In situ grown cyclodextrin metal-organic framework nanoparticles templated stripe nano-wrinkled polyamide nanofiltration membranes for efficient desalination and antibiotic removal

Abstract

Nanofiltration membranes composed of polyamide (PA) and characterized by a refined, periodic stripe pattern morphology are identified as promising solutions to address the permeability-selectivity trade-off in membrane technology. Modifying the morphology of PA membranes by utilizing pre-deposited soluble nanoparticles as templates has been investigated, yet the attainment of a periodic stripe pattern using this method is still a considerable challenge. This study successfully employed cyclodextrin-based metal-organic framework (CD-MOF) nanoparticles, grown in-situ, to create periodic stripe patterns on PA membranes. Morphological characterization revealed that in-situ grown CD-MOF nanoparticles, unlike those pre-deposited through vacuum filtration which formed noticeable aggregations and large flake-like PA structures, displayed a more evenly distributed pattern with reduced aggregation, aiding in the development of a striped PA morphology. The resulting membrane, with enhanced surface area, reduced thickness, increased hydrophilicity, and lower cross-linking degree, demonstrated an impressive 617 % augmentation in pure water permeance relative to the control PA membrane, achieving 29.4 L m-2 h-1 bar-1. Furthermore, this membrane displays a 99.0 % Na2SO4 rejection and maintained over 95 % efficacy in rejecting antibiotics. This research sheds light on the mechanisms by which nanoparticle templates influence polyamide morphology and introduces an innovative approach for precisely tailoring high-performance PA membranes.