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重大挑战。对天然水源进行处理以去除盐、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，因为它们可以选择性地输送纯净水，同时拒绝污染物。尽管前景光明，但目前的膜面临两个深刻的局限性：生物膜在膜上的粘附和生长，以及膜被氯降解。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新的聚合物膜材料，这些材料保留了商业膜的性能，并对聚合物进行了分子水平的改性，以提高对生物膜污染的抵抗力，减少氯的降解。通过大分子和工艺工程的整合，该项目将研究分子水平的聚合物设计如何影响加工、微观结构和分离性能。对聚芳醚砜前体进行聚合后改性，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丧失的膨胀。然后，将探讨新膜的抗污染机制，包括表面粗糙度、亲水性和电荷含量对蛋白质粘附的作用。此外，还将研究电荷含量的系统变化对膜物理特性的影响，包括水渗透性、不同盐浓度和压降下的盐分截留、膜孔隙度、自由体积、形态和分离/工艺成本。最后，电荷含量和处理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抗性以及长期污染的研究。该项目将培训一名研究生，本科生将参与实验室工作。其中包括一个教育推广计划，该计划将吸引亚利桑那州立大学和周边大都市社区的多元化学生团体。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值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.