PTFE平板微孔膜的超疏水改性研究

Surface superhydrophobic modification of PTFE flat-sheet membrane

通过溶胶凝胶法在聚四氟乙烯(PTFE)平板微孔膜表面形成Si O2微纳米粒子,再采用全氟癸基三甲氧硅烷(FAS-17)对其进行修饰,获得超疏水表面的PTFE平板微孔膜。考察了正硅酸乙酯(TEOS)和三甲基三乙氧基硅烷(MTES)配比、FAS-17浓度等对平板膜疏水性和微孔结构的影响,并研究了其膜蒸馏性能。结果表明,改性后Si O2纳米粒子可均匀附着和内嵌在膜的原纤-结点网络结构内;当MTES/TEOS的比例和FAS-17浓度增大时,膜表面静态接触角(WCA)先增加后减小,膜孔径和孔隙率也随之减小;当MTES/TEOS的比例为1∶1,FAS-17浓度为4%(质量分数)时,改性膜的WCA达到154°,滚动角(RA)为8°,达到超疏水效果;由于超疏水作用,改性膜在膜蒸馏运行过程中膜污染程度降低,产水通量恒定在3.65 kg/h·m2左右,脱盐率保持99.8%以上。

The polytetrafluoroethylene( PTFE) flat-sheet membrane with superhydrophobic surface was prepared by the formation of Si O2 nanoparticles on the surface of virgin membrane through the sol-gel method and the modification of perfluorodecyl trimethoxy silane( FAS-17) on the surface of Si O2 nanoparticles. The effects of ratio of tetraethyl orthosilicate( TEOS) and Trimethyl triethoxy silane( MTES) and the concentration of FAS-17 on the hydrophobility and microstructure of the membrane were studied. The membrane distillation property of the superhydrophobic modified membrane was also investigated. The results showed that the Si O2 nanoparticles adhered and embedded in the network structures of nodes interconnected by fibrils. The surface water contact angle( WCA) of membrane increased maximum and then decreased with the increase of the ratio of TEOS and MTES and the concentration of FAS-17. However,the pore size and porosity of membrane decreased with the increase of the ratio of TEOS and MTES and the concentration of FAS-17. When the ratio of TEOS and MTES and the concentration of FAS-17 were 1∶ 1 and 4wt%,respectively,the WCA and rolling angle were 154 and 8°,respectively. The result of membrane distillation test showed that the modified membrane suffered less membrane fouling compared to the virgin membrane due to superhydrophobic modification. The permeate flux of the modified membrane maintained at about 3. 65 kg / h·m2over the testing period and the salt rejection was more than 99.8%.