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Woods, Matthew P.Activity and Selectivity in Oxidation Catalysis
Doctor of Philosophy, The Ohio State University, 2008, Chemical Engineering

In oxidation catalysis, a fine balance must be struck between catalyst activity and selectivity. The existence of complex networks of reactions involving oxygen can prove difficult to deal with and obtaining high activity in the desired reaction without undesired consecutive or parallel reactions is a major challenge. This research investigates the challenges associated with achieving high activity and selectivity in the oxidative dehydrogenation of ethane and the preferential oxidation of carbon monoxide in hydrogen rich streams.

Worldwide production of olefins exceeds that of any other chemicals and constitutes a sizable fraction of total petrochemical production. Traditional methods of olefin production require high temperatures, high energy input and are also limited by coke deposition and thermodynamic considerations. Oxidative dehydrogenation (ODH) is an alternate method of olefin production and does not suffer from the drawbacks of traditional methods. The major drawback of ODH is selectivity control. The olefin produced can easily react with oxygen to form the undesired combustion products CO2 and H2O.

In this work, the use of N2O as oxidant, rather than O2, in ethane ODH was investigated. A 10%Mo/Si:Ti catalyst was tested for ethane oxidative dehydrogenation (ODH) activity using either O2 or N2O as the oxidant. Ethane ODH activity was tested at contact times varying from 0.46 to 1.0 mg s cm-3. N2O gives superior ethylene selectivities at a given ethane conversion outperforming oxygen at all contact times tested. Ethylene selectivities decrease with contact time at a far slower rate when using N2O as the oxidant. XPS experiments demonstrate that molybdenum in the catalyst is fully oxidized to Mo(VI) during ethane ODH using O2 while the reduction state decreases to an average of +5.8 when using N2O as the oxidant. Temperature programmed oxidation experiments of pre-reduced 10%Mo/Si:Ti were carried out at different temperature ramp rates. The activation energy of reoxidation when using N2O is 98 kJ/mol while that of O2 is 41 kJ/mol leading to a reoxidation rate of at least 1700 times faster when O2 is the oxidant. This difference in rates accounts for the less oxidized state of molybdenum during ethane ODH with N2O and explains the behavior observed during reaction experiments. The concept of site isolation provides a satisfactory framework for understanding the steady state reaction results. Some carbon deposition was observed when using N2O as oxidant during ethane ODH as determined from post ODH TPO and XPS experiments but it did not affect ODH activity.

Proton exchange membrane (PEM) fuel cells promise to be clean and efficient alternatives to combustion of fuels for power generation. Unfortunately, the catalysts used in PEM anodes are easily poisoned by trace amounts of carbon monoxide. Reduction of the carbon monoxide concentration to a level of approximately 10 ppm is currently necessary to prevent this poisioning. Preferential oxidation of carbon monoxide (PROX) offers an economic and simple method of CO removal but in high concentrations of hydrogen maintaining a high catalyst activity and selectivity simultaneously can be problematic due to unselective H2O oxidation and CO methanation.

This work demonstrates the preparation of a 10%CoOx/CeO2 catalyst that is highly effective for the preferential oxidation of carbon monoxide in a hydrogen rich feed. The CoOx/CeO2 catalyst had a high surface area of 78m2/g and was able to maintain a near 100% CO conversion while maintaining a selectivity of 58% during PROX experiments in high concentrations of hydrogen. The catalyst is able to obtain high CO conversions under a wide range of weight hourly space velocities. Introducing H2 into the feed has a negative effect on the CO consumption rate and decreases O2 selectivity to CO2. This shows that the reaction rates for CO oxidation and H2 combustion are not independent and suggests that hydrogen may competitively adsorb on sites responsible for CO oxidation. Separate H2 and CO oxidation experiments give activation energies of 74 and 52 kJ/mol, respectively. Additionally, the preexponential factor for H2 is 25 times higher than that for CO under the reaction conditions employed. It is possible that there are more sites available for H2 oxidation but this reaction requires high temperatures to occur at appreciable rates. Temperature programmed PROX reaction experiments show three temperature regions where different reactions are important. Below 175°C, CO oxidation is dominant but above this temperature, CO oxidation and H2 combustion compete with one another. The temperature necessary to obtain high activity in the PROX reaction occur near this transition at 175°C. At even higher temperatures, irrelevant to the PROX reaction, methanation begins to occur. Raman spectroscopy and X-ray diffraction experiments have demonstrated that the cobalt takes the form of Co3O4 and no CoO was detected under any experimental conditions.

Committee:

Umit Ozkan (Advisor); Jeffrey Chalmers (Committee Member); James Rathman (Committee Member)

Subjects:

Chemical Engineering

Keywords:

oxidative dehydrogenation; ODH; molybdenum; silica; titania; nitrous oxide; N2O; reoxidation; site isolation; temperature programmed oxidation; TPO; preferential CO oxidation; PROX; cobalt; ceria; Co3O4; CeO2; H2 oxidation; TPR

ZHANG, HAOELECTROCHEMICAL DEGRADATION OF 4-CHLOROPHENOL
MS, University of Cincinnati, 2006, Engineering : Environmental Engineering
In this study, an electrochemical reactor was used to investigate the degradation of 4-chlorophenol at neutral pH for studying the impact of three key parameters (initial concentration, ionic strength, and applied current) on the destruction process. A cathodic reduction of 4-chlorophenol was not practical because water splitting was the dominant reaction mechanism. Anodic oxidation of 4-chlorophenol was then investigated. The applied current ranged from 50mA to 350mA (14.75mA/cm 2to 103.24mA/cm 2), four initial concentrations (25ppm, 50ppm, 100ppm, and 200ppm), and three ionic strengths (0.5M, 1.0M, and 1.5M) were studied. Two oxidation modes, direct and combined (direct plus indirect) oxidation, were studied. Na 2SO 4was used as electrolyte in direct oxidation, and NaCl was used in combined oxidation. Direct oxidation was found to follow saturation reaction model, while combined oxidation followed Pseudo first order kinetics. For combined oxidation, the reaction rate constant increased with applied current up to 300mA (88.5mA/cm 2) and then started to drop afterward. Over 99% removal of 4-chlorophenol within 6hrs in combined oxidation and was much faster and effective than direct oxidation.

Committee:

Dr. George Sorial (Advisor)

Subjects:

Engineering, Environmental

Keywords:

4-chlorophenol(4CP); electrochemical; anode oxidation; cathode reduction; direct oxidation; combined oxidation

Wang, XiaoInvestigation of Anaplerosis from Propionyl-CoA Precursors and Fatty Acid Oxidation in the Brain of VLCAD and Control Mice
Doctor of Philosophy, Case Western Reserve University, 2009, Nutrition

Anaplerotic therapy with triheptanoin is currently investigated for the treatment of long-chain fatty acid oxidation disorders. The recently developed mouse model deficient in very long-chain acyl-CoA dehydrogenase (VLCAD mouse) provides a good tool to study anaplerotic therapy in vivo. The goal of this research was to characterize brain fatty acid oxidation and to test the effect of anaplerotic therapy on brain metabolism in VLCAD mice and their controls. First, concentrations of major acyl-CoA esters (C2-C20) were profiled in the brain of VLCAD and control mice. The data indicated significant reductions of acetyl-CoA, methylmalonyl-CoA, propionyl-CoA, butyryl-CoA, hexanoyl-CoA and octanoyl-CoA in VLCAD brains vs. controls. The data also revealed clear evidence of long-chain fatty acid oxidation defect suggested by the accumulations of stearoyl-CoA (C18:0-CoA) and linoleoyl-CoA (C18:2-CoA) in VLCAD brains vs. controls.

