources by oils and microplastics is a significant global issue affecting the environment and human health. However, developing a sustainable multifunctional adsorption material to remove multiple pollutants has always been a challenge. Herein, an eco-friendly superhydrophobic polyurethane sponge was developed using polydimethylsiloxane (PDMS) and dehydroabietic acid grafted Al2O3 nanoparticles by dip-coating technique. The green dehydroabietic acid has strong hydrophobicity, which can make the coated sponge have excellent separation of oil/water mixtures or emulsions and has a high oil absorption capacity (20–55 g/g) for various kinds of oils. Continuous oil/water separation was also achieved by gravity-driven or with the assistance of peristaltic pump. After 10 separation cycles, the coated sponge still exhibits excellent separation efficiency (greater than 97%) due to its outstanding mechanical durability and compressive performance. Moreover, various kinds of microplastics could be efficient captured from the aqueous solution at a higher rate using the coated sponge, which is mainly due to the capillary force of the coated sponge and the non-covalent force and conjugates between PDMS and microplastics. This work provides a new strategy to fabricate a sustainable multifunctional sponge for oily wastewater and microplastics and shows the great potential for large-scale practical application.