基于膜清洗响应的膜表面智能改性设计

Membrane fouling is a key barrier in membrane application. In this application, a multi-function smart membrane containing “PVDF substrate membrane - cleaning responsible macromolecule - adhering resistant fluoride island” structure was designed for membrane fouling control. The fluoride island outer layer may resist the adhering of infectant. The middle layer is consisted of smart cleaning responsible molecule, which can remove the infectant on membrane surface by the molecule chain variation. .The effect of cleaning responsible molecule and fluoride chain structure on the morphology, hydrophilicity, cleaning responsibility and adhering resistance of the membranes will be studied. The effect of surface modification method on the surface structure and performance of the membranes will be detected. The relationship between modification method and surface grafting molecules, membrane structure and properties will be clarified. Grafting molecule structure and membrane surface morphology adjusting method will be constructed and high fouling resistant smart PVDF hollow fiber membrane and relative preparation method will be obtained.

膜污染是影响分离膜性能的关键问题，现有膜改性方法虽可提升膜的亲水性和通量，但多难以解决污染问题。.本申请设计“PVDF基膜-清洗（pH）响应大分子-抗粘附‘氟岛’表面”多重结构智能膜。通过最外层适度疏松的抗粘附“氟岛”表面，抑制污染物在膜面的吸附沉积；通过中间层大分子链的智能清洗响应，促进膜表面污染物的清除。抑制膜污染、提高膜运行通量、提升清洗效率。.研究智能响应链段、氟基化链段化学结构对膜面微结构、亲水性、pH响应、抗污染粘附特性以及膜通量等的影响规律。研究基膜表面处理方法、接枝改性工艺对膜pH响应链接枝率、“氟岛”尺寸、两种功能链段长度及比例、膜表面形貌与性能的影响规律。探明pH响应与氟基化链段化学结构、改性反应工艺、膜微结构与性能之间的相关关系；建立pH响应亲水大分子层、“氟岛”外表面微结构及性能的调控方法；获得具有高抗污染智能响应特性的PVDF基中空纤维膜及制备方法。

对于膜污染，现有研究采用的通行策略是对疏水性的膜表面进行亲水化改性。本课题针对水体中膜污染物通常具有疏水亲油性的特点，首先构建具有化学响应的亲水性表面，然后采用两步酰胺化反应引入疏油性的全氟烷基，通过控制全氟烷基的接枝率，使其均匀、不连续地排布在膜表面，从而在膜表面形成均匀、非连续的疏水“氟岛”结构。一是通过亲水结构和疏油结构的协同增效作用进一步提高膜表面的抗污染性能，二是利用pH响应性分子的化学脉冲作用，使响应性分子链发生溶胀伸展变化，破坏污染层的完整性，以便污染物更容易在料液剪切力的作用下从膜表面洗脱，从而提高膜的清洗效率。