subject:(Iron oxides)

Oregon State University

1. Grover, Deeksha. Genesis of iron oxides in unsaturated porous media.

Degree: PhD, Environmental Science, 2010, Oregon State University

URL: http://hdl.handle.net/1957/18700

► The kinetics of physical and chemical processes controlling the precipitation of iron oxide minerals in unsaturated media were investigated in this study. The characteristic morphology,… (more)

▼ The kinetics of physical and chemical processes controlling the precipitation of iron oxide minerals in unsaturated media were investigated in this study. The characteristic morphology, mineralogy, and chemistry of iron oxides were also explored. Laboratory column experiments using fine and coarse grades of silica sand were conducted to compare the abiotic and biotic mechanisms governing the formation of Fe(III) oxides in unsaturated porous media. The samples of iron precipitates were analyzed using x-ray diffraction (XRD), scanning electron microscopy (SEM) and optical microscopy to identify the mineral and elemental composition of iron oxides. Two sets of iron bands appeared during the course of the experiments. Red oxidized bands (ferrihydrite) were formed at the upper extent of the capillary fringe. Whereas, black bands (magnetite) were formed below the oxidized iron bands. Additional visual observations were made to distinguish between abiotic and biotic origins of iron oxide minerals. A conceptual mechanistic framework for abiotic iron oxide formation was also proposed leading to the development of the kinetic equations for an unsaturated system that was exposed to a source of reduced iron at one end and oxygen at the other end. Finally, a numerical model was developed to investigate abiotic iron oxide formation with time at a particular location within an unsaturated porous media under different scenarios. These scenarios could include the use of different media, different unsaturation conditions and different time scales. This study reveals that abiotic iron oxide formation in unsaturated media is mainly a diffusion controlled mechanism. The location of iron oxide precipitation is regulated by the diffusion rates of Fe(II) (aq) and O₂ (g) and thus elucidates the importance of air-water and water-mineral interface properties and diffusive gradients on iron transformations in natural systems. These results can be implied to explain the formation of Fe (III) oxide cemented bands under hydrological processes and time scale in systems representative of natural environments. Advisors/Committee Members: Baham, John (advisor), Wood, Brian (committee member).

Subjects/Keywords: iron oxides; Iron oxides

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APA (6^th Edition):

Grover, D. (2010). Genesis of iron oxides in unsaturated porous media. (Doctoral Dissertation). Oregon State University. Retrieved from http://hdl.handle.net/1957/18700

Chicago Manual of Style (16^th Edition):

Grover, Deeksha. “Genesis of iron oxides in unsaturated porous media.” 2010. Doctoral Dissertation, Oregon State University. Accessed April 17, 2021. http://hdl.handle.net/1957/18700.

MLA Handbook (7^th Edition):

Grover, Deeksha. “Genesis of iron oxides in unsaturated porous media.” 2010. Web. 17 Apr 2021.

Vancouver:

Grover D. Genesis of iron oxides in unsaturated porous media. [Internet] [Doctoral dissertation]. Oregon State University; 2010. [cited 2021 Apr 17]. Available from: http://hdl.handle.net/1957/18700.

Council of Science Editors:

Grover D. Genesis of iron oxides in unsaturated porous media. [Doctoral Dissertation]. Oregon State University; 2010. Available from: http://hdl.handle.net/1957/18700

Cape Peninsula University of Technology

2. Kriedemann, Brett Craig. The critical process conditions for controlled growth of iron oxide nanoparticles synthesized using continuous hydrothermal synthesis .

Degree: 2014, Cape Peninsula University of Technology

URL: http://etd.cput.ac.za/handle/20.500.11838/920

► Iron oxide nanoparticles have recently become attractive for use in gas sensing, as catalysts and have also shown promise in other fields, such as biomedicine,… (more)

▼ Iron oxide nanoparticles have recently become attractive for use in gas sensing, as catalysts and have also shown promise in other fields, such as biomedicine, for targeted drug delivery and cancer treatment. Despite these growing applications, the ability to produce iron oxide and one dimensional (1D) iron oxide nanoparticles on an industrial scale has proven to be a challenge. The continuous hydrothermal synthesis, (CHS), method has been proposed as the most promising method, yet the effect of the operating parameters on particle characteristics are still widely contested in the literature. One such parameter, temperature, is still widely contested on its effect on APS. To address this issue, a CHS pilot plant was constructed and commissioned. The inability to isolate certain parameters in CHS is a common shortcoming. Parameters such as temperature and flow rate are prime examples, as changing the temperature has several effects on the system resulting in a change in reaction rate, a change in density and a change in the reactor residence time while the flow rate is closely linked to the residence time and mixing conditions. A 3-level Box-Behnken factorial design method was used to statistically analyze the correlations and interactions between operating parameters (temperature, concentration and flow rate) in CHS and evaluate their resulting effect on particle characteristics, with focus on morphology. All particles were characterized by X-ray diffraction (XRD) and high resolution transmission electron microscopy (HRTEM). Reactions in the presence of solvents or surfactants proved incapable of modifying particle morphology, although significant particle size reduction revealed that they were actively involved in particle growth and may be used as a further tool for controlling particle characteristics. The concentration was found to have the greatest effect on particle characteristics including a slight alteration of particle shape and a massive influence on the average particle size. The interactions between operating parameters were significant, especially in the case of temperature and concentration. The temperature and concentration were found to interact revealing three different trends on APS, offering a solution to conflicting reports in the literature. The temperature was also observed to interact favourably with the flow rate, presenting a method of increasing the PY and RC, with little change in APS and PSD. This knowledge will prove invaluable for the design of future experiments in CHS.

Subjects/Keywords: Iron oxides; Nanoparticles; Nanotechnology

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APA (6^th Edition):

Kriedemann, B. C. (2014). The critical process conditions for controlled growth of iron oxide nanoparticles synthesized using continuous hydrothermal synthesis . (Thesis). Cape Peninsula University of Technology. Retrieved from http://etd.cput.ac.za/handle/20.500.11838/920

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Kriedemann, Brett Craig. “The critical process conditions for controlled growth of iron oxide nanoparticles synthesized using continuous hydrothermal synthesis .” 2014. Thesis, Cape Peninsula University of Technology. Accessed April 17, 2021. http://etd.cput.ac.za/handle/20.500.11838/920.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Kriedemann, Brett Craig. “The critical process conditions for controlled growth of iron oxide nanoparticles synthesized using continuous hydrothermal synthesis .” 2014. Web. 17 Apr 2021.

Vancouver:

Kriedemann BC. The critical process conditions for controlled growth of iron oxide nanoparticles synthesized using continuous hydrothermal synthesis . [Internet] [Thesis]. Cape Peninsula University of Technology; 2014. [cited 2021 Apr 17]. Available from: http://etd.cput.ac.za/handle/20.500.11838/920.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Kriedemann BC. The critical process conditions for controlled growth of iron oxide nanoparticles synthesized using continuous hydrothermal synthesis . [Thesis]. Cape Peninsula University of Technology; 2014. Available from: http://etd.cput.ac.za/handle/20.500.11838/920

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Oregon State University

3. Schwarz, Sigmund Caesar. A study of by-product recovery from spent iron oxide gas purifying material.

Degree: MS, Chemical Engineering, 1936, Oregon State University

URL: http://hdl.handle.net/1957/52908

Subjects/Keywords: Iron oxides

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APA (6^th Edition):

Schwarz, S. C. (1936). A study of by-product recovery from spent iron oxide gas purifying material. (Masters Thesis). Oregon State University. Retrieved from http://hdl.handle.net/1957/52908

Chicago Manual of Style (16^th Edition):

Schwarz, Sigmund Caesar. “A study of by-product recovery from spent iron oxide gas purifying material.” 1936. Masters Thesis, Oregon State University. Accessed April 17, 2021. http://hdl.handle.net/1957/52908.

MLA Handbook (7^th Edition):

Schwarz, Sigmund Caesar. “A study of by-product recovery from spent iron oxide gas purifying material.” 1936. Web. 17 Apr 2021.

Vancouver:

Schwarz SC. A study of by-product recovery from spent iron oxide gas purifying material. [Internet] [Masters thesis]. Oregon State University; 1936. [cited 2021 Apr 17]. Available from: http://hdl.handle.net/1957/52908.

Council of Science Editors:

Schwarz SC. A study of by-product recovery from spent iron oxide gas purifying material. [Masters Thesis]. Oregon State University; 1936. Available from: http://hdl.handle.net/1957/52908

University of Waterloo

4. Baldwin, Janis Rachel. Evaluation of the Removal of Perfluoroalkyl Substances from Aqueous Matrices in the Presence of Zerovalent Iron.

Degree: 2018, University of Waterloo

URL: http://hdl.handle.net/10012/12875

► Per- and polyfluoroalkyl substances (PFASs) are a class of persistent organic pollutants present in the environment that pose a threat to human health. PFASs primarily… (more)

▼ Per- and polyfluoroalkyl substances (PFASs) are a class of persistent organic pollutants present in the environment that pose a threat to human health. PFASs primarily reside within aqueous phases and are present in groundwater environments. Perfluorooctane sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) are the most predominant PFASs. Remediation techniques focus on oxidation and sorption methods, both of which lack efficacy for all PFASs. There are few studies on reduction treatments such as zerovalent iron (ZVI), which demonstrate potential for both PFOS and PFOA removal and can be applied in subsurface environments. This thesis describes laboratory batch experiments that evaluate PFOS and PFOA removal in the presence of ZVI under a range of physical and geochemical conditions. Mechanisms of removal are explored utilizing PFAS mass balances based on a series of analyses that include aqueous phase fluoride and PFAS short chains, and PFAS extractions from the iron surface. Solid iron phase characterization provides supporting information regarding PFAS interaction with the iron surface. Laboratory batch experiments with PFOS in the presence of granular ZVI were conducted under combinations of initial pH (pH 2.0 and 6.6), temperature (~22°C and 60°C) and ZVI dosage (179 and 1792 mM). PFOS removal was enhanced under low initial pH likely due to a greater abundance of iron oxides compared to higher pH conditions. Higher temperatures also enhanced PFOS removal. PFOS removal by sorption generally increased under low pH and high ZVI dosed conditions, suggesting the abundance of iron oxides and surface area may play an important role. Laboratory batch experiments of PFOS and PFOA in the presence of zerovalent iron nanoparticles (nZVI) were conducted under combinations of initial pH (pH 2.0 and 8.3) and coating (uncoated and palladium-coated). The iron phase likely changed over time, as there was some release of PFOS and PFOA into aqueous solution compared to earlier sampling times. The presence of a palladium coating appeared to minimize the effects of iron corrosion, as PFOS and PFOA were released to a lesser degree at later time points compared to uncoated nZVI. PFOS and PFOA removal is likely dominated by electrostatic interaction, however functional group interaction with the iron surface may also play an important role.

Subjects/Keywords: groundwater; zerovalent iron; perfluoroalkyl acids; iron oxides

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APA (6^th Edition):

Baldwin, J. R. (2018). Evaluation of the Removal of Perfluoroalkyl Substances from Aqueous Matrices in the Presence of Zerovalent Iron. (Thesis). University of Waterloo. Retrieved from http://hdl.handle.net/10012/12875

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Baldwin, Janis Rachel. “Evaluation of the Removal of Perfluoroalkyl Substances from Aqueous Matrices in the Presence of Zerovalent Iron.” 2018. Thesis, University of Waterloo. Accessed April 17, 2021. http://hdl.handle.net/10012/12875.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Baldwin, Janis Rachel. “Evaluation of the Removal of Perfluoroalkyl Substances from Aqueous Matrices in the Presence of Zerovalent Iron.” 2018. Web. 17 Apr 2021.

Vancouver:

Baldwin JR. Evaluation of the Removal of Perfluoroalkyl Substances from Aqueous Matrices in the Presence of Zerovalent Iron. [Internet] [Thesis]. University of Waterloo; 2018. [cited 2021 Apr 17]. Available from: http://hdl.handle.net/10012/12875.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Baldwin JR. Evaluation of the Removal of Perfluoroalkyl Substances from Aqueous Matrices in the Presence of Zerovalent Iron. [Thesis]. University of Waterloo; 2018. Available from: http://hdl.handle.net/10012/12875

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

University of Ottawa

5. Gonzalez Lucena, Fedora. Mineral Magnetism of Environmental Reference Materials: Iron Oxyhydroxide Nanoparticles .

Degree: 2010, University of Ottawa

URL: http://hdl.handle.net/10393/19608

► Iron oxyhydroxides are ubiquitous in surface environments, playing a key role in many biogeochemical processes. Their characterization is made challenging by their nanophase nature. Magnetometry… (more)

▼ Iron oxyhydroxides are ubiquitous in surface environments, playing a key role in many biogeochemical processes. Their characterization is made challenging by their nanophase nature. Magnetometry serves as a sensitive non-destructive characterization technique that can elucidate intrinsic physical properties, taking advantage of the superparamagnetic behaviour that nanoparticles may exhibit. In this work, synthetic analogues of common iron oxyhydroxide minerals (ferrihydrite, goethite, lepidocrocite, schwertmannite and akaganéite) are characterized using DC and AC magnetometry (cryogenic, room temperature), along with complementary analyses from Mössbauer spectroscopy (cryogenic, room temperature), powder X-ray diffraction and scanning electron microscopy. It was found that all of the iron oxyhydroxide mineral nanoparticles, including lepidocrocite, schwertmannite and akaganéite were superparamagnetic and therefore magnetically ordered at room temperature. Previous estimates of Néel temperatures for these three minerals are relatively low and are understood as misinterpreted magnetic blocking temperatures. This has important implications in environmental geoscience due to this mineral group’s potential as magnetic remanence carriers. Analysis of the data enabled the extraction of the intrinsic physical parameters of the nanoparticles, including magnetic sizes. The study also showed the possible effect on these parameters of crystal-chemical variations, due to elemental structural incorporation, providing a nanoscale mineralogical characterization of these iron oxyhydroxides. The analysis of the intrinsic parameters showed that all of the iron oxyhydroxide mineral nanoparticles considered here have a common magnetic moment formation mechanism associated with a random spatial distribution of iv uncompensated magnetic spins, and with different degrees of structural disorder and compositional stoichiometry variability, which give rise to relatively large intrinsic magnetization values. The elucidation of the magnetic nanostructure also contributes to the study of the surface region of the nanoparticles, which affects the particles’ reactivity in the environment.

