Structure Design And Performance Study Of Polyethersulfone Loose Nanofiltration Membrane

With the rapid development of the textile printing and dyeing industry,the wastewater discharge has seriously jeopardized the ecological and human health,and restricted social and economic development.Loose nanofiltration membrane has a loose-porous structure and its pore size is between nanofiltration and ultrafiltration membrane,which can be used in dye desalination process to achieve recovery of dyes and salts,and solve the problem of dye wastewater and reuse.Polyethersulfone(PES)can be commonly used in the preparation of loose nanofiltration membranes,while its poor hydrophilicity and mechanical properties easily leads to low permeate flux,short service lifespan and high cost on equipment maintenance.Therefore,based on the nonsolvent solution phase inversion method(NIPS)and chemical fiber core-sheath spinning technology,PES loose nanofiltration plate and hollow fiber membrane were prepared with good hydrophilicity and high mechanical properties,and their structure and properties were also researched.The PES was used as membrane-forming polymer and graphene oxide(GO)was used as inorganic nanoparticle additive.The GO incorporated PES plate loose nanofiltration membranes were prepared by NIPS method.The effects of GO content on membrane structure,mechanical properties and permeability were investigated.The results show that the increased GO content could increase the surface roughness of the membrane and improve the hydrophilicity with high permeability.The pressure resistance and operating stability of the membrane were also enhanced.When the GO content was 0.05 wt%,the membrane has the highest permeability flux and excellent separation performance.The fiber reinforced PES loose nanofiltration hollow fiber membranes were successfully prepared by NIPS method with polyester(PET)twisted fiber bundle as supporting layer.The results show that the axial mechanical strengthen and radial pressure resistance of the membrane were enhanced by the introduction of PET twisted fiber bundles.After 100 h of testing at 0.6 MPa,the PST membranes did not show significant deformation or defects and remain stable permeation flux with high dye rejection of 99.9% and low NaCl rejection of 7%.In order to overcome the problem of low permeation flux of the mentioned hollow membrane,the fiber reinforced PES/GO hollow fiber membranes were prepared by NIPS method.The results show that the increased GO content could increase the surface roughness and surface electronegativity of the membrane with good hydrophilicity.The membrane has high permeation flux and good dye desalination efficiency with the dye retention of 99.9% and low salt rejection.These results indicate that the fiber reinforced PES/GO loose NF hollow fiber membranes have great potential application for practical textile wastewater treatment.