Surface Modification of UiO-66 on Hollow Fibre Membrane for Membrane Distillation

Abstract

The hydrophobicity of metal–organic frameworks (MOFs) is critical in enhancing the separation process in membrane distillation. Herein, a new superhydrophobic University of Oslo 66 (UiO-66) MOFs was successfully constructed on the top of alumina hollow fibre (AHF) membrane for desalination purposes. The fabrication methodology of the membrane involved in situ growth of pure crystalline UiO-66 on top of AHF and post-synthetic modification by fluorosilane grafting. The resultant membrane was characterised to study the physicochemical properties of the pristine and modified membrane. A superhydrophobic UiO-66 with a contact angle of 163.6° and high liquid entry pressure was obtained by introducing a highly branched fluorocarbon chain while maintaining its crystallinity. As a result, the modified membrane achieved 14.95 L/m2∙h water flux and 99.9% NaCl rejection with low energy consumption in the direct contact membrane distillation process. Furthermore, the high surface energy contributed by UiO-66 is maximised to produce the maximum number of accessible sites for the grafting process. The synergistic effect of surface hydrophobicity and porous UiO-66 membrane in trapping water vapour shows great potential for desalination application.

Fibril-Droplet Relationship Through Liquid-Liquid Phase Separation; A BSA-MOF Case

“…In this case, the functional groups' physico-chemical properties determined the differences in droplet and bril dimensions (Table 2). Measuring zeta potential and contact angle revealed that UiO-66-NH 2 had the highest contact angle and, thus, the greatest hydrophobicity, and UiO-66-(COOH) 2 had the highest zeta potential [35][36][37][38].…”