Subjects/Keywords: mineral magnetism; nanoparticles; iron oxides; iron oxyhydroxides

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APA (6^th Edition):

Gonzalez Lucena, F. (2010). Mineral Magnetism of Environmental Reference Materials: Iron Oxyhydroxide Nanoparticles . (Thesis). University of Ottawa. Retrieved from http://hdl.handle.net/10393/19608

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Gonzalez Lucena, Fedora. “Mineral Magnetism of Environmental Reference Materials: Iron Oxyhydroxide Nanoparticles .” 2010. Thesis, University of Ottawa. Accessed April 17, 2021. http://hdl.handle.net/10393/19608.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Gonzalez Lucena, Fedora. “Mineral Magnetism of Environmental Reference Materials: Iron Oxyhydroxide Nanoparticles .” 2010. Web. 17 Apr 2021.

Vancouver:

Gonzalez Lucena F. Mineral Magnetism of Environmental Reference Materials: Iron Oxyhydroxide Nanoparticles . [Internet] [Thesis]. University of Ottawa; 2010. [cited 2021 Apr 17]. Available from: http://hdl.handle.net/10393/19608.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Gonzalez Lucena F. Mineral Magnetism of Environmental Reference Materials: Iron Oxyhydroxide Nanoparticles . [Thesis]. University of Ottawa; 2010. Available from: http://hdl.handle.net/10393/19608

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

University of Florida

6. Oppong-Anane, Akua Bonsu. Insights into the Mechanisms of Iron Reductive Dissolution in Vadose Zone Soils and Implications for Landfill Activities Predicting the Potential for Groundwater Pollution.

Degree: PhD, Environmental Engineering Sciences, 2014, University of Florida

URL: https://ufdc.ufl.edu/UFE0046156

► Anomalously high iron (Fe) concentrations have beenmeasured in groundwater samples collected from monitoring wells downstream ofseveral landfill units in Florida. Based on monitoring data, vadose… (more)

▼ Anomalously high iron (Fe) concentrations have beenmeasured in groundwater samples collected from monitoring wells downstream ofseveral landfill units in Florida. Based on monitoring data, vadose zone soilsand aquifer sediments impacted by landfills could be sources of Fe thatpollutes the groundwater, and not landfilled wastes. Therefore, the objectivesof this study were to investigate the reductive dissolution of soil-Fe as afunction of biotic and abiotic processes; and to lay the groundwork for thedevelopment of a geochemical solubility model for Fe. Soil samples were collected from different locations in NorthFlorida, using a sampling strategy that included samples with a gradient in thedegree of Fe-mineral crystallization. After characterization, soil samples wereused in biotic (using bacteria from an anaerobic digester) and abiotic (usingsulfide as electron donor) Fe-reductive dissolution batch studies. Fe(II) wasreleased from all soils in concentrations that exceeded the secondary drinkingwater limit of 0.3 mg/L, when treated with bacteria and organic carbon (OC) or withsulfide but under abiotic conditions. Microbial respiration of OC in soils appearsto be a major pathway and could lead to Fe-reductive dissolution in Fe-richsoils that interact with OC-rich waters or leachates. The rates of Fe-reductivedissolution were positively correlated with soil Fe content when glucose wasused as the OC source, while no relationship was obvious when landfill leachatewas used as OC. Sulfide driven Fe-reductive dissolution was positivelycorrelated with soil-Fe content. However, despite the initial high release ofFe(II) into the aqueous phase in soil spiked with sulfide, temporal trends ofFe-reductive dissolution rates suggest that this pathway may not be assignificant as the biotic process due likely to the precipitation of solid FeSspecies. Finally, batchstudies were conducted using hematite, an Fe-oxide mineral, to investigate theeffects of pH, OC and ionic strength on Fe-reductive dissolution rates. Obtaineddata were used to develop a geochemical solubility model for soil-Fe; which wasthen validated using soil samples. However, an efficient fine tuning and validationof the model was not fully accomplished as more experimental and field data arestill needed. ( en ) Advisors/Committee Members: BONZONGO,JEAN-CLAUDE J (committee chair), TOWNSEND,TIMOTHY G (committee member), HARRIS,WILLIE G,JR (committee member).

Subjects/Keywords: Dissolution; Groundwater; Iron mining; Iron oxides; Landfills; Minerals; Oxides; Soil samples; Soils; Sulfides; dissolution – iron – landfill – oxides – reductive; Alachua County ( local )

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APA (6^th Edition):

Oppong-Anane, A. B. (2014). Insights into the Mechanisms of Iron Reductive Dissolution in Vadose Zone Soils and Implications for Landfill Activities Predicting the Potential for Groundwater Pollution. (Doctoral Dissertation). University of Florida. Retrieved from https://ufdc.ufl.edu/UFE0046156

Chicago Manual of Style (16^th Edition):

Oppong-Anane, Akua Bonsu. “Insights into the Mechanisms of Iron Reductive Dissolution in Vadose Zone Soils and Implications for Landfill Activities Predicting the Potential for Groundwater Pollution.” 2014. Doctoral Dissertation, University of Florida. Accessed April 17, 2021. https://ufdc.ufl.edu/UFE0046156.

MLA Handbook (7^th Edition):

Oppong-Anane, Akua Bonsu. “Insights into the Mechanisms of Iron Reductive Dissolution in Vadose Zone Soils and Implications for Landfill Activities Predicting the Potential for Groundwater Pollution.” 2014. Web. 17 Apr 2021.

Vancouver:

Oppong-Anane AB. Insights into the Mechanisms of Iron Reductive Dissolution in Vadose Zone Soils and Implications for Landfill Activities Predicting the Potential for Groundwater Pollution. [Internet] [Doctoral dissertation]. University of Florida; 2014. [cited 2021 Apr 17]. Available from: https://ufdc.ufl.edu/UFE0046156.

Council of Science Editors:

Oppong-Anane AB. Insights into the Mechanisms of Iron Reductive Dissolution in Vadose Zone Soils and Implications for Landfill Activities Predicting the Potential for Groundwater Pollution. [Doctoral Dissertation]. University of Florida; 2014. Available from: https://ufdc.ufl.edu/UFE0046156

Cape Peninsula University of Technology

7. Chowdhury, Faysol. The effect of temperature on the kinetics of microbial ferrous-iron oxidation in a packed column bioreactor .

Degree: 2012, Cape Peninsula University of Technology

URL: http://etd.cput.ac.za/handle/20.500.11838/889

► The microbial ferrous-iron oxidation process plays a significant role in bioleaching, providing ferric-iron (Fe3+) − a strong oxidising agent for the dissolution of most sulphide… (more)

Subjects/Keywords: Oxidation; Ferrous oxide; Iron oxides; Bioreactors

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APA (6^th Edition):

Chowdhury, F. (2012). The effect of temperature on the kinetics of microbial ferrous-iron oxidation in a packed column bioreactor . (Thesis). Cape Peninsula University of Technology. Retrieved from http://etd.cput.ac.za/handle/20.500.11838/889

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Chowdhury, Faysol. “The effect of temperature on the kinetics of microbial ferrous-iron oxidation in a packed column bioreactor .” 2012. Thesis, Cape Peninsula University of Technology. Accessed April 17, 2021. http://etd.cput.ac.za/handle/20.500.11838/889.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Chowdhury, Faysol. “The effect of temperature on the kinetics of microbial ferrous-iron oxidation in a packed column bioreactor .” 2012. Web. 17 Apr 2021.

Vancouver:

Chowdhury F. The effect of temperature on the kinetics of microbial ferrous-iron oxidation in a packed column bioreactor . [Internet] [Thesis]. Cape Peninsula University of Technology; 2012. [cited 2021 Apr 17]. Available from: http://etd.cput.ac.za/handle/20.500.11838/889.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Chowdhury F. The effect of temperature on the kinetics of microbial ferrous-iron oxidation in a packed column bioreactor . [Thesis]. Cape Peninsula University of Technology; 2012. Available from: http://etd.cput.ac.za/handle/20.500.11838/889

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Penn State University

8. Stewart, Sydney M. Explaining reaction rates between iron oxide associated ferrous iron and nitrobenzene.

Degree: 2017, Penn State University

URL: https://submit-etda.libraries.psu.edu/catalog/13958svs6250

► Redox reactions have important implications for contaminant fate and transport in the environment, as they can lead to transformations that affect chemical mobility, toxicity, and… (more)

▼ Redox reactions have important implications for contaminant fate and transport in the environment, as they can lead to transformations that affect chemical mobility, toxicity, and bioavailability. Many classes of contaminants can be reduced by ferrous iron (Fe2+) associated with iron oxides in subsurface anoxic environments. These include contaminants containing nitroaromatic functional groups, which are common due to their widespread release into the environment as pesticides and explosives. Understanding the transformations of these chemicals is essential for determining how to remediate contaminated sites. Nitrobenzene is a useful proxy for nitroaromatic contaminants because it provides a relatively simple model system that can give insight into how more complex or less reactive chemicals are transformed in the environment. While the reduced products that form as a result of these reactions are often well characterized, the rates at which they occur are typically difficult to predict. Measured values from well-controlled laboratory studies frequently vary by orders of magnitude. In principle, these rates can be described and possibly estimated by the thermodynamic driving force of the reaction (e.g., reduction potential values for the reductant and oxidant), but demonstrating this has been difficult to test due to the difficulty in obtaining meaningful and reliable reduction potential values for iron redox couples. Recently, that limitation was overcome using mediated potentiometry, a technique that has led to a quantitative understanding of the thermodynamics of Fe2+-Fe oxy(hydr)oxide redox couples. Using mediated potentiometry, reduction potentials for these redox couples can be measured, predicted, and controlled. The ability to determine reduction potential of the Fe2+-Fe oxide couple introduces the opportunity to evaluate the relationship between reaction rates and thermodynamic parameters. In this study, I hypothesized that reduction potentials could be used to explain redox reaction rates between nitrobenzene and the Fe2+-goethite (α-FeOOH) couple. This was tested by measuring nitrobenzene reduction rates as a function of solution pH, Fe2+ concentration, and goethite loading. With these results, the reduction potential of the Fe2+-goethite couple was correlated with the reaction rate constant over all solution conditions using a linear free energy relationship (LFER). The reduction of nitrobenzene was rate-limited by the first electron transfer and the first proton transfer steps, which appeared to be coupled. The best correlation for the data was achieved by normalizing the reaction rate constant to surface area of the oxide, implying nitrobenzene was reduced at the oxide surface by delocalized electrons within the solid, rather than directly by discrete oxide-associated Fe2+ sites. This LFER was further used to determine how changing the goethite particle size, and hence its thermodynamic properties, influence nitrobenzene reduction rates. From experiments with nanogoethite-associated Fe2+, it was found… Advisors/Committee Members: Christopher A. Gorski, Thesis Advisor/Co-Advisor, John M. Regan, Committee Member, William D. Burgos, Committee Member.

Subjects/Keywords: Iron oxides; LFER; Reaction rates; Reduction potential

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APA (6^th Edition):

Stewart, S. M. (2017). Explaining reaction rates between iron oxide associated ferrous iron and nitrobenzene. (Thesis). Penn State University. Retrieved from https://submit-etda.libraries.psu.edu/catalog/13958svs6250

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Stewart, Sydney M. “Explaining reaction rates between iron oxide associated ferrous iron and nitrobenzene.” 2017. Thesis, Penn State University. Accessed April 17, 2021. https://submit-etda.libraries.psu.edu/catalog/13958svs6250.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Stewart, Sydney M. “Explaining reaction rates between iron oxide associated ferrous iron and nitrobenzene.” 2017. Web. 17 Apr 2021.

Vancouver:

Stewart SM. Explaining reaction rates between iron oxide associated ferrous iron and nitrobenzene. [Internet] [Thesis]. Penn State University; 2017. [cited 2021 Apr 17]. Available from: https://submit-etda.libraries.psu.edu/catalog/13958svs6250.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Stewart SM. Explaining reaction rates between iron oxide associated ferrous iron and nitrobenzene. [Thesis]. Penn State University; 2017. Available from: https://submit-etda.libraries.psu.edu/catalog/13958svs6250

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

University of Ottawa

9. Meyers, Emily. Phosphate Cycling in the Presence of Biogenic Iron Oxides and Iron-Reducing Bacteria .

Degree: 2018, University of Ottawa

URL: http://hdl.handle.net/10393/37306

► Nutrient pollution from industrial activity is an environmental problem that persists in water bodies near urban settings, and has been a primary contributor to eutrophication,… (more)

▼ Nutrient pollution from industrial activity is an environmental problem that persists in water bodies near urban settings, and has been a primary contributor to eutrophication, bacterial contamination, and harmful algal blooms. Biogenic iron oxides offer a potential solution to the treatment of lakes and rivers containing high concentrations of phosphate, the limiting nutrient in aquatic systems. Soluble ferrous iron can act as an electron donor for iron-oxidizing bacteria, which thrive in low-oxygen environments. This results in the formation of insoluble ferric iron minerals, ideal adsorbents for negatively charged phosphate. Conversely, iron-reducing bacteria reduce ferric iron to form ferrous iron, resulting in the formation of secondary minerals depending on the chemistry of the particular environment. This project investigates the chemical conditions at which biogenic iron oxides have the maximum adsorptive capacity, especially with respect to organic carbon content. A simplified model of natural biogenic iron oxides was synthesized by co-precipitating the mineral ferrihydrite (a common iron oxide) with the polysaccharide alginate, an analogue to bacterial exopolysaccharides. At the levels of carbon investigated, organic matter was not found to affect the adsorptive capacity of iron oxides at the C/Fe ratios analyzed. Similarly, organic matter did not appear to significantly influence the rate of reduction of ferrihydrite by the iron-reducing bacterium Shewanella putrefaciens CN32. Presence of organics did however influence rates of reduction and the mineralogy of the post-reduction precipitates. Phosphate adsorbed to iron oxides prior to microbial reduction greatly increased both the rate and the extent of ferric iron reduced, and also had an impact on the secondary minerals that formed (vivianite, green rust). An improved understanding of these conditions could contribute to a more efficient process by which iron-oxidizing bacteria are used for large-scale industrial water treatment.

