ZnO Nanowires@PVDF nanofiber membrane with superhydrophobicity for enhanced anti-wetting and anti-scaling properties in membrane distillation

Abstract

The anti-wetting and anti-scaling abilities of membrane are two critical properties for the membrane distillation. In this work, a superhydrophobic hybrid composite nanofiber membrane with the construction of hydrophobic ZnO nanowires on PVDF nanofiber membrane (P–ZnO@PVDF) based on hydrothermal method and chemical vapor deposition (CVD) was presented. Imitating the growth of grass was employed to enhance the adhesion between ZnO nanowires and PVDF nanofiber membrane. The P–ZnO@PVDF membrane exhibited high porosity, narrow pore size distribution, superhydrophobicity, anti-wetting and anti-scaling, owing to the slip and Cassie-Baxter state caused by introduction of hydrophobic ZnO nanowires. Moreover, the membrane with robust durability presented the salt rejection of 99.9% and a stable permeation flux of 15.7 L m−2 h−1 for simulated seawater at the feed temperature of 60 °C and the distillate temperature of 20 °C after 60 h operation. The hybrid composite nanofiber membrane is to be a potential candidate for long-term operation of membrane distillation.