Surface Hydrophilic Modification And Separation Performance Of Hydrophobic Porous Membrane Materials

Most of the porous membrane materials commonly used have obvious hydrophobicity,which can easily lead to the reduction of permeate flux and membrane fouling and limit their application in water treatment.Therefore,the hydrophilic modification of membranes has become one of the focuses of water treatment.Based on the basic theory and method of "Living" /Controlled Radical Polymerization,in this thesis,we are dedicated to prepare new membrane materials with two aspects of optimizing the polymerization means and designing molecular structure.The hydrophobic polymer porous membrane materials modified by hydrophilic grouping aim to have special wettability,anti-protein pollution and adsorption performance.First,photoinduced living radical polymerization upon irradiation with UV radiation is used to control radical polymerization to perform hydrophilic graft modification on polypropylene films.We use surface chemical polydopamine deposition technology to deposit a macromolecular initiator on the surface of the polypropylene membrane materials to obtain an initiator film.Ultraviolet light is used to regulate the "Living" /Controlled Radical Polymerization.A hydrophilic monomer or a hydrophobic monomer is grafted on the surface of the membrane material.Through a series of characterization tests,the surface chemical composition and surface morphology of the membrane materials were characterized after modification.The special wettability or hydrophobicity and the anti-protein pollution performance of the membrane materials were characterized after modification to prove that the hydrophilic property of the polypropylene membrane materials can be effectively changed and the phenomenon of membrane fouling can be suppressed to a certain extent.Compared with the original PP membrane,the pure water flux of hydrophilic modified PP-HEA and PP-AGA increased by 2-3 times.The retention rate of PP-AGA grafted with sugar monomer was about 3 times of the original PP membrane,which indicated that AGA sugar monomer effectively improved the anti fouling performance of the membrane materials.Second,we obtained a new type of polysulfone molecule structure with block and graft hydrophilic group through "Living" /Controlled Radical Polymerization and blend these copolymers as additives to prepare new polysulfone separation membrane materials.In particular,after grafting a sugar-containing copolymer,the polysulfone grafted membrane material has a certain adsorption performance by utilizing a reversible chelation between boric acid and cis-dihydroxy group in the sugar structure.Through a series of representations,the chemical composition of the synthesized copolymer was characterized;and the surface morphology of the membrane materials prepared by blending was characterized.Through static water contact angle,protein solution flux test,and boric acid adsorption test,it was found that grafting hydrophilic monomers can give membrane materials effective hydrophilic modification,pH response,anti-pollution,and boric acid adsorption.After hydrophilic modification,the water contact angle of membrane materials generally decreased.PSF-b-poly(DEAEMA)and PSF-b-poly(DMAEMA)showed intelligent response to pH.The retention rate of the modified blend membrane is mostly about 90%,which indicated that the anti fouling performance is improved.PSF-g-ribose and PSF-g-GDL,fixed of functional polyols,can endow the membrane material with a certain boron adsorption capacity,and the adsorption equilibrium can be achieved in three hours.