Subjects/Keywords: adsorption; phosphate; iron oxides; environment; nutrient pollution

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APA (6^th Edition):

Meyers, E. (2018). Phosphate Cycling in the Presence of Biogenic Iron Oxides and Iron-Reducing Bacteria . (Thesis). University of Ottawa. Retrieved from http://hdl.handle.net/10393/37306

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Meyers, Emily. “Phosphate Cycling in the Presence of Biogenic Iron Oxides and Iron-Reducing Bacteria .” 2018. Thesis, University of Ottawa. Accessed April 17, 2021. http://hdl.handle.net/10393/37306.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Meyers, Emily. “Phosphate Cycling in the Presence of Biogenic Iron Oxides and Iron-Reducing Bacteria .” 2018. Web. 17 Apr 2021.

Vancouver:

Meyers E. Phosphate Cycling in the Presence of Biogenic Iron Oxides and Iron-Reducing Bacteria . [Internet] [Thesis]. University of Ottawa; 2018. [cited 2021 Apr 17]. Available from: http://hdl.handle.net/10393/37306.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Meyers E. Phosphate Cycling in the Presence of Biogenic Iron Oxides and Iron-Reducing Bacteria . [Thesis]. University of Ottawa; 2018. Available from: http://hdl.handle.net/10393/37306

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

10. Gharge, Uday. Impact of engineered nanoparticles on the growth of roots.

Degree: 2018, University of Tennessee – Chattanooga

URL: https://scholar.utc.edu/theses/553

► There is an increasing demand for food and bioenergy crops for growing world population. Conventional fertilizers used for increasing agricultural production are required to be… (more)

Subjects/Keywords: Environmental chemistry; Nanotechnology; Iron oxides – Environmental aspects

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APA (6^th Edition):

Gharge, U. (2018). Impact of engineered nanoparticles on the growth of roots. (Masters Thesis). University of Tennessee – Chattanooga. Retrieved from https://scholar.utc.edu/theses/553

Chicago Manual of Style (16^th Edition):

Gharge, Uday. “Impact of engineered nanoparticles on the growth of roots.” 2018. Masters Thesis, University of Tennessee – Chattanooga. Accessed April 17, 2021. https://scholar.utc.edu/theses/553.

MLA Handbook (7^th Edition):

Gharge, Uday. “Impact of engineered nanoparticles on the growth of roots.” 2018. Web. 17 Apr 2021.

Vancouver:

Gharge U. Impact of engineered nanoparticles on the growth of roots. [Internet] [Masters thesis]. University of Tennessee – Chattanooga; 2018. [cited 2021 Apr 17]. Available from: https://scholar.utc.edu/theses/553.

Council of Science Editors:

Gharge U. Impact of engineered nanoparticles on the growth of roots. [Masters Thesis]. University of Tennessee – Chattanooga; 2018. Available from: https://scholar.utc.edu/theses/553

University of Adelaide

11. Dmitrijeva, Marija. Multivariate statistical analysis of geochemical data to constrain the evolution, mineralization and alteration signatures of IOCG and BiF-hosted deposits.

Degree: 2019, University of Adelaide

URL: http://hdl.handle.net/2440/124164

► Iron-oxide copper gold (IOCG) and banded iron formation (BIF)-hosted iron deposits are the dominant styles of mineralization in the Gawler Craton, South Australia. Multivariate geochemical… (more)

▼ Iron-oxide copper gold (IOCG) and banded iron formation (BIF)-hosted iron deposits are the dominant styles of mineralization in the Gawler Craton, South Australia. Multivariate geochemical datasets of various types and complexity collected from whole-rock samples and individual mineral grains from these deposits form a previously untapped source of information that can be applied to characterization and genetic modelling of such deposits. Moreover, such datasets carry major implications for new approaches to regional-scale exploration. Despite this, the ever-increasing complexity and size of geochemical datasets necessitates development of bespoke multivariate statistical analysis techniques as a prerequisite to any reproducible quantitative characterization of mineralization and/or alteration signatures, especially when detailed petrographic data are either limited or absent altogether. Left-censored values, i.e., those concentrations that fall below minimum limit of detection (reflecting the analytical limitation of the instrument used for acquisition), are present in all types of geochemical datasets but are amplified in trace element datasets such as those obtained by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). A novel approach for imputation of values below detection limits using copula cumulative density functions (CDFs) is proposed. A case study involving imputation of left-censored data for Te in the presence of Au and Ag values is based upon fitting copula CDFs to the data and iteratively simulating new Te values from copula CDFs using the Metropolis-Hastings algorithm. Within BIF-associated iron ores of the Middleback Ranges, iron oxides display interconversion and replacement reactions between magnetite by hematite and reprecipitation of new generations of platy hematite. Quantitative assessment of such interconversions, when correlated with available textural evidence, allows definition of geochemical signatures associated with ore enrichment. Linear-mixed effects models support the statistically significant difference among prevailing textures. Such models can account for the high degree of correlation among the analyses within a single polished block and therefore respect the hierarchical structure of such data. The observed trace element signatures indicate the potential impact of hydrothermal fluids associated with the ~1.8 Myola Volcanics, ~1.6. Ga Hiltaba Suite granites and younger discordant mafic dykes on ore enrichment process in the Middleback Ranges. Statistical analyses of a large LA-ICP-MS dataset for pyrite shows the independence of several minor and trace elements of economic interest or of relevance to optimized ore processing. Principal Component Analysis shows that Au is contained in zoned pyrite, along with As-Co(- Ni), thus suggesting the presence of invisible Au as both nanoinclusions and within the sulphide lattice. Nevertheless, PC2 essentially discriminates Co-As-Au from Ni, thus suggesting that Co-As zoning in pyrite is not always accompanied by Ni.… Advisors/Committee Members: Ciobanu, Cristiana (advisor), Ehrig, Kathy (advisor), Metcalfe, Andrew (advisor), School of Chemical Engineering (school).

Subjects/Keywords: IOCG; BIF; multivariate statistics; pyrite; iron oxides

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APA (6^th Edition):

Dmitrijeva, M. (2019). Multivariate statistical analysis of geochemical data to constrain the evolution, mineralization and alteration signatures of IOCG and BiF-hosted deposits. (Thesis). University of Adelaide. Retrieved from http://hdl.handle.net/2440/124164

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Dmitrijeva, Marija. “Multivariate statistical analysis of geochemical data to constrain the evolution, mineralization and alteration signatures of IOCG and BiF-hosted deposits.” 2019. Thesis, University of Adelaide. Accessed April 17, 2021. http://hdl.handle.net/2440/124164.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Dmitrijeva, Marija. “Multivariate statistical analysis of geochemical data to constrain the evolution, mineralization and alteration signatures of IOCG and BiF-hosted deposits.” 2019. Web. 17 Apr 2021.

Vancouver:

Dmitrijeva M. Multivariate statistical analysis of geochemical data to constrain the evolution, mineralization and alteration signatures of IOCG and BiF-hosted deposits. [Internet] [Thesis]. University of Adelaide; 2019. [cited 2021 Apr 17]. Available from: http://hdl.handle.net/2440/124164.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Dmitrijeva M. Multivariate statistical analysis of geochemical data to constrain the evolution, mineralization and alteration signatures of IOCG and BiF-hosted deposits. [Thesis]. University of Adelaide; 2019. Available from: http://hdl.handle.net/2440/124164

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

University of New South Wales

12. Boland, Daniel Desmond. Fe(II)-accelerated Fe(III) oxyhydroxide transformation: geochemical controls and implications for contaminant reduction.

Degree: Civil & Environmental Engineering, 2014, University of New South Wales

URL: http://handle.unsw.edu.au/1959.4/53383 ; https://unsworks.unsw.edu.au/fapi/datastream/unsworks:12078/SOURCE02?view=true

► Interaction with aqueous Fe(II) accelerates the transformation of the Fe(III) oxyhydroxide ferrihydrite into more crystalline phases including lepidocrocite and goethite. This reaction is of importance… (more)

▼ Interaction with aqueous Fe(II) accelerates the transformation of the Fe(III) oxyhydroxide ferrihydrite into more crystalline phases including lepidocrocite and goethite. This reaction is of importance to both natural and engineered systems because of its impact on the reactivity of iron phases and for the potential of concurrent reduction and immobilisation of contaminants, such as uranium. The controls on, and mechanisms responsible for this transformation reaction are not completely understood and the aim of this thesis was to further understanding on these processes and examine the implications for the fate of co-occurring redox sensitive contaminants. This was achieved by varying the geochemical conditions under which transformation occurred (primarily by controlling pH and Fe(II) concentrations) and measuring the effect on iron phase and contaminant speciation, chiefly with X-ray absorption spectroscopy (XAS). An in situ kinetic XAS experiment suggested that the inner sphere sorption of Fe(II) was insufficient to explain Fe(II)-accelerated transformation of ferrihydrite. This notion was examined further in laboratory experiments in which the effect of pH and Fe(II) concentrations on transformation kinetics were elucidated. These results showed that both the degree of inner sphere sorption of Fe(II) to ferrihydrite and the rate of supply of Fe(II) from solution to the surface of ferrihydrite were important in determining rates of secondary mineralisation. An initial investigation on uranium fate in this system revealed that uranium reduction only occurred when there was Fe(II)-mediated transformation from ferrihydrite to goethite. Uranium was not reduced when ferrihydrite transformation was inhibited by the presence of silicate. Further investigation found that chromium was reduced (from +VI to +III) preceding signification ferrihydrite transformation whilst uranium reduction (+VI to +V) and incorporation into goethite occurred on the same timescale as iron phase transformation. These results are consistent with thermodynamic predictions, and suggest the existence of redox microenvironments forming around goethite as it forms. Redox potentials declined over time during transformation, and were well described by a prediction based on the solubility and relative proportions of Fe(III) phases present. This work furthers understanding of the behaviour of environmentally ubiquitous Fe(III) oxyhydroxides and their impact on the fate of potentially harmful co-occurring species. Advisors/Committee Members: Waite, T. David, Civil & Environmental Engineering, Faculty of Engineering, UNSW, Collins, Richard, Civil & Environmental Engineering, Faculty of Engineering, UNSW.

Subjects/Keywords: X-ray absorption spectroscopy; Iron oxides; Uranium

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APA (6^th Edition):

Boland, D. D. (2014). Fe(II)-accelerated Fe(III) oxyhydroxide transformation: geochemical controls and implications for contaminant reduction. (Doctoral Dissertation). University of New South Wales. Retrieved from http://handle.unsw.edu.au/1959.4/53383 ; https://unsworks.unsw.edu.au/fapi/datastream/unsworks:12078/SOURCE02?view=true

Chicago Manual of Style (16^th Edition):

Boland, Daniel Desmond. “Fe(II)-accelerated Fe(III) oxyhydroxide transformation: geochemical controls and implications for contaminant reduction.” 2014. Doctoral Dissertation, University of New South Wales. Accessed April 17, 2021. http://handle.unsw.edu.au/1959.4/53383 ; https://unsworks.unsw.edu.au/fapi/datastream/unsworks:12078/SOURCE02?view=true.

MLA Handbook (7^th Edition):

Boland, Daniel Desmond. “Fe(II)-accelerated Fe(III) oxyhydroxide transformation: geochemical controls and implications for contaminant reduction.” 2014. Web. 17 Apr 2021.

Vancouver:

Boland DD. Fe(II)-accelerated Fe(III) oxyhydroxide transformation: geochemical controls and implications for contaminant reduction. [Internet] [Doctoral dissertation]. University of New South Wales; 2014. [cited 2021 Apr 17]. Available from: http://handle.unsw.edu.au/1959.4/53383 ; https://unsworks.unsw.edu.au/fapi/datastream/unsworks:12078/SOURCE02?view=true.

Council of Science Editors:

Boland DD. Fe(II)-accelerated Fe(III) oxyhydroxide transformation: geochemical controls and implications for contaminant reduction. [Doctoral Dissertation]. University of New South Wales; 2014. Available from: http://handle.unsw.edu.au/1959.4/53383 ; https://unsworks.unsw.edu.au/fapi/datastream/unsworks:12078/SOURCE02?view=true

University of Notre Dame

13. Sarah Catherine Reiff. Radiation Induced Chemical Activity at Iron and Copper Oxide Surfaces</h1>.

Degree: Physics, 2015, University of Notre Dame

URL: https://curate.nd.edu/show/w9504x5413z

► The radiolysis of three iron oxides, two copper oxides, and aluminum oxide with varying amounts of water were performed using γ-rays and 5 MeV… (more)

Subjects/Keywords: Radiolysis; Water; Iron Oxides; Hydrogen Production; Copper Oxides

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APA (6^th Edition):

Reiff, S. C. (2015). Radiation Induced Chemical Activity at Iron and Copper Oxide Surfaces</h1>. (Thesis). University of Notre Dame. Retrieved from https://curate.nd.edu/show/w9504x5413z

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Reiff, Sarah Catherine. “Radiation Induced Chemical Activity at Iron and Copper Oxide Surfaces</h1>.” 2015. Thesis, University of Notre Dame. Accessed April 17, 2021. https://curate.nd.edu/show/w9504x5413z.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Reiff, Sarah Catherine. “Radiation Induced Chemical Activity at Iron and Copper Oxide Surfaces</h1>.” 2015. Web. 17 Apr 2021.

