Improvement of thin-film nanocomposite (TFN) membrane performance by CAU-1 with low charge and small size

Metal-organic framework material (MOF) can increase water flux greatly without reducing the retention performance due to its porous structure, large specific surface area and high compatibility with the polymer matrix. There are few studies on the influence of MOF particle size and charge to nano composite membranes. In this study, CAU-1 particles with different average sizes (300, 400 and 800 nm) were synthesized and dispersed in organic solvent to prepare a composite separation membrane for nanofiltration. The effect of MOF particle size on membrane properties was studied. It was found that CAU-1 particles with higher positive charge would lead to the formation of network separation layer structure. The results show that the high charge and large particle size of CAU-1 particles can enhance the membrane flux, but it is easy to cause membrane defects and reduce the retention. Compared with thin-film composite (TFC) membrane, the composite membrane with low charge and small particle size of CAU-1 (300 nm) has better separation performance. Compared with the TFC membrane, the flux increases by 40% with the retention rate unchanged.