The Construction Of Cyclodextrin And Polyrotaxane Modified Anti-fouling Membrane And Its Anti-fouling Behavior Research

The membrane fouling problem seriously restricts the development of membrane separation technology.So,the development of anti-fouling membrane is the fundamental way to solve the membrane fouling problem.It is particularly important to improve flux and anti-fouling performance simultaneously through anti-fouling membrane surface design and membrane structure regulation.In this paper,based on the synergistic intensification of multiple anti-fouling mechanisms of membrane surfaces,the aim is to improve flux and anti-fouling performance simultaneously.Cyclodextrin(CD)and its derivative polyropanes(PR)are introduced into ethylene vinyl alcohol(EVAL)membrane through surface segregation,blending modification and click chemistry.The relationship between preparation conditions,multiple structures and anti-pollution properties of the membrane were systematically studied,and the application characteristics of the membrane in oil-water separation were investigated.The main research contents and conclusions are as follows:(1)The preparation of CD modified anti-fouling membrane and the study of surface segregation.CD with a hydrophobic cavity and hydrophilic rim have been introduced into ethylene vinyl alcohol(EVAL)copolymer membrane by “segregation freedom” and “fixed grafting” strategies,CD surface segregation modified membrane and CD grafted membrane are designed and prepared.By comparing two modified membrane,the surface segregation behavior,anti-fouling performance and separation performance were investigated by EDX,XPS and performance test.The results show that the CD surface segregation modified membrane improves the hydrophilicity of the membrane surface,optimizes the cross section channel structure of the membrane,and has higher permeability flux and anti-fouling performance compared with the pure membrane and CD grafted membrane,which is related to the characteristics of CD and the fouling resist mechanism formed on the membrane surface.(2)The preparation of PR blended anti-fouling membrane and the study of anti-fouling behavior.Inspired by the self-cleaning function of human cilia,PR with self-mobile structure was prepared by click chemistry.Then,it was introduced into the EVAL membrane by blending method and PR/EVAL membrane was prepared.The successful preparation of PR and PR/EVAL membrane were proved by NMR,FT-IR and other methods.The structural performance relationship of PR/EVAL membrane was studied systematically.The results show that the introduction of PR improves the hydrophilicity and roughness of the membrane surface,the flux recovery rate was 94%,the flux decline rate was 12%,and the irreversible pollution index is significantly decreased.The anti-fouling behavior of PR/EVAL membrane was related to the hydrophilic effect,self-mobile characteristic and steric repulsive effect of the membrane surface.(3)The preparation of PR grafted antifouling membrane and the study of oil/water separation.The clickable sliding supramolecular polymer brushes(SSPB)was prepared by click chemistry and then the EVAL-SSPB membrane was prepared by phase inversion technology.The introdution of SSPB optimize the cross section channel structure and enhance the membrane flux,anti-fouling performance and surface properties,which was proved by water contact angle and SEM.EVAL-SSPB membrane demonstrated increased surface hydrophilicity,underwater oleophobicity,and oil contact was 159°,and showed a very low adhesion to oil on the surface of the membrane.Compared with the unmodified membrane,the anti-fouling and oil/water separation were improved simultaneously,which was related to the specific structure of PR and the multiple anti-fouling mechanism of the membrane.