Study On The Antifouling Performance Of PAN Ultrafiltration By Low Temperature Plasma Surface Modification And Vapor Phase Grafting

In order to modify antipollution performance of Polyacrylonitrile ultrafiltration membrane by plasma surface modification and the graft,the work of this experimental is to study the optimal conditions of plasma modification and grafting modification.The surface physical and chemical properties of the modified membrane were studied by analyzing the SEM images and X ray photoelectron spectroscopy.The antipollution performance of modified membrane was studied by the ultrafiltration experiment,membrane flux（water flux,BSA flux）,pollution rate,flux decay rate,water washing flux recovery,alkali washing flux recovery rate,retention rate and other parameters.The results show that the optimum conditions for the treatment of low temperature nitrogen and ammonia plasma are:the pressure is 10Pa,the power is100W,the processing time is 90s,the contact angle is from 57°to 25°and 27°;Under the optimum conditions of plasma treatment,the optimum conditions for gas phase of the film are:the temperature is 65℃and 55℃,the time is 20min and 10min,the concentration of the graft is 100%;Low temperature nitrogen plasma gas phase grafting of PAN super membrane fouling rate from 36.45%down to 25.00%,the retention rate increased from 89.68%to 95.57%;Low temperature plasma ammonia vapour phase grafting of PAN super membrane fouling rate decreased from 36.45%to11.09%,interception rate will increase from 89.68%to 99.78%.The above data shows that the improvement of the hydrophilic property of the PAN ultrafiltration membrane is obviously improved,and the antipollution performance is also improved.The results showed that grafted membranes not only overcome the disadvantage of poor timeliness of plasma modification,while increasing the anti pollution performance of the membrane,the persistence of membrane fouling resistance.By scanning electron microscopy（SEM）images analysis,ultra filtering membrane aperture increases after low temperature plasma surface modification,the flux of water flux and bovine serum albumin also increases.At the same time,the mesh structure of the membrane was not changed after the gas phase,grafting of acrylic monomers onto the surface of the polymer chains reduced the pore size and the flux.The surface elements of the film were analyzed by X ray photoelectron spectroscopy,AA is connected by gas phase after low temperature plasma treatment.The content of O was increased,and the content of N was unchanged.It is indicated that the amount of NH₂,COOH,which is introduced into the membrane,and AA can not change the main film surface.Through the characterization of film surface modification and performance modification,the results show that antipollution performance was improved by low temperature modification.