Study On Hydrophilicity And Antifouling Performance Of Polytetrafluoroethylene (PTFE) Hollow Fiber Membrane

Membrane separation technology （MST） is widely applied in air filtration and sewagetreatment due to its high efficiency and environment friendly. However, membrane foulingexisted in all membrane separation processes is inevitable, which will reduce the separationefficiency. Therefore, alleviation of membrane fouling is becoming a research hotspots in MSTfiled. Some researchers have restructured the membrane to alleviate the membrane fouling andenhance the separation efficiency via molecular design in this decade. Unfortunately, thesubstaintial mechanism of membrane fouling is rarely reported.Being based on the double ionic-layer and solid surface absorption theory, we study theeffects of structures （microstructure, chemical structure） on the surface properties （hydrophilicity,Zeta potential） via SEM, IR WCA and SurPASS. In addition, the relationship betweenhydrophilic groups on the PTFE hollow fiber membrane and antifouling is established. The mainresearch content and conclusion are listed as follows:（1） Hydroxyl group （-OH） is introduced on the PTFE membrane and we prepare thePTFE/PVA composite membrane via crosslink reaction between polyvinyl alcohol （PVA） andglutaraldehyde （GA）. The PVAhydrophilic layer is observed on the composite membrane, whichreduces the water contact angle （WCA） from146°to48°and weaken the static absorptionbehavior of BSA on membrane. Besides, the Zeta potential of composite membrane decreaseswith the increase of PVA content, which enhances the antifouling by increasing the electrostaticrepulsion between BSAand membrane.（2） Sulfonic group （-SO₃H） is introduced on the PTFE membrane and we fabricate thePTFE/P（AA-co-NaSS） composite membrane by free radical copolymerization of acrylic acid（AA） and sodium styrene sulfonate （NaSS）. The IR spectra indicate that massive copolymer canbe observed when the mass concentration of AA and NaSS is14%and12%, respectively. Inaddition, the WCA is decrease to78°, which is for the adsorption capacity of BSA. Finally, theionization of-SO₃H decreases the Zeta potential and improves the antifouling.（3） Amino group （-NH₂） is introduced and we prepare the PTFE/PVA-APTES composite membrane by coating hybrid gel prepared on the PTFE membrane, which is synthetized viacondensation polymerization of PVA and aminopropyltriethoxysilane （APTES）. The WCA ofcomposite membrane and adsorption capacity of BSA decrease with the result of the hybridhydrophilic layer. Besides, the hydrophilicity is weakened when the drying temperature increases,because the hydroxyl group is more consumed. In addition, the Zeta potential increases due tothe ionization of-NH₂and antifouling is enhanced.（4） In this work, the intrinsic factor for improvement of antifouling is proposed byanalyzing the mechanism of membrane fouling and comparing the effects of differenthydrophilic groups on the hydrophilicity and Zeta potential. The hydrophilicity can enhance theantifouling of hydrophobic PTFE membrane via decreasing the adsorption capacity of BSA. Inaddition, weakening the electrostatic attraction between BSA and membrane by decreasing theZeta potential can also enhance the antifouling.