Binder-free in-situ reinforced nanofibrous membrane with anti-deformable pore structures for seawater concentration

Abstract

Membrane distillation (MD) is a prospective thermal-membrane coupling technology suitable for desalination and concentrating hypersaline water. However, the structural instability and vulnerable salinity tolerance of membrane impede the large-scale implementation of MD technology. In particular, the defective pore structure and fragile hydrophobicity of the porous membrane compromise the repellency of salt components when dealing with hypersaline water. Herein, we engineered a binder-free in-situ reinforced nanofibrous membrane with remarkably anti-deformable pore structures and hydrophobic durability by a one-step electrospinning process. The mixing of different polymers changed the physicochemical properties of the solution, allowing the nanofibers to accumulate densely, reinforcing the pore structure of the membrane instead of the cumbersome post-treatment compaction process. In addition, the incorporation of PTFE nano-powders synchronously consummated the roughness and surface energy of the membrane. More significantly, the binder-free in-situ reinforced nanofibrous membrane operated stably during the 168 h desalination testing and was 2.5 times that of the commercial PVDF membrane when penetration occurred in concentrating synthetic seawater, demonstrating excellent permeability and durability. Mechanistic analysis of membrane structure stability has also been systematically elucidated.