Master of Science, Miami University, 2023, Geology and Environmental Earth Science

Goethite (α-FeOOH) is an iron-oxyhydroxide mineral that is commonly found in soils and is of importance within the context of industrial mineralogy and aqueous geochemistry. The structure of goethite is such that vacant rows of octahedral sites form “channels” or micropores within the structure. This study aims to investigate the role these “channels” have in distributing the force induced by dynamic shock compression. Shock compression of synthetic goethite powdered samples were achieved by using an inverted shock microscope and laser driven flyer plates. With this set-up a high-energy laser shoots small aluminum discs at high velocity towards the sample causing compression upon impact. In this experiment, 25 µm aluminum flyer plates with 3.5 km/s impact velocities were used. This resulted in the production of planar shock waves of 5 ns duration in the target goethite. Subsequent investigations of the experimental change via TEM documented that crystal morphology remained unchanged, and that goethite's “bird's nest” texture was maintained. Crystal lattices showed small zones of distortion shift in peaks and the formation of hematite. XRD interestingly identifies two blunt phases: goethite and magnetite. A thixotropic-like model for accompanying shock compression is proposed to account for goethites its shock resistant behavior.

Committee: Mark Krekeler (Advisor); Claire McLeod (Committee Member); Mithun Bhowmick (Committee Member) Subjects: Geology; Mineralogy

Master of Science, The Ohio State University, 2023, Aerospace Engineering

In this thesis there are two main studies. The first is an assessment of the role of mineral composition for Air Force Research Laboratory Test Dust (AFRL) for deposition in a realistic gas turbine engine environment. The second is an attempt to recreate Arizona Road Dust (ARD) synthetically by analyzing the chemical components of the natural dust and blending synthetic minerals together to match it. In the first study, experiments were performed on an effusion cooling test article with a coolant flow temperature of 894K and surface temperature of 1144K. Aerosolized dust with a 0-10 µm particle size distribution was delivered to the test article. The mineral recipe of AFRL was altered such that the presence of each of the five components ranged from 0% to 100%. For each of these AFRL recipe experiments several results were reported including capture efficiency, hole capture efficiency, mass flow reduction per gram, and normalized deposit height. Results are compared to a previous study of the inter-mineral synergies in an impingement cooling jet at the same temperature conditions. Despite differences in experimental facility flow geometry, overall agreement was found between the trends in deposition behavior of the dust blends. The strong deposition effects that were observed were shown to be related to adhesion forces of particles, mechanical properties, and chemical properties of the dust minerals. In the second study, X-Ray Diffraction (XRD) was performed on ARD to identify minerals present in a naturally sourced dust blend. Pure minerals were mixed in quantities that matched the XRD spectrum of ARD, and oxide content of this synthetic dust blend was shown to match the ISO standard (12103-1) to which ARD conforms. Particle size distribution was also matched to ARD (0-15 µm). Experiments were then conducted in four deposition facilities, one of which was representative of turbine hot section conditions (1500-1625K) and two were representative of internal coola (open full item for complete abstract)

Committee: Datta Gaitonde (Committee Member); Jeffrey Bons (Advisor) Subjects: Aerospace Engineering

BS, Kent State University, 2018, College of Arts and Sciences / Department of Earth Sciences

