Liquid-phase deposition functionalized wood sponges for oil/water separation

Due to frequent industrial wastewater discharge and oil spills, there is a need to develop sustainable and efficient absorbents and treatment methods. Herein, based on the unique microstructure of wood and functional requirements, super-hydrophobic, recyclable, and renewable wood sponges (SHWSs) with an ultralight density (35.4 mg cm−3) and high porosity (98.68%) were prepared from anisotropic natural balsa wood via a scalable and sustainable silanization reaction using liquid-phase deposition (LPD). The super-hydrophobicity of the SHWSs (contact angle = 159.2°) was due to the formation of polysiloxanes on the surface via silanization. The internal contact angle (CA) reached 137.2°, which was attributed to the uniformity of LPD. The SHWSs exhibited a high absorption capacity for various organic solvents and oils (23–60 g g−1) and reusability, allowing it to reach a contact angle of 150.8° and an absorption capacity of 52 g g−1 for CCl4 after 50 absorption cycles. The SHWSs also showed excellent super-hydrophobicity under acidic, alkaline, and saline conditions, as well as in hot water, demonstrating their excellent durability. A continuous oil/water separation device was made by using the SHWSs, which showed a high separation efficiency, with a flux rate of up to 72.8 L h−1 g−1. This green strategy for treating natural balsa wood with LPD provides a scalable way to produce sustainable oil/water separation materials while also developing high-value-added applications of natural balsa wood.