Second, concentrations of major citric acid cycle intermediates and related neurotransmitters (glutamate, glutamine, GABA) in the whole brain were found lower in VLCAD mice vs. control mice, with three significant decreases identified (α-ketoglutarate, glutamate, and GABA). These reductions implicated a compromised pool size of the citric acid cycle intermediates which possibly lead to abnormalities in the brain of VLCAD mice.

Last, VLCAD and control mice were infused intravenously with increasing amounts of odd-chain fatty acids or C5 ketone body (heptanoate, pentanoate, β-ketopentanoate or propionate). Other mice of the two genotypes were infused with non-anaplerotic octanoate. The concentration and labeling pattern of medium-chain acyl-CoAs demonstrated that the C8, C7, and C5 fatty acids were taken up by the brain and activated to form CoA esters. The odd-chain fatty acids infused were metabolized via the β-oxidation cascade and contributed to a substantial fraction of acetyl-CoA in mice brains of both genotypes. Ketone bodies derived from partial oxidation of infused fatty acids in the liver also contributed to the brain acetyl-CoA. All odd-chain fatty acids or C5 ketone body infused (heptanoate, pentanoate, and propionate) were strongly anaplerotic at low blood concentrations, and more so in VLCAD brains than in control brains. A fraction of anaplerosis from the odd-chain fatty acids involved their conversions in the liver to C5-ketone bodies which were also anaplerotic in the brain.

In conclusion, data of the present research revealed that medium-chain fatty acids enter the brain as such, where they are metabolized by the fatty acid oxidation cascade. Odd-chain fatty acids and C5-ketone bodies of propionyl-CoA precursors contribute to brain anaplerosis rapidly in normal mouse brains, and even more rapidly in VLCAD brains. In VLCAD brains the long-chain fatty acid oxidation occurs by a vicariant enzyme system to be identified.

Committee:

Henri Brunengraber, MD, PhD (Advisor); Jonathan Whittaker, MD (Committee Chair); Colleen Croniger, PhD (Committee Member); Janos Kerner, PhD (Committee Member); Stephen Previs, PhD (Committee Member)

Subjects:

Biochemistry; Biology; Biomedical Research; Nutrition

Keywords:

GC-MS; LC-MS; FOD; fatty acid oxidation; fatty acid oxidation disorders; VLCAD; very-long-chain fatty acid oxidation disorders; very-long-chain acyl-CoA dehydrogenase; anaplerosis; brain; triheptanoin; anaplerotic therapy; glutamate; glutamine; GABA

Yang, YuqingElectrochemical and Surface-enhanced Raman Spectroscopic Studies of CO and Methanol Oxidation
Master of Science, Miami University, 2008, Chemistry
Molecular level information for carbon monoxide and methanol electrooxidation is provided by in situ surface-enhanced Raman spectroscopy (SERS) in this work for better understanding the mechanism of CO and methanol electrooxidation on transition metals. Electrooxidation of CO and methanol on transition metals are studied by cyclic voltammetry and in situ SERS. Thickness effect of overlayer metals on CO adsorption and oxidation activity is studied and explained by the strain effect and ligand effect. The cumulative effect for CO oxidation on Pd is the positive shift of CO oxidation peak position. Both the strain effect and ligand effect cause the negative shift of CO oxidation on Pt. Methanol electrooxidation on Ru is demonstrated by the C-O stretching band from COads on Ru oxide in SER spectra, which suggests that at higher potentials methanol oxidation on Ru sites needs to be taken into account in the catalytic mechanism of Pt-Ru catalysts in the direct methanol fuel cell.

Committee:

Shouzhong Zou (Advisor); James Cox (Committee Chair); Neil Danielson (Committee Member); Benjamin Gung (Committee Member)

Subjects:

Chemistry

Keywords:

CO oxidation; methanol oxidation; electrochemistry; SERS

Sander, Zachary HugoHeat Transfer, Fluid Dynamics, and Autoxidation Studies in the Jet Fuel Thermal Oxidation Tester (JFTOT)
Master of Science (M.S.), University of Dayton, 2012, Mechanical Engineering
Modern military aircraft use jet fuel as a coolant before it is burned in the combustor. Prior to combustion, dissolved O2 and other heteroatomic species react with the heated fuel to form insoluble particles and surface deposits that can impair engine performance. For safe aircraft operation, it is important to minimize jet fuel oxidation and resultant surface deposition in critical aircraft components. The Jet Fuel Thermal Oxidation Tester (JFTOT) is a thermal stability test that measures the tendency for fuel to form such deposits and delivers a pass/fail grade for each fuel tested. However, the extent of oxidation and the corresponding deposition occurring in the JFTOT is not fully understood. A JFTOT Model Mark II was modified to include a bulk outlet thermocouple measurement and a downstream oxygen sensor to measure bulk oxygen consumption. Experimental results show a direct relationship between the bulk outlet temperature and JFTOT setpoint temperature with the bulk outlet less than the setpoint temperature. Several fuels were also tested at varying setpoint temperatures with complete oxygen consumption by 320°C and a wide range of oxygen consumption from 10-85% at 260°C. Due to the complex fluid flows in the JFTOT, computational fluid dynamics (CFD) was used to model the heat transfer and fluid flow. A three-dimensional simulation showed considerable recirculation within the JFTOT due to buoyancy effects from gravity and resulted in complex residence time behavior. In addition, CFD simulations performed with a pseudo-detailed chemical kinematic mechanism showed an under prediction in both oxidation and deposition for similar fuels tested experimentally but yielded bulk outlet temperature predictions of less than 2% error. Simulations of deposition were of the right order of magnitude and matched the deposit profile of comparable experimental ellipsometry data.

Committee:

Steven S. Zabarnick, PhD (Committee Co-Chair); Jamie S. Ervin, PhD (Committee Co-Chair); James T. Edwards, PhD (Committee Member)

Subjects:

Aerospace Engineering; Chemical Engineering; Chemistry; Energy; Engineering; Fluid Dynamics; Mechanical Engineering; Petroleum Engineering

Keywords:

JFTOT;CFD; heat transfer; oxidation; autoxidation; deposition; ellipsometry; jet fuel thermal oxidation tester; oxygen consumption; FT; fischer tropsh; hrj; jp-8; jet a-1; thermal stability; fluid mechanics; astm d3241; flir; interferometry; udri

Farkas, NataliaSCANNING PROBE MICROSCOPE OXIDATION AND HIGH-VOLTAGE PARALLEL WRITING ON METAL AND METAL NITRIDE THIN FILMS
Doctor of Philosophy, University of Akron, 2006, Chemistry
Systematic investigation of the scanning probe microscope (SPM) oxidation of transition metal and metal nitride thin films is presented. An extensive range of process and material specific parameters such as exposure time, voltage, humidity and nitrogen content of the sputtering plasma are investigated. During the intrinsic part of the SPM oxidation of ZrN, the density of the oxide increases until the total oxide thickness is approximately twice the feature height. Further oxide growth is sustainable, and in fact faster yet controlled, as the system crosses over from the space charge limited to a nitrogen-enhanced growth regime. Selective etching of the oxides and nitrides lead us to propose that as the oxidation reaches the ZrN/silicon interface delamination occurs resulting in hollow oxide feature formation through stress-induced plastic flow. Interpretations of the underlying processes and film properties responsible for the unique behavior of ZrN in all regimes are provided along with an explanation for the observed non-linear voltage dependence. To our knowledge, manifestation of three distinct transition points in SPM oxidation kinetics has never been reported. In addition, we exploit the nitrogen-enhanced growth of ZrN to fabricate high-voltage parallel oxide patterns 70 nm in height covering areas in the square centimeter range. The nitrogen-to-oxygen conversion is verified by Auger microprobe analysis. To show the versatility of the inherently simple high-voltage parallel writing technique, we demonstrate pattern transfer onto 15-100 nm thick FeN films. As opposed to ZrN, the iron oxide dissolves during the process fully exposing the substrate beneath and therefore eliminating the need for any post-exposure etching. This comparison is of fundamental interest in that Zr oxidation is driven by oxygen migration, whereas Fe oxidizes by metal ion transport. Implication of the use of patterned ZrN and FeN thin films for biomedical and magnetic applications are also discussed. In particular, with precisely controlled height and methodically designed lateral size, the synthetic FeN arrays are potential candidates for MRI sensitivity and resolution measurements.