Vancouver:

Reiff SC. Radiation Induced Chemical Activity at Iron and Copper Oxide Surfaces</h1>. [Internet] [Thesis]. University of Notre Dame; 2015. [cited 2021 Apr 17]. Available from: https://curate.nd.edu/show/w9504x5413z.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Reiff SC. Radiation Induced Chemical Activity at Iron and Copper Oxide Surfaces</h1>. [Thesis]. University of Notre Dame; 2015. Available from: https://curate.nd.edu/show/w9504x5413z

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Penn State University

14. Joshi, Prachi. Kinetics and mechanisms of Fe2+-catalyzed recrystallization of iron oxides.

Degree: 2018, Penn State University

URL: https://submit-etda.libraries.psu.edu/catalog/15115puj115

► Iron oxides and oxyhydroxides are coupled to the biogeochemical cycles of macronutrients such as carbon, trace metals such as Ni, and radionuclides such as U.… (more)

▼ Iron oxides and oxyhydroxides are coupled to the biogeochemical cycles of macronutrients such as carbon, trace metals such as Ni, and radionuclides such as U. Recent work has found that iron oxides such as goethite and magnetite, previously thought to be stable, may recrystallize in reducing redox conditions without undergoing overt changes in morphology, structure, and reactivity as measured by chemical dissolution rates. This process, referred to as Fe2+-catalyzed recrystallization, can result in the release/uptake of ions (e.g, Cu or U) into/from the surrounding water, thus affecting water quality. Recrystallization may also affect the use of iron oxides as paleoenvironmental proxies due to the alteration of the oxides’ isotopic and elemental composition post formation. The goal of this dissertation was to elucidate the kinetics and mechanisms of recrystallization in order to account for this process in the fields of water quality and paleoenvironmental reconstructions. In Chapter 2 of this dissertation, I examined the morphological changes in goethite nanoparticles over the course of recrystallization. Previous studies observed no substantial changes between goethite before and after recrystallization. Here, I investigated if changes were occurring in the morphology and aggregation of goethite nanoparticles at intermediate time points during the goethite-aqueous Fe2+ reaction using transmission electron microscopy (TEM) and cryogenic-TEM. The goethite particle morphology changed anisotropically over 30 days, suggesting that multiple transformation mechanisms may be occurring. In chapters 3 and 4, I investigated the kinetics of recrystallization. Based on a multiple tracer addition experiment, goethite was observed to become less susceptible to recrystallization over time. Box models were constructed to infer the kinetics of recrystal- lization; the results of the fitting suggested that <20% of goethite recrystallized over 60 days, which was a much lower estimate that previous studies. These two studies together suggested that Fe2+-catalyzed recrystallization may be important only over short time pe- riods. Using box models, a better constrained approach to quantification of the extent and rate was developed. Chapters 5 and 6 focused on the mechanisms of recrystallization. In Chapter 5, I proposed that recrystallization was driven by mineral crystallinity. To test this hypothesis, I reinterpreted the isotopic data reported by previous studies that varied mineral structure on the basis of aging, metal substitution, and the isotopic data reported for hematite and magnetite. The results of fitting indicated that the kinetics of recrystallization were inversely related to the crystallinity of the unrecrystallized mineral. In the final chapter of this dis- sertation, halite was developed as a model system to further investigate the mechanisms and controls on stable mineral recrystallization using a combined isotopic and microscopic approach. Advisors/Committee Members: Christopher Aaron Gorski, Dissertation Advisor/Co-Advisor, Christopher Aaron Gorski, Committee Chair/Co-Chair, Matthew S Fantle, Committee Member, William D Burgos, Committee Member, Peter J Heaney, Outside Member.

Subjects/Keywords: Iron oxides; Iron chemistry; Geochemistry; Mineral processes; Nanoparticles

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APA (6^th Edition):

Joshi, P. (2018). Kinetics and mechanisms of Fe2+-catalyzed recrystallization of iron oxides. (Thesis). Penn State University. Retrieved from https://submit-etda.libraries.psu.edu/catalog/15115puj115

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Joshi, Prachi. “Kinetics and mechanisms of Fe2+-catalyzed recrystallization of iron oxides.” 2018. Thesis, Penn State University. Accessed April 17, 2021. https://submit-etda.libraries.psu.edu/catalog/15115puj115.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Joshi, Prachi. “Kinetics and mechanisms of Fe2+-catalyzed recrystallization of iron oxides.” 2018. Web. 17 Apr 2021.

Vancouver:

Joshi P. Kinetics and mechanisms of Fe2+-catalyzed recrystallization of iron oxides. [Internet] [Thesis]. Penn State University; 2018. [cited 2021 Apr 17]. Available from: https://submit-etda.libraries.psu.edu/catalog/15115puj115.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Joshi P. Kinetics and mechanisms of Fe2+-catalyzed recrystallization of iron oxides. [Thesis]. Penn State University; 2018. Available from: https://submit-etda.libraries.psu.edu/catalog/15115puj115

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Temple University

15. Cerkez, Elizabeth B. Investigations of Surface Redox Chemistry on Environmentally Relevant Iron Oxides and Sulfides.

Degree: PhD, 2016, Temple University

URL: http://digital.library.temple.edu/u?/p245801coll10,383744

►

Chemistry

Important reactions in the environment often occur at the interface between a mineral surface and aqueous phase. Reactions occurring at this interface often control… (more)

▼

Chemistry

Important reactions in the environment often occur at the interface between a mineral surface and aqueous phase. Reactions occurring at this interface often control the uptake or release of harmful components resulting in the geochemical cycling of elements in the environment. Additionally, minerals are commonly used in the remediation of contaminated areas, where similar chemistry occurs at their interfaces. Thus, studies of the chemistry of these interfaces are essential to our understanding of complex environments. Many of these processes are controlled by electron transfer reactions between adsorbates and the mineral interface, and it is here where this research presented will concentrate. The studies in this thesis key in on redox chemistry on various environmentally relevant iron minerals, including ferrihydrite, pyrite, and amorphous iron sulfide. A large portion of this body of work is dedicated to the understanding of the surface mediated reaction between chromate (Cr(VI)) and arsenite (As(III)). Both of these species are present in the environment and are detrimental to human health. Using in- and ex-situ experiments we have monitored the coupled redox transformation of Cr(VI) and As(III) to chromite (Cr(III)) and arsenate (As(V)). Quantum mechanical modeling was used to support the experimental studies of this novel redox chemistry. The reaction was monitored in situ, using attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), on the surface of the iron oxyhydroxide, ferrihydrite, at various solution pH values by following vibrational modes unique to Cr(VI), As(III), and As(V). At pH < 9 we observed an initial growth of Cr(VI) vibrational modes due to adsorption, followed by the simultaneous decrease in Cr(VI) vibrational modes and increase in As(V) vibrational modes. Ex situ analysis of the reaction products via X-ray absorption spectroscopy (XAS) and X-ray photoelectron spectroscopy (XPS) indicated that there was an increase in the percentage of reaction products as the pH decreased. Quantum mechanical calculations were completed to model the reaction of Cr(VI) and As(III) on the ferrihydrite surface by analyzing differences in geometric and electronic structural changes and thermodynamic preferences. The results indicate that Cr(VI) and As(III) adsorbed physically separated from each other is not only thermodynamically favorable but results in changes in As(III)-Fe and Cr(VI)-Fe atomic distances, towards those characteristic of As(V)-Fe and Cr(III)-Fe. Thus a mechanism where electron transport occurs through bulk states is plausible. Additionally, natural bond order analysis reveals a redistribution of electron density away from the Cr(VI) atomic center upon adsorption, indicating probable changes in Cr(VI) reduction potential. The electrochemical reduction of Cr(VI) on three surfaces, ferrihydrite, titanium dioxide, and aluminum oxides, indicate that Cr(VI) reduction potential is surface dependent, an observation that has significance for redox chemistry in…

Advisors/Committee Members: Strongin, Daniel R.;, Valentine, Ann M., Stanley, Robert J., Reeder, Richard J.;.

Subjects/Keywords: Chemistry; Geochemistry;

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APA (6^th Edition):

Cerkez, E. B. (2016). Investigations of Surface Redox Chemistry on Environmentally Relevant Iron Oxides and Sulfides. (Doctoral Dissertation). Temple University. Retrieved from http://digital.library.temple.edu/u?/p245801coll10,383744

Chicago Manual of Style (16^th Edition):

Cerkez, Elizabeth B. “Investigations of Surface Redox Chemistry on Environmentally Relevant Iron Oxides and Sulfides.” 2016. Doctoral Dissertation, Temple University. Accessed April 17, 2021. http://digital.library.temple.edu/u?/p245801coll10,383744.

MLA Handbook (7^th Edition):

Cerkez, Elizabeth B. “Investigations of Surface Redox Chemistry on Environmentally Relevant Iron Oxides and Sulfides.” 2016. Web. 17 Apr 2021.

Vancouver:

Cerkez EB. Investigations of Surface Redox Chemistry on Environmentally Relevant Iron Oxides and Sulfides. [Internet] [Doctoral dissertation]. Temple University; 2016. [cited 2021 Apr 17]. Available from: http://digital.library.temple.edu/u?/p245801coll10,383744.

Council of Science Editors:

Cerkez EB. Investigations of Surface Redox Chemistry on Environmentally Relevant Iron Oxides and Sulfides. [Doctoral Dissertation]. Temple University; 2016. Available from: http://digital.library.temple.edu/u?/p245801coll10,383744

University of Exeter

16. Anderson, Kelvin Frederick Esebewa. Geometallurgical evaluation of the Nkout (Cameroon) and Putu (Liberia) iron ore deposits.

Degree: PhD, 2014, University of Exeter

URL: http://hdl.handle.net/10871/15019

► The Nkout (Cameroon) and Putu (Liberia) oxide facies iron ore deposits comprise fresh magnetite banded iron formation (BIF) at depth, which weathers towards the surface,… (more)

▼ The Nkout (Cameroon) and Putu (Liberia) oxide facies iron ore deposits comprise fresh magnetite banded iron formation (BIF) at depth, which weathers towards the surface, forming high grade martite–goethite ores. This study aimed to improve the mineralogical understanding of these deposits in order to predict their metallurgical responses. It concentrated on developing the QEMSCAN® technique and testing its application to these ore types, but also used a variety of other analysis methods. The QEMSCAN® species identification protocol was developed to include three goethite entries: goethite/limonite, phosphorus-bearing and aluminium-bearing goethite. QEMSCAN® was also used to distinguish between the iron oxides using their backscattered electron signals. To test the correlation between the mineralogy and metallurgical characteristics, magnetic separations were carried out. The samples were divided into 4 main groups based on their whole rock Fe content, determined by XRF analysis, and their degree of weathering: enriched material, weathered magnetite itabirite, transitional magnetite itabirite and magnetite itabirite. Quartz and Al oxide and hydroxide minerals such as gibbsite are the major gangue minerals in the magnetite BIF and martite–goethite ores respectively. From the QEMSCAN® analysis it was concluded that the iron oxides are closely associated and liberation of them individually is poor. Liberation increases when they are grouped together as iron oxide. Chamosite concentrations > 6 wt. % significantly lower liberation of the iron oxides. From the metallurgical testing, it was concluded that iron oxide modal mineralogy gives an indication of iron recovery but other QEMSCAN® data such as mineral association and liberation could be important especially if the iron oxide minerals are not liberated. Grain size and instrument characteristics also affect recovery of iron minerals. There is no evidence to show that there is any structural control on the BIF mineralisation at Nkout because metamorphism has significantly affected the lithological characteristics. The BIF mineralised zones occur as stacks with no particular stratigraphic relationship. Alteration and stratigraphy are the main controls on the martite–goethite ores. These results are applicable to most other BIFs so that as direct shipping ores are exhausted, the approach used here can help to develop the lower grade portions of the deposits.

Subjects/Keywords: 553.3; Iron oxides; Iron ore; Material characterisation; Automated mineralogy; QEMSCAN®;

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APA (6^th Edition):

Anderson, K. F. E. (2014). Geometallurgical evaluation of the Nkout (Cameroon) and Putu (Liberia) iron ore deposits. (Doctoral Dissertation). University of Exeter. Retrieved from http://hdl.handle.net/10871/15019

Chicago Manual of Style (16^th Edition):

Anderson, Kelvin Frederick Esebewa. “Geometallurgical evaluation of the Nkout (Cameroon) and Putu (Liberia) iron ore deposits.” 2014. Doctoral Dissertation, University of Exeter. Accessed April 17, 2021. http://hdl.handle.net/10871/15019.

MLA Handbook (7^th Edition):

Anderson, Kelvin Frederick Esebewa. “Geometallurgical evaluation of the Nkout (Cameroon) and Putu (Liberia) iron ore deposits.” 2014. Web. 17 Apr 2021.

Vancouver:

Anderson KFE. Geometallurgical evaluation of the Nkout (Cameroon) and Putu (Liberia) iron ore deposits. [Internet] [Doctoral dissertation]. University of Exeter; 2014. [cited 2021 Apr 17]. Available from: http://hdl.handle.net/10871/15019.

Council of Science Editors:

Anderson KFE. Geometallurgical evaluation of the Nkout (Cameroon) and Putu (Liberia) iron ore deposits. [Doctoral Dissertation]. University of Exeter; 2014. Available from: http://hdl.handle.net/10871/15019

Temple University

17. Taujale, Saru. INTERACTIONS BETWEEN METAL OXIDES AND/OR NATURAL ORGANIC MATTER AND THEIR INFLUENCE ON THE OXIDATIVE REACTIVITY OF MANGANESE DIOXIDE.

