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dc.contributor.advisorKatz, Lynn Ellenen
dc.creatorVieira, Adriano Rosaen
dc.date.accessioned2008-08-28T22:58:49Zen
dc.date.available2008-08-28T22:58:49Zen
dc.date.issued2006en
dc.identifierb64881404en
dc.identifier.urihttp://hdl.handle.net/2152/2618en
dc.descriptiontexten
dc.description.abstractMany environmental problems require reliable quantitative prediction of the fate and transport of metal ion contaminants in surface and groundwaters. Surface Complexation Models (SCMs) have emerged as the most promising tools for predicting contaminant ion sorption to iron (hydr)oxides. The reliability of SCMs is highly dependent on the ability to select appropriate surface complexation reactions and model parameters. This research focused on developing a strategy for developing a selfconsistent database for the Triple Layer Model (TLM) parameters for two iron (hydr)oxides, ferrihydrite (HFO) and goethite (α-FeOOH). To this end, spectroscopic data were used to guide the selection of surface complexation model reactions, and to the extent possible, theoretically based parameter estimation techniques were used to characterize the mineral surfaces throughout this work. The adsorption of two divalent metals, Cd(II) and Pb(II), and one oxyanion, Se(IV) onto α-FeOOH and ferrihydrite was modeled in single and bi-solute systems using the TLM. Selection of all surface complexes was supported by evidence from extended x-ray absorption fine structure spectroscopy. The fixed surface site density values based on tritium exchange experiments were used (Ns = 10.2 and 16.4 sites /nm2 for ferrihydrite and goethite, respectively). Ferrihydrite was modeled using one surface site while goethite was modeled with strong and weak sites, with the following distribution: Nwk = 90% and Nst =10%. Cd(II) and Pb(II) adsorption were modeled using bidentate and monodentate surface complexes onto ferrihydrite. The model was able to predict the competitive adsorption behavior of Cd(II) and Pb(II) in bisolute systems. For the goethite system, Cd(II) and Pb(II) adsorption was modeled using bidentate surface complexes on both weak and strong goethite surface sites. The TLM was able to predict the competitive adsorption behavior of Cd(II) and Pb(II) in bisolute systems. Se(IV) adsorption onto goethite was investigated in the presence of Cd(II) or Pb(II) and was modeled using bidentate surface complexes. The TLM predicted data reasonably well in low and medium surface coverage single-solute systems; however, it did not predict adsorption behavior for a high surface coverage adsorption edge. In bisolute systems, the TLM overestimated adsorption enhancement for low and medium surface coverage adsorption edges. TLM predictions using lower surface site densities improved the oxyanion predictions but diminished the quality of the divalent metal ion predictions.
dc.format.mediumelectronicen
dc.language.isoengen
dc.rightsCopyright is held by the author. Presentation of this material on the Libraries' web site by University Libraries, The University of Texas at Austin was made possible under a limited license grant from the author who has retained all copyrights in the works.en
dc.subject.lcshFerric hydroxidesen
dc.subject.lcshAdsorptionen
dc.titleSurface complexation modeling of Pb(II), Cd(II) and Se(IV) onto iron hydroxides in single and bisolute systemsen
dc.description.departmentCivil, Architectural, and Environmental Engineeringen
dc.identifier.oclc85600886en
dc.type.genreThesisen
thesis.degree.departmentCivil, Architectural, and Environmental Engineeringen
thesis.degree.disciplineCivil Engineeringen
thesis.degree.grantorThe University of Texas at Austinen
thesis.degree.levelDoctoralen
thesis.degree.nameDoctor of Philosophyen


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