Magnetic Separations for Environmentally Benign Processing

建议编号：CTS-9985489建议类型：响应NSF99-108，美国国家科学基金会/环境保护局可持续环境计划技术主要研究人员：詹姆斯·A·里特和哈里·J·普罗恩研究所：哥伦比亚南卡罗来纳大学磁力分离用于环境友好的过程该项目正在为一种新的磁场增强分离过程开发坚实的理论基础和操作上的理解。新的高梯度磁选(HGMS)工艺是基于使用固定床上负载的磁性吸附剂，如磁铁矿。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，还可以作为磁能元件从悬浮液中吸引和保持顺磁性纳米粒子。在这样的系统中，磁铁矿用作金属离子吸附剂或高梯度磁过滤器，或两者兼而有之，具体取决于待处理水流的特性。具体地说，这项研究描述、分析和论证了这种新的磁选工艺相对于其他磁场增强分离和传统的金属离子吸附工艺的优势，这种新的磁场增强分离工艺的应用非常广泛。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物种，以及通过去除二硫化二铁对煤进行脱硫，从而避免在源头产生污染物。另一个有前景的应用是将HGMS用于生物磁分离，在生物磁分离中，可以通过功能化磁性氧化物的选择性标记来分离病毒和细胞。此外，蛋白质和酶可以通过偶联到带有生物选择性官能团的磁性颗粒上进行分级。对于这些应用，所提出的HGMS工艺的主要优点在于磁铁矿颗粒较小以及伴随而来的高局部磁场梯度。这导致可以捕获的颗粒大小和所需的施加磁场减少了数量级。甚至有可能捕获与顺磁离子络合的单个蛋白质分子。所需外部磁场的减少首次使得在HGMS操作中使用具有相对较高磁场强度(高达1特斯拉)的永久陶瓷磁体成为可能。这些类型的磁铁不需要外部电源，因此对环境真正无害。通过建立对所提议的HGMS技术的合理的理论和操作上的理解，这项研究为去除、浓缩、回收和循环化学流程中的弱顺磁性金属物种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.