The synthesis, characterization and application of iron oxide nanocrystals in magnetic separations for arsenic and uranium removal

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dc.contributor.advisorColvin, Vicki L.en_US
dc.creatorMayo, John Thomasen_US
dc.date.accessioned2013-03-08T00:36:28Zen_US
dc.date.available2013-03-08T00:36:28Zen_US
dc.date.issued2012en_US
dc.description.abstractArsenic and uranium in the environment are hazardous to human health and require better methods for detection and remediation. Nanocrystalline iron oxides offer a number of advantages as sorbents for water purification and environmental remediation. First, highly uniform and crystalline iron oxide nanocrystals (nMAG) were prepared using thermal decomposition of iron salts in organic solutions; for the applications of interest in this thesis, a central challenge was the adaptation of these conventional synthetic methods to the needs of low infrastructure and economically disadvantaged settings. We show here that it is possible to form highly uniform and magnetically responsive nanomaterials using starting reagents and equipment that are readily available and economical. The products of this approach, termed the 'Kitchen Synthesis', are of comparable quality and effectiveness to laboratory materials. The narrow size distributions of the iron oxides produced in the laboratory synthesis made it possible to study the size-dependence of the magnetic separation efficiency of nanocrystals; generally as the diameter of particles increased they could be removed under lower applied magnetic fields. In this work we take advantage of this size-dependence to use magnetic separation as a tool to separate broadly distributed populations of magnetic materials. Such work makes it possible to use these materials in multiplexed separation and sensing schemes. With the synthesis and magnetic separation studies of these materials completed, it was possible to optimize their applications in water purification and environmental remediation. These materials removed both uranium and arsenic from contaminated samples, and had remarkably high sorption capacities -- up to 12 wt% for arsenic and 30 wt% for uranium. The contaminated nMAG is removed from the drinking water by either retention in a sand column, filter, or by magnetic separation. The uranium adsorption process was also utilized for the enhanced detection of uranium in environmental matrices. By relying on α-particle detection in well-formed and dense nMAG films, it was possible to improve soil detection of uranium by more than ten-thousand-fold. Central for this work was a detailed understanding of the chemistry at the iron oxide interface, and the role of the organic coatings in mediating the sorption process.en_US
dc.format.extent169 p.en_US
dc.format.mimetypeapplication/pdfen_US
dc.identifier.callnoTHESIS CHEM. 2012 MAYOen_US
dc.identifier.citationMayo, John Thomas. "The synthesis, characterization and application of iron oxide nanocrystals in magnetic separations for arsenic and uranium removal." (2012) Diss., Rice University. <a href="https://hdl.handle.net/1911/70343">https://hdl.handle.net/1911/70343</a>.en_US
dc.identifier.digitalMayoJen_US
dc.identifier.urihttps://hdl.handle.net/1911/70343en_US
dc.language.isoengen_US
dc.rightsCopyright is held by the author, unless otherwise indicated. Permission to reuse, publish, or reproduce the work beyond the bounds of fair use or other exemptions to copyright law must be obtained from the copyright holder.en_US
dc.subjectApplied sciencesen_US
dc.subjectPure sciencesen_US
dc.subjectIron oxideen_US
dc.subjectNanocrystalsen_US
dc.subjectMagnetic separationsen_US
dc.subjectArsenicen_US
dc.subjectUraniumen_US
dc.subjectInorganic chemistryen_US
dc.subjectNanoscienceen_US
dc.subjectEnvironmental engineeringen_US
dc.titleThe synthesis, characterization and application of iron oxide nanocrystals in magnetic separations for arsenic and uranium removalen_US
dc.typeThesisen_US
dc.type.materialTexten_US
thesis.degree.departmentChemistryen_US
thesis.degree.disciplineNatural Sciencesen_US
thesis.degree.grantorRice Universityen_US
thesis.degree.levelDoctoralen_US
thesis.degree.nameDoctor of Philosophyen_US
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