Committee:

Rex Ramsier (Advisor)

Keywords:

ZrN; SPM; sccm; SPM oxidation; oxide feature; OXIDATION; oxide

Daramola, Oludamilola A.Theoretical Characterization of Ammonia Oxidation Species on Platinum Clusters
Doctor of Philosophy (PhD), Ohio University, 2011, Chemical Engineering (Engineering and Technology)

Ammonia oxidation is being considered as a viable technology for hydrogen production for use in fuel cells. This study was undertaken to gain insight into current issues related to catalytic inactivity with time. Density Functional Theory was used in modeling the chemical species present during ammonia oxidation: NHx (x = 0 - 3), OHy (y = 1 & 2) and N2Hz (z = 0 - 4) and the adsorption of these molecules on the surface of platinum clusters. Using comparison with experimental measurements where possible, it was found that the strength of adsorption for these molecules followed this trend: N2 < H2O < NH3 < N2H2 < N2H4 < N2H < N2H3 < OH < NH2 < NH < N. This suggests that the species present towards the right of this spectrum were especially relevant to surface blockage and could play a role in catalytic inactivity.

In addition, the formation and oxidation of the N2Hz molecules could possibly be tracked by spectrochemical analysis of the position of the N - N bond, which went from single (N2H4) to double (N2H2) to triple (N2) as the oxidation of ammonia progressed. The presence or absence of this peak is an indicator of the orientation of the molecule formed and an indicator of the progress of the reaction.

Finally, an exploratory investigation of a mechanism of ammonia oxidation, where ammonia is deprotonated in successive steps, predicted that the conversion of the imide radical to nitrogen, although thermodynamically favorable, exhibits slow kinetics in comparison to deprotonation of ammonia or amidogen

Committee:

Gerardine Botte, PhD (Advisor); Howard Dewald, PhD (Committee Member); Daniel Gulino, PhD (Committee Member); Nancy Sandler, PhD (Committee Member); Valerie Young, PhD (Committee Member)

Subjects:

Chemical Engineering

Keywords:

Ammonia Adsorption; Ammonia Catalysis; Ammonia Oxidation Mechanism; Ammonia Oxidation Thermodynamics; Density Functional Theory Methods; Hydrogen Production

Chen, Meng-HsienA STUDY OF SELECTIVE SURFACE AND INTERNAL OXIDATION OF ADVANCED HIGH STRENGTH STEEL GRADES
Doctor of Philosophy, Case Western Reserve University, 2014, Materials Science and Engineering
Advanced high-strength steels (AHSS) have been widely used in automotive industry to improve safety and fuel economy. However, unintentional selective oxidation of alloying elements of AHSS during the thermal cycles employed on a continuous galvanizing line (CGL) complicates the coating process. Amongst the observed effects, external oxides can cause incomplete reactive wetting, resulting in bare spot defects in the zinc coating. This study focuses on developing and validating &#x201c;oxidation maps&#x201d; to define regions of selective oxidation for alloying elements in PO2-T space. Oxidation maps use CALPHAD method in combination with the Wagner&#x2019;s model to determine regions where no oxidation, internal oxidation or external oxidation will occur. Experiments were carried out in an attempt to validate the predictions. Three types of AHSS grade steels, with variation in Mn, Si, Al contents, were used for experiments to validate the oxidation maps. Samples of selected steels were subjected to four different simulated CGL thermal cycles with two heating rates and two hold times, that bracket much of the range expected in industrial practice. Experiments were also undertaken for two of the steels under much higher dew point annealing conditions to probe the predicted boundary between external and internal oxidation. Samples were characterized by SEM, AES, XPS, and TEM to determine the oxide phases as well as the oxidation modes. Analysis results demonstrated that the formation of oxide phase on or in each steel is consistent with the thermodynamic modeling. A calculated Ellingham diagram clearly illustrates the formation sequence of oxide phases for the steels studied. For the prediction of oxidation mode, the oxidation maps are generally consistent with the analysis result. Inconsistency was observed only in one circumstance, and this is attributed to the highly heterogeneous surface caused by cold rolling. Otherwise, a kinetic model was studied to simulate the amount of atoms diffusing across steel surface and incorporated into the oxide(s). The number of oxide particles of a given size formed on a selected area was also consistent with predictions.

Committee:

James McGuffin-Cawley (Advisor); Mark De Guire (Committee Member); Frank Ernst (Committee Member); Jay Mann, Jr. (Committee Member)

Subjects:

Automotive Materials; Engineering; Materials Science; Metallurgy

Keywords:

CALPHAD; AHSS; advanced high strength steel; selective oxidation; oxidation map; CGL; galvanizing

Singh, RahulElectrochemical and Partial Oxidation of CH4
Doctor of Philosophy, University of Akron, 2008, Chemical Engineering
Hydrogen has been the most common fuel used for the fuel cell research but there remains challenging technological hurdles and storage issues with hydrogen fuel. The direct electrochemical oxidation of CH4 (a major component of natural gas) in a solid oxide fuel cell (SOFC) to generate electricity has a potential of commercialization in the area of auxiliary and portable power units and battery chargers. They offer significant advantages over an external reformer based SOFC, namely, (i) simplicity in the overall system architecture and balance of plant, (ii) more efficient and (iii) availability of constant concentration of fuel in the anode compartment of SOFC providing stability factor. The extreme operational temperature of a SOFC at 700-1000 °C provides a thermodynamically favorable pathway to deposit carbon on the most commonly used Ni anode from CH4 according to the following reaction (CH4 = C + 2H2), thus deteriorating the cell performance, stability and durability. The coking problem on the anode has been a serious and challenging issue faced by the catalyst research community worldwide. This dissertation presents (i) a novel fabricated bi-metallic Cu-Ni anode by electroless plating of Cu on Ni anode demonstrating significantly reduced or negligible coke deposition on the anode for CH4 and natural gas fuel after long term exposure, (ii) a thorough microstructural examination of Ni and Cu-Ni anode exposed to H2, CH4 and natural gas after long term exposure at 750 °C by scanning electron microscopy, energy dispersive X-ray spectroscopy and X-ray diffraction and (iii) in situ electrochemical analysis of Ni and Cu-Ni for H2, CH4 and natural gas during long term exposure at 750 °C by impedance spectroscopy. A careful investigation of variation in the microstructure and performance characteristics (voltage-current curve and impedance) of Ni and Cu-Ni anode before and after a long term exposure of CH4 and natural gas would allow us to test the validation of a negligible coke formation on the novel fabricated anode by electroless plating process. Hydrogen is an environmentally cleaner source of energy. The recent increase in the demand of hydrogen as fuel for all types of fuel cells and petroleum refining process has boosted the need of production of hydrogen. Methane, a major component of natural gas is the major feedstock for production of hydrogen. The route of partial oxidation of methane to produce syngas (CO + H2) offers significant advantages over commercialized steam reforming process for higher efficiency and lower energy requirements. Partial oxidation of methane was studied by pulsing O2 into a CH4 flow over Rh/Al2O3 in a sequence of in situ infrared (IR) cell and fixed bed reactor at 773 K. The results obtained from the sequence of an IR cell followed by a fixed bed reactor show that (i) adsorbed CO produced possesses a long residence time, indicating that adsorbed oxygen leading to the formation of CO is significantly different from those leading to CO2 and (ii) CO2 is not an intermediate species for the formation of CO. In situ IR of pulse reaction coupled with alternating reactor sequence is an effective approach to study the primary and secondary reactions as well as the nature of their adsorbed species. As reported earlier, hydrogen remains to be the most effective fuel for fuel cells, the production of high purity hydrogen from naturally available resources such as coal, petroleum, and natural gas requires a number of energy-intensive steps, making fuel cell processes for stationary electric power generation prohibitively uneconomic. Direct use of coal or coal gas as the feed is a promising approach for low cost electricity generation. Coal gas solid oxide fuel cell was studied by pyrolyzing Ohio #5 coal to coal gas and transporting to a Cu anode solid oxide fuel cell to generate power. The study of coal-gas solid oxide fuel cell is divided into two sections, i.e., (i) understanding the composition of coal gas by in situ infrared spectroscopy combined with mass spectrometry and (ii) evaluating the performance of coal gas for power generation based on the composition on a Cu-SOFC. The voltage-current performance curve for coal gas suggests that hydrogen and methane rich coal gas performed better than CO2 or D2O concentrated coal gas. A slow rate of reforming reaction of D2O than CO2 with coal and coal gas was observed during pyrolysis reaction. The coal and coke (by-product of pyrolysis) were characterized by Raman spectrometer to reveal the effect of pyrolysis on the structural properties of coal.

