Preparation Of ZIF-8 Modified Aromatic Polyamide Nanofiltration Membrane And Dye Purification Performance

As the largest textile producing country in the world,textile industry made great contributions to the economic development of china.However,the textile industry also produced large amount of wastewater which cause deterioration to environment,especially the printing and dyeing wastewater.Hence,it is very important for treating and recycling the printing and dyeing wastewater.Among the water purification technologies,membrane separation is frequently used in wastewater purification field due to the obvious advantages,such as high efficiency and low energy consumption.As a new burgeoning pressure driven membrane,whose characteristic pore size lies between those of ultrafiltration membrane and reverse osmosis membrane,nanofiltration membrane can separate dye molecules and water molecules in printing and dyeing wastewater effectively.Poly(m-phenyleneisophthalamide)(PMIA)is widely used in high-performance fiber field due to its excellent thermal stability and mechanical property.While there are few reports which explored its application in membrane separation.For this purpose,the PMIA nanofiltration membranes with PMIA as the main material were prepared through immersion-precipitation phase inversion method and interfacial polymerization method,respectively.And the ZIF-8 was used as the additive to improve the performance of PMIA nanofiltration membrane.Besides,the application of PMIA nanofiltration membrane in dye wastewater treatment field was explored.The specific research contents and conclusions are as follows:Firstly,the PMIA/ZIF-8 blended nanofiltration membrane with PMIA as the matrix and ZIF-8 as modified additive was prepared via immersion-precipitation phase inversion method.The effect of ZIF-8 content and acid treatment on the performance of blended nanofiltration membrane were investigated.The morphology,chemical composition and PMIA/ZIF-8 blended nanofiltration membrane were characterized by XRD,ATR-FTIR,and SEM.The water contact angle of the PMIA/ZIF-8 blended nanofiltration membrane were measured by contact angle meter.When ZIF-8 content was 3 wt%compared to PMIA,PMIA/ZIF-8 blended membrane had a better performance of water flux and dye rejection.While the water flux and Congo red rejection of the PMIA/ZIF-8 nanofiltration membrane can reach 104.7 L·m^-2·h^-1 and 98.6%under 0.1 MPa after acid treatment.Secondly,the PMIA/PA-MZIF-8 thin film nanocomposite(TFNC)nanofiltration(NF)membrane with PMIA porous membrane as substrate and the modified ZIF-8(MZIF-8)as aqueous solution additive was prepared via interfacial polymerization method.The effect of MZIF-8 content on the structure and performance of PMIA/PA-MZIF-8 TFNC NF membrane was investigated.The morphology of the composite nanofiltration membrane were characterized by SEM.Chemical composition of the composite nanofiltration membrane were analyzed using XPS and FTIR.When MZIF-8 content in aqueous phase solution was 0.1 w/v%,the water flux and Congo red rejection can reach 174.5 L·m^-2·h^-1and 98.9%under 0.1 MPa.The PMIA/PA-MZIF-8 TFNC NF membrane can separate Congo red molecules and water molecules effectively.