Preparation And Performance Study Of Meta-aromatic Polyamide Separation Membrane

The rapid development of membrane separation technology makes a higher demand for the performance of membrane.Therefore,the research of membrane materials with high performance have recently gained significant attention.As an aromatic polyamide,poly(m-phenyleneisophthalamide)(PMIA)shows excellent hydrophilicity,superior mechanical property,thermal stability and chemical stability due to its benzene ring,amide bond and 3D jungle-gym-type hydrogen bond network.However,the application of PMIA in membrane separation technology is much less.Therefore,the focus of this article is to study the preparation and performance of PMIA membrane.The PMIA hollow fiber membrane with dimethylacetamide(DMAC)as solvent,LiC1、CaCl2 as additives and polyethylene glycol(PEG)as pore-forming agent was fabricated by dry-wet spinning technology.The effect of PEG content on the structure and performance of PMIA hollow fiber membrane was investigated.The addition of PEG can improve the permeability and hydrophilicity of PMIA hollow fiber membrane.The optimal addition of PEG was 8 wt%.Moreover,the PMIA hollow fiber membrane had a lower flux decline ratio due to its superior hydrophilicity and mechanical property compared to PVDF hollow fiber membrane.In order to further improve the mechanical property of PMIA hollow fiber membrane,a novel braid reinforced(BR)PMIA hollow fiber membrane with tubular braid as the reinforced matrix and PMIA casting solution as the separation layer were prepared by dry-wet spinning technology.The results indicated that the homogeneous BR PMIA hollow fiber membrane showed a superior interfacial bonding state between the tubular braid and separation layer.The flux recovery ration of BR PMIA hollow fiber membrane was higher than 96.68%,which indicated that the BR PMIA hollow fiber membrane had an excellent antifouling property.Moreover,the water flux of BR PMIA hollow fiber membrane under 90 ℃ was higher than under 25 ℃,while the rejection remaind stable.The result indicated that the BR PMIA hollow fiber membrane had a superior thermal stability.A tubular braid reinforced(TBR)PMIA/Ag@RGO nanofiber membrane with tubular braid as the collector,PMIA solution as electrospining solution and the Ag@RGO nanocomposite as the functional additive was prepared via electrospinning technology.The TBR PMIA/Ag@RGO nanofiber membrane can be applied in dynamic catalysis process due to its superior mechanical property.The apparent rate constant of dynamic catalysis process was 100 times higher than static catalysis process.Moreover,the reusability of PMIA/Ag@RGO nanofiber membrane was far better than Ag@RGO nanosheets.The TBR PMIA nanofiber membrane with tubular braid as the collector,PMIA solution as electrospining solution was prepared via electrospinning technology.Then,a novel TBR PMIA/CA-PEI/Ag nanofiber membrane was prepared via mussel-inspired method.The unique tubular shape and superior mechanical property of TBR PMIA/CA-PEI/Ag nanofiber membrane made it can be applied in dynamic catalysis process.The apparent rate constant of dynamic catalysis process was 30 times higher than static catalysis due to the faster mass transfer.Moreover,the TBR PMIA/CA-PEI/Ag nanofiber membrane showed a superior stability and recyclability as Ag nanoparticles tightly loaded on the surface of PMIA/CA-PEI/Ag nanofiber.A novel PMIA/PA TFC NF membrane with PMIA porous membrane as the substrate was prepared via interfacial polymerization(IP)method.The PMIA/PA TFC NF membrane showed an excellent permeability,thermal stability and mechanical property compared to PSf/PA TFC NF membrane.The permeability of PMIA/PA TFC NF membrane remained stable when it was tested under 90 ℃.The PMIA/PA TFC NF membrane showed a superior thermal stability.A high flux and thermally stable PMIA/PA TFC NF membrane was prepared by adding LiCl in aqueous phase solution during IP process.The addition of LiCl can regulate the reaction rate of interfacial polymerization,which would led to a high performance of PMIA/PA TFC NF membrane.The water flux of TFC3 NF membrane was higher than 170 L·m-2·h-1,while the rejection remained stable.When the operating temperature was 80℃,the water flux of TFC3 NF membrane was higher than 300 L·m-2·h-1 under 0.6 MPa.The TFC3 NF membrane showed a high efficiency when it was used in dye desalination due to its superior permeability.