Committee:

Steven Chuang, PhD (Advisor); Lu-Kwang Ju, PhD (Committee Member); George Chase, PhD (Committee Member); Jerry Young, PhD (Committee Member); Chris Miller, PhD (Committee Member)

Subjects:

Chemical Engineering

Keywords:

Solid oxide fuel cell; coking; methane; natural gas; Cu; partial oxidation; electrochemical oxidation; electroless plating

White, Colin P.Molecular Microbial Ecology and Operational Evaluation of a Full-scale and Pilot-scale Biologically Active Filter for Drinking Water Treatment
MS, University of Cincinnati, 2010, Arts and Sciences : Biological Sciences
Nitrification in drinking water distribution systems is a problem prevalent throughout the world, and it has become more pertinent since chloramination has become a popular disinfectant technique. Because nitrification requires ammonia, removing ammonia in source waters prior to treatment would benefit both the utility and consumers. Biologically active filtration is a well known technology in Europe but its reliability, and thus implementation, is questioned in the United States. In this study, natural microbial flora from a full-scale treatment plant in Greene County, Ohio was used to seed two pilot scale rapid sand filters. These filters were evaluated for their ability to oxidize ammonia-nitrogen. Molecular techniques, including 16S ribosomal RNA and amoA gene sequencing and denaturing gradient gel electrophoresis (DGGE) analysis, were used to phylogenetically identify and fingerprint the isolates. In addition to investigating nitrification, microbial arsenic oxidation was also investigated in pilot-scale filters. Chemical analysis and microbial ecology is compared and discussed in terms of operational changes and water chemistry.

Committee:

Ronald Debry, PhD (Committee Chair); Jodi Shann, PhD (Committee Member); Darren Lytle, PhD (Committee Member)

Subjects:

Microbiology

Keywords:

Biological treatment;Arsenic oxidation;Drinking water;Molecular ecology;Nitrification;Ammonia oxidation

BURBANO, ARTURO ANTONIOCHEMICAL DEGRADATION OF METHYL TERT-BUTYL ETHER (MTBE) BY FENTON REAGENT
PhD, University of Cincinnati, 2004, Engineering : Environmental Engineering
The fundamentals of the degradation of Methyl tert-Butyl Ether (MTBE) in aqueous solution using Fenton Reagent (FR) were investigated. Initial MTBE concentrations of 1.0 and 2.0 mg⁄L were treated with FR in batch reactors, in order to establish the extent of degradation and⁄or mineralization in a one-hour reaction period. The selected MTBE concentrations as well as other reaction conditions such as reduced concentrations of dissolved oxygen (DO<0.01mg⁄L) and absence of light, were used in order to simulate some of the actual conditions found in MTBE-contaminated aquifers. When using an initial [FR]:[MTBE] molar ratio of 10:1 and pH of approximately 3.0, the extent of MTBE degradation at the end of one hour was significantly higher (i.e., 90-99&per;) than its mineralization (i.e, 31.7&per;max.). Tert-butyl formate (TBF), tert-butyl alcohol (TBA), acetone and methyl acetate were identified and quantified as the major reaction intermediates. pH was a critical variable of this process. Experiments at acidic pH exhibited degradation efficiencies over 90&per; while those at neutral or close to neutral pH were below 10&per;. Additional experiments revealed that MTBE degradation efficiency peaked when FR was used as an equimolar mixture of its components. The degradation efficiency of MTBE intermediates was proportional to their values of the second order rate constant of their reaction with OH (kOH). From these studies it was also established that: (i) TBA is generated from both MTBE and TBF, (ii) acetone is formed independently from MTBE, TBF and TBA, and (iii) methyl acetate is formed exclusively from MTBE. A [FR]0:[MTBE]0 molar ratio of 20:1 was sufficient to achieve total transformation of an initial MTBE concentration of 2.0 mg⁄L, but complete MTBE mineralization was not achieved even at molar ratios as high as 200:1.

Committee:

Dr. Dionysios Dionysiou (Advisor)

Keywords:

MTBE; Fenton Reagent; chemical oxidation; Advanced Oxidation Technologies

Jose-Cunilleras, EduardoEffect of exercise and of meals of differing starch content on glucose kinetics and muscle glycogen utilization and replenishment in horses
Doctor of Philosophy, The Ohio State University, 2004, Veterinary Clinical Sciences
A combination of plasma and muscle biochemical methods, indirect calorimetry, isotopic tracer studies ([6,6-2H]glucose as constant rate infusion) and real-time reverse transcription polymerase chain reaction techniques were used to gain a better understanding of the effect of ingestion of meals of differing starch content prior to or after exercise by horses. In the first study (Chapter 3), horses were fed before exercise either (1) corn, (2) an isocaloric amount of alfalfa cubes (51.4 KJ/kg DE), or (3) not fed. The main finding was that meal type prior to exercise modestly altered substrate use during exercise such that corn feeding resulted in greater carbohydrate oxidation due to higher skeletal muscle utilization of blood-borne glucose, unchanged muscle glycogenolysis and lower whole body lipid oxidation. In the second study (Chapter 4), the glycemic response to ingestion of cereals (cracked corn, steamed oat groats or rolled barley) and intragastric administration of glucose was assessed by giving equal amounts of hydrolyzable carbohydrates. We determined that oat groats, corn and barley have similar areas under the plasma glucose concentration time curve in horses, and compared with the glycemic index of 100, these cereals were approximately 60. In the third study (Chapter 5), horses with exercise-induced muscle glycogen depletion were either not fed for 8 h, fed mixed alfalfa and grass hay (~15 Mcal, ~62 MJ DE), or fed an isocaloric amount of corn immediately and 4 h after exercise. The main findings were that corn feeding, when compared to feed withholding, resulted in mild to moderate hyperglycemia and hyperinsulinemia, and a 3-fold greater whole body availability and utilization of glucose. However, muscle glycogen replenishment was only minimally enhanced. In the last study (Chapter 6), we described the effect of glycogen-depleting exercise and of meal type after exercise (as in Chapter 5) on the insulin responsive glucose transporter (GLUT4) gene expression in skeletal muscle. We found that GLUT 4 gene expression in muscle increased by ~2-4 fold during 24 h after exercise, when compared to that prior to exercise but no differences were observed due to meal type fed after exercise.