Degree: PhD, 2015, Temple University

URL: http://digital.library.temple.edu/u?/p245801coll10,347169

►

Civil Engineering

Mn oxides have high redox potentials and are known to be very reactive, rendering many contaminants susceptible to degradation via oxidation. Although Mn… (more)

▼

Civil Engineering

Mn oxides have high redox potentials and are known to be very reactive, rendering many contaminants susceptible to degradation via oxidation. Although Mn oxides typically occur as mixtures with other metal oxides (e.g., Fe, Al, and Si oxides) and natural organic matter (NOM) in soils and aquatic environments, most studies to date have studied the reactivity of Mn oxides as a single oxide system. This study, for the first time, examined the effect of representative metal oxides (Al2O3, SiO2, TiO2, and Fe oxides) and NOM or NOM-model compounds (Aldrich humic acid (AHA), Leonardite humic acid (LHA), pyromellitic acid (PA) and alginate) on the oxidative reactivity of MnO2, as quantified by the oxidation kinetics of triclosan (a widely used phenolic antibacterial agent) as a probe compound. The study also examined the effect of soluble metal ions released from the oxide surfaces on MnO2 reactivity. In binary oxide mixtures, Al2O3 decreased the reactivity of MnO2 as a result of both heteroaggregation and complexation of soluble Al ions with MnO2. At pH 5, the surface charge of MnO2 is negative while that of Al2O3 is positive resulting in intensive heteroaggregation between the two oxides. Up to 3.15 mM of soluble Al ions were detected in the supernatant of 10 g/L of Al2O3 at pH 5.0 whereas the soluble Al concentration was 0.76 mM in the mixed Al2O3 + MnO2 system at the same pH. The lower amount of soluble Al in the latter system is the result of Al ion adsorption by MnO2. The experiments with the addition of 0.001 to 0.1 mM Al3+ to MnO2 suspension indicated the triclosan oxidation rate constant decreased from 0.24 to 0.03 h-1 due to surface complexation. Fe oxides which are also negatively charged at pH 5 inhibited the reactivity of MnO2 through heteroaggregation. The concentration of soluble Fe(III) ions ( 4 mg-TOC/L or [alginate/PA] > 10 mg/L, a lower extent of heteroaggregation was also observed due to the negatively charged surfaces for all oxides. Similar effects on aggregation and MnO2 reactivity as discussed above were observed for ternary MnO2‒Al2O3‒NOM systems. HAs, particularly at high concentrations (2.0 to 12.5 mg-C/L), alleviated the effect of soluble Al ions on MnO2 reactivity as a result of the formation of soluble Al-HA complexes. Alginate and PA, however, did not form soluble complexes with Al ions so they did not affect the effect of Al ions on MnO2 reactivity. Despite the above observations, the amount of Al ions dissolved in MnO2+Al2O3+NOM mixtures was too low, as a result of NOMs adsorption on the surface to passivate oxide dissolution, to have a major impact on MnO2 reactivity. In conclusion, this study provided, for the first time, a systematical understanding of the redox activity of MnO2 in complex model systems. With this new knowledge, the gap between single oxide systems and complex environmental systems is much narrower so that it is possible to have a more accurate prediction of the fate of contaminants in the environment.

Temple University – Theses

Advisors/Committee Members: Zhang, Huichun;, Van Aken, Benoit, Suri, Rominder P.S., Strongin, Daniel R.;.

Subjects/Keywords: Environmental engineering;

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Taujale, S. (2015). INTERACTIONS BETWEEN METAL OXIDES AND/OR NATURAL ORGANIC MATTER AND THEIR INFLUENCE ON THE OXIDATIVE REACTIVITY OF MANGANESE DIOXIDE. (Doctoral Dissertation). Temple University. Retrieved from http://digital.library.temple.edu/u?/p245801coll10,347169

Chicago Manual of Style (16^th Edition):

Taujale, Saru. “INTERACTIONS BETWEEN METAL OXIDES AND/OR NATURAL ORGANIC MATTER AND THEIR INFLUENCE ON THE OXIDATIVE REACTIVITY OF MANGANESE DIOXIDE.” 2015. Doctoral Dissertation, Temple University. Accessed April 17, 2021. http://digital.library.temple.edu/u?/p245801coll10,347169.

MLA Handbook (7^th Edition):

Taujale, Saru. “INTERACTIONS BETWEEN METAL OXIDES AND/OR NATURAL ORGANIC MATTER AND THEIR INFLUENCE ON THE OXIDATIVE REACTIVITY OF MANGANESE DIOXIDE.” 2015. Web. 17 Apr 2021.

Vancouver:

Taujale S. INTERACTIONS BETWEEN METAL OXIDES AND/OR NATURAL ORGANIC MATTER AND THEIR INFLUENCE ON THE OXIDATIVE REACTIVITY OF MANGANESE DIOXIDE. [Internet] [Doctoral dissertation]. Temple University; 2015. [cited 2021 Apr 17]. Available from: http://digital.library.temple.edu/u?/p245801coll10,347169.

Council of Science Editors:

Taujale S. INTERACTIONS BETWEEN METAL OXIDES AND/OR NATURAL ORGANIC MATTER AND THEIR INFLUENCE ON THE OXIDATIVE REACTIVITY OF MANGANESE DIOXIDE. [Doctoral Dissertation]. Temple University; 2015. Available from: http://digital.library.temple.edu/u?/p245801coll10,347169

University of Florida

18. Bobek, Michael M. Investigation of Oxide Morphology, Reaction Kinetics and Mechanisms for Thermochemical Solar Fuel Production.

Degree: PhD, Mechanical Engineering - Mechanical and Aerospace Engineering, 2014, University of Florida

URL: https://ufdc.ufl.edu/UFE0047431

► There are many methods available for capturing solar energy, most notably, photovoltaic methods provide a direct conversion of the light into electricity, and solar concentrators… (more)

Subjects/Keywords: Data lines; Electrons; Hydrogen; Ions; Iron oxides; Oxidation; Oxides; Oxygen; Signals; Water splitting; energy – solar

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Bobek, M. M. (2014). Investigation of Oxide Morphology, Reaction Kinetics and Mechanisms for Thermochemical Solar Fuel Production. (Doctoral Dissertation). University of Florida. Retrieved from https://ufdc.ufl.edu/UFE0047431

Chicago Manual of Style (16^th Edition):

Bobek, Michael M. “Investigation of Oxide Morphology, Reaction Kinetics and Mechanisms for Thermochemical Solar Fuel Production.” 2014. Doctoral Dissertation, University of Florida. Accessed April 17, 2021. https://ufdc.ufl.edu/UFE0047431.

MLA Handbook (7^th Edition):

Bobek, Michael M. “Investigation of Oxide Morphology, Reaction Kinetics and Mechanisms for Thermochemical Solar Fuel Production.” 2014. Web. 17 Apr 2021.

Vancouver:

Bobek MM. Investigation of Oxide Morphology, Reaction Kinetics and Mechanisms for Thermochemical Solar Fuel Production. [Internet] [Doctoral dissertation]. University of Florida; 2014. [cited 2021 Apr 17]. Available from: https://ufdc.ufl.edu/UFE0047431.

Council of Science Editors:

Bobek MM. Investigation of Oxide Morphology, Reaction Kinetics and Mechanisms for Thermochemical Solar Fuel Production. [Doctoral Dissertation]. University of Florida; 2014. Available from: https://ufdc.ufl.edu/UFE0047431

Drexel University

19. Pai, Rahul Nagesh Neeta. Iron-oxide based electrodes in aqueous supercapacitors.

Degree: 2017, Drexel University

URL: http://hdl.handle.net/1860/idea:7810

►

Climate change and the limited availability of fossil fuels have greatly affected the world economy and ecology. The demand of energy is not coping up… (more)

▼

Climate change and the limited availability of fossil fuels have greatly affected the world economy and ecology. The demand of energy is not coping up the supply of the same. With a fast-growing market for portable electronic devices and the development of hybrid electric vehicles, there has been an ever increasing and urgent demand for environmentally friendly high-power energy resources. This has led to development of energy storage devices, mostly supercapacitors and batteries. In the recent times it is seen that li-ion batteries have been dominating energy storage device sector (Portable electronics, hybrid vehicles and grids). Li-ion still lacks when there is sudden demand in high power. The development of higher energy and power density systems highly rely upon the advancement of new materials used in these devices. Transition oxides and conducting polymers based nanofibers are excellent candidates for application as electrodes in the energy storage devices because of their unique properties such as high capacitance, chemical durability, nature friendly and high specific surface area. Electrospinning is a simple, fast and a scalable technique wherein fiber formation is done with the help of a strong electric field to stretch out a polymer solution to form nanofibers with diameters in the range of 100-800 nm. This fiber-formation technique results in formation of free-standing, binder free and non-woven fiber mat. My thesis focuses on preparation of Iron oxide based nanofibers through electrospinning method, characterizing these nanofibers via spectroscopic/microscopic techniques and developing understanding of their electrochemical mechanisms in an aqueous medium. My work focusses more on structurally supporting these oxides in the conductive carbon fiber matrix which otherwise delaminates while cycling reducing performance in energy storage devices.

M.S., Chemical Engineering – Drexel University, 2017

Advisors/Committee Members: Kalra, Vibha, College of Engineering.

Subjects/Keywords: Chemical engineering; Power resources; Carbon nanofibers; Electrospinning; Iron oxides; Supercapacitor; Transition metal oxides

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Pai, R. N. N. (2017). Iron-oxide based electrodes in aqueous supercapacitors. (Thesis). Drexel University. Retrieved from http://hdl.handle.net/1860/idea:7810

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Pai, Rahul Nagesh Neeta. “Iron-oxide based electrodes in aqueous supercapacitors.” 2017. Thesis, Drexel University. Accessed April 17, 2021. http://hdl.handle.net/1860/idea:7810.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Pai, Rahul Nagesh Neeta. “Iron-oxide based electrodes in aqueous supercapacitors.” 2017. Web. 17 Apr 2021.

Vancouver:

Pai RNN. Iron-oxide based electrodes in aqueous supercapacitors. [Internet] [Thesis]. Drexel University; 2017. [cited 2021 Apr 17]. Available from: http://hdl.handle.net/1860/idea:7810.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Pai RNN. Iron-oxide based electrodes in aqueous supercapacitors. [Thesis]. Drexel University; 2017. Available from: http://hdl.handle.net/1860/idea:7810

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

University of Ottawa

20. Najem, Tarek. The Impact of Ageing, Gamma(γ)-irradiation, and Varying Concentrations of Phosphate on the Stability and Solubility of Biogenic Iron Oxides (BIOS) in the Presence of Shewanella putrefaciens CN32 .

Degree: 2017, University of Ottawa

URL: http://hdl.handle.net/10393/35683

► The redox cycling of iron is intimately linked to the cycling of C, S, N, P as well as the speciation, mobility, and bioavailability of… (more)

▼ The redox cycling of iron is intimately linked to the cycling of C, S, N, P as well as the speciation, mobility, and bioavailability of various toxic contaminants in soils and sediments. Within these environments, the cycling of iron is catalytically driven by iron-oxidizing (FeOB) and iron reducing bacteria (FeRB) which mediate the formation, transformation, and dissolution of various iron-bearing minerals. Under oxic conditions, FeOB promote the formation of iron oxides on or in close proximity of their cell walls and extracellular polymeric substances, and such composite, termed biogenic iron oxides (BIOS), offers highly reactive heterogenous sites that efficiently immobilize trace metals and contaminants alike. However, under reducing conditions, FeRB mediate the reductive dissolution of BIOS and in turn lead to the remobilization of associated contaminants. Conversely, contaminants may become immobilized by secondary iron minerals that form from the metabolic activity of FeRB. Therefore, determining the factors that influence the reactivity of BIOS, as well as the formation of secondary iron minerals is of critical importance to develop a better understanding of the geochemical cycling of iron and in turn the transport of contaminants in the environment. This thesis investigated (1) the impact of simulated diagenesis (ageing for ~5 years at 4ºC) on the mineral stability and reactivity of BIOS towards reduction by Shewanella putrefaciens CN32, (2) the effects of phosphate at an environmentally relevant (10µM) and excess (3.9mM) concentration on the rates and extent of microbial reduction of synthetic 2-line ferrihydrite and BIOS, as well as the formation of secondary iron minerals, and (3) the impact of sterilization by γ-irradiation on the mineral stability and reactivity of BIOS. It was found that simulated diagenesis did not affect the mineralogical composition of BIOS but significantly lowered the reactivity of BIOS towards microbial reduction. The concentration of phosphate was found to have contrasting effects on the rates of reduction of ferrihydrite and BIOS, but in general, excess concentration of phosphate enhanced the extent of Fe(III) reduction. The formation of a specific secondary iron mineral was also found to depend on the concentration of phosphate, as well as, in the case for BIOS, the presence of intermixed cell derived organic matter. γ-irradiation did not alter the mineralogy and reactivity of BIOS towards microbial reduction, and it was concluded to be a suitable technique to sterilize BIOS.

Subjects/Keywords: Biogenic iron oxides; Shewanella putrefaciens; Aggregation; Ferrihydrite; Phosphate; Molybdate; Gamma(γ)-irradiation; Iron reduction; Ageing

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Najem, T. (2017). The Impact of Ageing, Gamma(γ)-irradiation, and Varying Concentrations of Phosphate on the Stability and Solubility of Biogenic Iron Oxides (BIOS) in the Presence of Shewanella putrefaciens CN32 . (Thesis). University of Ottawa. Retrieved from http://hdl.handle.net/10393/35683

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Najem, Tarek. “The Impact of Ageing, Gamma(γ)-irradiation, and Varying Concentrations of Phosphate on the Stability and Solubility of Biogenic Iron Oxides (BIOS) in the Presence of Shewanella putrefaciens CN32 .” 2017. Thesis, University of Ottawa. Accessed April 17, 2021. http://hdl.handle.net/10393/35683.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Najem, Tarek. “The Impact of Ageing, Gamma(γ)-irradiation, and Varying Concentrations of Phosphate on the Stability and Solubility of Biogenic Iron Oxides (BIOS) in the Presence of Shewanella putrefaciens CN32 .” 2017. Web. 17 Apr 2021.

