Preparation And Application Of Modified Polyethersulfone Ultrafiltration Membrane With Nano Molecular Sieve And Multi-walled Carbon Nanotubes

In this paper,polyethersulfone?PES?ultrafiltration membrane was prepared by immersion precipitation phase transformation.Polyvinylpyrrolidone?PVP?was used as porogen and N,N-dimethylamide?DMAc?as solvent.ZSM-5 nano molecular sieve,MWCNTs and functionalized carbon nanotubes?M-NH₂,M-OH and M-COOH?were used as modified materials.The purpose of modifying PES membrane is to improve the performance of PES membrane,to make organic polymer membrane have the advantage of inorganic materials,and to broaden the application range of ultrafiltration membrane.The components of the membrane were characterized by X-ray diffraction?XRD?and Fourier infrared spectroscopy?FTIR?,the three-dimensional morphology and roughness of the membrane were analyzed by atomic force microscopy?AFM?,the morphology of the surface and cross section of the membrane were characterized by scanning electron microscopy?SEM?,the pure water flux,BSA rejection rate and flux recovery rate of the modified membrane were measured.The modified membrane was used to purify simulated dye wastewater.Through experiments and analyses,the following results are obtained:?1?ZSM-5 was dispersed on the membrane and had physical interaction with PES,which did not damage the molecular structure of ZSM-5,so that ZSM-5 could play its unique advantages of inorganic materials;and with the increase of ZSM-5 molecular sieve content from 0 wt%to 0.4 wt%,the rejection rate remained at about 98.0%.At the same time,the roughness of the membrane was reduced,the accumulation of pollutants on the membrane surface was decreased,and the flux recovery rate?FRR?was increased by 1.2times.?2?Functionalized carbon nanotubes can promote the flux and recovery rate of the membrane.The water flux of the modified carbon nanotubes?PES/M-OH?was the largest,at 439.8 L/m²h,1.3 times and 1.2 times higher than that of the PES membrane and the PES/M membrane.The FRR increased from 46.3%to 70.2%.The results showed that carbon nanotubes could promote the modification of PES,the order of the effect of permeability improvement is PES/M-OH>PES/M-COOH>PES/M-NH₂>PES.?3?PES membrane,0.4 wt%PES/ZSM-5 membrane and 0.36 wt%PES/M-OH membrane were respectively applied to the treatment of dye wastewater.It was found that modified PES membrane had better water purification effect than PES membrane,not only the flux was stable,but also the removal efficiency of COD and turbidity was significantly improved.