Advanced Responsive Low-Fouling Membranes for Water Treatment

将开发一种新的用于水处理的刺激响应性纳米过滤和超滤膜，其与现有膜相比具有上级抗污染性。由表面改性产生的更亲水的膜表现出更好的抗污染性能。这里提出的研究涉及从市售的纳滤膜和超滤膜的表面接枝已知具有高度防污性的聚合物纳米刷。这项研究非常新颖，因为这些纳米刷可以被磁性激活。在振荡磁场中，它们将像微生物的纤毛一样旋转，导致在膜流体界面处混合。初步的粒子图像测速数据表明，nanobrush运动导致混合的液体层从膜表面的0.5毫米。因此，与以前的工作不同，表面改性不仅用于在膜上产生抗污染表面层，而且用于抑制在实际膜流体界面处通过流体动力学混合的污染。用于水处理应用的基于膜的分离通常由于膜污染特别是胶体颗粒而受到限制。该提案旨在开发一种新型的低污染自清洁纳滤膜和超滤膜。抗污染纳米刷将从市售的纳米过滤和超滤膜的表面生长。原子转移自由基聚合（ATRP）将用于生长纳米刷。ATRP允许对纳米刷的厚度和密度进行精细控制。使用ATRP，可以将单个反应性官能团添加到链末端。在这里，胺基被添加到链端，这允许共价地并且因此永久地附着涂覆有羧基的超顺磁性纳米颗粒。在振荡磁场中，聚合物链像微生物的纤毛一样移动。这种运动将在膜表面引起局部混合，这将抑制胶体污染。开发实用的磁响应纳米过滤和超滤膜将需要优化纳米刷的长度和密度以及超顺磁性颗粒的尺寸和外部磁场强度和振荡频率。这些参数还控制能量使用和热量产生，因此优化需要能够预测任何给定配置的混合特性。将使用计算流体动力学开发流体-结构计算模型，以研究作为颗粒尺寸、间距和纳米刷长度的函数的混合。平行的理论研究将被用来预测作为超顺磁性颗粒尺寸的函数的作用在颗粒上的力，以及磁场强度和频率。所获得的基础科学知识可以改变目前用于赋予膜抗污染性的方法。研究结果将发表在Journal of Membrane Science、Environmental Science Technology和Macromolecules等期刊上。 这个多学科的国际合作研究项目将有助于发展高技能的美国劳动力，能够在日益全球化的环境中运作。研究生和本科生将从独特的国际研究和培训经验中获益，并获得科罗拉多州立大学无法获得的设备和专业知识。科罗拉多州立大学提供了一个？富水？研究生和本科生的研究和教育环境。学生将了解美国西部许多与水相关的复杂问题。来自科学和工程领域代表性不足的群体的学生将通过CSU现有的项目招募，如科罗拉多AEGP。本科生将在一个团队中工作的子项目，符合他们的教育水平。将通过网络会议与德国合作者举行项目会议。开发抗污染的水处理膜将产生巨大的社会影响和效益。通过进一步关注纳滤膜和超滤膜，研究将为开发响应性反渗透和微滤膜建立科学知识和可行性。成功完成拟议的研究将导致一类新的抗污染膜，可以在其他领域，如生物分离中找到应用。

1066505WickramasingheA new class of stimuli responsive nanofiltration and ultrafiltration membranes for water treatment will be developed with superior fouling resistance compared to current membranes. More hydrophilic membranes resulting from surface modification demonstrates better anti-fouling properties. The research proposed here involves grafting polymer nanobrushes known to be highly fouling resistant, from the surface of commercially available nanofiltration and ultrafiltration membranes. The research is extremely novel in that these nanobrushes can be magnetically activated. In an oscillating magnetic field they will rotate like the cila of microorganisms leading to mixing at the membrane fluid interface. Preliminary particle-image velocimetry data indicate that nanobrush movement causes mixing in the liquid layer up to 0.5 mm from the membrane surface. Thus unlike previous work, surface modification is used not only to create an anti-fouling surface layer on the membrane, but also, to suppress fouling by hydrodynamic mixing at the actual membrane fluid interface. Membrane based separations for water treatment applications are often limited due to membrane fouling especially by colloidal particles. This proposal aims to develop a new class of low fouling selfcleaning nanofiltration and ultrafiltration membranes. Fouling resistant nanobrushes will be grown from the surface of commercially available nanofiltration and ultrafiltration membranes. Atom transfer radical polymerization (ATRP) will be used to grow the nanobrushes. ATRP allows fine control over the thickness and density of the nanobrushes. Using ATRP a single reactive functional group may be added to the chain ends. Here an amine group is added to the chain ends, which allows covalent and therefore permanent attachment of superparamagnetic nanoparticles coated with carboxylic groups. In an oscillating magnetic field, the polymer chains move like the cilia of microorganisms. This movement will cause local mixing at the membrane surface which will suppress colloidal fouling. Development of practical magnetically responsive nanofiltration and ultrafiltration membranes will require optimization of nanobrush length and density as well as the superparamagnetic particle size and the external magnetic field strength and oscillation frequency. These parameters also govern energy usage, and heat production, thus optimization requires the ability to predict mixing characteristics for any given configuration. A fluid-structure computational model will be developed using computational fluid dynamics to study mixing as a function of particle size, spacing, and nanobrush length. Parallel theoretical studies will be used to predict the force that acts on the particles as a function of superparamagnetic particle size, and magnetic field strength and frequency. The fundamental scientific knowledge gained could transform the approaches currently used to impart fouling resistance to membranes. Results will be published in journals such as Journal of Membrane Science, Environmental Science & Technology and Macromolecules. This multidisciplinary international collaborative research project will contribute to the development of highly skilled US workforce that is able to operate in an increasingly global environment. Graduate and undergraduate students will gain from unique international research and training experiences as well as access to equipment and expertise not available at Colorado State University. Colorado State University provides a ?water rich? research and educational environment for graduate and undergraduate students. Students will learn about the many complex water related issues in the western United States. Students from underrepresented groups in science and engineering will be recruited through the existing programs at CSU such as the Colorado AEGP. Undergraduates will work in a team on subprojects that match their educational level. Project meetings will be held with the German collaborators via web-conferencing. Development of fouling resistant membranes for water treatment will have tremendous societal impacts and benefits. Further by focusing on nanofiltration and ultrafiltration membranes, the research will establish the scientific knowledge and feasibility for development of responsive reverse osmosis and microfiltration membranes. Successful completion of the proposed research will lead to a new class of fouling resistant membranes that could find applications in other area such as bioseparations.