Vancouver:

Najem T. The Impact of Ageing, Gamma(γ)-irradiation, and Varying Concentrations of Phosphate on the Stability and Solubility of Biogenic Iron Oxides (BIOS) in the Presence of Shewanella putrefaciens CN32 . [Internet] [Thesis]. University of Ottawa; 2017. [cited 2021 Apr 17]. Available from: http://hdl.handle.net/10393/35683.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Najem T. The Impact of Ageing, Gamma(γ)-irradiation, and Varying Concentrations of Phosphate on the Stability and Solubility of Biogenic Iron Oxides (BIOS) in the Presence of Shewanella putrefaciens CN32 . [Thesis]. University of Ottawa; 2017. Available from: http://hdl.handle.net/10393/35683

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

University of Pretoria

21. [No author]. Determination of factors influencing the degree of reduction disintegration in Northern Cape lump ore and the role of gangue minerals in the propagation of cracks .

Degree: 2010, University of Pretoria

URL: http://upetd.up.ac.za/thesis/available/etd-10202008-123653/

► The fundamental cause of low temperature breakdown (reduction disintegration) is reduction of hematite to magnetite, resulting in a volume expansion and stress relief through the… (more)

▼ The fundamental cause of low temperature breakdown (reduction disintegration) is reduction of hematite to magnetite, resulting in a volume expansion and stress relief through the formation of cracks. Serious reduction disintegration causes poor gas permeability, high flue dust production and scaffolding, poor gas distribution, higher fuel consumption and lower productivity. Northern Cape iron ore generally performs well when tested for reduction disintegration properties both for blast furnaces and Corex; nevertheless, significant breakdown is experienced when used in the Corex process (at Saldanha Steel). This study was hence conducted to determine the effects of the following on reduction disintegration: different ore types (from Northern Cape) initial particle size temperature range reduction gas composition Although disintegration is clearly triggered by reduction, no direct correlation could be established between the percentage reduction and the percentage fines generated. The results indicated that the presence of gangue minerals alone does not cause fractures to form, but does influence the direction and intensity of fractures to some extent. In many cases cracks form randomly, with no specific preference for either gangue minerals or iron oxides. For most of the samples, an incubation period was observed before the first cracks formed. No crack propagation was observed after initial cracking. This study indicates that the degree of reduction disintegration depends mostly on furnace conditions. Reduction disintegration increased with higher hydrogen percentages (>5%), higher temperatures (in the 500ºC-700ºC range) and longer exposure. Disintegration of the samples decreased at temperatures higher than 750°C. For particles smaller than 16 mm an inverse relationship was found between the average particle size and the percentage of fines generated, in line with the observation that most of the disintegration is due to spalling from particle edges rather than particles breaking into smaller clumps. The results indicate that it is important to manage the temperature in the top of the blast furnace and the COREX shaft, and the time spent at temperatures below 750°C, to minimize the amount of fines generated. Advisors/Committee Members: Pistorius, Petrus Christiaan (advisor).

Subjects/Keywords: Reduction disintegration; Gang minerals; Iron oxides; Cracks; UCTD

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

author], [. (2010). Determination of factors influencing the degree of reduction disintegration in Northern Cape lump ore and the role of gangue minerals in the propagation of cracks . (Doctoral Dissertation). University of Pretoria. Retrieved from http://upetd.up.ac.za/thesis/available/etd-10202008-123653/

Chicago Manual of Style (16^th Edition):

author], [No. “Determination of factors influencing the degree of reduction disintegration in Northern Cape lump ore and the role of gangue minerals in the propagation of cracks .” 2010. Doctoral Dissertation, University of Pretoria. Accessed April 17, 2021. http://upetd.up.ac.za/thesis/available/etd-10202008-123653/.

MLA Handbook (7^th Edition):

author], [No. “Determination of factors influencing the degree of reduction disintegration in Northern Cape lump ore and the role of gangue minerals in the propagation of cracks .” 2010. Web. 17 Apr 2021.

Vancouver:

author] [. Determination of factors influencing the degree of reduction disintegration in Northern Cape lump ore and the role of gangue minerals in the propagation of cracks . [Internet] [Doctoral dissertation]. University of Pretoria; 2010. [cited 2021 Apr 17]. Available from: http://upetd.up.ac.za/thesis/available/etd-10202008-123653/.

Council of Science Editors:

author] [. Determination of factors influencing the degree of reduction disintegration in Northern Cape lump ore and the role of gangue minerals in the propagation of cracks . [Doctoral Dissertation]. University of Pretoria; 2010. Available from: http://upetd.up.ac.za/thesis/available/etd-10202008-123653/

Temple University

22. Bhandari, Narayan. Investigations of the (Photo)Chemistry of Nano- and Micron-dimensioned Iron Oxides for Metal(loid) Remediation.

Degree: PhD, 2013, Temple University

URL: http://digital.library.temple.edu/u?/p245801coll10,225174

►

Chemistry

Anthropogenic activities and natural processes over time have led to the release of toxic heavy metal contaminants into the environment. As a consequence, there… (more)

▼

Chemistry

Anthropogenic activities and natural processes over time have led to the release of toxic heavy metal contaminants into the environment. As a consequence, there is an increasing number of illnesses caused by the exposure of humans to heavy metals and metalloids. The dissertation work presented here focused on the synthesis, characterization, and understanding of the surface chemistry, as well as the photo-reactivity, of a variety of iron (oxyhydr)oxide nano-materials that have relevance for the remediation of heavy metal contaminants, such as arsenic and chromium in aqueous environments. The research focused on the photo-induced reductive dissolution of a nano-dimensioned iron oxyhydroxide, ferrihydrite, in the presence of oxalate, the photo-induced arsenite oxidation, and the simultaneous redox transformation of arsenite and chromate in the presence of ferrihydrite and another environmentally relevant iron oxyhydroxide, goethite. The photo-reductive dissolution of ferrihydrite (using simulated solar radiation) in the presence of oxalic acid was investigated with surface sensitive in situ and ex situ techniques that included attenuated total reflectance Fourier transform infrared spectroscopy. Ferrihydrite at a solution pH of 4.5 exhibited an induction period where the rate of Fe(II) release was limited by a low concentration of adsorbed oxalate due to the site-blocking of carbonate that was intrinsic to the surface of the ferrihydrite starting material. The photo-induced decarboxylation of adsorbed oxalate also ultimately led to the appearance of carbonate reaction product (distinct from carbonate intrinsic to the starting material) on the surface. Ferrihydrite that was prepared under carbonate free condition showed a rapid release of Fe(II) upon irradiation and no induction period was observed. Arsenite [As(III)] oxidation in the presence of ferrihydrite and goethite was also investigated. Ferrihydrite or goethite when exposed to As(III) in the dark led to no change in the oxidation state of As(III) reactant. However, exposure of As(III) in the presence of ferrihydrite or goethite to simulated solar light resulted in the oxidation of As(III) and a reduction of surface Fe(III) leading to an overall increase in the total As removal. At a solution pH of 5, this conversion of As(III) to As(V) on ferrihydrite resulted in the partitioning of a stoichiometric amount of Fe(II) into the aqueous phase and the majority of the As(V) product remained bound to the ferrihydrite surface. In contrast, the As(III)/goethite system showed a different photochemical behavior in the absence or presence of dissolved oxygen. Under oxic conditions, in contrast to ferrihydrite, the majority of the As(V) product was in the aqueous phase and the relative amount of aqueous Fe(II) was significantly less than in the ferrihydrite circumstance. Experimental observations suggested that in the oxic environment, Fe(II) on the goethite surface was heterogeneously oxidized to Fe(III) by dissolved oxygen resulting in the formation of…

Advisors/Committee Members: Strongin, Daniel R., Valentine, Ann M., Zdilla, Michael J., Van Aken, Benoit;.

Subjects/Keywords: Chemistry;

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APA (6^th Edition):

Bhandari, N. (2013). Investigations of the (Photo)Chemistry of Nano- and Micron-dimensioned Iron Oxides for Metal(loid) Remediation. (Doctoral Dissertation). Temple University. Retrieved from http://digital.library.temple.edu/u?/p245801coll10,225174

Chicago Manual of Style (16^th Edition):

Bhandari, Narayan. “Investigations of the (Photo)Chemistry of Nano- and Micron-dimensioned Iron Oxides for Metal(loid) Remediation.” 2013. Doctoral Dissertation, Temple University. Accessed April 17, 2021. http://digital.library.temple.edu/u?/p245801coll10,225174.

MLA Handbook (7^th Edition):

Bhandari, Narayan. “Investigations of the (Photo)Chemistry of Nano- and Micron-dimensioned Iron Oxides for Metal(loid) Remediation.” 2013. Web. 17 Apr 2021.

Vancouver:

Bhandari N. Investigations of the (Photo)Chemistry of Nano- and Micron-dimensioned Iron Oxides for Metal(loid) Remediation. [Internet] [Doctoral dissertation]. Temple University; 2013. [cited 2021 Apr 17]. Available from: http://digital.library.temple.edu/u?/p245801coll10,225174.

Council of Science Editors:

Bhandari N. Investigations of the (Photo)Chemistry of Nano- and Micron-dimensioned Iron Oxides for Metal(loid) Remediation. [Doctoral Dissertation]. Temple University; 2013. Available from: http://digital.library.temple.edu/u?/p245801coll10,225174

Temple University

23. Lammers, Kristin D. Carbon dioxide sequestration by mineral carbonation of iron-bearing minerals.

Degree: PhD, 2015, Temple University

URL: http://digital.library.temple.edu/u?/p245801coll10,339925

►

Chemistry

Carbon dioxide (CO2) is formed when fossil fuels such as oil, gas and coal are burned in power producing plants. CO2 is naturally found… (more)

▼

Chemistry

Carbon dioxide (CO2) is formed when fossil fuels such as oil, gas and coal are burned in power producing plants. CO2 is naturally found in the atmosphere as part of the carbon cycle, however it becomes a primary greenhouse gas when human activities disturb this natural balanced cycle by increasing levels in the atmosphere. In light of this fact, greenhouse gas mitigation strategies have garnered a lot of attention. Carbon capture, utilization and sequestration (CCUS) has emerged as a possible strategy to limit CO2 emissions into the atmosphere. The technology involves capturing CO2 at the point sources, using it for other markets or transporting to geological formations for safe storage. This thesis aims to understand and probe the chemistry of the reactions between CO2 and iron-bearing sediments to ensure secure storage for millennia. The dissertation work presented here focused on trapping CO2 as a carbonate mineral as a permanent and secure method of CO2 storage. The research also explored the use of iron-bearing minerals found in the geological subsurface as candidates for trapping CO2 and sulfide gas mixtures as siderite (FeCO3) and iron sulfides. Carbon dioxide sequestration via the use of sulfide reductants of the iron oxyhydroxide polymorphs lepidocrocite, goethite and akaganeite with supercritical CO2 (scCO2) was investigated using in situ attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), X-ray diffraction (XRD) and transmission electron microscopy (TEM). The exposure of the different iron oxyhydroxides to aqueous sulfide in contact with scCO2 at ~70-100 ˚C resulted in the partial transformation of the minerals to siderite (FeCO3). The order of mineral reactivity with regard to siderite formation in the scCO2/sulfide environment was goethite < lepidocrocite ≤ akaganéite. Overall, the results suggested that the carbonation of lepidocrocite and akaganéite with a CO2 waste stream containing ~1-5% H2S would sequester both the carbon and sulfide efficiently. Hence, it might be possible to develop a process that could be associated with large CO2 point sources in locations without suitable sedimentary strata for subsurface sequestration. This thesis also investigates the effect of salinity on the reactions between a ferric-bearing oxide phase, aqueous sulfide, and scCO2. ATR-FTIR was again used as an in situ probe to follow product formation in the reaction environment. X-ray diffraction along with Rietveld refinement was used to determine the relative proportion of solid product phases. ATR-FTIR results showed the evolution of siderite (FeCO3) in solutions containing NaCl(aq) concentrations that varied from 0.10 to 4.0 M. The yield of siderite was greatest under solution ionic strength conditions associated with NaCl(aq) concentrations of 0.1-1 M (siderite yield 40% of solid product) and lowest at the highest ionic strength achieved with 4 M NaCl(aq) (20% of solid product). Based partly on thermochemical calculations, it is suggested that a decrease in the…

Advisors/Committee Members: Strongin, Daniel R.;, Stanley, Robert J., Wunder, Stephanie, Schoonen, Martin A. A.;.

Subjects/Keywords: Analytical chemistry; Geochemistry;

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Lammers, K. D. (2015). Carbon dioxide sequestration by mineral carbonation of iron-bearing minerals. (Doctoral Dissertation). Temple University. Retrieved from http://digital.library.temple.edu/u?/p245801coll10,339925

Chicago Manual of Style (16^th Edition):

Lammers, Kristin D. “Carbon dioxide sequestration by mineral carbonation of iron-bearing minerals.” 2015. Doctoral Dissertation, Temple University. Accessed April 17, 2021. http://digital.library.temple.edu/u?/p245801coll10,339925.

MLA Handbook (7^th Edition):

Lammers, Kristin D. “Carbon dioxide sequestration by mineral carbonation of iron-bearing minerals.” 2015. Web. 17 Apr 2021.

Vancouver:

Lammers KD. Carbon dioxide sequestration by mineral carbonation of iron-bearing minerals. [Internet] [Doctoral dissertation]. Temple University; 2015. [cited 2021 Apr 17]. Available from: http://digital.library.temple.edu/u?/p245801coll10,339925.

