Magnetic Separations for Environmentally Benign Processing

摘要提案编号：csts -9985489提案类型：响应NSF 99-108， NSF/EPA可持续环境技术项目项目负责人：James a . Ritter和Harry J. ploehn机构：南卡罗莱纳大学哥伦比亚分校磁选环境良性处理该项目旨在为新型磁场增强分离工艺提供良好的理论基础和操作理解。新的高梯度磁选（HGMS）工艺是基于使用磁性吸附剂，如磁铁矿支撑在固定床上。由于其铁磁性，磁铁矿不仅可以作为吸附剂从溶液中去除金属离子，而且可以作为磁性可激活元素从悬浮液中吸引和保留顺磁性纳米颗粒。在这样的系统中，磁铁矿作为金属离子吸附剂，高梯度磁性过滤器，或两者兼而有之，这取决于待处理流体的特性。具体来说，本研究描述、分析并论证了这种新型磁分离工艺相对于其他磁场增强分离和传统金属离子吸附工艺的优势。这种新型磁场增强分离工艺的应用比比皆是。在无害环境的加工领域，应用包括在采矿和冶金作业中从源头回收和再循环金属种类，以及通过除去FeS2对煤进行脱硫，从而避免在源头产生污染物。另一个有前景的应用是HGMS在生物磁学分离中的应用，在生物磁学分离中，病毒和细胞可以通过功能化磁性氧化物的选择性标记分离。此外，蛋白质和酶可以通过偶联到具有生物选择性官能团的磁性颗粒来分离。在这些应用中，HGMS工艺的主要优点在于磁铁矿粒度小，并伴随有高的局部磁场梯度。这导致可以捕获的颗粒尺寸和所需的施加磁场的数量级减小。它甚至有可能捕获与par磁性离子络合的单个蛋白质分子。由于所需外部外加磁场的减少，HGMS操作中首次使用了具有相对高磁场强度（高达1特斯拉）的永久陶瓷磁铁。这种磁铁不需要外部电源，因此对环境是真正无害的。通过对所提出的HGMS技术建立良好的理论和操作理解，本研究为化学工艺流中弱顺磁性金属的去除、浓缩、回收和再循环开辟了许多不同的途径。

AbstractProposal Number: CTS-9985489 Proposal type: Response to NSF 99-108, NSF/EPA Technology for a Sustainable Environment ProgramPrincipal Investigators: James A. Ritter and Harry J. PloehnInstitution: University of South Carolina at ColumbiaMAGNETIC SEPARATIONS FOR ENVIRONMENTALLY BENIGN PROCESSINGThis project is developing a sound theoretical foundation and operational understanding of a novel magnetic-field-enhanced separation process. The new high-gradient magnetic separation (HGMS) process is based on the use of a magnetic adsorbent such as magnetite supported on a fixed bed. Due to its ferromagnetic property, magnetite can be used not only as an adsorbent for removing metal ions from solution but also as a magnetically energizable element for attracting and retaining paramagnetic nanoparticles from suspension. In such a system, the magnetite serves as a metal ion adsorbent, a high-gradient magnetic filter, or both, depending on the characteristics of the stream to be treated. Specifically, this research describes, analyzes, and demonstrates the advantages of this new magnetic separation process over other magnetic-field-enhanced separations and conventional metal-ion adsorption processes.Applications for this new, magnetic-field-enhanced separation process abound. In the area of environmentally benign processing, applications include the recovery and recycling of metal species at the source in mining and metallurgical operations and for desulfurization of coal by removing FeS2, thereby avoiding the generation of pollutants at the source. Another promising application is the use of HGMS in biomagnetic separations, in which viruses and cells can be separated through selective tagging with functionalized magnetic oxides. Also, proteins and enzymes can be fractionated by coupling to magnetic particles bearing bio-selective functional groups. The primary advantage of the proposed HGMS process for these applications lies in the small magnetite particle size and the concomitant high local magnetic field gradients. This leads to order-of-magnitude reductions in the particle sizes that can be captured and in the applied magnetic fields required. It may even be possible to capture individual protein molecules complexed with parmagnetic ions. The reduction in the externally applied magnetic field required enables, for the first time, the use of permanent ceramic magnets with relatively high magnetic field strengths (up to 1 Tesla) in the HGMS operations. These kinds of magnets do not require an external power source and thus are truly benign to the environment. By establishing a sound theoretical and operational understanding of the proposed HGMS technology, this research opens up many different avenues for removing, concentrating, recovering, and recycling weakly paramagnetic metal species in chemical process streams.