Committee:

Kenneth Hinchcliff (Advisor)

Keywords:

horses; glucose; glycogen; muscle; carbohydrate oxidation; lipid oxidation; grains; roughage

Mattox, Mathew AllenElectrochemical and Surface-enhanced Raman Studies of CO and Methanol Oxidation in the Presence of Sub-monolayer Co-adsorbed Sulfur
Master of Science, Miami University, 2006, Chemistry
Electrooxidation of carbon monoxide (CO) and methanol on platinum are two important reactions in direct methanol fuel cells. The presence of coadsorbates often modifies the reaction significantly. In this thesis we report our studies on the effects of adsorbed sulfur on CO and methanol electrooxidation on Pt. Although adsorbed sulfur is often considered a surface poison, the cyclic voltammetric and chronoamperometric results show that the presence of a sub-monolayer of adsorbed sulfur promotes the aforementioned reactions. Surface-enhanced Raman spectroscopy, together with electrochemical results, was used to elucidate a possible mechanism of the enhancement effect.

Committee:

Shouzhong Zou (Advisor)

Subjects:

Chemistry, Analytical

Keywords:

CO; electrochemistry; surface enhanced raman; methanol oxidation; CO oxidation

Paul, Ryan MichaelModeling the Effect of Thermal Oxidation on the Pore Structure of Artificial Graphite
Doctor of Philosophy, The Ohio State University, 2011, Materials Science and Engineering

A persistent concern for applications of artificial graphite materials is loss of graphite due to thermal oxidation reactions with air or steam. Oxidation is insidious since it enlarges the inherent pores, which rapidly degrades microstructure and properties. Artificial graphites vary in their initial pore microstructure, yet the currently used 2D Random Pore Model (2D-RPM) cannot accurately predict oxidation rates from initial microstructure. Therefore, empirical methods have remained widely used to quantify oxidation rates.

This goal of this dissertation work was to predict the oxidation rates of artificial graphite during isothermal air oxidation. A new analytical 3D Random Pore Model (3D-RPM) was created to account for uniform and nonuniform oxidation. In the model, the pore microstructure is created by randomly placed spheres of initial number per unit volume and initial radius. For uniform oxidation, it is assumed that all the spheres are growing at a constant rate. For nonuniform oxidation, there is a sample size and the internal oxidation front moves in one direction at a constant rate connecting the pores as it moves inward. The front rate is presumed to be a function of initial pore microstructure. The general formulation of the nonuniform 3D-RPM can account for surface and sample size effects on oxidation and includes uniform oxidation as a special case. The model inputs can be estimated from experimental data.

This work was also the first application of a phase field model to visualize and quantify the evolution of pore microstructure in artificial graphite. The phase field model was validated with the 3D-RPM. Importantly, the phase field simulations provided the link between the model inputs and the pore clusters that form as a result of sphere overlap. Additionally, oxidation experiments were performed to investigate pore microstructure evolution and validate the models. It was found that the evolution in the number of pores in both the experiments and phase field simulations followed the exponential decay trend as predicted by percolation theory. In agreement with the 3D-RPM concepts, the application of percolation theory indicates that the pore evolution depends on initial pore number, size and uniformity of oxidation.

As an example application, the 3D-RPM was applied to experimental data from the oxidation of G-90 graphite. The model inputs were estimated from image analysis. It was found that the experimental data could be bound by model predictions when the inputs were varied within the scatter of image analysis. This is despite the fact that the 3D-RPM assumes the pores are clusters composed of spheres that the clusters do not have a broad distribution in size. The data also confirmed that the front rate was constant and can be estimated from experiments. In order to compare the initial oxidation rate slope to model predictions, the initial portion of the data was adjusted because the experimental samples were cubes and had three times the external surfaces than is assumed in the 3D-RPM. When the data was adjusted, the measured slope and predicted slope were within 5.5 per cent. The 3D-RPM was a better fit to the data than the 2D-RPM by all quantifiable measures.

Committee:

John Morral (Advisor); Jianjun Guan (Committee Member); Glenn S. Daehn (Committee Member); Charles H. Drummond, III, (Committee Member)

Subjects:

Materials Science

Keywords:

thermal oxidation; artificial graphite; nuclear graphite; pores; oxidation rate

Chen, YuminOxidation of Polymeric Polyphenols (Tannins) in Biologically Relevent Systems
Doctor of Philosophy, Miami University, 2004, Chemistry
Reactive oxygen species (ROS) are produced in human metabolic processes and uncontrolled ROS are detrimental to human health. In vitro chemical assays show that dietary tannins have potent ROS scavenging activity. My research is designed to use model systems to reveal interactions between tannins and factors (pH and protein) found in the human digestive tract where tannins work as biological antioxidants. Pentagalloyl glucose (PGG), bovine serum albumin (BSA), and NaIO4 were chosen as the model tannin, protein and oxidant, respectively. PGG was prepared from tannic acids via a methanolysis reaction. [14C]PGG was synthesized from [U-14C]-D-glucopyranose and tri-O-benzylgallic acid as a radiochemical tracer. When PGG was oxidized by NaIO4, the formation of different oxidation products was controlled by the reaction pH. PGG oxidation produced an o-semiquinone radical intermediate, which formed polymeric products at low pH (e.g. pH 2.1). The o-semiquinone radical ionized at pH > 5 and was labile to being further oxidized to o-quinone. Reaction pH similarly affected the formation of oxidation products of epicatechin16 (4→8) catechin (procyanidin) or epigallocatechin gallate (EGCG), suggesting that these three different tannins followed the same oxidation mechanism. When PGG was oxidized in the presence of BSA at various pH values, BSA promoted the formation of quinone but inhibited the formation of polymeric products. In addition to affecting PGG oxidation, BSA interacted with PGG under oxidizing conditions and formed oxidized PGG-BSA complexes. A radiochemical method was devised to quantitate oxidized PGG-BSA complexes. The complexes were treated with sodium dodecyl sulfate (SDS) to remove any non-covalently bound PGG and were co-precipitated with BSA by trichloroacetic acid (TCA) for radiochemical assessment. The molar ratio of PGG and BSA determined the solubility of oxidized PGG-BSA complexes. Soluble complexes were formed at low molar ratios (e.g. PGG/BSA=1). At high molar ratios (e.g. PGG/BSA=22), soluble complexes were rapidly converted to insoluble complexes. Besides NaIO4, 2,2’-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) radical cation (ABTS•+) and 2,2’-azobis(isobutyramidine) dihydrochloride (AAPH) were tested as oxidants. It was found that NaIO4 and ABTS•+ induced the formation of oxidized PGG-BSA complexes more rapidly than AAPH.

