High Efficient UiO-66-NH₂/PS Hierarchical Membrane for Vacuum Membrane Distillation

Membrane distillation (MD), a sustainable desalination technology by low-grade heat, has garnered significant attention, but it suffers from low permeate flux and intensive energy. This work integrates hydrophilic metal–organic framework (MOF) into a hydrophobic polystyrene (PS) matrix, utilizing water capillary condensation within UiO-66-NH₂ to lower local vapor pressure and improve evaporation rate. Moreover, the confined evaporation enhancement effect facilitates the continuous evaporation of condensed water within these “reservoirs,” enabling the establishment of a dynamic equilibrium. The UiO-66-NH₂ near the vacuum side does not undergo condensation, further enhancing water vapor transport by providing favorable pathways for vapor diffusion. The UiO-66-NH₂/PS-HP membrane (hot-pressed UiO-66-NH₂/polystyrene fiber membrane) achieves an impressive flux of 137.6 L m⁻² h⁻¹ and a salt rejection rate of 99.95% under 70 °C and −85 kPa vacuum pressure, surpassing the performance of both commercial and most reported polymer membranes. Moreover, this UiO-66-NH₂/PS-HP membrane demonstrates excellent antifouling behavior, long-term stability for 80 h, and scalability for large-area fabrication (120 cm × 30 cm). This work provides valuable insights for developing high-performance membrane distillation membranes for desalination applications.