2026-09-19T16:53:47Zhttps://dspace.mit.edu/server/oai/request

oai:dspace.mit.edu:1721.1/598722022-01-13T07:54:19Zcom_1721.1_7582com_1721.1_7581col_1721.1_131022

T. Alan Hatton and Kenneth A. Smith. Annavarapu, V. N. Ravikanth (Venkata Nagandra Ravikanth) Massachusetts Institute of Technology. Dept. of Chemical Engineering. Massachusetts Institute of Technology. Department of Chemical Engineering 2010-11-08T17:38:36Z 2010-11-08T17:38:36Z 2010 2010 http://hdl.handle.net/1721.1/59872 672403401 Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 2010. Cataloged from PDF version of thesis. Includes bibliographical references. The focus of this work was on developing a novel scalable size based separation technology for nonmagnetic particles in the submicron size range utilizing magnetophoretic forces. When a nonmagnetic particle is immersed in a magnetic fluid and subjected to magnetic field gradients, it behaves like a magnetic hole and experiences magnetic buoyancy forces proportional to its volume. This size dependence of magnetic buoyancy forces can be exploited to selectively focus larger nonmagnetic particles from a mixture and thus we can fractionate nonmagnetic particles on the basis of size. We designed a separation system composed of a regular array of iron obstacle posts which utilized magnetic buoyancy forces to perform size based separations. A Lagrangian particle tracking model was developed which could describe the behavior of a nonmagnetic particle in regions of inhomogeneous magnetic field gradients. Particle trajectories were simulated for a number of obstacle array geometries and over a range of operating conditions in order to understand the nature of the magnetic buoyancy force and aid in separation system design. Based on the results of the trajectory simulations, an experimental set up was conceptualized and built to demonstrate capture and separation of nonmagnetic particles using magnetic buoyancy forces. Capture visualization experiments were performed utilizing fluorescence microscopy which showed visual evidence of focusing and preferential capture of larger nonmagnetic particles. Experiments also yielded results qualitatively consistent with the Lagrangian trajectory model. Pulse chromatography experiments were also performed in order to quantitatively understand the capture and separation behavior. The results obtained showed quantitative evidence of preferential capture of larger particles. Particle capture efficiencies were compared with predictions from simulations and were found to be qualitatively consistent. Finally, the potential of this separation technology was demonstrated by performing proof-of-concept separation experiments with a mixture of 840 nm and 240 nm particles. by V. N. Ravikanth Annavarapu. Ph.D. 204 p. eng Massachusetts Institute of Technology M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission. http://dspace.mit.edu/handle/1721.1/7582 Chemical Engineering. Size based separation of submicron nonmagnetic particles through magnetophoresis in structured obstacle arrays Thesis application/pdf false Publication unknown unknown <Publication xmlns="https://www.openaire.eu/cerif-profile/1.1/" id="7d922390-8a1f-4e82-bcb4-9c9d189e5bec"> <Type xmlns="https://www.openaire.eu/cerif-profile/vocab/COAR_Publication_Types">http://purl.org/coar/resource_type/c_1843</Type> <Language>eng</Language> <Title>Size based separation of submicron nonmagnetic particles through magnetophoresis in structured obstacle arrays</Title> <PublishedIn> <Publication> </Publication> </PublishedIn> <PublicationDate>2010</PublicationDate> <Authors> <Author> <DisplayName>Annavarapu, V. N. Ravikanth (Venkata Nagandra Ravikanth)</DisplayName> <Affiliation> <OrgUnit> </OrgUnit> </Affiliation> </Author> </Authors> <Editors> </Editors> <Publishers> <Publisher> <DisplayName>Massachusetts Institute of Technology</DisplayName> <OrgUnit /> </Publisher> </Publishers> <License>http://dspace.mit.edu/handle/1721.1/7582</License> <Keyword>Chemical Engineering.</Keyword> <Abstract>The focus of this work was on developing a novel scalable size based separation technology for nonmagnetic particles in the submicron size range utilizing magnetophoretic forces. When a nonmagnetic particle is immersed in a magnetic fluid and subjected to magnetic field gradients, it behaves like a magnetic hole and experiences magnetic buoyancy forces proportional to its volume. This size dependence of magnetic buoyancy forces can be exploited to selectively focus larger nonmagnetic particles from a mixture and thus we can fractionate nonmagnetic particles on the basis of size. We designed a separation system composed of a regular array of iron obstacle posts which utilized magnetic buoyancy forces to perform size based separations. A Lagrangian particle tracking model was developed which could describe the behavior of a nonmagnetic particle in regions of inhomogeneous magnetic field gradients. Particle trajectories were simulated for a number of obstacle array geometries and over a range of operating conditions in order to understand the nature of the magnetic buoyancy force and aid in separation system design. Based on the results of the trajectory simulations, an experimental set up was conceptualized and built to demonstrate capture and separation of nonmagnetic particles using magnetic buoyancy forces. Capture visualization experiments were performed utilizing fluorescence microscopy which showed visual evidence of focusing and preferential capture of larger nonmagnetic particles. Experiments also yielded results qualitatively consistent with the Lagrangian trajectory model. Pulse chromatography experiments were also performed in order to quantitatively understand the capture and separation behavior. The results obtained showed quantitative evidence of preferential capture of larger particles. Particle capture efficiencies were compared with predictions from simulations and were found to be qualitatively consistent. Finally, the potential of this separation technology was demonstrated by performing proof-of-concept separation experiments with a mixture of 840 nm and 240 nm particles.</Abstract> <Access xmlns="http://purl.org/coar/access_right" > </Access> </Publication>