Tailoring Structural Property and Surface Wettability of Omniphobic Membranes for Superhigh Flux and Competent Wetting Resistance in Membrane Distillation

Recently, omniphobic membranes have attracted great attention in membrane distillation (MD) to recover water from challenging wastewaters due to their promising wetting resistance. However, an omniphobic membrane with high flux is still lacking to make MD a more efficient and viable water treatment technology. Herein, a series of polyvinylidene fluoride (PVDF)-based omniphobic membranes with tailored structural properties and surface wettability were fabricated via electrospinning and utilizing fluorosilanized silica nanoparticles (SiO2 NPs) as additives. Results showed that the optimized PVDF@100%SiO2 presented a superhigh flux of 68.5 LMH at 60 degrees C when treating simulated seawater, which was highly competitive among the reported studies. PVDF@100%SiO2 also showed stable desalination performance in the treatment of hypersaline solutions with 7.0 and 14.0 wt % NaCl or surfactant-containing solutions (0.1 mM SDS). Moreover, in addition to the conventional wetting criteria based on liquid entry pressure, the wetting resistance of omniphobic membranes was also revealed to be strongly dependent on membrane flux by the wetting kinetic changes. Our study suggested the significant application potential of the prepared omniphobic membranes in MD and provided useful insights into the design of high-performance MD membranes with both high flux and competent wetting resistance for challenging feeds with different wetting potentials.