Engineering a covalently constructed superomniphobic membrane for robust membrane distillation

Wetting, scaling, and functionality loss of the active layer are critical challenges facing membrane distillation (MD) technology that substantially hinder its practical applications. Herein, we propose an effective strategy to fabricate a superomniphobic MD membrane with excellent wetting/scaling resistance and mechanical robustness. Specifically, a hierarchical re-entrant architecture was created by immobilizing spherical silica nanoparticles onto a poly(vinylidene fluoride) membrane surface via covalent bonds, followed by fluorination via thiol–ene click chemistry. An ultrahigh water contact angle (166.5 ± 1.4°) and low sliding angle (5.0 ± 1.1°) confirmed the superhydrophobicity and slippery characteristics of the modified membrane, which were further illustrated by its excellent wetting resistance toward various liquids with low surface tension. The membrane sustained a long-duration MD for the treatment of a highly saline brine, with a surfactant content of approximately 2.0 mM, outperforming all the MD membranes reported in the exiting literature. In addition, the membrane exhibited excellent desalination performance for synthetic multi-component hypersaline wastewater, achieving a high water recovery ratio of approximately 60% without a significant decline in water flux. Overall, this study provides a novel and effective approach to fabricate high-performance MD membranes with robust functionality for operations under harsh environments.