Abandoned coal mines are common throughout the Appalachian region of the United States as surface and underground mines. The exposed mine waste from mining operations has led to the contamination of multiple streams throughout the region with acid mine drainage (AMD). The AMD at these sites is caused by the oxidation of the iron sulfides (pyrite, mracasite, etc.) within the coal mine waste. Associated with the AMD, heavy metals and metalloids such as As, Se, Co, Cd, Ni, Mn, Mg, Pb, and Zn are released into these streams. These can lead to associated water quality issues for drinking water and local environments near abandoned coal mine sites.The research conducted here seeks to better define the nature of the iron sulfides in coal mine waste and to demonstrate a method to observe and analyze the mineralogical transformations of iron oxides from ferrihydrite to hematite that occur in AMD settings at abandoned coal mines in the Huff Run Watershed. We use a combination of x-ray diffraction (XRD) and scanning electron microscopy (SEM) to determine the mineralogical differences between the coal shale parent material and the soils developing on the coal mine waste, the crystal form of the iron sulfides within the coal shale parent material, and the mineralogical transformations of the subsequent iron oxides as a result of dry heating. We determine that pyrite is not a primary constituent of the bulk mineralogical phases picked up by XRD in the the soils developed on the coal mine spoil although present as a bulk mineral phase in the coal shale parent material, and the method of dry heating iron oxides to simulate the mineralogical transformations over time is hindered by a persistence of ferrihydrite at high temperature ranges. From this, implications on the rate of oxidation of pyrite in these soils and the release of heavy metals and metalloids can be further inferred.

Committee: David Singer Dr. (Advisor); Alison Smith Dr. (Committee Member); Christopher Fenk Dr. (Committee Member); Elizabeth Herndon Dr. (Committee Member) Subjects: Environmental Geology; Environmental Science; Geology

Master of Science, The Ohio State University, 2017, Environment and Natural Resources

This study utilized atomic force microscopy (AFM) to study single-molecule interactions between hematite-binding peptides and a hematite-coated surface. The goal of this study was to investigate the relationship between amino acid sequence and peptide affinity for hematite (α-Fe2O3), with a focus on the influence of serine versus threonine residues in a peptide sequence. Data from these single molecule binding experiments suggest that substituting serine with threonine in a hematite-binding peptide increases peptide affinity for a hematite surface. Molecular dynamics (MD) simulations, carried out by our collaborators, were done in parallel with the single molecule binding experiments to model how two serine to threonine substitutions would alter how peptides bound to a hematite matrix. The results of these MD simulations agree with the trends from our single molecule experiments and support the conclusion that replacing serine residues with threonine residues increases peptide affinity for hematite. These findings could be utilized to improve existing biotechnology, including biological fuel cells, biosensing, solar energy production, and medical treatment in humans.

Committee: Brian Lower PhD (Advisor); Steven Lower PhD (Committee Member); Michael Wilkins PhD (Committee Member); Deric Learman PhD (Committee Member) Subjects: Biophysics

Doctor of Philosophy, The Ohio State University, 1984, Graduate School

Committee: Not Provided (Other) Subjects: Engineering

Doctor of Philosophy, The Ohio State University, 2015, Civil Engineering

Lead is a common and very toxic contaminant in the environment. Consumption of lead by children can cause irreversible harm to the brain and central nervous system. It is crucial to understand the behavior of lead in the environment in order to protect the population from coming to harm. Colloidal iron oxide particles and organic acids are ubiquitous in the natural environment. In combination and independently, they play an important role in the fate of lead and other heavy metal contaminants. Lead can adsorb onto the surface of the particles and remain mobile as the small particles do not settle out of suspension. Organic acids can adsorb on the surface of the mineral particles changing their surface charge, stability and reactivity as well as interacting with lead in solution. It is therefore important to understand the interactions of organic acids and colloidal particles with and without lead in order to fully understand the fate of lead in the environment. Throughout this project, the iron oxide hematite was used as the adsorbent mineral phase. In the first chapter, we investigated the adsorption mechanisms that bond the common organic acid, citric acid, to the hematite surface using batch adsorption, Fourier transform infrared spectroscopy (FTIR), and molecular modeling and surface complexation modeling (SCM). All of the methods used indicated that the dominant adsorption mode is as an outer-sphere complex that changes protonation state with pH, going from singly protonated at low pH to deprotonated at higher pH conditions. There was also evidence of an inner-sphere bidentate complex at low pH. In Chapter 3, the adsorption of lead on bare hematite particles and single crystal surfaces was examined using two synchrotron based X-ray techniques, extended X-ray adsorption fine structure (EXAFS), on particles, and X-ray reflectivity (XR) on single crystal surface with a known surface exposed. The results of the two techniques confirm that lead adsorbs (open full item for complete abstract)

