Preparation And Performance Research Of Composite Nanofiltration Membrane Based On Metal Organic Frameworks CAU-1

TFN membranes are prepared by introducing nanoparticles into the selective layer of separation membranes,and the addition of nanoparticles can improve the efficiency of the membranes.MOFs,a class of porous nanoparticles as additive materials,have been used to prepare TFN membranes.MOFs provide additional channels for the passage of water molecules thus improving the flux.Among the MOFs,the effective pore diameters of CAU-1 are 1 nm and 0.45 nm.However,the dispersion of CAU-1 particles in n-hexane is poor,so it is necessary to modify the surface with dodecyl aldehyde.TFN membranes were prepared by IP using CAU-1 and modified CAU-1 as nanoparticles and PSF membrane as the support layer,and the main studies were as follows.1)CAU-1 with different particle sizes were synthesized using a solvent thermal method with anhydrous methanol as the solvent,NH₂-BDC as the organic ligand and Al Cl₃·6H₂O as the metal ion.The experimental results showed that changing the amount of anhydrous methanol affected the p H of the reaction system,which in turn affected the deprotonation rate of the organic ligand,and CAU-1 particles of 100,250 and 300 nm were prepared.2)The surface modification of CAU-1 was carried out using 100 nm CAU-1 as raw material and acetic acid as the catalyst for the modification reaction,and dodecyl aldehyde was used.The experiment showed that the modified CAU-1 is still well suspended in n-hexane 30 minutes after the end of ultrasound,which proves that the surface modification of CAU-1 by dodecyl aldehyde can improve the dispersion of nanoparticles in n-hexane.3)100,250 and 300 nm CAU-1 particles as well as modified 100 nm CAU-1 particles were dispersed in TMC/n-hexane solution,and the effects of CAU-1 particle size variation and surface modification on the production of composite nanofiltration membranes were analyzed.The pure water flux of TFN-0.1 was about four times higher than that of TFC membrane(40.25±0.50 L·m^-2·h^-1)under 0.4 MPa applied pressure,the Na₂SO₄ rejection reached 95.35%,and the pure water flux of TFN membrane increased to 79.89±1.24 L·m^-2·h^-1,which is about 7.9 times higher than that of the TFC membrane.Figure 33,Table 6,Reference 120.