Accordion-shaped Ni-metal-organic framework based thin-film composite forward osmosis membranes for seawater desalination

Nowadays, water scarcity is becoming an increasingly serious problem. Metal-organic framework (MOF) forward osmosis membranes show great potential for use in seawater desalination applications due to their high chemical stability, high ion retention rate, and high mechanical strength. Currently, there are relatively few studies on the application of MOF membranes in forward osmosis. In this study, the application of Ni-BDC in forward osmosis membranes is highlighted. Ni-BDC/polyvinylidene fluoride (PVDF) forward osmosis composite membranes were prepared by combining accordion-shaped Ni-BDC particles with the surface of PVDF support membranes under gravity deposition, which greatly improved the hydrophilicity and surface roughness of the membranes and provided additional flow channels for water molecules. The experimental results prove that the addition of Ni-BDC significantly improves the water flux of the membrane and the retention rate of salt ions (K+, Li+, Mg2+, Na+), and the retention rate of salt is more stable. After 10 h, the composite membrane still had a retention rate of over 99.85% for all salt ions, with a water flux of 7.22 l m−2 h−1. These results demonstrate the potential of Ni-BDC/PVDF forward osmosis membranes for desalination.