Implications of Oxidation on the Colloidal Stability of Magnetite Nanoparticles and Cluster

dc.contributor.authorRebodos, Robert Louie Fermoen
dc.contributor.committeechairVikesland, Peter J.en
dc.contributor.committeememberWalz, John Y.en
dc.contributor.committeememberEdwards, Marc A.en
dc.contributor.committeememberNovak, John T.en
dc.contributor.committeememberLittle, John C.en
dc.contributor.departmentCivil Engineeringen
dc.date.accessioned2017-04-06T15:42:51Zen
dc.date.adate2010-07-20en
dc.date.available2017-04-06T15:42:51Zen
dc.date.issued2010-06-10en
dc.date.rdate2016-10-17en
dc.date.sdate2010-06-24en
dc.description.abstractSynthetic nanomagnetite has been suggested as a potential reactant for the in-situ treatment of contaminated groundwater. Although the application of nanomagnetite for environmental remediation is promising, a full understanding of its reactivity has been deterred by the propensity of the nanoparticles to aggregate and form clusters. To characterize the factors responsible for this aggregation behavior, we determined the magnetic properties of magnetite using a superconducting quantum interference device (SQuID). Importantly, because magnetite readily reacts with O2 to produce maghemite, we analyzed the effect of oxidation on its magnetic properties. We observed that oxidation caused a decrease in the saturation magnetization and the anisotrophic barrier of magnetite resulting in less significant magnetic interactions between particles. Consequently, a decrease in the aggregation of magnetite clusters and a potential increase in stability are expected after oxidation. To support these findings, an extended series of experiments to measure the aggregation and the sedimentation of clusters of unoxidized and oxidized magnetite nanoparticles were conducted. Although the individual particle diameter remained constant after oxidation, the cluster size and the aggregation and sedimentation kinetics of magnetite were determined to be different. Oxidized samples of magnetite tended to have lower aggregation rates and were more resistant to sedimentation. These findings can be used to have a better understanding of the overall fate, transport, and reactivity of nanomagnetite, and to gain new insights on its role as a remediation agent in the subsurface environment.en
dc.description.degreePh. D.en
dc.identifier.otheretd-06242010-222951en
dc.identifier.sourceurlhttp://scholar.lib.vt.edu/theses/available/etd-06242010-222951/en
dc.identifier.urihttp://hdl.handle.net/10919/77117en
dc.language.isoen_USen
dc.publisherVirginia Techen
dc.rightsIn Copyrighten
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.subjectMaghemiteen
dc.subjectSedimentationen
dc.subjectCluster-cluster aggregationen
dc.subjectMagnetiteen
dc.subjectOxidationen
dc.titleImplications of Oxidation on the Colloidal Stability of Magnetite Nanoparticles and Clusteren
dc.typeDissertationen
dc.type.dcmitypeTexten
thesis.degree.disciplineCivil Engineeringen
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen
thesis.degree.leveldoctoralen
thesis.degree.namePh. D.en
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