Collaborative Research: A Bioinspired Approach towards Sustainable Membranes for Resilient Brine Treatment

许多水处理和工业过程产生大量高盐度卤水，包括海水淡化、内陆微咸水淡化以及通过水力压裂生产石油和天然气。来自海水淡化厂和石油/天然气生产井的危险高盐度盐水的管理已成为一项全球性的环境挑战。膜蒸馏是处理高盐度卤水的一种很有前途的技术，它可以减少需要处理的盐水的量，同时产生纯净水渗透液，以支持工农业用途。在过去的十年中，在开发更有效的MD膜方面取得了重大进展，这些膜具有高润湿性和抗结垢性能，用于高盐度盐水处理。然而，这些膜通常是通过用长链的全氟和多氟烷基物质(PFAS)修饰其表面来制备的，由于其在环境中的持久性、稳定性以及对人类和生物的毒性越来越受到关注，这些物质已成为优先污染物。该项目的总体目标是探索在不使用全氟磺酸的情况下用于盐水处理的防湿防垢MD膜的设计和制造。受弹尾虫对低表面张力液体的独特排斥作用的启发，首席研究人员建议测试这样一种假设，即通过将弹尾虫激发的超胶体结构共价附着到疏水平板薄膜的表面上，可以制造出高效的MD膜，具有高润湿和高防垢性能。该项目的成功完成将通过发展新的基础知识来指导设计和制造用于坚固和高效的盐水处理的不含PFAS的膜材料，从而造福社会。还将通过外展和教育活动为社会带来更多好处，包括对田纳西大学诺克斯维尔分校的一名研究生和科罗拉多州立大学的一名研究生进行指导。膜蒸馏(MD)作为一种盐水处理技术的有效性受到盐水侵入膜孔(膜孔湿)和膜表面矿物质沉淀(膜结垢)的限制。该项目的目标是设计和制造一种新的仿生耐湿和防结垢MD膜家族，而不使用PFAS构建块。为了推进这一目标，首席调查员建议探索新的策略，通过共价附着模仿弹尾虫悬垂纹理的超胶体结构和它们排斥低表面张力液体的独特能力来修饰商业上可用的疏水平板薄膜的表面。这些超胶体结构将通过控制地将较小的胶体组装到具有负曲率的突出结构和非氟化配体的较大胶体的表面上来形成。这项研究的具体目标是：1)阐明耐湿膜超胶体结构的设计标准；2)表征和揭示新型仿生MD膜的阻垢机理；3)利用模拟盐水混合物和科罗拉多州某油气田的高矿化度采出水，评估新型MD膜的处理效果。该项目的成功完成有可能通过产生新的基础知识和功能材料产生变革性的影响，以推动无全氟辛烷磺酸的MD膜的开发，用于高效和经济有效地处理高盐度盐水。为了实现该项目的教育和培训目标，首席调查员计划将这项研究的结果纳入田纳西大学诺克斯维尔分校(UTK)和科罗拉多州立大学(CSU)现有的本科和研究生课程。此外，PIs建议利用UTK和CSU的现有计划发起外联活动，从代表不足的群体中招募和吸引高中生，重点是利用生物启发材料来改善水的可持续性。这一奖项反映了NSF的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。

Many water treatment and industrial processes generate significant amounts of high-salinity brines including seawater desalination, inland brackish water desalination, and oil and gas production by fracking. The management of hazardous high-salinity brines from water desalination plants and oil/gas production wells has emerged as a global environmental challenge. Membrane distillation (MD) is a promising technology for the treatment of high-salinity brines that could reduce the amounts of brine that need to be disposed of while generating a purified water permeate to support industrial and agricultural usages. During the last decade, significant progress has been made toward the development of more efficient MD membranes with high wetting and scaling resistance for high-salinity brine treatment. However, these membranes are typically prepared by modifying their surfaces with long-chain per- and polyfluoroalkyl substances (PFAS), which have become priority pollutants due to increasing concerns about their persistence in the environment, stability, and toxicity to humans and living organisms. The overarching goal of this project is to explore the design and fabrication of wetting- and scaling-resistant MD membranes for brine treatment without the use of PFAS. Inspired by the unique repellency of springtails towards low surface tension liquids, the Principal Investigators propose to test the hypothesis that efficient MD membranes, with both high wetting resistance and high scaling resistance, can be fabricated by covalent attachment of springtail-inspired supracolloidal structures onto the surface of a hydrophobic flat sheet membrane. The successful completion of this project will benefit society through the development of new fundamental knowledge to guide the design and fabrication of PFAS-free membrane materials for robust and efficient brine treatment. Additional benefits to society will be achieved through outreach and educational activities including the mentoring of one graduate student at the University of Tennessee, Knoxville and one graduate student at Colorado State University.The effectiveness of membrane distillation (MD) as a brine treatment technology is limited by both the intrusion of brines into membrane pores (membrane pore wetting) and the precipitation of minerals on the membrane surfaces (membrane scaling). The goal of this project is to design and fabricate a new family of biomimetic wetting- and scaling-resistant MD membranes without using PFAS building blocks. To advance this goal, the Principal Investigators (PIs) proposal to explore new strategies to modify the surface of a commercially available hydrophobic flat sheet membrane by covalent attachment of supracolloidal structures that mimic the overhang texture of springtails and their unique capability to repel low surface tension liquids. These supracolloidal structures will be formed through controlled assembly of smaller colloids onto the surfaces of larger colloids that have overhang structures with negative curvature and non-fluorinated ligands. The specific objectives of the research are to: 1) Elucidate the design criteria of supracolloidal structures for wetting resistant membranes, 2) Characterize and unravel the mechanisms of scaling resistance of the new biomimetic MD membranes, and 3) Evaluate the treatment effectiveness of the new MD membranes using model brine mixtures and a high salinity produced water from an oil and gas production field in Colorado. The successful completion of this project has the potential for transformative impact through the generation of new fundamental knowledge and functional materials to advance the development of PFAS-free MD membranes for efficient and cost-effective treatment of high salinity brines. To implement the educational and training goals of this project, the Principal Investigators (PIs) plan to integrate the findings from this research into existing undergraduate and graduate courses at the University of Tennessee, Knoxville (UTK) and Colorado State University (CSU). In addition, the PIs propose to leverage existing programs at UTK and CSU to launch outreach activities to recruit and engage high and middle school students from underrepresented groups with a focus on the utilization of bioinspired materials to improve water sustainability.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.