Committee:

Ann Hagerman (Advisor); Robert Minto (Other); Christopher Makaroff (Other); Michael Crowder (Other); Helaine Alessiio (Other)

Subjects:

Chemistry, Biochemistry

Keywords:

Polyphenol; Tannins; Hydrolyzable tannins; Tannin-protein interaction; Polyphenol-protein interaction; Polyphenol oxidation; Tannin oxidation; Antioxidant; Pentagalloyl glucose; Oxidized tannin-protein complexes; Oxidized polyphenol-protein comp

Shaw, Caitlin H. A Preliminary Investigation of Treating Metal Pollutants in Water by Slow-Release Hydrogen Peroxide
Master of Science (MS), Ohio University, 2017, Geological Sciences (Arts and Sciences)
Urban runoff can come into contact with a range of pollutants. Metal pollutants can pose an especially significant threat to water quality. This study focused on metals: Cd, Zn, Cu, Pb, Fe and Mn. These metals were chosen after previous studies reported finding them in first flush stormwater collected throughout the Midwestern US. This study tested the effectiveness of SR-HP forms to remove metals from DI water with standard solutions of metals added. Two sizes of SR-HP forms were constructed from sodium percarbonate (Na2CO3·1.5H2O2) salts and resin and release rates were quantified. The smaller size released hydrogen peroxide (H2O2) at a steady average rate of 0.063 mg/min after 6.2 hours. One proof-of-concept treatment test was conducted utilizing smaller SR-HP forms and DI water containing dissolved metals. During the treatment test, SR-HP released H2O2 and alkalinity at the rates ranging from 1.35 mM to 0.135 mM and 0.90 mM to 0.09 mM, respectively. The pH of metal loaded deionized water was raised from 1.74 to 1.87 indicating slight neutralization by added carbonate. This resulted in removal efficacies ranging from 4.17% - 0.65%, 4.52% - +0.76%, 8.59% - 2.92%, 7.44% – 0.29%, 0.52% - +2.24% for Cd, Cu, Fe, Pb and Zn respectively. No consistent treatment was evident for all metals except for iron, which saw a modest removal of 8.6%. This 8.6 removal was most likely due to Fe2+ being used during Fenton’s reaction. This result indicates effective removal by SR-HP could be feasible, especially if the pH is more alkaline. Further investigation of SR-HP form performance in a wide range of pHs could be possible.

Committee:

Eung Seok Lee (Advisor); Greg Nadon (Committee Member)

Subjects:

Analytical Chemistry; Aquaculture; Aquatic Sciences; Area Planning and Development; Chemical Engineering; Chemistry; Environmental Geology; Environmental Science; Environmental Studies; Experiments; Geology; Hydrologic Sciences; Hydrology; Organic Chemistry

Keywords:

Slow release; oxidation; stormwater; urban runoff; fentons; stormwater treatment; iron; manganese; zinc; cadmium; copper; lead; metal pollutants; treatment by oxidation; pH; Hydrogen peroxide

Muraco, Cory E.Isolation and Characterization of Oxidized Lysozyme Variants Produced by a Copper (II)/Hydrogen Peroxide Metal-Catalyzed Oxidation System
Master of Science in Chemistry, Youngstown State University, 2013, Department of Chemistry
Protein oxidation has been correlated with several chronic diseases including Alzheimer’s disease, Parkinson’s disease, and cataractogenesis. The purpose of this project was to isolate and characterize the various oxidized forms of hen egg white lysozyme that were produced by a copper(II)/hydrogen peroxide metal-catalyzed oxidation system. Five oxidized protein variants were purified using high performance liquid chromatography on a cation-exchange column. Tandem mass spectrometry determined that several amino acids were oxidized in each variant with histidine 15 being the most readily oxidized residue. Bacteriolytic assays showed decreased activity of Peaks IB, IIB, and III (31.4%, 61.2%, and 86.5%, respectively) relative to native enzyme while the activity for Peaks IV and V was greater than that of native enzyme (215% and 308%, respectively). Crystals of Peaks IB, III, IV, and V were grown, but attempts to determine the crystal structure were unsuccessful.

Committee:

Michael Serra, PhD (Advisor); Nina Stourman, PhD (Committee Member); Gary Walker, PhD (Committee Member)

Subjects:

Biochemistry

Keywords:

Metal-catalyzed oxidation; lysozyme; site specific oxidation; HPLC; HEWL; tandem mass spectrometry

Yung, Matthew MauriceOxidation catalysis in environmental applications: nitric oxide and carbon monoxide oxidation for the reduction of combustion emissions and purification of hydrogen streams
Doctor of Philosophy, The Ohio State University, 2007, Chemical Engineering
The environmental applications of oxidation catalysis were examined as part of a two-stage strategy for the reduction of nitrogen oxides (NOx) and also for the removal of carbon monoxide from hydrogen streams. Cobalt-based catalysts were examined. Reduction of NOx, Co/TiO2 and Co/ZrO2 were studied for the oxidation of NO to NO2 in excess oxygen. NO oxidation was studied as the first step in a two-step catalytic scheme where NO is oxidized to NO2 and, in turn, NO2 is reduced with CH4 to N2 under lean conditions. Catalysts were prepared by sol-gel and incipient-wetness impregnation techniques. It was found that increasing the calcination temperature had an adverse effect on the activity of the IWI catalysts. Catalyst characterization showed higher activity for NO oxidation on Co/ZrO2 than on Co/TiO2 which was observed to correlate with the formation of the Co3O4 phase. For the preferential oxidation of CO, cobalt on several metal oxide supports were investigated and showed the highest activity on Co/ZrO2. A variety of reaction experiments were performed to examine the effects of reactant concentrations, residence time, and temperature on the CO conversion and O2 selectivity to CO2.

Committee:

Umit Ozkan (Advisor)

Subjects:

Engineering, Chemical

Keywords:

Catalyst; NO oxidation; CO oxidation; NOx reduction; Cobalt; Cobalt oxide; ZrO2; TiO2; PROX

Dickerson, Lyndel DwayneAutoxidation of lacunar iron(II) dioxygen carriers /
Doctor of Philosophy, The Ohio State University, 1985, Graduate School

Committee:

Not Provided (Other)

Subjects:

Chemistry

Keywords:

Oxidation;Oxidation;Oxygen;Iron

Ray, AnirbanIdentification, Enumeration and Diversity of Nitrifying Bacteria in the Laurentian Great Lakes
Master of Science (MS), Bowling Green State University, 2012, Biological Sciences

In the past 100 years the nitrate levels in Lake Superior have increased more than five times (Sterner et al. 2007). Based on stable isotope assays, previous research has shown that most of this nitrate is coming from in-lake nitrification process in the lake (Finlay et al. 2007), reflecting an imbalanced nitrogen cycle. By contrast, in Lake Erie the nitrate levels are declining. Lake Erie is the shallowest of the Great Lakes. The shallowness of the lake, the warmer temperature of the water, and nutrient inputs from urban and agricultural sources make it most biologically productive of the Great lakes.

Nitrification is a major process in the nitrogen cycle mainly carried out by the nitrifying microbial community (both Archaea and Bacteria), during which ammonia (NH3) is converted to Nitrite (NO2-) and then to nitrate (NO3-) by ammonia oxidizers (both Bacteria and Archaea) and Nitrite oxidizers (Bacteria only) respectively. Ammonia is oxidized by the enzyme ammonia monooxygenase, and hydroxylamine oxidoreductase (HAO). Nitrite (NO2-) converted to nitrate (NO3–) by Nitrite oxidizers (Bacteria) and enzyme nitrite oxidoreductase, carries this reaction.

In this thesis, I investigated the microbial nitrifier community structure by identifying and enumerating the ammonia-oxidizing bacteria (AOB) and nitrite oxidizing bacteria (NOB) present in these two lakes using the technique of fluorescence in-situ hybridization (FISH). This is the first study on Lake Superior and Lake Erie proving the overview of the abundance and diversity of these organisms. This study is focusing on understanding the nitrifying microbial community structure, contribution to other studies dealing with how these organisms function in the nitrogen cycling in these lakes. Therefore, the goal of this study is to provide measure of abundance of AOB and NOB in Lake Superior and Lake Erie as well as the diversity of AOB in these lakes.

