Construction Of High-Flux,Antifouling Ultrafiltration Membranes And Membrane Performance Intensification

Water shortage and deterioration of water quality are common challenges facing mankind in the 21st century.As a new separation technology with high efficiency,green and continuous operation,membrane technology is known as the 21st century water treatment technology.High-performance membrane material is the core of high efficiency and stable operation of water treatment.The development of high-performance membrane materials is faced with two common key scientific problems:low permeation flux and serious membrane fouling.Based on the platform technique of nonsolvent induced phase separation process,reaction induced phase separation process and vacuum-assisted self-assembly process,this study establishes the synergistic manipulation methods for mass transfer channels in membrane and physical and chemical microstructures on membrane surface,and puts forward the theories for the synergistic intensification of membrane permeability and antifouling property.This study is in pursuit of offering academic thoughts to the materials design and preparation of high-flux,antifouling membranes for water treatment applications.The details are summarized as follows:Manipulation of phase inversion and intensification of membrane performance:1)Based on the phenomenon and principle of nonsolvent induced phase separation process,surface segregation modification technology is utilized,and amphiphilic surface segregation modifier with crosslinked hydrophobic section is prepared.During phase inversion process,the hydrophilic segments of the amphiphilic surface segregation modifier enriches on the membrane surface to reduce the interaction between foulants and membrane surface,leading to the improvement of antifouling property.Meanwhile,the crosslinked segments of the amphiphilic surface segregation modifier can regulate the phase inversion process of membrane matrix effectively,to form a loose structure and decrease the mass transfer resistance,leading to the improvement of membrane permeability,which intensifies membrane performance.2)Based on the phenomenon and principle of reaction induced phase separation process,the self-crosslinking reaction of polyvinyl alcohol（PVA）is used to prepare the aerogel membrane with asymmetric structure,which possesses super-hydrophilic separation layer and hydrophobic high-porous supportion layer.The super-hydrophilic membrane surface can inhibit the deposition of foulants on membrane surface and improve the antifouling property.Meanwhile,the supportion layer with high porosity can reduce the mass transfer resistance,effectively.The permeate flux reaches to135.5*10³ L m^-2h^-1bar^-1,and flux recovery ratio is more than 93%,which intensifies membrane performance.Manipulation of assembly process and intensification of membrane performance:1)Bases on the phenomenon and principle of vacuum-assisted self-assembly process of one-dimensional materials,the interaction between carbon nanotube（CNT）and a series of polymers is utilized to manipulate the structure and surface physical and chemical microenvironment of CNT hybrid membrane.CNT assembly membrane possesses high porosity,which can help to reduce the mass transfer resistance and improve the membrane permeability.Meanwhile,modifying CNT by polymer can effectively manipulate the physical and chemical microenvironment of membrane surface,such as wettability,charge,roughness,etc.,to reduce the deposition of foulants on membrane surface.The permeate flux reaches to 4592.5 L m^-2h^-1bar^-1,and flux recovery ratio reaches to 100%,which intensifies membrane performance.2)Based on the phenomenon and principle of vacuum-assisted self-assembly process of two-dimensional materials,the intercalation technology is utilized to manipulate the interlayer spacing between GO nanosheets and physical and chemical microenvironment of GO-based membrane surface.The introduction of intercalation materials can improve the interlayer spacing between GO nanosheets,to construct mass transfer channels and improve membrane permeability.Meanwhile,the introduction of intercalation materials can manipulate the physical and chemical microenvironment of membrane surface,to endow the membrane with excellent antifouling property,such as photocatalytic antifouling property and hydrophilic antifouling property.The permeate flux reaches to 11800 L m^-2h^-1bar^-1,and flux recovery ratio is more than 94%,which intensifies membrane performance.