Committee: John Lenhart PhD. (Advisor); Heather Allen PhD. (Committee Member); Yu-Ping Chin PhD. (Committee Member); Linda Weavers PhD. (Committee Member) Subjects: Environmental Engineering

PhD, University of Cincinnati, 2007, Engineering : Chemical Engineering

The first part of this thesis encompasses fundamental studies on the attachment and growth of biofilms onto synthetic non adsorbing, macroporous solid foams aiming at supporting bioactive microorganisms in the removal of intricate hydrogen sulfide polluted airstreams in trickle bed columns at negligible pressure drop. A new theoretical model that predicts the performance of biofilters packed with non adsorbing, macroporous media was simultaneously developed based in the distribution of the fouled airstream within the porous media and around it, so that the geometric properties of the packing media can be chosen as to maximize the amount of air passing within the media where most microorganisms are located. During the experimental phase of this study, colonization of such non adsorbing, macroporous media with microorganisms was enhanced by the addition of positively charged, polymeric coatings which increase the attachment and spreading of the biofilms due to cell binding and electrostatic charge cancellation at physiological pH. Impedimetric tests using golden microelectrodes were applied separately to corroborate such results, and other cofactors reported in the Literature for the attachment of animal cells onto plastic surfaces were tested with the methodology. The use of such cofactors for biofilm attachment purposes and the impedimetric tests for the determination of the kinetics of the biofilm morphology development based in the transient change of observables such as resistance and capacitance, are the first attempts on such approaches to date. In the second part of this thesis, the macroporous, non adsorbing foams were replaced by adsorbing, reactive units of similar geometric properties but containing iron (III) (oxy)(hydr)oxides operating as adsorption towers and trickle bed biofilters. The abiotic H2S removal capability of such iron bearing media was found to be enhanced by dripping water down the bed, which allowed for complete elimination of the sulfide (open full item for complete abstract)

Committee: Dr. Rakesh Govind (Advisor) Subjects:

Doctor of Philosophy, The Ohio State University, 2008, Civil Engineering

Numerous naturally-occurring organic acids (low- or high-molecular weight organic acids) are commonly found in the natural environment, often at significant concentrations. These acids adsorb strongly to mineral surfaces and affect the fate and transport of contaminants and nutrients as well as other basic biogeochemical processes (e.g., mineral dissolution). An accurate assessment of the impact the adsorbed organic acid has on these processes hinges on developing, at the molecular-level, an understanding of the interactions occurring at the mineral-water interface. The objectives of this investigation were 1) to evaluate how differences in the molecular structure of organic acids can affect adsorption behavior at the mineral-water interface as a function of environmental conditions; 2) to develop a surface complexation modeling strategy to successfully integrate the molecular-level information with observations made at the macroscopic results; 3) to elucidate how competitive interactions between multiple organic acids and the mineral-water interface alters adsorption behavior in advective systems. To meet these objectives, a systematic investigation of the adsorption of four low- molecular weight (LMW) dicarboxylic acids (phthalic acid, maleic acid, succinic acid, and fumaric acid) on the hematite surface was performed. These acids were chosen to determine the influence of simple structural differences, in particular the orientation of the carboxylic groups, on adsorption. Results are presented for a variety of systems studied using traditional equilibrium batch adsorption experiments, in-situ attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), theoretical molecular orbital calculations, potentiometric titration experiments, surface complexation models (SCMs), and column experiments. From the batch adsorption experiment, it was found that the orientation of the carboxylic groups in each dicarboxylic acid and their pKa values signific (open full item for complete abstract)

Committee: John Lenhart PhD (Advisor); Harold Walker PhD (Committee Member); Linda Weavers PhD (Committee Member); Nicholas Basta PhD (Committee Member) Subjects: Environmental Engineering; Environmental Science; Geochemistry