Committee:

George Bullerjahn, PhD (Advisor); Robert McKay, PhD (Committee Member); Zhaohui Xu, PhD (Committee Member)

Subjects:

Biology; Ecology; Environmental Science; Limnology; Microbiology; Molecular Biology

Keywords:

nitrification; nitrate; ammonia oxidation; nitrite oxidation; Lake Superior; Lake Erie; ammonia monooxygenase; hydroxylamine oxidoreductase; FISH

Gutierrez Orozco, FabiolaInfluence of Tea Catechins on the Viability, IL-8 Synthesis and Secretion, and NF-κB Activation of Gastric Epithelial AGS Cancer Cells
Master of Science, The Ohio State University, 2009, OSU Nutrition
Chronic inflammation is involved in the development of gastric cancer, the second leading cause of cancer-related death worldwide. Epidemiological evidence suggests that increased consumption of catechin rich tea may be associated with reduced risk of gastrointestinal cancers. The goal of this study was to evaluate the effects of catechin-rich extracts of green (GT) and black tea (BT) and individual tea catechins (EGC, EGCG, EGC/EGCG) on cell viability, intracellular oxidation and inflammation in the AGS gastric cancer cell line. Cell viability was measured using the MTT assay. Intracellular oxidation was evaluated using the probe dichlorofluorescin. Inflammatory markers included measurement of intracellular and secreted Interleukin 8 (IL-8) protein and the activation of nuclear factor-kappa B (NF-kB). Treatment of AGS cells (48h) with EGC, EGC/EGCG and EGCG, reduced cell viability by 36%, 31% and 19%, respectively. Interestingly, a similar reduction in cell viability (27%) was observed upon treatment of cells with BT and GT extracts. Treatment of cells with GT (1.5 mg/ml), BT (1.5 mg/ml) and EGCG (1.5 mg/ml) also inhibited cytokine-induced IL-8 production and subsequent secretion. These anti-inflammatory effects are due, in part, to a reduced activation of NF-kB in the AGS cell line. This study demonstrates a potential mechanism by which tea catechins may reduce inflammation associated with gastric cancer.

Committee:

Joshua A. Bomser, PhD (Advisor); Mark L. Failla, PhD (Committee Member); Martha A. Belury, PhD (Committee Member)

Subjects:

Food Science; Health; Nutrition

Keywords:

tea catechins; cell viability; chronic inflammation; interleukin 8; NF-kB; intracellular oxidation

King, Robert EdwardThe inhibition of photosensitized oxidation and autooxidation in lard by tocopherol isomers
Doctor of Philosophy, The Ohio State University, 2007, Food Science and Nutrition

Lipid oxidation is a serious concern for the food industry, due to the production of off-flavors and odors, discoloration, and toxic compounds. Oxidation can also decrease the nutritional content in food products. There are two forms of oxygen which participant in lipid oxidation; singlet and triplet. Singlet oxygen (1O2) is a nonradical, high energy molecule that can react directly with fatty acids. Singlet oxygen can be formed during photosensitized oxidation, a process in which a photosensitizer, such as chlorophyll, absorbs light energy and becomes excited. Triplet oxygen (3O2)is the most stable and common form of oxygen. Autooxidation is triplet oxygen mediated lipid oxidation, and requires both the oxygen and the fatty acids to be in radical form.

The lipid oxidation process can be slowed or prevented by compounds known as antioxidants. Tocopherols (α, β, γ, and δ), which are commonly known as vitamin E, have been showed to have antioxidant activity. The present study examines the effect of tocopherol isomers on chlorophyll photosensitized oxidation and heat induced autooxidation of lard. The effects of tocopherol isomers on lard oxidation were measured by headspace oxygen and peroxide value analyses. α-, β-, γ-, and δ-Tocopherol were all found to prevent photosensitized oxidation of lard by quenching singlet oxygen. α-Tocopherol had the highest singlet oxygen quenching rate at 1.42 x 107M-1s-1 followed by β-tocopherol (1.11 x 107M-1s-1), γ-tocopherol (9.70 x 106M-1s-1), and δ-tocopherol (4.23 x 106M-1s-1). Lard thermal stability was increased, via autooxidation inhibition, by γ- and δ-tocopherol. The optimum concentrations were determined to be 250-1000ppm and 500ppm for the γ- and δ-isomer, respectively. α-Tocopherol did significantly increase lard stability, but it was found to have significant prooxidant activity (p<0.05) at concentrations greater than 250ppm.

Tocopherol isomers are able to inhibit both photooxidation and autooxidation in lard, however there is not one isomer that is superior than the others at preventing both types of oxidation.

Committee:

David Min (Advisor)

Subjects:

Chemistry, Analytical

Keywords:

tocopherols; photosensitized oxidation; autooxidation; chlorophyll

Miller, Duane D.In Situ Infrared Study of G-S/L-S Adsorption and Photocatalytic Processes
Doctor of Philosophy, University of Akron, 2009, Chemical Engineering

Coal fired power plants release large quantities of CO2 and trace amounts of SO2 into the atmosphere, affecting global warming and worldwide climate change. CO2 is a concern as a greenhouse gas in relation to global temperature raise. SO2 is a concern in environmental protection as a precursor for acid rain. The impact of CO2, SO2, and H2S on the environment demonstrate the removal process is a subject of study of great importance. Removal of these gases has been focused on the development of amine based sorbents for sequestration by the adsorption and desorption process. Fourier Transform Infrared spectroscopy (FTIR) is a powerful tool for investigating the adsorption/desorption process and structure of adsorbing molecules. The application of FTIR, coupled with ab initio quantum chemistry, can provide a direct means for understanding the interactions that occur during chemisorption.

The removal of CO2 and H2S by an amine based sorbent has been studied. The hypothesis for this study is to investigate the use of polyethylene glycol (PEG) to promote tetraethylenepentamine (TEPA) CO2 and H2S removal capacity. It is thought that the use of PEG may improve the catalytic adsorption capacity through hydrogen bonding. This study used in situ FTIR and ab initio quantum chemistry to investigate the adsorption and desorption processes during CO2 and H2S capture at the molecular level. The FTIR results determine that PEG interacts with the primary amine functional groups of TEPA dispersing the adsorption sites leading to improved adsorption capacity for CO2 and H2S. Ab initio quantum chemistry determined that PEG lowers the binding energy of CO2 and H2S leading to a lower desorption temperature.

Removal of the nauseous gas SO2 by an amine based sorbent is studied. The hypothesis investigated the use of 1,3-phenylenediamine low basic property for creating a reusable solid amine based sorbent for SO2 removal. It is thought that the low basic property of the aromatic amine will allow the effective SO2 adsorption and desorption at low temperature. This study used in situ FTIR spectroscopy to investigate the adsorption and desorption processes during SO2 capture. The result of this study determined that 1,3-phenylenediamine basic property allowed SO2 adsorption and desorption at 373 K, however, sorbent deactivation occurs. The in situ UV-Visible spectroscopic technique provided insight that deactivation is the result of agglomeration of 1,3-phenylenediamine. Addition of PEG prevented the agglomeration and improved the adsorption capacity of 1,3-phenylenediamine through hydrogen bonding with the primary amine functional group.

