Ultrathin Nanocomposite Membrane With Robust Anti-Wettability for Stable Membrane Distillation

Abstract

Hydrophobic porous membrane is the key to the desalination performance of membrane distillation (MD). However, traditional MD membranes suffer from poor hydrophobicity of pore surfaces, leading to pore wetting and causing the loss of desalination stability. In this study, we present an ultrathin polyvinylidene fluoride (PVDF) nanocomposite membrane with robust anti-wetting properties and high permeability for stable MD desalination. The improved anti-wetting properties are achieved by enhancing the hydrophobicity of membrane pore surfaces via introducing hydrophobic silica nanoparticles to build nanostructures on the pore surfaces. The hydrophobic nanostructured pore surfaces induce the formation of the nano-Cassie state upon contact with water, thereby enhancing the specific liquid entry pressure of water (LEP_w) with 788% compared to commercial PVDF membranes. The resulted porous structure and 10 μm membrane thickness (i.e., 20 times thinner than commercial PVDF membranes) enable the stable desalination flux of 20.30 kg m⁻² h⁻¹ and high salt rejection of > 99.9% with 60°C seawater. Our ultrathin nanocomposite membranes provide a promising solution for long-term MD seawater desalination.