Preparation And Performance Of Anti-fouling Ultrafiltration Membrane

Poly(vinylidene fluoride)(PVDF)is widely used in ultrafiltration(UF)membrane due to its excellent chemical resistance,well-controlled porosity,and good thermal property.However,the hydrophobicity of PVDF membranes restricted its application to water phase sepatation systerms such as bio-pharmaceutical,food and beverage,as well as water purification.Hence,hydrophilic modification has to be done to PVDF ultrafiltration membranes in order to get good pollution-resistance,thus expanding its application areas.In this thesis,flat PVDF ultrafiltration membranes were prepared by the phase inversion method.In order to improve the hydrophilicity and anti-fouling performance of the membrane,plasma-induced grafting of poly(ethylene glycol)(PEG)have been investigatied.The results showed that PEG could be covalently grafted onto the PVDF ultrafiltration membrane surfaces by low-temperature plasma-induced grafting method.When the treatment time is 3 minutes and the RF power of the Argon plasma is 30 W,the membrane exhibited good anti-fouling performance while its pore structure remains almost unchanged.Furthermore,CO2/O2 plasma modification of PVDF ultrafiltration membrane was also carried out.The results reveal that it is a reasonable approach to introduce-OH and-C=O to the surface of membrane,consequently,the hydrophilicity and anti-fouling of the membrane were improved.As the discharge time is 3 min,the RF power of the plasma is 30 W,and the pressure of CO2 is 40 Pa,the PVDF ultrafiltration membrane with high properties can be obtained.Meanwhile,blengding modification of PVDF Ultrafiltration with CA and SiO2 have been studied.The results showed that when the concentration of solid content is 15%,PVDF:(CA+SiO2)=20:1 and CA:SiO2=1:1,the performances of blended membrane are ideal.