Council of Science Editors:

Lammers KD. Carbon dioxide sequestration by mineral carbonation of iron-bearing minerals. [Doctoral Dissertation]. Temple University; 2015. Available from: http://digital.library.temple.edu/u?/p245801coll10,339925

Penn State University

24. Joshi, Prachi. Morphological Changes in Goethite during Atom Exchange with Aqueous Fe2+.

Degree: 2015, Penn State University

URL: https://submit-etda.libraries.psu.edu/catalog/25092

► Iron (Fe) (oxyhydr)oxides play important, dynamic roles in the biogeochemical cycling of trace elements, nutrients, and radionuclides, especially under reducing conditions. Recent work has shown… (more)

▼ Iron (Fe) (oxyhydr)oxides play important, dynamic roles in the biogeochemical cycling of trace elements, nutrients, and radionuclides, especially under reducing conditions. Recent work has shown that when goethite, a common Fe hydroxide, is exposed to aqueous Fe2+, it undergoes extensive atom exchange, as evidenced by Fe isotope tracer experiments. The effect of Fe atom exchange on the goethite is currently unclear - some studies observed no differences between the original and final exchanged goethite, while others saw evidence of particle growth. Here, we hypothesized that Fe2+-goethite atom exchange does indeed result in detectable changes. To test this hypothesis, we reacted nanoscale goethite, (rod-like crystals, 107 nm by 20 nm) with aqueous Fe2+ at pH 7.0 over 60 days and used high resolution transmission electron microscopy (HR-TEM) and cryogenic transmission electron microscopy (cryo-TEM) to see changes in particle shape, size, and structure at intermediate time points. Over 60 days, we observed that goethite nanoparticles became smaller and then regrew, while forming oriented aggregates. At the start of atom exchange, goethite nanoparticles dissolved to produce much smaller particles (<30 nm long, <3 nm wide) until 40 days. As exchange proceeded, particles started regrowing and approached their original dimensions. Dissolution and regrowth occurred over both the length and width of the nanoparticle. Using cryo-TEM, we observed that as goethite nanoparticles regrew, they aggregated along the longitudinal edge, forming “bundles” of attached nanorods. These time-resolved changes in size and aggregation behavior show that goethite-aqueous Fe2+ atom exchange occurs via both dissolution-reprecipitation and oriented aggregation. To see if these particle changes affect the crystal coordinate chemistry of Fe in goethite over the course of atom exchange, we used Mӧssbauer spectroscopy. Mössbauer spectra of the original, reacted and control goethite were indistinguishable at t = 10 days suggesting that there is no mineralogical change in goethite during couple shrinking regrowth and oriented aggregation. In addition to microscopy, we used a 55Fe isotopic tracer method to quantify the fraction of goethite involved in atom exchange. We found that nanoscale goethite undergoes 6.3% exchange over 30 days at pH 7.0. Our observations suggest that Fe atom exchange proceeds via dissolution followed by a combination of coarsening and oriented aggregation. Advisors/Committee Members: Christopher Aaron Gorski, Thesis Advisor/Co-Advisor.

Subjects/Keywords: Iron oxides; Atom Exchange; Goethite; Mineral-Water Interface; trace metals sequestration

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APA (6^th Edition):

Joshi, P. (2015). Morphological Changes in Goethite during Atom Exchange with Aqueous Fe2+. (Thesis). Penn State University. Retrieved from https://submit-etda.libraries.psu.edu/catalog/25092

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Joshi, Prachi. “Morphological Changes in Goethite during Atom Exchange with Aqueous Fe2+.” 2015. Thesis, Penn State University. Accessed April 17, 2021. https://submit-etda.libraries.psu.edu/catalog/25092.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Joshi, Prachi. “Morphological Changes in Goethite during Atom Exchange with Aqueous Fe2+.” 2015. Web. 17 Apr 2021.

Vancouver:

Joshi P. Morphological Changes in Goethite during Atom Exchange with Aqueous Fe2+. [Internet] [Thesis]. Penn State University; 2015. [cited 2021 Apr 17]. Available from: https://submit-etda.libraries.psu.edu/catalog/25092.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Joshi P. Morphological Changes in Goethite during Atom Exchange with Aqueous Fe2+. [Thesis]. Penn State University; 2015. Available from: https://submit-etda.libraries.psu.edu/catalog/25092

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Penn State University

25. Rojas Alvarado, Claudia Macarena. Effect of vegetative reclamation on microbial diversity and iron biogeochemistry in acid mine drainage precipitates at a 50-yr-old barrens.

Degree: 2013, Penn State University

URL: https://submit-etda.libraries.psu.edu/catalog/19379

► Acid mine drainage (AMD) barrens result from the death of vegetation resulting from overland flow of acidic metal-rich waters emerging from abandoned underground mines. As… (more)

▼ Acid mine drainage (AMD) barrens result from the death of vegetation resulting from overland flow of acidic metal-rich waters emerging from abandoned underground mines. As acidic waters flow overland, oxidation and hydrolysis reactions result in accumulation of ferric iron (oxy) hydroxide precipitates on soil surfaces. AMD barrens can become a source of further pollution if exposed acidic precipitates are not protected against surface runoff. In 2006, a restoration experiment was conducted by our research group at a 50-year-old AMD barrens to determine whether vegetation could be established by altering, rather than removing, surface layers of acidic iron-rich precipitates at the site which is representative of other mining-degraded areas. In that study, three zones were distinguished by thickness and color of precipitate surface layers and by moisture content as influenced by depth to fragipan layers in underlying native soils. Acidic precipitates in experimental plots were amended in place by a one- time incorporation of lime and compost (top 15 cm) and a first-year oats nurse crop to improve growth of a sown reclamation seed mixture. Plant composition in the first, second, and fourth growing season consisted mainly of oats, sown species, and indigenous species, respectively. In all three zones, plots that received compost had greater than 70% vegetative cover at the end of the fourth growing season. The research presented in this dissertation builds on the investigation initiated in 2006 in the zone where subsurface AMD flow was most shallow and focuses on non- reclaimed (control) precipitates covered by mossy biological crusts and reclaimed precipitates sustaining vegetation. Iron (Fe) biogeochemistry in AMD precipitates was studied to gain an understanding of potential losses of redox-active metals after plant-based reclamation. As mobility of redox-active metals can be increased by enhanced microbial activity in the rooting zones of growing plants, we compared the forms of Fe in the reclaimed and control precipitates five years post-reclamation. Since Fe is the most abundant metal in many mine drainages, root exudation by growing plants could stimulate Fe(III)-reducing activity in rhizospheres, resulting in losses of soluble Fe(II) from the system. Precipitates were sampled from moist yet unsaturated surface sections (8-cm depth) excised from replicate plots. Four precipitate types, reclaimed root-adhering (RR); reclaimed below-roots (RB); control crust-adhering (CC); and control below-crust (CB) were obtained before selective-extraction analyses and microbial counts were performed. Reclaimed and control precipitates had mean Fe contents of 454 and 690 g kg-1, respectively. Ferrozine tests of extracts indicated that Fe(II) concentrations were three- to five-fold higher in reclaimed precipitates than in control precipitates. Organically bound Fe and amorphous iron oxides, as fractions of total Fe, were also higher in reclaimed than in control precipitates. Estimates of Fe-reducing and Fe- oxidizing bacteria were… Advisors/Committee Members: Maryann Victoria Bruns, Dissertation Advisor/Co-Advisor, Carmen E Martínez, Committee Member, Patrick Joseph Drohan, Committee Member, Sridhar Komarneni, Committee Member, Rachel Alice Brennan, Committee Member.

Subjects/Keywords: acid mine drainage; iron oxides; soil microbiology; bacteria; fungi; microbial diversity

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APA (6^th Edition):

Rojas Alvarado, C. M. (2013). Effect of vegetative reclamation on microbial diversity and iron biogeochemistry in acid mine drainage precipitates at a 50-yr-old barrens. (Thesis). Penn State University. Retrieved from https://submit-etda.libraries.psu.edu/catalog/19379

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Rojas Alvarado, Claudia Macarena. “Effect of vegetative reclamation on microbial diversity and iron biogeochemistry in acid mine drainage precipitates at a 50-yr-old barrens.” 2013. Thesis, Penn State University. Accessed April 17, 2021. https://submit-etda.libraries.psu.edu/catalog/19379.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Rojas Alvarado, Claudia Macarena. “Effect of vegetative reclamation on microbial diversity and iron biogeochemistry in acid mine drainage precipitates at a 50-yr-old barrens.” 2013. Web. 17 Apr 2021.

Vancouver:

Rojas Alvarado CM. Effect of vegetative reclamation on microbial diversity and iron biogeochemistry in acid mine drainage precipitates at a 50-yr-old barrens. [Internet] [Thesis]. Penn State University; 2013. [cited 2021 Apr 17]. Available from: https://submit-etda.libraries.psu.edu/catalog/19379.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Rojas Alvarado CM. Effect of vegetative reclamation on microbial diversity and iron biogeochemistry in acid mine drainage precipitates at a 50-yr-old barrens. [Thesis]. Penn State University; 2013. Available from: https://submit-etda.libraries.psu.edu/catalog/19379

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

University of Pretoria

26. Van der Vyver, W.F. (Wilhelmina Fredrika). Determination of factors influencing the degree of reduction disintegration in Northern Cape lump ore and the role of gangue minerals in the propagation of cracks.

Degree: Materials Science and Metallurgical Engineering, 2010, University of Pretoria

URL: http://hdl.handle.net/2263/28867

► The fundamental cause of low temperature breakdown (reduction disintegration) is reduction of hematite to magnetite, resulting in a volume expansion and stress relief through the… (more)

▼ The fundamental cause of low temperature breakdown (reduction disintegration) is reduction of hematite to magnetite, resulting in a volume expansion and stress relief through the formation of cracks. Serious reduction disintegration causes poor gas permeability, high flue dust production and scaffolding, poor gas distribution, higher fuel consumption and lower productivity. Northern Cape iron ore generally performs well when tested for reduction disintegration properties both for blast furnaces and Corex; nevertheless, significant breakdown is experienced when used in the Corex process (at Saldanha Steel). This study was hence conducted to determine the effects of the following on reduction disintegration: different ore types (from Northern Cape) initial particle size temperature range reduction gas composition Although disintegration is clearly triggered by reduction, no direct correlation could be established between the percentage reduction and the percentage fines generated. The results indicated that the presence of gangue minerals alone does not cause fractures to form, but does influence the direction and intensity of fractures to some extent. In many cases cracks form randomly, with no specific preference for either gangue minerals or iron oxides. For most of the samples, an incubation period was observed before the first cracks formed. No crack propagation was observed after initial cracking. This study indicates that the degree of reduction disintegration depends mostly on furnace conditions. Reduction disintegration increased with higher hydrogen percentages (>5%), higher temperatures (in the 500ºC-700ºC range) and longer exposure. Disintegration of the samples decreased at temperatures higher than 750°C. For particles smaller than 16 mm an inverse relationship was found between the average particle size and the percentage of fines generated, in line with the observation that most of the disintegration is due to spalling from particle edges rather than particles breaking into smaller clumps. The results indicate that it is important to manage the temperature in the top of the blast furnace and the COREX shaft, and the time spent at temperatures below 750°C, to minimize the amount of fines generated. Advisors/Committee Members: Pistorius, Petrus Christiaan (advisor).

Subjects/Keywords: Reduction disintegration; Gang minerals; Iron oxides; Cracks; UCTD

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APA (6^th Edition):

Van der Vyver, W. F. (. (2010). Determination of factors influencing the degree of reduction disintegration in Northern Cape lump ore and the role of gangue minerals in the propagation of cracks. (Doctoral Dissertation). University of Pretoria. Retrieved from http://hdl.handle.net/2263/28867

Chicago Manual of Style (16^th Edition):

Van der Vyver, W F (Wilhelmina. “Determination of factors influencing the degree of reduction disintegration in Northern Cape lump ore and the role of gangue minerals in the propagation of cracks.” 2010. Doctoral Dissertation, University of Pretoria. Accessed April 17, 2021. http://hdl.handle.net/2263/28867.

MLA Handbook (7^th Edition):

Van der Vyver, W F (Wilhelmina. “Determination of factors influencing the degree of reduction disintegration in Northern Cape lump ore and the role of gangue minerals in the propagation of cracks.” 2010. Web. 17 Apr 2021.

Vancouver:

Van der Vyver WF(. Determination of factors influencing the degree of reduction disintegration in Northern Cape lump ore and the role of gangue minerals in the propagation of cracks. [Internet] [Doctoral dissertation]. University of Pretoria; 2010. [cited 2021 Apr 17]. Available from: http://hdl.handle.net/2263/28867.

Council of Science Editors:

Van der Vyver WF(. Determination of factors influencing the degree of reduction disintegration in Northern Cape lump ore and the role of gangue minerals in the propagation of cracks. [Doctoral Dissertation]. University of Pretoria; 2010. Available from: http://hdl.handle.net/2263/28867

University of Wollongong

27. Karamiqucham, Behrooz. Geochemistry and dating of iron (III) oxides and clays of the Australian regolith.

Degree: M. Phil., 2014, University of Wollongong

URL: ; https://ro.uow.edu.au/theses/4335

► This project focused on the study of oxygen-isotope variations in iron (III) oxides and their corresponding clays during their formation in selected weathered profiles… (more)

Subjects/Keywords: geochemistry; dating; oxygen isotope study; iron oxides; clay minerals; regolith; Australia

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APA (6^th Edition):

Karamiqucham, B. (2014). Geochemistry and dating of iron (III) oxides and clays of the Australian regolith. (Masters Thesis). University of Wollongong. Retrieved from ; https://ro.uow.edu.au/theses/4335

Chicago Manual of Style (16^th Edition):

Karamiqucham, Behrooz. “Geochemistry and dating of iron (III) oxides and clays of the Australian regolith.” 2014. Masters Thesis, University of Wollongong. Accessed April 17, 2021. ; https://ro.uow.edu.au/theses/4335.

MLA Handbook (7^th Edition):

Karamiqucham, Behrooz. “Geochemistry and dating of iron (III) oxides and clays of the Australian regolith.” 2014. Web. 17 Apr 2021.

Vancouver:

Karamiqucham B. Geochemistry and dating of iron (III) oxides and clays of the Australian regolith. [Internet] [Masters thesis]. University of Wollongong; 2014. [cited 2021 Apr 17]. Available from: ; https://ro.uow.edu.au/theses/4335.

