Double-drying 3D lamellar-structured aerogel membrane for efficient oil-water separation and long-lasting antibacterial activity.

Conventional oil-water separation membranes are difficult to establish a trade-off between membrane flux and separation efficiency, and often result in serious secondary contamination due to their fouling issue and non-degradability. Herein, a double drying strategy was introduced through a combination of oven-drying and freeze-drying to create a super-wettable and eco-friendly oil-water separating aerogel membrane (TMA). Due to the regular nacre-like structures developed in the drying process and the pores formed by freeze-drying, TMA aerogel membrane finally develops regularly arranged porous structures. In addition, the aerogel membrane possesses excellent underwater superoleophobicity with a contact angle above 168° and antifouling properties. TMA aerogel membrane can effectively separate different kinds of oil-water mixtures and highly emulsified oil-water dispersions under gravity alone, achieving exceptionally high flux (3693 L·m·h) and efficiency (99 %), while being recyclable. The aerogel membrane also displays stability and universality, making it effective in removing oil droplets from water in corrosive environments such as acids, salts and alkalis. Furthermore, TMA aerogel membrane shows long-lasting antibacterial properties (photothermal sterilization up to 6 times) and biodegradability (completely degraded after 50 days in soil). This study presents new ideas and insights for the fabrication of multifunctional membranes for oil-water separation.