Thermal Shielding and Vapor Transport Enhancement in MOF-Enabled Membranes for Membrane Distillation

Desalination via membrane distillation (MD) powered by low-grade or waste heat is an emerging approach to energy-efficient water purification. However, conventional membranes suffer from significant conductive heat loss, which limits their thermal performance. Developing membranes with low thermal conductivity is crucial for enhancing thermal efficiency. This study introduces a metal-organic framework-enabled membrane (MEM) by embedding zeolite imidazole framework 8 (ZIF-8) onto Poly(vinylidene fluoride-co-hexafluoropropylene) (PH) nanofiber. The MEM features a hierarchical porous structure, with an ultralow thermal conductivity (0.03 W m^-1 K^-1), thereby minimizing heat dissipation. It outperforms conventional membranes, demonstrating a vapor flux of 44.5 LMH and a thermal efficiency of 71.3%, improving MD performance. Multi-scale simulations reveal that the dual improvements in thermal shielding and vapor flow facilitation enable the MEM to effectively harness low-grade heat sources inaccessible to traditional membranes, positioning it as a promising solution for a sustainable water-energy-environment nexus.