Fouling resistant, freestanding zwitterionic polysulfones for osmotically driven membrane processes

提供可持续和安全的饮用水是这一代人面临的一项重大挑战。天然水源经过处理以去除盐分、有机物和生物有机体。随着用水需求的增加，必须利用需要更严格的预处理的水源。聚合物膜是一种很有前途的技术，可以满足这些更严格的水净化要求，因为它们选择性地输送净化水，同时拒绝污染物。尽管目前的膜前景看好，但它面临着两个严重的局限性：生物膜在膜上的附着和生长，以及膜的氯气降解。由于需要清洗或更换膜，这两种影响都会降低膜的性能并增加成本。该项目将设计和测试保持商用膜性能的新型聚合物膜材料，对聚合物进行分子水平的改性，以提高对生物膜污染的抵抗力，并减少氯的降解。通过整合大分子和过程工程，这个项目将研究分子水平的聚合物设计如何影响加工、微结构和分离性能。聚芳醚砜的前驱体将通过后聚合改性，引入磺基甜菜碱、两性离子和一系列交联剂。电荷和交联密度将被优化，以平衡亲水性和吸水性与导致机械稳定性损失的膨胀之间的关系。然后，对新型膜的抗污染机理进行了探讨，包括表面粗糙度、亲水性和电荷含量对蛋白质粘附性的影响。此外，还将研究电荷含量的系统变化对物理膜特性的影响，包括透水率、不同盐浓度和压降下的盐截留率、膜孔隙率、自由体积、形态和分离/处理成本。最后，电荷含量和工艺条件将与膜寿命相关，特别是不对称膜在各种跨膜压降下的结构完整性、对氯介导的氧化降解的抵抗力以及长期污染研究。一名研究生将接受该项目的培训，本科生将参与实验室工作。亚利桑那州立大学的不同学生团体和周围的大都市社区将参与其中的教育推广计划。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Providing sustainable and secure access to potable water is a critical challenge facing this generation. Natural water sources are treated to remove salt, organic matter, and biological organisms. As water demand increases, water sources that require more rigorous pretreatment must be utilized. Polymer membranes are a promising technology for these more rigorous water purification demands, as they selectively transport purified water while rejecting contaminants. Although promising, current membranes face two profound limitations: adhesion and growth of biological films on the membrane, and membrane degradation by chlorine. Both effects reduce membrane performance and increase cost due to the need to clean or replace the membrane. This project will design and test new polymeric membrane materials that retain the performance of commercial membranes, with molecular-level modification of the polymer for increased resistance to fouling by biofilms and decreased degradation by chlorine. Through an integration of macromolecular and process engineering, this project will investigate how molecular level polymeric design impacts processing, microstructure, and separation performance. Poly(arylene ether sulfone) precursors will be modified using post-polymerization modifications to introduce sulfobetaine zwitterions and a series of crosslinkers. The charge and crosslink densities will be optimized to balance hydrophilicity and water sorption versus swelling that leads to a loss of mechanical stability. Then, (anti)fouling mechanisms for the new membranes will be probed, including the role of surface roughness, hydrophilicity, and charge content on protein adhesion. Also, the influence of systematic changes in charge content on physical membrane characteristics will be studied, including water permeability, salt rejection at various salt concentrations and pressure drops, membrane porosity, free volume, morphology, and separation/process costs. Finally, the charge content and processing conditions will be correlated to membrane longevity, specifically structural integrity at various transmembrane pressure drops for asymmetric membranes, resistance to chlorine-mediated oxidative degradation, and long-term fouling studies. One graduate student will be trained in this project and undergraduate students will be involved in the laboratory work. An educational outreach plan is included that will engage the diverse student body of Arizona State University and the surrounding metropolitan community.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.