Advanced Responsive Low-Fouling Membranes for Water Treatment

一种新型的刺激响应式水处理纳滤和超滤膜将被开发出来，与现有膜相比，它具有更好的抗污染能力。表面改性后的亲水膜越多，抗污性能越好。本文提出的研究涉及从商用纳滤和超滤膜表面接枝已知具有高度抗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激活。在振荡磁场中，它们会像微生物的纤毛一样旋转，导致膜流体界面的混合。初步的粒子图像测速数据表明，纳米刷的运动导致了距离膜表面0.5 mm的液体层的混合。因此，与以往的工作不同，表面改性不仅用于在膜上创建抗污染的表面层，而且还用于在实际的膜流体界面上通过流体动力混合来抑制污染。由于膜污染，特别是胶体颗粒的污染，膜分离在水处理中的应用常常受到限制。本课题旨在开发一种新型的低污染自清洁纳滤膜和超滤膜。耐污纳米刷将从市售的纳滤和超滤膜表面生长出来。原子转移自由基聚合（ATRP）将用于纳米刷的生长。ATRP允许对纳米刷的厚度和密度进行精细控制。使用ATRP可以在链端添加单个活性官能团。在这里，一个胺基被添加到链的末端，这使得涂有羧基的超顺磁性纳米颗粒具有共价，因此可以永久附着。在振荡磁场中，聚合物链像微生物的纤毛一样运动。这种运动将在膜表面引起局部混合，从而抑制胶体污染。开发实用的磁响应纳滤和超滤膜需要优化纳米刷的长度和密度、超顺磁粒度、外磁场强度和振荡频率。这些参数还控制能源使用和产热，因此优化需要能够预测任何给定配置的混合特性。将开发一个流体结构计算模型，使用计算流体动力学来研究混合作为颗粒大小，间距和纳米刷长度的函数。平行理论研究将用于预测作用在粒子上的力作为超顺磁粒子大小、磁场强度和频率的函数。获得的基础科学知识可以改变目前用于赋予膜抗污染能力的方法。研究结果将发表在《膜科学》、《环境科学与技术》、《大分子》等期刊上。这个多学科的国际合作研究项目将有助于美国高技能劳动力的发展，使其能够在日益全球化的环境中运作。研究生和本科生将获得独特的国际研究和培训经验，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？水丰富吗?为研究生和本科生提供研究和教育环境。学生将学习到美国西部许多复杂的与水有关的问题。来自未被充分代表的科学和工程群体的学生将通过科罗拉多大学现有的项目（如科罗拉多aep）被招募。本科生将在一个团队中完成与他们的教育水平相匹配的子项目。项目会议将通过网络会议与德国合作者举行。开发用于水处理的抗污膜将产生巨大的社会影响和效益。进一步，以纳滤和超滤膜为重点，为开发响应式反渗透和微滤膜建立科学知识和可行性。这项研究的成功完成将导致一种新型的抗污染膜的出现，这种膜可以在生物分离等其他领域得到应用。

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.