Bioinspired hierarchical structure with intensified anti-scaling capacity for real seawater membrane distillation

Membrane distillation (MD) holds immense promise for the treatment of solutions with high salinity. However, widespread adoption of MD is hindered by the persistent issue of membrane scaling, which results in the failure of MD operation. Our study focuses on enhancing the anti-scaling performance of the polyvinylidene difluoride (PVDF) membranes by creating hierarchical microstructure resembling lotus leaves on the membrane surface. PVDF hollow fiber membranes are produced through a thermally induced phase separation process coupled with advanced co-extrusion technology, a scalable technique that allows for precise tuning of membrane structure by adjusting the preparation conditions. The preparation conditions were optimized using response surface methodology. The optimal membrane shows not only a high-water vapor flux of 10.13 kg·m −2 ·h −1 at 60 °C but also an enhanced hydrophobicity with a water contact angle of 154°. Most importantly, the optimized PVDF membrane achieved stable operation for 350 h in a real seawater DCMD process without any flux decline. The excellent performance of the membrane with hierarchically micro-nanostructured surface offers valuable insights for advancing the development of novel MD membranes with superior anti-scaling properties. • PVDF membrane with hierarchically micro-nanostructured was optimized by RMS method. • Nanoparticle-free and fluoride-free superhydrophobic surface was obtained one-step co-extrusion method. • The optimal PVDF membrane showed excellent anti-scaling performance and long-term stablility in real seawater. • Spontaneous crystal detachment has been observed during DCMD tests for the first time.