Robust Hilly Polyamide Membrane for Fast Desalination

Tailoring the microstructure of a selective layer is a highly attractive way to improve the water flux of a reverse osmosis (RO) membrane by forming a crumpled surface without altering its chemical structure required for high salt rejection. However, it is challenging to maintain its structural integrity and stability and high flux at high pressure during desalination. Herein, a robust hilly thin-film composite (TFC) polyamide (PA) membrane is developed based on composite substrates made of cellulose nanofibers (CNFs) and metal-organic frameworks (MOFs). Water-stable, highly crystalline, submicrometer-sized MOF crystals, NH2-MIL-53(Al), are integrated with CNFs to form a robust and highly porous intermediate layer for the formation of a hilly PA layer. The resulting TFC RO membrane exhibits an excellent water permeance of 5.55 LMH/bar and a NaCl rejection of ∼94.8%. The strategy reported here has great potential for the fabrication of polyamide desalination membranes with enhanced flux and mechanical stability.