摘要
由于聚偏氟乙烯(PVDF)微孔膜疏水,易形成表面及孔污染,本文采用一步涂层(涂层膜)或者羟基化-接枝交联法(化学交联膜),在膜孔表面引入磺酸甜菜碱-硅氧烷型两性离子, 3-(三甲氧基硅烷)丙氨基-丙烷-1-磺酸,提高PVDF微滤膜耐污染性.接枝两性离子后膜的接触角下降为零,而涂层膜接触角仅略降低.但是交联膜及涂层膜的纯水通量均提升为原膜2倍左右.在处理腐殖酸(HA)溶液时,交联膜和涂层膜的稳定通量提高了70%~90%.而过滤牛血清蛋白(BSA)溶液时,两种膜的稳定通量与原膜接近.采用阻力模型和Hermia模型分析了污染机理.结果表明,两性离子改性后较好地耐腐殖酸污染,但是对蛋白质耐污染较差.表面电位分析表明,腐殖酸高负电性被改性膜表面排斥是膜耐污染重要原因;而蛋白质弱负电性和与膜表面其他相互作用,以及蛋白质之间优先作用,导致易于吸附,覆盖膜表面,两性离子改性优势无法表现出来.本文科学分析了两性离子耐污染的优势和劣势,为表面改性膜的实际应用提供了数据和方法.
PVDF membrane is accessible to surface and pore fouling due to its hydrophobicity. In this paper, the fouling resistance of sulfobetaine siloxane zwitterionic grafted and coated zwitterionic polymer introduced to PVDF membrane was systematically evaluated. The grafted membrane showed improved hydrophilicity of zero contact angle and doubled water flux. At nearly the same contact angle, the coated PVDF membrane showed flux increase as well. FTIR results indicated successful modification of PVDF membrane with zwitterionic chemicals. In treating HA, both grafted and coated PVDF membrane showed improvement in water flux;in treating BSA, no obvious flux improvement was found for both grafted and coated membranes. Resistance-in-series and Hermia's models deduced the same fouling mechanisms: cake layer contributed to the main fouling sources;surface modification with zwitterionic chemicals showed improvement in fouling resistance for HA-like foulants due to loose cake layer and strong negative change repulsion;but for BSA-like foulants, the foulant-foulant interaction incurred severe fouling independent from the surface chemistry. Present results provide useful information and methodology for evaluation fouling resistance of membranes.
作者
汪孟良
宋健峰
黄涛
何涛
WANG Mengliang;SONG Jiangfeng;HUANG Tao;HE Tao(Shanghai Advanced Research Institute, Chinese Academy of Science, Shanghai 201210, China;University of Chinese Academy of Science, Beijing 100049, China;Shanghai Tech University, Shanghai 201210, China)
出处
《膜科学与技术》
CAS
CSCD
北大核心
2019年第3期29-35,共7页
Membrane Science and Technology
基金
国家自然科学基金项目(21676290,51861145313,21808236)
迪士尼研发项目(CA1501)
关键词
微滤
两性离子
膜污染
污染模型
microfiltration
zwitterionic
membrane fouling
fouling models
