Custom-tailoring metal-organic framework in thin-film nanocomposite nanofiltration membrane with enhanced internal polarity and amplified surface crosslinking for elevated separation property

Abstract

A polyamide (PA) thin-film nanocomposite (TFN) membrane embedded with post-synthetically functionalized metal-organic framework (MOF) nanofillers of imidazole-2-carbaldehyde (ICA) decorated UiO-66-NH2 nanofillers (ICA_d_UiO-66-NH2) was developed using the interfacial polymerization method. The ICA_d_UiO-66-NH2 nanofiller couples a surface water-capturing ICA decoration, facilitating the rapid transport of water molecules owing to the enhanced internal polarity, while achieving an amplified crosslinking between the terminal amine groups of ICA and trimesoyl chloride, enabling the perfect incorporation of MOF nanofillers within the PA matrix. The resultant ICA_d_UiO-66-NH2@PA TFN membrane with elevated separation property performed comparably high water permeance of 9.4 l m−2 h−1 bar−1 (achieving a nearly 2-fold increase from the initial value of the thin-film composite membrane), and a favorable rejection ratio of 97.4% (Na2SO4). Owing to the unique hierarchical surface microstructure embedded with the intrinsically hydrophilic ICA_d_UiO-66-NH2 nanofillers, the newly-developed TFN membrane exhibited superior antifouling properties. Furthermore, the ICA_d_UiO-66-NH2@PA TFN membrane also retained excellent reusability and durability without significant compromise even after long-term salt, and acid/alkali treatments. Overall, this work provides an insight into the embedding of different functionalized nanofillers inside TFN membranes with elevated separation properties.