PA/ZIF-8/PVDF复合纳滤膜的制备及其性能

采用反向扩散法在聚偏氟乙烯(PVDF)基膜表面原位生长一层均匀、致密的金属有机骨架材料ZIF-8纳米晶体层,并进一步优化界面聚合反应,制备高性能聚酰胺(PA)/ZIF-8/PVDF复合纳滤膜.采用SEM、XRD、FTIR、AFM、XPS、水接触角测定仪以及固体表面Zeta电位仪对ZIF-8/PVDF复合膜及PA/ZIF-8/PVDF复合纳滤膜的组成、结构和形貌进行了表征,考察了ZIF-8亚层的生长对界面聚合反应、复合纳滤膜结构及性能的影响.结果表明,ZIF-8晶体亚层在PVDF膜表面的均匀连续生长改善了PA分离层与PVDF基膜的界面相容性,提高复合纳滤膜PA分离层的交联度.在0.6 MPa下,复合纳滤膜纯水通量可达24.05 L/(m2·h),对MgSO4、Na2SO4、NaCl和MgCl24种盐的截留率分别达到97.34％、93.57％、89.31％和85.16％,具有优异的抗污染性能.

Preparation and characterization of PA/ZIF-8/PVDF composite nanofiltration membranes with high desalination performance

Uniform and dense zeolitic imidazole framework-8 (ZIF-8) sub-layer was fabricated on the surface of polyvinylidene fluoride (PVDF) membrane via an in-situ contra-diffusion method, and the interfacial polymerization (IP) procedure was further used to prepare polyamide/ZIF-8/PVDF composite nanofiltration (NF) membranes with polyamide (PA) top thin layers and ZIF-8 sub-layers. SEM, XRD, FTIR, AFM, XPS, contact angle analyzer and zeta potential analyzer were utilized to measure the chemical compositions, structures and morphologies of the prepared ZIF-8/PVDF composite membranes and the PA/ZIF-8/PVDF composite NF membranes. The effect of ZIF-8 sub-layer on the structure and performance of these composite NF membranes were investigated systematically. Results indicated that the existence of ZIF-8 sub-layer increased the crosslinking degree of the polyamide and improved the compatibility of polyamide layer and PVDF support membrane. Under the pressure of 0.6 MPa, the composite NF membrane exhibited high flux of 24.05 L/m2?h and good anti-fouling property. Furthermore, the composite NF membranes showed excellent desalination performance, with the rejection ratio of 97.34%, 93.57%, 89.31% and 85.16% for MgSO4, Na2SO4, NaCl and MgCl2, respectively.