Council of Science Editors:

Karamiqucham B. Geochemistry and dating of iron (III) oxides and clays of the Australian regolith. [Masters Thesis]. University of Wollongong; 2014. Available from: ; https://ro.uow.edu.au/theses/4335

University of Delaware

28. Wu, Yun. The effects of iron(II) on arsenic(III) oxidation and arsenic sorption/desorption on manganese oxides.

Degree: PhD, University of Delaware, Department of Plant & Soil Sciences, 2014, University of Delaware

URL: http://udspace.udel.edu/handle/19716/13455

► Arsenic contamination of groundwater and soils is a major global environmental challenge. Both As(III) and As(V) are carcinogens, but As(III) is more toxic and more… (more)

▼ Arsenic contamination of groundwater and soils is a major global environmental challenge. Both As(III) and As(V) are carcinogens, but As(III) is more toxic and more mobile. Thus, oxidation of As(III) to As(V) is an effective way to reduce As toxicity. As(III) oxidation by Mn-oxides has been extensively studied, however, the oxidation/sorption kinetics and mechanisms of As(III) under natural heterogeneous environments remains unclear. As(III) and Fe(II) coexist in many As contaminated environments and the presence of Fe(II) can influence the behavior of As(III) on Mn oxides. In this study, As(III) oxidation by a poorly-crystalline phyllomanganate (δ-MnO 2 ) in the presence and absence of dissolved Fe(II) was investigated using stirred-flow and batch experiments. The solids after reaction are characterized by X-ray absorption spectroscopy (XAS), Mössbauer spectroscopy and transmission electron microscope coupled with energy-dispersive X-ray spectroscopy (TEM-EDS). Results showed that in the presence of Fe(II), As(III) oxidation was inhibited due to the competitive oxidation of Fe(II) as well as the formation of Fe(III)-(hydr)oxides on the δ-MnO 2 surface. However, the sorption of As(III), As(V) and Mn(II) increased, since the newly formed Fe(III)-(hydr)oxides provided additional sorption sites. XAS analysis revealed that at low Fe(II) concentration, As(V) was the predominant As species on the solid phase, while at high Fe(II) concentration, both As(III) and As(V) were sorbed on the solid phase. As preferred to bind with the newly formed Fe(III)-(hydr)oxides through a bidentate binuclear corner-sharing complex. Fe(III)-(hydr)oxides formed during Fe(II) oxidation by δ-MnO 2 were predominantly ferrihydrite and goethite as well as a small amount of lepidocrocite. The adsorbed As can be desorbed from the Fe/Mn-oxides surface, to some extent, and more As(III) is desorbed than As(V), due to the weaker binding of As(III) with Fe/Mn-oxides. This study suggests that the oxidation of As(III) by δ-MnO 2 in the presence of Fe(II) is very complex, involving several simultaneous reactions. A comprehensive understanding of the As(III) oxidation and As sorption on Mn-oxides as impacted by Fe(II) is essential and will provide significant information that can be used to better predict the toxicity and mobility of As in the environment as well as to develop strategies for remediation of As-contaminated waters and soils. Advisors/Committee Members: Sparks, Donald L..

Subjects/Keywords: Iron.; Arsenic – Oxidation.; Arsenic – Absorption and adsorption.; Manganese oxides.

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APA (6^th Edition):

Wu, Y. (2014). The effects of iron(II) on arsenic(III) oxidation and arsenic sorption/desorption on manganese oxides. (Doctoral Dissertation). University of Delaware. Retrieved from http://udspace.udel.edu/handle/19716/13455

Chicago Manual of Style (16^th Edition):

Wu, Yun. “The effects of iron(II) on arsenic(III) oxidation and arsenic sorption/desorption on manganese oxides.” 2014. Doctoral Dissertation, University of Delaware. Accessed April 17, 2021. http://udspace.udel.edu/handle/19716/13455.

MLA Handbook (7^th Edition):

Wu, Yun. “The effects of iron(II) on arsenic(III) oxidation and arsenic sorption/desorption on manganese oxides.” 2014. Web. 17 Apr 2021.

Vancouver:

Wu Y. The effects of iron(II) on arsenic(III) oxidation and arsenic sorption/desorption on manganese oxides. [Internet] [Doctoral dissertation]. University of Delaware; 2014. [cited 2021 Apr 17]. Available from: http://udspace.udel.edu/handle/19716/13455.

Council of Science Editors:

Wu Y. The effects of iron(II) on arsenic(III) oxidation and arsenic sorption/desorption on manganese oxides. [Doctoral Dissertation]. University of Delaware; 2014. Available from: http://udspace.udel.edu/handle/19716/13455

29. Cheng, Wei. Fate and transport of quinolones at iron oxides/water interface : Devenir et transport des quinolones à l'interface oxydes de fer/eau.

Degree: Docteur es, Chimie, 2019, Rennes, Ecole nationale supérieure de chimie

URL: http://www.theses.fr/2019ENCR0058

►

En raison de leur utilisation accrue, de nombreux contaminants émergents, comme les antibiotiques de type quinolone sont retrouvés dans l’environnement. Leur devenir étant fortement contrôlé… (more)

▼

En raison de leur utilisation accrue, de nombreux contaminants émergents, comme les antibiotiques de type quinolone sont retrouvés dans l’environnement. Leur devenir étant fortement contrôlé par leur interaction avec surfaces minérales, cette thèse a eu pour objectif de comprendre et prédire l’adsorption de quinolones sur des minéraux dans des conditions environnementales variées (pH, salinité, présence de cations et d’anions naturels, etc…) et de développer des modèles de transport réactif. Une approche innovante a alors été développée, combinant des données cinétiques et thermodynamiques, des mesures spectroscopiques in situ et de la modélisation de la complexation de surface. Cette thèse est divisée en deux sections. La première a eu pour but de déterminer les mécanismes de complexation de quinolones sur des oxydes de fer (goethite et magnétite) dans des conditions réduites et dans l’eau de mer. La stœchiométrie de la magnétite (Fe(II)/Fe(III)) s’est avéré être un facteur majeur de contrôle de l’adsorption de l’acide nalidixique (NA). Les effets compétitifs et coopératifs de différents ions présents dans l’eau de mer ont pu être prédits avec précision en réacteur fermé et en colonne (conditions de flux). La deuxième partie de la thèse s’est penchée sur les interactions entre goethite avec des ligands ubiquistes dans l’environnement, comme la matière organique naturelle (MON), et leur impact sur le transport de quinolones. L’adsorption de NA sur la goethite en présence et en l’absence de MON, ainsi que le fractionnement de la MON, ont été étudiés en colonne. Ces résultats pourraient permettre de mieux comprendre et prédire le devenir des quinolones dans l’environnement.

Due to their extensive use, many emerging contaminants, such as quinolone antibiotics, are released to the environment. Because their environmental fate is largely controlled by their interaction with mineral surfaces, such as iron oxides, this thesis aimed to assess quinolones adsorption onto minerals under environmental relevant conditions (pH, ionic strength, presence of ubiquitous cations and anions, etc.) and develop reactive transport models. To address these issues, an innovative approach combining kinetic and thermodynamic data, in situ spectroscopic measurements and surface complexation modeling, was proposed. This thesis manuscript consists of two parts. The first part investigated the binding mechanisms of quinolones onto iron oxides (goethite and magnetite) under reducing or seawater conditions. Considerable impact of the magnetite stoichiometry (Fe(II)/Fe(III)) on its sorption capability towards nalidixic acid has been demonstrated. Competitive and synergetic effects of different seawater ions on quinolone adsorption to goethite were accurately predicted under static and water saturated flow-through conditions. The second part investigated the interactions of goethite with naturally occurring ligands such as natural organic matter (NOM) and their impacts on the mobility/transport of quinolones. Interactions of NOM and goethite and…

Advisors/Committee Members: Hanna, Khalil (thesis director), Marsac, Rémi (thesis director), Boily, Jean-François (thesis director).

Subjects/Keywords: Quinolones; Oxydes de fer; Modélisation numérique; Quinolones; Iron oxides; Numerical Modeling

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APA (6^th Edition):

Cheng, W. (2019). Fate and transport of quinolones at iron oxides/water interface : Devenir et transport des quinolones à l'interface oxydes de fer/eau. (Doctoral Dissertation). Rennes, Ecole nationale supérieure de chimie. Retrieved from http://www.theses.fr/2019ENCR0058

Chicago Manual of Style (16^th Edition):

Cheng, Wei. “Fate and transport of quinolones at iron oxides/water interface : Devenir et transport des quinolones à l'interface oxydes de fer/eau.” 2019. Doctoral Dissertation, Rennes, Ecole nationale supérieure de chimie. Accessed April 17, 2021. http://www.theses.fr/2019ENCR0058.

MLA Handbook (7^th Edition):

Cheng, Wei. “Fate and transport of quinolones at iron oxides/water interface : Devenir et transport des quinolones à l'interface oxydes de fer/eau.” 2019. Web. 17 Apr 2021.

Vancouver:

Cheng W. Fate and transport of quinolones at iron oxides/water interface : Devenir et transport des quinolones à l'interface oxydes de fer/eau. [Internet] [Doctoral dissertation]. Rennes, Ecole nationale supérieure de chimie; 2019. [cited 2021 Apr 17]. Available from: http://www.theses.fr/2019ENCR0058.

Council of Science Editors:

Cheng W. Fate and transport of quinolones at iron oxides/water interface : Devenir et transport des quinolones à l'interface oxydes de fer/eau. [Doctoral Dissertation]. Rennes, Ecole nationale supérieure de chimie; 2019. Available from: http://www.theses.fr/2019ENCR0058

Colorado State University

30. Daugherty, Ellen E. Role of organic matter chemistry in iron redox transformations, sorption to iron oxides, and wetland carbon storage, The.

Degree: PhD, Chemistry, 2018, Colorado State University

URL: http://hdl.handle.net/10217/191354

► Organic carbon comprises a versatile and complex class of compounds that influence water quality, soil health, fate and transport of environmental contaminants, biogeochemical cycles, and… (more)

▼ Organic carbon comprises a versatile and complex class of compounds that influence water quality, soil health, fate and transport of environmental contaminants, biogeochemical cycles, and climate change. Key to predicting the responses of these systems and processes to environmental change is a molecular-level understanding of how organic carbon reacts with other components of soil and water. Yet due to its complexity and that of the systems in which it is found, organic carbon dynamics remain poorly understood. In both terrestrial and aquatic environments, the reactivity and biological necessity of iron and carbon link the biogeochemical cycling of these elements. Complexation of iron by dissolved organic carbon molecules alters its solubility and oxidation-reduction behavior and may explain the persistence of reduced iron (Fe(II)) in oxic aquatic environments. By examining the coordination environment of Fe(II) complexed by dissolved organic matter (DOM) and evaluating the effects of complexation on Fe(II) oxidation, I determined that the majority of Fe(II)–DOM complexes were characterized by coordination with citrate-like ligands, which were unlikely to inhibit oxidation by molecular oxygen. Nonetheless, association with reduced organic matter could extend the lifetime of Fe(II) in oxic environments by several hours. In soils and sediments, iron minerals act as effective sorbents of organic matter, preserving substantial amounts of carbon from microbial decomposition. These interactions have increasingly been recognized as important components of carbon sequestration, yet the effects of temperature on sorption behavior remain unknown. Through several batch and continuous flow experiments, I demonstrated a positive relationship between temperature and sorption of DOM on iron oxide surfaces. The temperature sensitivity of sorption behavior varied among riverine, peat, and soil DOM types, with riverine natural organic matter sorbing and desorbing the most at all temperatures. Analyses of effluents also revealed preferential sorption of aromatic compounds during the initial stages of sorption. In soils, organic matter quantity and composition are determined primarily by the balance between plant productivity and microbial decomposition, which are in turn dependent upon climate, temperature, hydrology, nutrient availability, and soil composition. Wetlands store disproportionately large amounts of carbon, yet the processes controlling storage are poorly understood. I investigated how different environments created by the hydrology and geomorphic setting of two wetland types, depressional and slope, impacted soil organic carbon storage and composition. Results showed a prevalence of aliphatic structures in depressional wetlands, especially in deeper soils, suggestive of anaerobic decomposition processes. By comparison, carbon in slope wetlands was dominated by labile plant carbohydrates in surface soils and aromatic compounds at depth, a likely indication of less anaerobic conditions. These results demonstrate divergent… Advisors/Committee Members: Borch, Thomas (advisor), Barisas, George (committee member), Conant, Richard (committee member), Neilson, James (committee member).

Subjects/Keywords: iron oxides; organo-mineral associations; wetlands; organic matter; carbon cycling; temperature

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APA (6^th Edition):

Daugherty, E. E. (2018). Role of organic matter chemistry in iron redox transformations, sorption to iron oxides, and wetland carbon storage, The. (Doctoral Dissertation). Colorado State University. Retrieved from http://hdl.handle.net/10217/191354

Chicago Manual of Style (16^th Edition):

Daugherty, Ellen E. “Role of organic matter chemistry in iron redox transformations, sorption to iron oxides, and wetland carbon storage, The.” 2018. Doctoral Dissertation, Colorado State University. Accessed April 17, 2021. http://hdl.handle.net/10217/191354.

MLA Handbook (7^th Edition):

Daugherty, Ellen E. “Role of organic matter chemistry in iron redox transformations, sorption to iron oxides, and wetland carbon storage, The.” 2018. Web. 17 Apr 2021.

Vancouver:

Daugherty EE. Role of organic matter chemistry in iron redox transformations, sorption to iron oxides, and wetland carbon storage, The. [Internet] [Doctoral dissertation]. Colorado State University; 2018. [cited 2021 Apr 17]. Available from: http://hdl.handle.net/10217/191354.

Council of Science Editors:

Daugherty EE. Role of organic matter chemistry in iron redox transformations, sorption to iron oxides, and wetland carbon storage, The. [Doctoral Dissertation]. Colorado State University; 2018. Available from: http://hdl.handle.net/10217/191354

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Open Access Theses and Dissertations