Amine based sorbents have been proven as an effective and economic process for the removal of CO2 and the hazardous gases H2S and SO2. Advancing knowledge in the area of amine based sorbents will improve our ability for hazardous waste management. Hazardous waste management may also be achieved by the oxidation and reduction (redox) of toxic materials. TiO2 based catalysts have the ability to oxidize a number of hazardous materials to nontoxic products where TiO2 has become the benchmark semiconductor in photo-detoxification of contaminated water. This work also investigates the photocatalytic dehydrogenation process over TiO2 based catalysts. The hypothesis investigated the relationship of the photogenerated electrons and adsorbed species during the photocatalytic dehydrogenation of 2-propanol. It is thought that the interaction of the photogenerated electrons and adsorb species may be elucidated from the reaction mechanism during the photocatalytic dehydrogenation of 2-propanol. 2-propanol is used as a model compound because it provides a simple and standard way to measure the photo-catalytic activity during the gas/liquid phase reactions. This study suggest that in the presence of adsorbed H2O, the dehydrogenation process proceeded by a hydroxyl radical species while in the absence of adsorbed H2O the active species is an adsorbed ion. Au/TiO2 unique ability to generate adsorbed oxygen ions resulted in higher catalytic activity in the absence of adsorbed H2O under UV-irradiation. The reaction pathway for the photocatalytic dehydrogenation of 2-propanol is strongly dependent on the coverage of surface H2O.

Committee:

Steven Chuang, PhD (Advisor)

Subjects:

Chemical Engineering

Keywords:

CO2; H2S; SO2; sequestration; NOx removal; Pohotcatalytic oxidation

Agarwal, UditFactors Affecting Ventricular Remodeling Post Myocardial Infarction
PHD, Kent State University, 2010, College of Arts and Sciences / School of Biomedical Sciences

The term ventricular remodeling refers to the series of events that lead to the orchestration of the biological processes that determine left ventricular size, shape, and function following acute myocardial infarction (AMI). The present study focuses on defining the mechanisms of two distinct phenomena that are known to regulate this process; namely, extracellular matrix (ECM) degradation via protease inactivation and cardiac myocyte death.

AMI is followed by degradation of ECM of the heart leading to thinning and rupture of the left ventricular wall. A critical regulator of ECM degradation is plasmin, a protease. The generation of plasmin in turn is regulated by the oxidation-sensitive enzyme, Plasminogen Activator Inhibitor -1 (PAI-1). PAI-1 is an inhibitor of urokinase-like plasminogen activator (uPA), which converts plasminogen into plasmin. PAI-1 deficient (Pai-1-/-) mice die of ventricular rupture within 7 days following infarction. It has been previously reported that the activity of PAI-1 is sensitive to oxidation and hence inhibited by leukocyte-derived oxidant-generating systems, such as Myeloperoxidase (MPO) and inducible nitric oxide synthase (iNOS). Furthermore, the expression of ceruloplasmin (CP), another oxidant- generating enzyme, is increased in the blood post-AMI. Reduced nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activity regulates the oxidant-generating capacity of MPO, iNOS, and CP. However, the relative contributions of each of these leukocyte-derived oxidant producing enzymes in PAI-1 oxidation is not known. We hypothesized that leukocyte-derived NADPH oxidase oxidizes PAI-1 and hence participates in ventricular rupture post-AMI. To address this issue, we transplanted Pai-1-/- mice with Pai-1-/-, wild type (WT), p47phox-/- (a subunit of NADPH oxidase complex, also known as neutrophil cytosolic factor-1), Mpo-/-, iNOS-/- and Cp-/- bone marrow, performed Left Anterior Descending (LAD) artery ligation in all the groups, and measured their survival for 21 days. Data demonstrate Pai-1-/- mice were dead by day 7 due to ventricular rupture and WT marrow partially rescued Pai-1-/- mice survival. Interestingly, p47phox-/--/- marrow-transplanted mice had a significantly better survival compared to WT marrow-transplanted Pai-1-/- mice suggesting that, NADPH oxidase is critical in inhibiting PAI-1-induced protease inactivation and ventricular rupture. PAI-1 activity was higher in p47phox-/- marrow-transplanted Pai-1-/- animals compared to WT marrow-transplanted Pai-1-/- animals, indicating that leukocyte-derived NADPH oxidase inhibit PAI-1 activity in this model of ventricular remodeling.

Another determinant of ventricular remodeling is cardiac myocyte death. Several studies have identified the stromal cell-derived factor-1 α (SDF-1α)/CXC chemokine receptor 4 (CXCR4) axis to be important for the homing and survival of stem cells at the site of injury post-AMI. It has also been reported that Sdf-1-/- and Cxcr4-/- mice exhibit defects in hematopoesis, neurogenesis, vacsulogenesis, and ventricular septum formation and die within a few days of birth. Multiple reports claim that overexpression of SDF-1 at the infarcted region improves ventricular function by preservation of cardiac myocytes and increased vasculogenesis. Since the role of cardiac myocyte-derived CXCR4 was not well-defined in this context, we hypothesized that normal cardiac development is dependent on cardiac myocyte-derived CXCR4 expression. In the adult heart, SDF-1α and its receptor, CXCR4 do not get expressed at the same time. Post-AMI, there is a short and immediate period of SDF-1α expression, which is followed by CXCR4 expression in cardiac myocytes. Therefore, we postulated that cardiac myocyte-derived CXCR4 expression is not critical in adulthood post-AMI. To address these issues, we developed congenital and conditional cardiac myocyte-specific Cxcr4-/- mouse models. Our results demonstrate that congenital deletion of CXCR4 has no effect on cardiac function and septal defect. Furthermore, the ventricular function of conditionally deleted cardiac myocyte-specific CXCR4 was not significantly different from their WT littermates.

Collectively, our observations suggest that leukocyte-generated NADPH oxidase-derived free radicals participate in ventricular rupture post-AMI by oxidizing PAI-1 and cardiac myocyte-derived CXCR4 has no major role in cardiogenesis during development and ventricular remodeling post-AMI due to mismatch in the timing of expression of SDF-1 and CXCR4 in the heart.

Committee:

Marc S. Penn, MD, PhD (Committee Chair); Suneel Apte, MD, PhD (Committee Member); Jennifer Marcinkiewicz, PhD (Committee Member); Mary Russell, PhD (Committee Member)

Subjects:

Biomedical Research; Cellular Biology

Keywords:

Plasminogen Activator Inhibitor-1 oxidation; Cardiac myocyte specific CXCR4; Post Myocardial Infarction; Ventricular remodeling

Cooper, MatthewElectrocatalysis of the Oxidation of Ammonia by Raney Nickel, Platinum and Rhodium
Master of Science (MS), Ohio University, 2005, Chemical Engineering (Engineering)

The optimization of a novel anode for the production of hydrogen via an ammonia alkaline electrolytic cell is presented. The novel anode is prepared by electrodeposition and contains Raney nickel, platinum and rhodium in its catalytic layer. Optimization of current density and charge density for deposition of the Raney nickel layer is performed via a factorial design experimental method to maximize the percentage of Raney nickel powder on a titanium grid. The platinum and rhodium layers are optimized by considering their influence on reaction kinetics. It is proven by electrochemical analysis that platinum and rhodium realize a synergistic catalytic effect on the oxidation of ammonia, showing higher activity than platinum-only electrodes with comparable catalyst loading. Hydrogen is successfully produced from a 1 M NH3 / 5 M KOH solution at 14.54 Wh/g H2 by an anode containing 1 mg/cm2 Rh and 10 mg/cm2 Pt at ambient temperature and pressure.

Committee:

Gerardine Botte (Advisor)

Subjects:

Engineering, Chemical

Keywords:

Electrodeposition; Hydrogen production; Bimetallic catalyst; Water reduction; Ammonia oxidation; Raney Nickel

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