The Preparation And The Key Factors To The Nano-Fiber Based Membrane

With the globalization of industry,which leads to serious water pollution,the demand for water resources is growing.The best way to solve the problem of water resources at present is wastewater recycling and seawater desalination.Compared with the traditional desalination and sewage treatment,membrane separation technology has the advantages of environmental protection and energy saving.The core membrane separation technology for the nanofiltration membrane and reverse osmosis membrane.It is of great significance to prepare nanofiltration membranes with high-throughput and high rejection.High-volume production of PVA-co-PE nanofibers with good hydrophilicity and biocompatibility and great potential in water treatment.In this project,a polyamide composite nanofiltration membrane is prepared by interfacial polymerization of reactive monomer,m-phenylenediamine and trimesoyl chloride.To explore the key influencing factors of nanofiltration membrane.The effects of contact angle?CA?,Fourier transform infrared?FT-IR?,scanning electron microscope?SEM?,atomic force microscopy?AFM?X-ray photoelectron spectrometer?XPS?and sodium sulfate filtration performance were used to characterize the effect of polyamide composite nanofiltration membrane.The operation pressure of the experiment is 30psi and the concentration of sodium sulfate is 100ppm.The flux and the interception rate are expressed by the membrane flux tester and the plasma spectrometer.This topic explores the addition of cosolvent carbamide in aqueous solution to improve its flux.In this experiment,the infrared of the composite polyamide membrane was tested.A special absorption vibration peak of C=O appeared around 1700cm^-1,the special peak of amides appeared at 1550cm^-1,Through SEM,AFM analysis,it can be clearly seen that the polymerized functional layer formed by interfacial polymerization,The existence of polyamide small particles further proves the successful formation of polyamide composite nanofiltration membrane.When the elements were analyzed by XPS,there were also N elements that were not on the basement membrane.Filtration performance of composite membrane,the addition of carbamide is 3%,the flux and rejection of the polyamide composite nanofiltration membrane are best,the flux is above40 L/?m²*h?,and the rejection rate reaches about 95%.Further research on the spraying of polyacrylate on the substrate to improve its strength.When the polyacrylate is added at 5%,the flux is best without affecting the rejection rate.The flux is above 40 L/?m²*h?,and the interception rate is about 90%.Because the flux of the polyamide composite nanofiltration membrane was reduced by spraying polyacrylate on the substrate.That is not to join the more the better.Finally,the ratio of carbamide is further explored after spraying polyacrylate in order to achieve the best flux.The polymer network structure can be observed by SEM,AFM,XPS analysis,dense and uniform cross-linked structure can be formed,and it's asymmetrical.The main reason is the wide spread between water and solvent,especially the addition of solvent carbamide to speed up its diffusion and improve the hydrophilicity of the composite membrane.The best flux was found when 5%carbamide was added,the flux was above 35 L/?m²*h?,and the rejection rate was about 95%.Finally,we explore the high-throughput high retention rate and good strength polyamide composite nanofiltration membrane.The hydrophilicity and flux of the composite nanofiltration membrane can be improved by adding urea.Improving the strength of polyamide composite film by adding polyacrylate.Adding too much polyacrylate can greatly reduce its flux,the best effect of spraying polyacrylate 5%on the base material.After adding polyacrylate,the flux of polyamide composite membrane reaches the best carbamide addition from 3%to 5%.Comparing the changes in flux before and after,the flux is relatively reduced after the addition of polyacrylate,but its strength is increased.